THE BASIN PLAN
Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
NSW Department of Planning, Industry and Environment | dpie.nsw.gov.au
Published by NSW Department of Planning, Industry and Environment
dpie.nsw.gov.au
Title: Water quality technical report for the Murray Lower Darling surface water resource plan area (SW8)
First published: February 2020
Department reference number: INT18/36342
Acknowledgments
The soils maps in this report contain data sourced from the NSW Office of Environment and Heritage.
© State of New South Wales through Department of Planning, Industry and Environment [2020]. You may copy, distribute, display, download and otherwise freely
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Disclaimer: The information contained in this publication is based on knowledge and understanding at the time of writing (December 2018) and may not be accurate, current or complete. The State of New South Wales (including the NSW Department of Planning, Industry and Environment), the author and the publisher take no
responsibility, and will accept no liability, for the accuracy, currency, reliability or correctness of any information included in the document (including material provided by third parties). Readers should make their own inquiries and rely on their own advice when making decisions related to mate rial contained in this publication.
Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
Summary Good quality water protects public health, supports economic production and maintains a healthy river ecosystem. Water quality is mostly determined by land use, geology, climate, riparian vegetation and stream flow, and reflects the interactions of natural and man-made practices that occur in a drainage area and the riparian zone.
Degradation of water quality can put stress on a range of aquatic organisms, impinge on Aboriginal cultural and spiritual uses of water, increase the cost of drinking water treatment, contribute to public health risks and decreases the suitability of water for irrigation and agriculture.
Alteration of the Australian landscape since European settlement has resulted in marked changes in catchment conditions. Runoff from cropping areas, erosion of soil and nutrients from stream banks and discharge from saline areas have led to increased turbidity, salinity, sedimentation, nutrient loads and chemical residues. These in turn can degrade aquatic ecosystem health. The regulation of rivers through the construction of large storages and weirs lead to changes to flow regimes, thermal pollution, harmful algal blooms and disruption of longitudinal connectivity of river processes.
Water quality condition in the Murray Lower Darling water resource planning area (WRPA) varies from poor to excellent. Water quality issues occurring within the catchment are the result of a combination of factors. These include alteration to natural flow regimes, in particular disruption by Hume Dam, changes to catchment conditions and land use change. Table 1 summarises the major water quality issues in the Murray Lower Darling WRPA.
Table 1: Summary of major issues and causes of water quality degradation
Issue Location Potential causes
Harmful algal blooms
uplands, midlands, lowlands
Stratification and warm water temperatures in Hume Dam and Menindee Lakes. Seeding of Murray River by Hume Dam and Lake Mulwala. Low flows in Murray and Darling Rivers. Nutrient inputs.
Dissolved oxygen and pH outside of normal ranges
uplands, midlands, lowlands
Reduced flow and increased low flow and cease to flow periods disrupting dissolved oxygen dynamics and increased eutrophication.
Increased nutrients and turbidity
uplands, midlands, lowlands
Stream bank and riparian condition, grazing and cropping practices, carp and feral species. Increased sediment and nutrient input associated with erosion.
Hypoxic blackwater events
midlands, lowlands
Less frequent flooding allows increased organic material to accumulate on river banks and floodplains.
Poor water
quality events
following
releases
during cease
to flow periods
lowlands Poor water quality events in the Darling River (in terms of dissolved oxygen, salinity
and pH) following the commencement of water releases from Menindee Lakes during
cease to flow periods, flushing of poor quality water downstream from isolated
standing pools.
Thermal
pollution
uplands,
midlands
Cold water released from Khancoban and Hume Dams in summer. Warm water
releases in winter.
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Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
Disruption to organic carbon cycling
midlands, lowlands
Reduced freshes and high flows, disruption of longitudinal connectivity by Hume Dam.
Toxicants and pesticides
midlands, lowlands
Pesticide use in cropping areas.
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Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
Contents Summary ......................................................................................................................................................i
Contents ..................................................................................................................................................... iii
List of tables.................................................................................................................................................v
List of figures............................................................................................................................................... vi
1. Introduction ...........................................................................................................................................1
1.1. Purpose..........................................................................................................................................1
1.2. Context...........................................................................................................................................2
1.3. Catchment description ....................................................................................................................3
1.4. Water quality targets .......................................................................................................................4
1.4.1. Assessment using Basin Plan water quality targets ...................................................................5
1.4.2. Water quality targets for water-dependent ecosystems ..............................................................5
1.4.3. Water quality targets for raw water for treatment for human consumption ...................................6
1.4.4. Water quality targets for irrigation water ....................................................................................7
1.4.5. Water quality targets for recreational water ...............................................................................7
1.4.6. Salinity targets for managing water flows...................................................................................7
2. Water quality parameters .......................................................................................................................8
2.1. Turbidity and suspended sediment ..................................................................................................8
2.2. Nutrients.........................................................................................................................................9
2.3. Dissolved oxygen..........................................................................................................................10
2.4. pH................................................................................................................................................11
2.5. Water temperature and thermal pollution .......................................................................................11
2.6. Salinity .........................................................................................................................................12
2.7. Harmful algal blooms ....................................................................................................................13
2.8. Toxicants......................................................................................................................................14
2.9. Pathogens ....................................................................................................................................14
3. Water access rules and flow management in the Murray Lower Darling WRPA ......................................15
4. NSW Salt Interception Schemes...........................................................................................................17
4.1. Buronga SIS.................................................................................................................................18
4.2. Mallee Cliffs SIS ...........................................................................................................................18
5. Methods ..............................................................................................................................................18
5.1. Site selection and monitoring.........................................................................................................18
5.2. Water quality index (WaQI) ...........................................................................................................23
5.3. Catchment stressor identification ...................................................................................................23
5.3.1. Conceptual mapping ..............................................................................................................24
5.3.2. Literature review ....................................................................................................................24
5.3.3. Summary statistics.................................................................................................................24
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Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
5.3.4. Data analysis .........................................................................................................................24
5.3.5. Spatial and GIS......................................................................................................................24
5.3.6. Local and expert knowledge ...................................................................................................25
5.4. Murray Lower Darling WRPA Risk Assessment..............................................................................25
6. Results................................................................................................................................................26
6.1. Water quality index (WaQI) ...........................................................................................................26
6.1.1. Water-dependent ecosystems ................................................................................................26
6.1.2. Water temperature .................................................................................................................28
6.1.3. Dissolved oxygen ...................................................................................................................29
6.1.4. Irrigation ................................................................................................................................30
6.1.5. Recreation .............................................................................................................................33
6.2. Literature review ...........................................................................................................................35
6.3. Lower Darling flow release and water quality event ........................................................................36
6.4. Summary statistics........................................................................................................................40
6.4.1. Total annual flow....................................................................................................................43
6.5. Risk assessment...........................................................................................................................43
7. Discussion...........................................................................................................................................45
7.1. Elevated levels of salinity ..............................................................................................................45
7.2. Elevated levels of suspended matter..............................................................................................47
7.3. Elevated levels of nutrients............................................................................................................49
7.4. Elevated levels of cyanobacteria....................................................................................................51
7.5. Water temperature outside natural ranges .....................................................................................52
7.6. Dissolved oxygen outside natural ranges .......................................................................................52
7.7. Elevated levels of pesticides and other contaminants .....................................................................54
7.8. pH outside natural ranges .............................................................................................................54
7.9. Elevated pathogen counts .............................................................................................................55
7.10. Knowledge gaps........................................................................................................................55
8. Conclusion ..........................................................................................................................................56
References ................................................................................................................................................58
Appendix A. Water quality monitoring site locations .....................................................................................64
Appendix B. Water quality index (WaQI) method..........................................................................................66
Appendix C. Literature Review ....................................................................................................................68
Appendix D. Water quality summary statistics..............................................................................................71
Appendix E. Draftsman plots and Box plots by site ......................................................................................78
Murray River at Indi Bridge......................................................................................................................79
Tooma River at Warbrook .......................................................................................................................81
Murray River at Jingellic ..........................................................................................................................83
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Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
Murray River at Albury (Union Bridge)......................................................................................................85
Murray River downstream Yarrawonga Weir ............................................................................................87
Edward River at Deniliquin ......................................................................................................................89
Wakool River at Stoney Crossing.............................................................................................................91
Wakool River at Kyalite ...........................................................................................................................93
Murray River at Barham ..........................................................................................................................95
Murray River upstream Euston Weir ........................................................................................................97
Murray River at Merbein Pump Station.....................................................................................................99
Darling River at Weir 32 ........................................................................................................................101
Darling River at Burtundy ......................................................................................................................103
List of tables Table 1: Summary of major issues and causes of water quality degradation ....................................................i
Table 2: Water quality processes ..................................................................................................................3
Table 3: Water quality targets for water dependent ecosystems objective for all aquatic ecosystems ...............5
Table 4: Salinity targets for irrigation water ....................................................................................................7
Table 5: Blue-green algae targets for recreational water.................................................................................7
Table 6: Salinity targets for purposes of long term salinity planning in the Murray Lower Darling WRPA...........8
Table 7: List of routine water quality monitoring stations in the Murray Lower Darling WRPA .........................19
Table 8: List of Irrigation Infrastructure Operators and relevant continuous electrical conductivity monitoring
stations in the Murray Lower Darling WRPA ................................................................................................19
Table 9: List of selected blue-green algae monitoring stations in the Murray Lower Darling WRPA ................20
Table 10: List of continuous water temperature monitoring stations in the Upper Murray River WRPA ...........21
Table 11: List of continuous dissolved oxygen monitoring stations in the Murray Lower Darling River WRPA .22
Table 12: Water quality index scores for the Murray and Lower Darling WRPA 2010-2015 water quality data 26
Table 13: Water quality index scores for the Murray Lower Darling WRPA 2005-2015 continuous electrical
conductivity data ........................................................................................................................................31
Table 14: Electrical conductivity profiles upstream of Darling and Murray Rivers junction – 31 August ...........39
Table 15: Electrical conductivity profiles upstream of Darling and Murray Rivers junction – 7 September .......39
Table 16: Electrical conductivity profiles upstream of Darling and Murray Rivers junction – 12 September .....39
Table 17: Electrical conductivity profiles upstream of Darling and Murray Rivers junction – 19 September .....39
Table 18: Electrical conductivity profiles upstream of Darling and Murray Rivers junction – 26 September .....40
Table 19: Electrical conductivity profiles from Lock 10 and Darling River at Wentworth – 13 October .............40
Table 20: Sites with high and medium risk to the health of water dependent ecosystems from turbidity ..........44
Table 21: Sites with high and medium risk to the health of water dependent ecosystems from total phosphorus
..................................................................................................................................................................44
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Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
Table 22: Sites with high and medium risk to the health of water dependent ecosystems from total nitrogen ..44
: Sites with high and medium risk to the health of water dependent ecosystems from dissolved oxygen
: Water quality summary statistics for the Murray Lower Darling WRPA 2007-2015 water quality data
Table 23: Sites with high and medium risk to the health of water dependent ecosystems from pH .................44
Table 24
..................................................................................................................................................................44
Table 25: Location of water quality monitoring stations in the Murray Lower Darling WRPA ...........................64
Table 26: Review of published literature ......................................................................................................68
Table 27
..................................................................................................................................................................71
Table 28: Electrical conductivity in the Darling River at Burtundy and Murray River at Lock 6 for purposes of
long term salinity planning...........................................................................................................................76
Table 29: Electrical conductivity in Edward and Wakool Rivers for purposes of long term salinity planning .....76
Table 30: Electrical conductivity in the mid Murray River for purposes of long term salinity planning ..............77
List of figures Figure 1: Flow diagram illustrating the components of the Murray Lower Darling surface water resource plan ..2
Figure 2: Water quality zones and water quality monitoring sites for the Murray Lower Darling WRPA .............4
Figure 3: Continuous water temperature monitoring sites in the Upper Murray River .....................................21
Figure 4: Continuous dissolved oxygen monitoring sites in the Murray River catchment ................................22
Figure 5: Conceptual diagram of the CSI process ........................................................................................24
Figure 6: Murray Lower Darling WRPA water quality index scores ................................................................27
Figure 7: Water temperature downstream of Hume Dam compared to estimated 20th and 80th percentile of
natural temperature ....................................................................................................................................28
Figure 8: Minimum daily water temperature in the Murray River upstream and downstream of Hume Dam.....29
Figure 9: Dissolved oxygen in the Darling River at Burtundy from 2012 to 2017 ............................................30
Figure 10: Dissolved oxygen in the mid Murray River and Edward-Wakool system from 2012 to 2017 ...........30
Figure 11: Mean daily electrical conductivity (µS/cm) at selected sites in the Murray valley from 2005 to 2015
..................................................................................................................................................................31
Figure 12: Mean daily electrical conductivity (µS/cm) and mean daily flow (ML/day) in the Wakool River at
Stoney Crossing from 2007 to 2015 ............................................................................................................32
Figure 13: Mean daily electrical conductivity (µS/cm) and mean daily flow (ML/day) in the Darling River at
Burtundy from 2005 to 2017 (red line indicates 833 µS/cm irrigation salinity target) .......................................33
Figure 14: Mean daily electrical conductivity (µS/cm) and mean daily flow (ML/day) in the Murray River at Lock
6 from 2008 to 2017 (red line indicates 580 µS/cm flow target) .....................................................................33
Figure 15: Potentially toxic algal biovolume (mm3/L) at selected sites in the Murray River from January to July
2016 ..........................................................................................................................................................34
Figure 16: Harmful algal blooms at selected sites in the Edward Wakool River system from January to July
2016 ..........................................................................................................................................................35
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Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
Figure 17: Electrical conductivity (µS/cm) in Lake Wetherell compared to inflows from the Darling River at
Wilcannia gauging stations .........................................................................................................................38
Figure : Continuous electrical conductivity (µS/cm) at Darling River gauging stations ................................38
Figure : Water quality data for water quality parameters by site ................................................................42
Figure : Annual flow (ML/year) at selected gauging stations......................................................................43
Figure : River styles recovery potential in the Murray and Lower Darling Rivers catchment........................48
Figure : Soil total nitrogen for the Murray and Lower Darling Rivers catchment..........................................50
Figure : Soil total phosphorus for the Murray and Lower Darling Rivers catchment ....................................50
Figure : Soil pH for the Murray and Lower Darling Rivers catchment .........................................................55
Figure : Draftsman plots for Murray River at Indi Bridge............................................................................79
Figure : Water quality data for Murray River at Indi Bridge ........................................................................80
Figure : Draftsman plots for Tooma River at Warbrook .............................................................................81
Figure : Water quality data for Tooma River at Warbrook .........................................................................82
Figure : Draftsman plots for Murray River at Jingellic................................................................................83
Figure : Water quality data for Murray River at Jingellic ............................................................................84
Figure : Draftsman plots for Murray River at Albury ..................................................................................85
Figure : Water quality data for Murray River at Albury...............................................................................86
Figure : Draftsman plots for Murray River downstream Yarrawonga Weir..................................................87
Figure : Water quality data for Murray River downstream Yarrawonga Weir ..............................................88
Figure : Draftsman plots for Edward River at Deniliquin ............................................................................89
Figure : Water quality data for Edward River at Deniliquin ........................................................................90
Figure : Draftsman plots for Wakool River at Stoney Crossing ..................................................................91
Figure : Water quality data for Wakool River at Stoney Crossing...............................................................92
Figure : Draftsman plots for Wakool River at Kyalite.................................................................................93
Figure : Water quality data for Wakool River at Kyalite .............................................................................94
Figure : Draftsman plots for Murray River at Barham ................................................................................95
Figure : Water quality data for Murray River at Barham ............................................................................96
Figure : Draftsman plots for Murray River upstream Euston Weir ..............................................................97
Figure : Water quality data for Murray River upstream Euston Weir ..........................................................98
Figure : Draftsman plots for Murray River at Merbein Pump Station ..........................................................99
Figure : Water quality data for Murray River at Merbein Pump Station.....................................................100
Figure : Draftsman plots for Darling River at Weir 32..............................................................................101
Figure : Water quality data for Darling River at Weir 32 ..........................................................................102
Figure : Draftsman plots for Darling River at Burtundy ............................................................................103
Figure : Water quality data for Darling River at Burtundy ........................................................................104
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Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
1. Introduction
1.1. Purpose The Murray Darling Basin Plan (2012) is an instrument of the Commonwealth Water Act (2007). It provides the framework for long term integrated management of water resources of the Murray Darling Basin. The Basin Plan requires that water quality management plans (WQMP) are developed for all water resource areas in the Basin. Each WQMP will:
Establish water quality objectives and targets for freshwater dependent ecosystems, irrigation water and recreational purposes;
Identify key causes of water quality degradation;
Assess risks arising from water quality degradation, and
Identify measures that contribute to achieving water quality objectives.
This report provides an overview of the water quality condition of the Murray Lower Darling water resource plan area (WRPA) by comparing data to the Basin Plan water quality targets (Basin Plan 2012, Schedule 11). The Basin Plan water quality targets set out the appropriate water quality required for environmental, social, cultural and economic benefits in the Murray Darling Basin. Monitoring progress towards achieving the targets will identify trends and inform actions that address the causes of water quality decline. These targets have been used to assess existing water quality data, and to identify areas of risk to aquatic ecosystems, and recreational and irrigation use.
The report also outlines the factors influencing water quality in the region, specifically the likely causes of water quality degradation issues, as required by Chapter 10, Section 10.30 of the Basin Plan.
BASIN PLAN 10.30 Water quality management plan to identify key causes of water quality degradation. The water quality management plan must identify the causes or likely causes, of water quality degradation in the water resource plan area having regard to the key causes of water quality degradation identified in Part 2 of Chapter 9 and set out in Schedule 10.
The information in this report supports the development of the Murray Lower Darling WQMP. It provides the background and technical information to develop water, land and vegetation management measures to maintain or improve water quality in the Murray Lower Darling WRPA. Figure 1 is a flow diagram illustrating how this report supports other components of the surface water resource planning process.
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Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
Water Resource Plan
Land and
Vegetation
Management
Develop,
implement and
evaluate best
practice land
and vegetation
management
practices to
increase
productivity
and
sustainability
of riverine
landscapes
Long Term
Watering Plan
Primary
mechanism
outlining
watering
requirements
for key
environmental
assets.
Guides the
use of
environmental
water over a
20 year period
Resource DescriptionDescription of water resource plan area to provide an understanding of the region and its resources
Risk assessmentIdentifies risks of not achieving Basin Plan
environmental, social and economic outcomes
and proposes strategies for mitigation
Status and issues paperSummarises the current condition of water
resources and issues to consider when
developing the Water Resource Plan
Salinity Technical
ReportTechnical information and analysis
to develop water and land
management measures that
protect or improve salinity.
Water Quality Technical
ReportTechnical information and analysis
to develop water and land
management measures that
protect or improve water quality
Water Quality Management PlanProvides a framework to protect, improve and
restore water quality and salinity that is fit for
purpose
Water Sharing PlanDescribes water rights, compliance with
sustainable diversion limits, water quality
management, environmental watering, and
risks to water resources meeting critical human
needs
Incident Response GuideDescribes how water resources will be managed
during an extreme event
Monitoring Evaluation and Reporting PlanMonitoring the effectiveness of measures for the purpose of adaptive management and reports progress
against requirements of Schedule 12 of the Basin Plan
Issues
Assessment
Report
Figure 1: Flow diagram illustrating the components of the Murray Lower Darling surface water resource plan
1.2. Context Water quality can be defined in terms of the physical, chemical and biological content of water and in terms of purpose and use. Water quality may be fit for one purpose, but not another. For example, water may be of good quality to irrigate crops, but may not support a healthy population of fish.
This report refers to water quality degradation, or poor water quality, as:
Elevated levels of nutrients, turbidity, blue-green algae, salinity, toxicants or pathogens, and
Water temperature, pH and dissolved oxygen outside of certain ranges.
Water quality is dynamic. The physical, chemical and biological content of water varies with time and location. Table 2 shows how water quality can be defined in three related, but slightly different ways.
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Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
Table 2: Water quality processes
Long term water quality Poor water quality event Ecosystem processes
This describes long-term average
trends over a period of months to
years. In this report, the water
quality parameters used are from
monthly measurements at a
selection of locations.
Major trends are reported in five
year periods. Indicator targets are
listed in Tables 3 to 6.
These refer to occurrences of
water quality issues for set
periods of time that are generally
not ongoing.
Examples may include a
potentially toxic algal bloom or
anoxic blackwater (low-oxygen)
event. While the occurrence of
these events may be short lived,
their effects can be long-term.
Water quality parameters are bound
up in fundamental ecological
functions of rivers and catchments.
These are less easy to define as
‘good’ or ‘bad’, and often involve complex interrelationships.
Examples may include the movement
of organic carbon from floodplains to
rivers to support productivity, or the
delivery of sediment from upstream
to downstream.
1.3. Catchment description The New South Wales Murray WRPA is bounded by the Murray River to the south, the Billabong Creek catchment (Murrumbidgee River WRPA) to the north and the Australian Alps to the east. The Murray River rises in the Australian Alps at 1 430 m above sea level. The catchment above Hume Dam is the major source of water for the Murray River. The total length of the Murray River is 2 530 km, of which 1 880 km of its length creates the border between NSW and Victoria, before flowing to the river mouth in South Australia. The natural flow regime is characterised by high winter/spring flows and low summer/autumn flows resulting from run-off derived from its alpine headwaters and associated tributaries. The five longest tributaries are the Mitta Mitta River, Kiewa River, Tooma River, Black Dog Creek and Swampy Plain River. The significant inter-valley diversions of both the Snowy-Tumut and Snowy-Murray Developments of the Snowy Mountains Hydroelectric Scheme impact on the Upper Murray River Water Source. This is a direct result of the operation of Murray 1 and Murray 2 Power Stations and their final storage dam, Khancoban Pondage.
Flows in the Murray River system are modified by a highly regulated weir system, water extraction and structures. Yarrawonga Weir is the point of the greatest diversion of water from the Murray River. The two main irrigation channels from Lake Mulwala are the Mulwala Canal, on the New South Wales side, and the Yarrawonga Main Channel, on the Victorian side. The Mulwala Canal has a discharge capacity of about 10 000 ML/day, and provides flows to the Edward and Wakool Rivers and numerous distributary streams and canals. Torrumbarry Weir diverts flows into Deniboota Canal in NSW and National Channel in Victoria, and Euston Weir regulates water for the Robinvale Irrigation District. The Murrumbidgee River flows into the Murray River upstream of Euston Weir.
Flows in the Lower Darling are regulated by releases from Menindee Lakes. There are two major river systems in the Lower Darling, the Darling River and the Great Darling Anabranch. The Darling River flows into Lock 10 on the Murray River at Wentworth.
There are two sites in the Murray Lower Darling WRPA listed as wetlands of international importance under the Ramsar Convention. The NSW Central Murray State Forests consist of three discrete but interrelated forest areas; the Millewa, Koondrook-Perricoota and Werai forests. Blue Lake in Kosciuszko National Park was listed under the Ramsar Convention in 1996. The Darling Anabranch Lakes are listed in the Directory of Important wetlands. The Living Murray icon sites within NSW include the Millewa Forest, Koondrook-Perricoota Forest, the eastern section of Chowilla floodplain and the River Murray Channel.
Land use in the Murray and Lower Darling catchment is largely grazing in the upper catchment with increased cultivation and irrigation with distance down the catchment. A detailed description of climate, land and water usage and water regulation infrastructures can be found in the Murray Lower Darling resource description report (DoIW 2018a).
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Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
1.4. Water quality targets The Basin Plan water quality targets set out the appropriate water quality required for environmental, social, cultural and economic benefits in the Murray Darling Basin. Monitoring progress towards achieving the targets will identify trends and inform actions that address the causes of water quality decline. The Basin Plan identifies water quality “target application zones” approximating lowland, upland and montane areas of the major river valleys. Lowland areas have an altitude of less than 200 m, upland areas fall between 200 and 700 m and montane areas have an altitude greater than 700 m. The boundaries of these zones are shown in Figure 2.
Two water-dependent ecosystems are described in the Basin Plan; Declared Ramsar wetlands (streams and rivers; lakes and wetlands) and Other water-dependent ecosystems (streams, rivers, lakes and wetlands). The assessment of water quality targets in this report is focused on Other water-dependent ecosystems, as there are currently no routine water quality monitoring programs undertaken in the Ramsar listed wetlands in the Murray Lower Darling WRPA. A revision of the current water quality monitoring program is to be undertaken to fill identified information gaps.
The Basin Plan water-dependent ecosystem targets for turbidity, total phosphorus, total nitrogen, dissolved oxygen and pH were developed following the methods outlined in the ANZECC Guidelines (2000). Water quality data for rivers and streams in ‘reference’ condition from each of the water quality zones were used to develop the target values for each zone (Tiller and Newall 2010). In zones where there were no reference sites, the appropriate default trigger value from the ANZECC Guidelines (2000) for slightly to moderately disturbed systems was used as the Basin Plan water quality target (Tiller and Newall 2010).
Figure 2: Water quality zones and water quality monitoring sites for the Murray Lower Darling WRPA
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Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
1.4.1.Assessment using Basin Plan water quality targets
The ANZECC Guidelines (2000) are currently under revision (Guideline Document 4: Australian and New Zealand Guidelines for Fresh and Marine Water Quality 2000) as part of the broader revision of the National Water Quality Management Strategy. It is anticipated that there will be no default trigger values in the revised guidelines for Basin States as it is expected that these states have developed regional water quality targets as part of other water planning processes. Basin States may choose to use the water quality targets of the Basin Plan in lieu of the default trigger values of the ANZECC Guidelines (2000) if local water quality guidelines are not available. Trigger values and management targets are conceptually different. A trigger value is a concentration below which there is a low risk of adverse effects and if exceeded indicates that some form of action should commence. Management targets are long term objectives used to assess whether an environmental value is being achieved or maintained.
An assessment of Basin Plan water quality targets in NSW (Mawhinney and Muschal 2015) identified targets in some zones and zone boundaries as being inappropriate. Perceived poor water quality at a monitoring site may be due to an inappropriate target, rather than excessive pollutants. In these cases, the Basin Plan targets should be revised in preference for location specific targets which consider local catchment conditions.
It is anticipated the revision of the National Water Quality Management Strategy will improve the advice about comparing results from individual monitoring sites against water quality targets, with more emphasis on catchment assessments and flow-dependant trigger values. The Basin Plan allows an alternate target to be specified in the WQMP under certain conditions. It is expected that the recommendation to develop specific targets will also be retained in the revised National Water Quality Management Strategy. There will be further discussion of water quality targets in the Murray Lower Darling WQMP.
1.4.2.Water quality targets for water-dependent ecosystems
The targets for water dependent ecosystems are to ensure water quality is sufficient to:
Protect and restore ecosystems;
To protect and restore ecosystem functions;
Ensure ecosystems are resilient to climate change, and
Maintain the ecological character of wetlands.
Turbidity, total phosphorus and total nitrogen annual medians in the Murray Lower Darling WRPA should be below the target values listed in Table 3. For dissolved oxygen and pH, the annual median should fall within the stated range. The toxicants targets are taken from the ANZECC water quality guidelines (2000) using the values for the protection of 95% of species. The 95% protection of species trigger values applies to typical, slightly to moderately disturbed systems.
Table 3: Water quality targets for water dependent ecosystems objective for all aquatic ecosystems
Water Quality
Zone
Ecosystem
Type
Turbidity
(NTU)
Total
Phosphorus
(µg/L)
Total
Nitrogen
(µg/L)
Dissolved
oxygen
(mg/L; or
% saturation)
pH Salinity Temperature
Toxicants
(must not
exceed
values in
3.4.1 of the
ANZECC
guidelines)
Water dependent ecosystems (not including Ramsar sites)
C6 (Mitta Mitta,
Upper Murray
Montane zone)
Streams, rivers,
lakes and
wetlands
5 25 150 >9 mg/L or
95-110% 6.4-7.7
End of valley
targets for
salinity in
Appendix 1 of
Schedule B to
the agreement
Between the
20th and 80th
percentile of
natural monthly
water
temperature
The
protection of
95% of
species
B6 (Kiewa,
Mitta Mitta,
Upper Murray,
Upland zone)
Streams, rivers,
lakes and
wetlands
5 30 350 >8.5 mg/L or
85-110% 6.4–7.7
cMum (Murray
Valley Central,
Streams, rivers,
lakes and
wetlands
15 40 500 >7.7 mg/L; or
90-110% 6.5–7.5
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Upper Middle
zone)
cMI (Central
Murray Lower
zone)
Streams, rivers,
lakes and
wetlands
35 80 700 >8.0 mg/L or
90-110% 6.8-8.0
Dml (Darling
valley, Middle
Lower zone)
Streams, rivers,
lakes and
wetlands
50 50 500 85-110% 6.5-8.0
IM (Lower
Murray zone)
Streams, rivers,
lakes and
wetlands
50 100 1000 85-110% 6.5-9.0
Ramsar listed water dependent ecosystems
C6 (Mitta Mitta
Upper Murray
Montane zone)
Streams and
rivers 5 25 150
>9mg/L or 95-
110% 6.4-7.7
End of valley
targets for
salinity in
Appendix 1 of
Schedule B to
the agreement
Between the
20th and 80th
percentile of
natural monthly
water
temperature
The
protection of
99% of
species
Lakes and
wetlands 20 10 350 90–110% 6.5–8.0
B6 (Kiewa,
Mitta Mitta,
Upper Murray,
Upland zone)
Streams and
rivers 5 20 230
>8.5 mg/L or
85-110% 6.4–7.7
Lakes and
wetlands 20 10 350 90–110% 6.5–8.0
cMum (Murray
Valley Central,
Upper Middle
zone)
Streams and
rivers 15 40 500
>7.7 mg/L; or
90-110% 6.5–7.5
Lakes and
wetlands 20 10 350 90-110% 6.5-8.0
cMI (Central
Murray Lower
zone)
Streams and
rivers 35 80 700
>8.0 mg/L or
90-110% 6.8-8.0
Lakes and
wetlands 20 10 350 90-110% 6.5-8.0
Dml (Darling
valley, Middle
Lower zone)
Streams and
rivers 50 50 500 85-110% 6.5-8.0
Lakes and
wetlands 20 10 350 90-110% 6.5-8.0
IM (Lower
Murray zone)
Streams and
rivers 50 100 1000 85-110% 6.5-9.0
Lakes and
wetlands 20 10 350 90-110% 6.5-8.0
1.4.3.Water quality targets for raw water for treatment for human consumption
The target is to minimise the risk that raw water taken to be treated for human consumption results in adverse human health effects. The quality of raw water for treatment should also maintain palatability and odour ratings. The Public Health Act 2010 and the Public Health Regulation (2012) require drinking water suppliers to develop and adhere to a Drinking Water Management System (DWMS). The DWMS addresses the elements of the Framework for Management of Drinking Water Quality (Australian Drinking Water Guidelines (NHMRC and NRMMC, 2011)) and is a requirement of water suppliers operating licence (NSW Ministry of Health 2013). Water providers in the Murray Lower Darling WRPA include: Albury City Council, Balranald Shire Council, Berrigan Shire Council, Broken Hill City Council, Central Darling Shire Council, Federation Council, Greater Hume Shire Council, Murray River Council, Snowy Valleys Council and Wentworth Shire Council.
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1.4.4.Water quality targets for irrigation water
The aim of the agriculture and irrigation target is that the quality of surface water, when used in accordance with the best irrigation and crop management practices and principles of ecologically sustainable development, does not result in crop yield loss or soil degradation. The target is for the electrical conductivity 95th percentile of each 10 year period that ends at the end of the water accounting period, not exceed 833 µS/cm. The target in Table 4 applies at sites where water is extracted by an irrigation infrastructure operator for the purpose of irrigation. In NSW, irrigation infrastructure operators are defined as a separate third party that holds a water access entitlement and delivers water to shareholders. These include NSW Irrigation Corporations, Private Irrigation Districts and Private Water Trusts. The development of a Sodium Adsorption Ratio (SAR) target is outside the scope of this document and will be determined in future reporting when data is available. The time series electrical conductivity data collected by the gauging station network was used to assess this target rather than monthly manual grab samples.
Table 4: Salinity targets for irrigation water
Water Quality Zones Ecosystem Type
Electrical
conductivity
(µS/cm)
Sodium adsorption
ratio
All Streams, rivers, lakes
and wetlands 833 undetermined
1.4.5.Water quality targets for recreational water
The primary aim of these targets is to protect the health of humans from threats posed by the recreational use of water. This includes a low level of risk to human health from water quality threats posed by exposure to blue-green algae (cyanobacteria) through ingestion, inhalation or contact during recreational use of water resources. The targets are based on Chapter 6 of the National Health and Medical Research Council Guidelines for Managing Risk in Recreational Water (NHMRC 2008). In addition, it is also a general target that cyanobacterial scums should not be consistently present. The recreational water targets are listed in Table 5.
Table 5: Blue-green algae targets for recreational water
Water Quality
Zone
Ecosystem
Type Guidelines
All Recreational
water bodies
10 µg/L total microcystins; or 50 000 cells/mL toxic Microcystis aeruginosa; or
biovolume equivalent of 4 mm3/L for the combined total of all cyanobacteria where
suitable for a known toxin producer is dominant in the total biovolume; or
primary contact. 10 mm3/L for total biovolume of all cyanobacterial material where known toxins are
not present; or
Cyanobacterial scums consistently present
1.4.6.Salinity targets for managing water flows
Electrical conductivity targets have not been described for each water quality zone of the Murray Darling Basin. Instead, the Murray Darling Basin End-of-Valley salinity targets, as described in Schedule B, Appendix 1 of the Commonwealth Water Act (2007), have been incorporated into the water quality targets. There are no End-of-Valley targets for the Murray Lower Darling WRPA. Section 9.14 (5)(c) of the Basin Plan lists salinity targets for managing water flows. The levels of salinity at the reporting sites set out in Table 6
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should not be exceeded 95% of the time. The time series electrical conductivity data has been assessed against the targets in Table 6.
Table 6: Salinity targets for purposes of long term salinity planning in the Murray Lower Darling WRPA
Reporting site Target value (µS/cm)
Darling River downstream of Menindee Lakes at Burtundy 830
River Murray at Lock 6 (downstream of the NSW/South
Australian border)
580
2. Water quality parameters This report focuses on assessment of water quality parameters listed in the Basin Plan. These parameters represent general water quality condition and are most likely to demonstrate change over time from broad scale implementation of natural resource management.
2.1. Turbidity and suspended sediment Turbidity is a measure of water clarity. As light passes through water it is scattered by suspended material; the higher the scattering of light, the higher the turbidity. For example, after rain, water in rivers may appear brown due to scattering of light from high levels of suspended soils. Turbidity and the amount of total suspended solids are closely related in the Murray and Lower Darling catchments.
The amount of suspended sediment in water is generally related to the intensity of human activity in the catchment, such as land clearing, accelerated erosion from agricultural land, stream banks or channels and localised issues such as the dispersive nature of the soil and stock access. High turbidity is often associated with increased flow following storm events.
Increased turbidity can lead to reduction in light penetration and primary production. It can also lead to blooms of some harmful blue-green algae species as they are able to out compete other algal species for light in highly turbid conditions (Oliver et al. 2010). Increased suspended sediments can also have negative impacts on plants through smothering (Brookes 1986) and on fish, for example, by clogging gills (Bruton 1985). Suspended matter can also provide a mode of transport for pollutants, such as heavy metals, (Chapman et al. 1998), nutrients and pesticides (Mawhinney 1998) and bacteria (Wilkinson et al. 1995).
Turbidity should be measured immediately without altering the original sample conditions such as temperature and pH (APHA 1995). Field turbidity is more representative of instream conditions and should be used in preference to laboratory measurement (Buckland et al. 2008).
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Declining stream morphology, gully
erosion, side wall cut and head migration
Elevated levels of
suspended matter
Poor soil conservation
practices
Volume and manner of water
release for storages
Wave wash from
boats
Inappropriate frequency timing and
location of cultivation
Overgrazing of catchments, grazing of
riverbank and floodplains
Carp
Rapid drawdown of
water
2.2. Nutrients Nutrients such as nitrogen and phosphorus are important for sustaining growth and productivity within rivers but at high concentrations can become an issue in freshwater ecosystems. In many circumstances the inputs of nutrients to rivers has increased due to human activities. This process is known as eutrophication (meaning well-nourished) (Smith et al. 1999).
Sources of nutrient contamination include discharge from sewage treatment works, farms and industry, and runoff from agricultural land and urban storm water (Smith et al. 2006). Nutrients can be dissolved, bound within sediments, or adsorbed onto suspended material (i.e. soil or organic matter). Increased nutrient concentration can cause issues including nuisance algal blooms (Anderson et al. 2002), dissolved oxygen depletion (Dodds 2006) or inversely supersaturated and toxic effects to aquatic organisms (e.g. ammonia) (Davis and Koop 2006). This document generally refers to total nitrogen or total phosphorus as a basic measure of all forms of these two elements.
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Elevated levels of
nutrients
Fertilisers
Nutrients from water storages
Animal waste
Sewage and industrial discharge
Soil and organic matter
Atmospheric
deposition
2.3. Dissolved oxygen Dissolved oxygen in water is essential for supporting fish and aquatic animals. If oxygen levels rise too high or drop too low it places stress on animals and can be fatal (Boulton et al. 2014). Dissolved oxygen may be measured as either the concentration of oxygen in water (mg/L), or as a percentage of the maximum amount of oxygen that may dissolve in water (% saturation). Dissolved oxygen concentrations vary throughout the day and are generally lowest at night when plants and algae are not producing oxygen.
Dissolved oxygen levels drop when respiration (microbes and animals breathing oxygen) out paces oxygen replenishment by primary production (photosynthesis from aquatic plants and algae, and atmospheric adsorption). This process is called ecosystem metabolism. Factors that influence metabolism include the concentration of organic carbon and nutrient bioavailability, temperature, light penetration, turbidity and hydrology (Caffrey 2004; Young et al. 2008). The Basin Plan targets for dissolved oxygen include a lower and upper range. Maintaining dissolved oxygen levels within this range indicates that ecosystem metabolism is largely in equilibrium.
When there is a sudden input of bioavailable organic carbon and nutrients, for example when flood waters inundate an area with high levels of fresh leaf litter and flush this material back into the river, microbial respiration can increase rapidly causing oxygen levels to drop to very low concentrations. These are known as anoxic blackwater events (Whitworth et al. 2012). Alternatively, high nutrient inputs can lead to excessive aquatic plant growth resulting in very high oxygen levels or supersaturation.
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High microbial respiration as a result of
organic matter loading
Dissolved oxygen
outside natural
ranges
Eutrophication and excessive
plant and algal growth
Oxygen depletion in standing pools
Release of low oxygen bottom waters
from dams and weirs
2.4. pH The pH is a measure of how acidic or basic water is. The pH ranges between 0 (very acidic) to 14 (very basic) with 7 being neutral. A pH outside of natural ranges can be harmful to plants and animals (Boulton et al. 2014). It influences the solubility and bioavailability of nutrients and carbon and the toxicity of pollutants (Closs et al. 2009). Very high or low pH can affect the taste of water, increase corrosion in pipes and pumps and reduce the effectiveness of drinking water treatment (WHO 2004).
The pH in water varies with soil type, geology and surface water and groundwater interactions. Human activities such as agricultural practices that expose acid sulphate soils and increase erosion may lead to decreased pH (Dent and Pons 1995). Eutrophication and excessive algal growth can lead to increases in pH (Boulton et al. 2014). Detrimental effects from pH on aquatic ecosystems are unlikely at the levels found across much of the Murray Darling Basin (Watson et al. 2009).
Eutrophication and excess plant
and algal growth
pH outside of
natural ranges
Agricultural practices that lead to
soil acidification
Urban runoff
Exposure to the air of soils containing
iron sulfide material
2.5. Water temperature and thermal pollution Water temperature influences many biological and ecosystem processes. Warmer temperatures can increase growth rates and metabolism of microbes, animals, plants and algae (Boulton et al. 2014; Kaushal et al. 2010). Temperature is also linked to spawning, breeding and migration patterns of many aquatic animals (Astles et al.
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2003; Lessard and Hayes 2003). Higher temperatures can result in increased solubility of salts and decreased solubility of oxygen (Boulton et al. 2014).
Temperature is highly dynamic and varies at different time scales (e.g. seasonally and day/night). Human activities can have large impacts on temperature. Thermal water pollution can occur when dams stratify creating a cold bottom layer. If water is released from this bottom layer, it can lead to considerably colder water temperature than normal (Preece 2004). Thermal water pollution has had significant negative impacts on fish recruitment and can potentially influence ecosystem productivity and carbon cycling downstream of dams (Lugg and Copeland 2014; Webb et al. 2008).
The removal of riparian vegetation reduces shading, leading to increased water temperatures (Marsh et al. 2005; Rutherford et al. 2004). Other human activities such as discharge from power plants or warmer groundwater can also lead to increased river temperature (Lardicci et al. 1999). Climate change is also affecting river temperatures in the Murray Darling Basin (Pittock and Finlayson 2011).
Reduced flow
Thermal pollution
Water released from below
thermocline of large storages
Removal of shading riparian
vegetation
Climate change
2.6. Salinity Salinity is the presence of soluble salts in water. It is generally measured as electrical conductivity (the ability of dissolved salts to transmit an electric current). Increased salinity can have harmful effects on many plants and animals (James et al. 2003), effect drinking water supplies (WHO 2004) and cause damage and loss to cropping and horticulture sectors (Hillel 2000). The suitability of water for irrigation is often measured as a sodium adsorption ratio (SAR), which is a measure of the relative concentration of sodium, calcium and magnesium (Sposito and Mattigod 1977).
Increased electrical conductivity in rivers may be caused by the presence of salt in underlying soil, or bedrock released by weathering, salt deposited during past marine inundation of an area, or salt particles being carried over the land surface from the ocean. Australia’s arid climate provides insufficient rainfall to dilute the high levels of salt in the landscape. This has been further exacerbated by the increased mobilisation of salts by the use or discharge of saline groundwater to surface water, removal of deep-rooted native vegetation to be replaced with shallow-rooted crops or pastures and discharge of saline water from mining or industrial processes.
The initial stage of a flood is characterised by high electrical conductivity, often called a ‘first flush’. These appear as sharp spikes in the data followed by a rapid decline. As rainfall first starts to run off the landscape, it mobilises salts concentrated on the soil surface and washes them into the waterways. As flow increases, salts concentrated in the bottom of pools are also flushed out. Following this peak, electrical conductivity drops rapidly due to the dilution of salts by rainwater. The irrigation industry is more likely to experience difficulties with these high salinity spikes before impacts of any long term accumulation are realised. It is advisable for irrigators to let this first flush pass downstream before commencing to pump.
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Saline surface and shallow groundwater
drainage from irrigated landElevated levels of
salinity
Irrigation with groundwater at locations
where highly saline upper aquifer water
drains to lower aquifer
Replacement of deep-rooted
vegetation with shallow-rooted
vegetation
De-watering of
saline groundwater
Reduction of in-stream flows
limiting dilution
Use of water with a high ratio of sodium
to calcium and magnesium for irrigation
Increased deep drainage below
irrigated agricultural land displacing
saline groundwater to surface water
Irrigation at high
salinity risk locations
Saline water discharges
2.7. Harmful algal blooms Most algae are safe and are a natural part of aquatic ecosystems. However, some types of blue-green algae (cyanobacteria) can produce hepatotoxins, neurotoxins and contact irritants. When these species occur in bloom proportions (harmful algal blooms) they pose a serious risk to human, animal and ecosystem health (Chorus and Bartram 1999). In addition to toxin production, algal blooms can produce taste and odour problems in water supplies and blockages in irrigation systems. Harmful algal blooms can occur when there are suitable conditions including high levels of nitrogen and phosphorus, warm water temperatures and sunny days, low turbidity and calm water conditions where water may stratify (Anderson et al. 2002; Hudnell 2008). Blue-green algal blooms are normally associated with lakes and reservoirs, but do occur in rivers when conditions are favourable.
Harmful algal
blooms
Stratification
Water with little or no flow
Nutrients
Seeding from upstream
High temperatures
Sunlight
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2.8. Toxicants Toxicants refer to chemical contaminants that have the potential to be toxic at certain concentrations. These include metals, inorganic and organic toxicants (Warne 2002; Warne et al. 2014). Toxicants can have public health impacts and induce stress and fatalities in plants and animals (Heugens et al. 2001; Newman 2009). Toxicants enter water from a range of human activities including agriculture, industry and mining, and can also enter surface waters naturally through groundwater connectivity.
Spray drift, vapour transport and runoff are the main pathways for pesticide transport into river systems (Mawhinney 1998, Raupach et al. 2001). Spray drift and vapour can both contribute low level but almost continuous inputs to the riverine ecosystem during the peak spraying season. The likelihood of pesticide drift is influenced by weather conditions, the method of application, equipment used and crop structure. Runoff tends to provide occasional high concentrations of pesticide contamination. Pesticides in runoff can be dissolved in the water, bound within sediments or adsorbed on to suspended particles.
Inappropriate disposal of pesticides
and toxicants
Elevated levels of
toxicants
Erosion of contaminated land
Carp
Leaching of toxicants
into groundwater
Increased deep drainage below
irrigated agricultural land displacing
saline groundwater to surface water
Toxicants in sewage
Runoff of pesticides and
other toxicants
2.9. Pathogens Bacteria and microorganisms occur naturally in rivers. Certain species that have the potential to elicit disease symptoms are referred to as pathogens. In certain concentrations, pathogens can have negative impacts on public health (Prüss 1998; WHO 2004), aquatic animals (Gozlan et al. 2006), stock watering (LeJeune et al. 2001) and inhibit the use of water for irrigation (Steele and Odumeru 2004).
Human activities can increase the potential risk from pathogens, including discharge of human and animal waste and sewage, and access of stock and animals to rivers and water supplies (Ferguson et al. 1996; Fong and Lipp 2005; Hubbard et al. 2004). Deal and Wood (1998) reported high levels of faecal coliforms were generally reported in spring and summer whilst autumn and winter had lower levels. The sources of the Escherichia coli in river samples were identified as both animal and human in origin. Current monitoring and knowledge of the presence of pathogen issues in the Murray and Lower Darling catchments is limited.
It is expected that increased runoff will result in increased faecal coliforms, as material such as soil and faecal matter is washed into waterways. Additionally, periods of low rainfall, low flow, and warm water temperatures provide appropriate conditions for faecal coliforms to multiply (Deal 1997).
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Elevated levels of
pathogens
Major waterbird breeding events
Human and animal
waste
Sewage and
wastewater discharges
3. Water access rules and flow management in the Murray Lower Darling WRPA
In parts of the catchment where flows are unregulated, there are very limited opportunities to manage water quality through flow management. Under the water sharing plan for the New South Wales Murray unregulated and alluvial water sources (2011), pumping is not permitted from natural pools when the water level in the pool is lower than its ‘full capacity’. Full capacity can be approximated by the pool water level at the point where there is no visible flow out of that pool. The Cease to Pump rule ensures that additional pressure is not placed on pools by extracting water when the waterway has stopped flowing. During low flows, as pools contract, water quality can deteriorate, algal blooms occur, dissolved oxygen levels decline and fauna compete for the reducing food supplies.
Unregulated streams in western NSW experience long periods of no flow, interspersed with rare flows of varying magnitude. The water sharing plan for the Lower Murray-Darling unregulated and alluvial water sources (2012) focuses on water management in pools and lagoons.
In the regulated systems downstream of Hume Dam and Menindee Lakes, there is more scope to utilise flow rules and environmental flows to benefit water quality. In the water sharing plan for the NSW Murray and Lower Darling regulated rivers water sources (2016), there are rules for both planned and adaptive environmental water. The following environmental water rules have been included in the NSW Murray and Lower Darling water sharing plan.
Barmah-Millewa Environmental Water Allowance (Barmah-Millewa Allowance) – The management of this allowance is a shared NSW and Victorian responsibility. Releases from this account must be used to provide environmentally beneficial outcomes for Barmah-Millewa Forest in accordance with relevant interstate agreements. The volume credited to the Allowance depends on a variety of factors, which are detailed in the NSW Murray and Lower Darling regulated rivers water sharing plan. Water may be carried over from one year to the next up to a maximum volume of 350 000 ML. Releases are made based on advice from the Murray Lower Darling Environmental Water Advisory Group.
Barmah-Millewa Overdraw Environmental Water Allowance (Barmah-Millewa Overdraw) – A volume of up to 50 000 ML is credited to the account when there are sufficient water reserves available without constraining available water determinations. Releases must be used to provide environmentally beneficial outcomes for the Barmah-Millewa Forest. Water may be carried over from one water year to the next, provided the volume does not exceed 50 000 ML. As for the Barmah-Millewa Allowance, releases are made based on advice from the Murray Lower Darling Environmental Water Advisory Group.
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NSW Murray regulated river water source additional environmental water allowance (Murray Additional Allowance) – The method for calculating the volume credited to the account is detailed in the water sharing plan. Water may be released from this account for any purpose consistent with environmental objectives listed in the plan, including:
Maintain and enhance the ecological condition and their water dependent ecosystems;
Maintain and enhance downstream processes and habitats, and
Maintain and enhance water quality.
Environmental water allowance for the Lower Darling Water Source (Lower Darling Allowance) – The volume of water credited to the Lower Darling Allowance is 30 000 ML, less any release that has resulted in a loss of total water volume available under the accounting rules applying to interstate water sharing in the Murray and Lower Darling River. The volume credited is zero if the volume stored in Menindee Lakes is less than 480 000 ML, or if the volume has not risen above 640 000 ML since the volume stored, last fell below 480 000 ML. Releases from the Lower Darling Allowance may be made whenever a high blue-green algae alert is announced. The release rate must be less than 2 000 ML/day during May to October and 5 000 ML/day from November to April, or at a lower rate determined by the Minister.
Minimum flows from Hume Dam - Minimum flows from combined resources are to be maintained out of Hume Dam to ensure that downstream diversion needs are met, as well as for environmental maintenance and water quality purposes. The minimum flows are currently:
Minimum flows downstream of Hume Dam and upstream of the Kiewa River are 600 ML/day, and
Minimum flows downstream of Hume Dam at Doctors Point are 1 200 ML/day.
Minimum flows downstream of the Curlwaa pumps on the Murray - Minimum flows from combined resources are to be maintained downstream of the Curlwaa Irrigation District pumps on the Murray River during summer, to ensure that downstream diversion needs are met, as well as for environmental maintenance and water quality purposes. The recommended minimum flow is 1 200 ML/day during summer. The rates may be reduced below their minimum recommended flows according to conditions in the plan.
Flows in the Murray River at the South Australian border – A total contribution of 1 850 GL per annum is provided to the South Australian border as per the Murray Darling Basin Agreement. South Australia is also entitled to additional water to mitigate the impacts of surface water salinity. The delivery of this water to the border provides water quality benefits to the Murray River.
Long-term extraction limits – The Murray Lower Darling plan establishes a long-term extraction limit and rules for adjustment of the maximum amount of water that may be made available. All water above the plan extraction limit is to be used for the environment, and preserved for the maintenance of basic environmental health. Maintaining base flow is important to slow the decline in water quality by preventing pools from stratifying and stagnating.
Supplementary flow access rules - There are restrictions on extractions under supplementary water access licences. Holders of these licences are able to extract water during announced periods as a result of high tributary inflows, when flows exceed those required to meet other obligations and environmental needs. These restrictions are in place to:
Preserve a significant proportion of natural tributary flows for river health;
Protect important rises in water levels;
Maintain floodplain and wetland inundation, and
Maintain natural flow variability.
Rates of rise and fall – Releasing large volumes water as a block, with very steep rising and falling limbs, has the potential to pose threats to the Murray River through bank slumping and bank erosion. Rates of water level rise and fall, rates for drawdown for weir pools, rivers streams and waterways are listed in the plan to minimise river bank degradation.
The Commonwealth Environmental Water Office (CEWO) has environmental surface water entitlement in NSW, with additional water held in Victoria and South Australia that must be managed to protect or restore
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environmental assets. The CEWO water must also be managed in accordance with the Basin Plan and the Basin Watering Strategy.
The NSW Office of Environment and Heritage (OEH) holds environmental water which was acquired under the Riverbank Program or Wetlands Recovery Program, either through water efficiency works or by purchase of entitlement.
It is not the intent of the Water Quality Management Plan to propose the use of environmental water to address water quality issues. However, the release of environmental water for its designated purpose, will provide water quality benefits for the Murray and Lower Darling Rivers, such as breaking up stratification in pools, diluting salts, mobilising dissolved organic carbon and making conditions less favourable for harmful algal bloom development. Holders of environmental water in their independent decision making, must 'have regard' to dissolved oxygen, salinity and recreational water quality when making decisions about the use of environmental water.
Environmental water is to be managed in accordance with the Long Term Watering Plan (LTWP), Basin Watering Strategy and Annual Basin Watering Priorities. In relation to water quality, the draft Murray and Lower Darling LTWP recognises water being of a quality unsuitable for use, as a risk to achieving environmental outcomes. Issues identified include poor water quality in terms of nutrients, dissolved oxygen and salinity, blue-green algae, chemical contaminants and cold water pollution.
There are opportunities to adjust the way water is delivered from Hume Dam to provide additional water quality and environmental benefits to the aquatic ecosystem. Mimicking a natural flood event by maintaining natural flow variability and natural rates of change in water levels, with more gradual rising and falling limbs, can help reduce bank slumping. Increased water levels can inundate lower benches, flushing carbon into the system providing fuel to stimulate riverine food webs. High flow velocities can also scour silt and biofilms from rocks and logs in the river, resetting biofilm development and improving habitat quality.
The trade of water entitlement is another potential rule to manage risks to water quality. Trading entitlement out of an over allocated water source or away from a potentially sensitive area, could have long term benefits by assisting in mitigating the impact on instream values via reduced levels of extraction. Similarly, the trade of held environmental water into a stressed water source could provide benefits to water quality. Water trade has not been identified in this report as an immediate mitigation measure, as there is no certainty of where, when, or if it may occur.
4. NSW Salt Interception Schemes Salt interception schemes (SIS) have been constructed as a key component of the Basin Salinity Management Strategy under a joint works and measures program, encompassing a total of 19 schemes within the Murray-Darling Basin. The Salinity Management Strategy was developed to manage the problems of river salinity, waterlogging and land salinisation in the Basin. The schemes are constructed at ‘high risk’ river reaches, where saline groundwater discharges from the alluvial sediments of the floodplain, into the river. The primary purpose of the schemes is to reduce groundwater pressures immediately adjacent to the river by extracting and redirecting saline groundwater to disposal lakes located some distance from the river. In most cases, a bore and pump system extracts the groundwater, and pumps it to salt disposal basins, where a significant portion of the water is evaporated, leaving a concentrated brine to strategically seep back into the groundwater system at very low rates, or the salt is harvested.
Investigations have shown significant salt load inflows or ‘hot spots’ occur in two localised areas: from Mallee Cliffs to Psyche Bend, and from Lock 11 to Merbein Common. There are two salt interception schemes in the Murray Lower Darling WRPA. These include the Buronga SIS and Mallee Cliffs SIS.
Operating protocols are in place for each SIS, relating to in-stream flows. Flows above a threshold generally dictate the cessation of a scheme’s operation, due to the hydraulic pressure preventing groundwater flow into the river.
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4.1. Buronga SIS Investigations undertaken in the 1970s identified groundwater movement around the Mildura Weir as a major contributor to the salt load in the Murray River immediately downstream of the weir. The main mechanism for saline groundwater seepage to the river is the up-welling of deeper saline groundwater in response to the vertical hydraulic pressure resulting from the head difference between the upstream and downstream river levels at the weir. The salinity problem is further exacerbated by groundwater mounding under nearby irrigation areas at Mildura-Merbein, Buronga and Coomealla (AWE 2011). These activities have increased the pressures in the Parilla Sands aquifer system, resulting in the displacement of saline groundwater from that aquifer into the Murray River on the downstream side of the weir, over a reach of approximately 3.5 km.
A series of eight groundwater bores with submersible pumps were installed along the section of the Murray River both upstream and downstream of Lock 11, where the saline water is believed to be entering the river. The submersible pumps are located in the deeper Parilla Sands aquifer. Saline water is pumped from this aquifer to lower the pressure that is driving the saline water into the river. By lowering the pressure in the aquifer, the pressure gradient is reversed away from the river. The intercepted saline water is pumped approximately seven kilometres to the Mourquong disposal complex.
The Buronga SIS intercepts the saline groundwater seepage, preventing around 17 500 tonnes of salt from entering the Murray River annually. The salinity of the groundwater being pumped is around 65 000 µS/cm. It is estimated that the interception of saline water by the Buronga SIS will result in a reduction in river salinity of 6.7 µS/cm in the Murray River at Morgan, South Australia. The Buronga scheme, together with the companion Mildura-Merbein scheme located in Victoria, contribute a combined benefit of approximately 14 µS/cm at Morgan.
4.2. Mallee Cliffs SIS Mallee Cliffs SIS was commissioned in 1994 and comprises seven production bores designed to intercept regional groundwater flow and pump it to a disposal basin located 13 km north east of the SIS. The Mallee Cliffs disposal basin has a number of sections, where water is progressively concentrated and ultimately, to a brine storage area. Regional groundwater flow is concentrated at Mallee Cliffs due to the connection between the Parilla Sands and Monoman Formation (AWE 2009). The interception strategy of the scheme is to pump saline groundwater from the Parilla Sands aquifer before it discharges to the Monoman Formation and then to the river. Bores are located on both the floodplain and highland. Head pressures in the Parilla Sands aquifer have been found to be affected regionally by river level fluctuations, rainfall variability, and by operation of the scheme. Each affect is significant in terms of scheme operation and targets (AWE 2009).
The Mallee Cliffs SIS has a maximum pumping capacity of 14 ML/day, but is inoperative during river flows of greater than 20 000 ML/day. The scheme reduces the average salinity at Morgan by an estimated 13 µS/cm. NSW has developed a Responsive Management Monitoring Plan for Mallee Cliffs SIS. Rather than the scheme operating full-time, it is proposed to allow in-river conditions and the salinity risk outlook, guide the level of operation.
5. Methods
5.1. Site selection and monitoring The water quality data used in this report were compiled from 14 routine water quality monitoring stations located within the Murray Lower Darling WRPA. The data were collected on a monthly basis for two monitoring programs, with the data for three sites collected for the Murray Darling Basin Authority (MDBA) and 11 sites for the State Water Quality Assessment and Monitoring Program (SWAMP). The MDBA water quality monitoring program was established in the early 1990’s as a coordinated catchment based water quality program. The aim is to provide long-term quality assured data to describe the baseline condition of the river systems and identify any emerging issues. SWAMP is responsible for collecting, analysing and reporting the ambient water quality condition of rivers in NSW. The program in its current form commenced in November 2007 replacing
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numerous regionally based water quality monitoring programs. The data set used in this report covers a five year period from July 2010 to June 2015. A five year time period was chosen as it is consistent with the Basin Plan (Schedule 12) five yearly review against water quality targets. There is only two years of water quality data for the Murray River at Lock 8. Monitoring commenced at this site in July 2013 in response to the identification of a water quality data gap in the Lower Murray zone.
A full station list is given in Table 7 and the location of these sites in relation to the Basin Plan water quality zones is shown in Figure 2. The coordinates for all monitoring sites are listed in Appendix A.
Table 7: List of routine water quality monitoring stations in the Murray Lower Darling WRPA
Basin Plan WQ zone Station Number
Station Name
B6 401556 Murray River at Indi Bridge
B6 401003 Tooma River at Warbrook
B6 401201 Murray River at Jingellic
cMum 409001 Murray River at Albury (Union Bridge)
cMum 409025 Murray River downstream Yarrawonga Weir
cMum 409003 Edward River at Deniliquin
cMum 409013 Wakool River at Stoney Crossing
cMum 409034 Wakool River at Kyalite
cMum 409005 Murray River at Barham
cMl 414209 Murray River upstream Euston Weir
cMl 414206 Murray River at Merbein Pump Station
Dml 425012 Darling River at Menindee Weir 32
Dml 425007 Darling River at Burtundy
lM 4261001 Murray River at Lock 8
There are 43 continuous electrical conductivity sites monitored by NSW in the Murray Lower Darling WRPA, with additional sites monitored by the Victorian state government. These are located at existing river gauging stations and take electrical conductivity readings every 15 minutes. All NSW continuous electrical conductivity data is stored in the Hydstra database. The data from stations located close to the offtakes of irrigation infrastructure operators have been assessed against the electrical conductivity target. These sites are listed in Table 8.
Table 8: List of Irrigation Infrastructure Operators and relevant continuous electrical conductivity monitoring stations in the Murray Lower Darling WRPA
Irrigation Operators Offtake location Electrical conductivity monitoring
station
Murray Irrigation Limited Mulwala Canal offtake from Murray River at Lake
Mulwala (Yarrawonga Weir)
Wakool Canal Offtake from Colligen Creek via the
Edward River
409025 Murray River downstream
Yarrawonga Weir
409023 Edward River downstream Stevens
Weir
Western Murray Irrigation
limited
Buronga pumping station on Murray River
Curlwaa pumping station on Murray River
Coomealla pumping station on Murray River
414216 Murray River downstream Mildura
Weir (VIC)
414217 Murray River at Curlwaa (VIC)
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Moira Private Irrigation District Murray River upstream of Barmah. Diversion
channel at Moira Lake.
409215 Murray River at Barmah (VIC)
West Corurgan Private
Irrigation District
West Corurgan Canal offtake from the Murray
River between Corowa and Lake Mulwala
409002 Murray River at Corowa
Bama Irrigation Trust Murray River near Moama 409215 Murray River at Barmah (VIC)
Bringan Irrigation Trust Murray River near Barham 409005 Murray River at Barham
Bullatale Creek Waters Trust Murray River west of Tocumwal 409202 Murray River at Tocumwal (VIC)
Bungunyah Koraleigh
Irrigation Trust
Murray River near Koraleigh, upstream of
Tooleybuck
409204 Murray River at Swan Hill (VIC)
Glenview Irrigation Trust Murray River near Barham 409005 Murray River at Barham
Goodnight Irrigation Trust Murray River near Goodnight, downstream of
Tooleybuck and upstream of Wakool junction
409204 Murray River at Swan Hill (VIC)
Pomona Irrigation Trust
(Pomona Water)
Darling River upstream of Wentworth. Located in
the Lock 10 weir pool.
425017 Darling River at Wentworth (VIC)
West Cadell Irrigation Trust Murray River near Moama 409215 Murray River at Barmah (VIC)
There is an extensive blue-green algae monitoring program in the Murray Lower Darling WRPA with approximately 140 sites, including rivers, diversion channels, town water supplies, lakes and major storages. Water samples are collected by government agencies and industry groups, including WaterNSW, Goulburn Murray Water, Lower Murray Water, North East Water, Goulburn Valley W ater and numerous councils. Samples are collected more frequently in summer when there is an increased risk of algal blooms developing. Data from 14 sites has been assessed in this report. A list of the selected sites is in Table 9.
Table 9: List of selected blue-green algae monitoring stations in the Murray Lower Darling WRPA
Station Number Station Name
409001 Murray River at Albury (Union Bridge)
409026 Mulwala Canal at Offtake
409025 Murray River downstream of Yarrawonga Weir
409202 Murray River at Tocumwal
40910089 Murray River at Picnic Point
40910087 Murray River at Moama (Echuca)
409005 Murray River at Barham
41310021 Murray River at Mount Dispersion
409003 Edward River at Deniliquin
40910090 Edward River at Old Morago Road
409014 Edward River at Moulamein
409015 Gulpa Creek at Mathoura
409045 Wakool River at Wakool-Barham Road
409034 Wakool River at Kyalite
Water temperature data is collected at all routine water quality monitoring sites, however as it is collected monthly, it does not give an indication of diurnal variation or detect cold water impacts. Continuous water
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temperature data is collected at 43 sites in the Murray Lower Darling WRPA by NSW agencies. Additional sites are monitored by Victoria. All these sites have permanent sensors installed at gauging stations. A list of sites in the upper Murray in close proximity to Hume Dam is given in Table 10 and the location of these sites is shown in Figure 3.
Table 10: List of continuous water temperature monitoring stations in the Upper Murray River WRPA
Station Number
Station Name
401012 Murray River at Biggara
401013 Jingellic Creek at Jingellic
401201A Murray River at Jingellic
409016 Murray River at Heywooods
409017 Murray River at Doctors Point
409001 Murray River at Albury (Union Bridge)
409037 Murray River at Howlong
409002 Murray River at Corrowa
409025 Murray River downstream Yarrawonga Weir
Map produced by NSW Industry I Lands & Water 10 October 2018
GF Water tempertaure monitoring sites
! Towns
Rivers
Murray Lower Darling Boundary
Data Sources:
NSW Industry I Lands & Water I Water.
Office of Environment and Heritage.
Murray Darling Basin Authority.
Geoscience Australia.0 20 40 60 80
kilometres
±
!
!
!
GF
GF
GF
GFGF
GF
GFGFGF
Murray
River atBiggara
Jingellic
Creek atJingellic
Murray
River atJingellic
Murray
River d/sHume DamMurray River
at DoctorsPoint
Murray
River atAlbury
Murray
River atHowlong
Murray
River atCorowa
Murray River d/s
Yarrawonga Weir
JING
ELLIC
CR
EE
K TOOMA
RIVER
MURRAYRIVER
LAKE
HUME
LAKE
MULWALA
KHANCOBAN
MULWALA
TUMBARUMBA
MURRAY AND LOWER DARLING WATER RESOURCE PLAN AREA- WATER TEMPERATURE MONITORING SITES
Mur
ray
Darli
ng
Ba
sin
Figure 3: Continuous water temperature monitoring sites in the Upper Murray River
The Murray Lower Darling is the only WRPA in NSW with an extensive continuous dissolved oxygen monitoring network. There are currently 11 sites in the Murray River catchment and one on the Lower Darling
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(Table 11). The location of the dissolved oxygen monitoring sites in the Murray catchment is shown in Figure 4.
Table 11: List of continuous dissolved oxygen monitoring stations in the Murray Lower Darling River WRPA
Station Number
Station Name
409005 Murray River at Barham
409047 Edward River at Toonalook
409003 Edward River at Deniliquin
409014 Edward River at Moulamein
409062 Wakool River at Gee Gee Bridge
409013 Wakool River at Stoney Crossing
409048 Niemur River at Barham – Moulamein Road
409086 Niemur River at Mallan School
409044 Little Merran Creek at Franklins Bridge
409036 Merran Creek upstream Wakool River
409111 Barber Creek at Sandy Bridge Road
425007 Darling River at Burtundy
Map produced by NSW Industry I Lands & Water 10 October 2018
GF Dissolved oxygen monitoring sites
! Towns
Murray Lower Darling Boundary
Regulated Rivers
Data Sources:
NSW Industry I Lands & Water I Water.
Office of Environment and Heritage.
Murray Darling Basin Authority.
Geoscience Australia.0 20 40 60 80
kilometres
±
!
!
!
!
!
GF GF
GF
GF
GF
GF
GF
GF
GF
GF
GF
Murray
River at
Barham
Edward
River at
Toonalook
Edward
River at
Deniliquin
Edward
River at
Moulamein
Wakool River at
Gee Gee Bridge
Wakool River
at Stoney
Crossing
Niemur River
at Barham –
Moulamein Road
Niemur River at
Mallan School
Little Merran Creek at
Franklins Bridge
Merran
Creek u/s
Wakool River Junction
Barber Creek at
Sandy Bridge Road
LAKE
MULWALA
BARHAM
SWAN
HILL
MOAMA
MULWALA
DENILIQUIN
MURRAY AND LOWER DARLING WATER RESOURCE PLAN AREA- DISSOLVED OXYGEN MONITORING SITES
Mur
ray
Darli
ng
Ba
sin
Figure 4: Continuous dissolved oxygen monitoring sites in the Murray River catchment
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5.2. Water quality index (WaQI) A water quality index (WaQI) is an important tool to communicate and report water quality condition. It conveys information that is complex and on different scales (e.g. 75% saturation dissolved oxygen, 50 µg/L total phosphorus) to a common score and rating.
A literature review was conducted in 2015 to understand the different approaches and techniques for calculating and using water quality indexes globally. A method based on a modified Canadian Council of Ministers of the Environment (CCME) water quality index (Lumb et al. 2006) was then defined, that incorporated both frequency and exceedance of water quality targets. The method scales five years of data into a single number between 1 and 100 which corresponds to four categories: poor, fair, good and excellent. It is applied to both individual parameters and parameters combined to provide an overall score (Appendix B).
For New South Wales WQMP, the WaQI is calculated for each water quality parameter individually and as an overall integrated index. It includes total nitrogen, total phosphorus, turbidity, dissolved oxygen and pH. There is no weighting of individual parameters. It is based on the exceedance of water quality targets as prescribed in Schedule 11 of The Basin Plan. Where data is available, temperature, salinity and blue-green algae have also been scored as individual parameters.
The outcome provides a number between 1 and 100, and is categorised according to the following water quality rating.
5.3. Catchment stressor identification The Catchment Stressor Identification process (CSI) (Figure 5) helps describe the status, issues and potential causes of water quality degradation. The process uses an eco-epidemiological approach (Cormier 2006), and is broadly related to the approach developed by Cormier et al. (2003) for water quality planning in North America for the United States Environmental Protection Agency (USEPA). It identifies issues and causes based on the idea of abductive inference that is; considering possible causes of water quality degradation, weighing evidence and putting forward factors likely contributing to water quality degradation. Once the water quality degradation issues are defined, evidence is gathered and weighed before conclusions on probable causes synthesised.
The CSI process is intended to be iterative and involves conceptual mapping, data evaluation, literature reviews, GIS mapping and input of local and expert knowledge. The process consists of a standard set of procedures and outputs. The final output expresses what water quality degradation is present and the likely cause, using narrative, figures and maps.
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Figure 5: Conceptual diagram of the CSI process
5.3.1.Conceptual mapping
Conceptual models are a useful step in mapping out possible causes of water quality degradation. They help define the scope of possible causes of water quality degradation and show interlinkages between both causes of degradation and between water quality parameters. A standard conceptual diagram for overall water quality and each parameter has been created based primarily on Schedule 10 of the Basin Plan. These standard models will then be revised for each parameter in each WRP area during the CSI process.
5.3.2.Literature review
A review of both published and grey literature has been undertaken for the Murray Lower Daring WRPA. Published literature was reviewed using a standardised approach through the Web of Science database. Grey literature was reviewed in an informal manner through web searches.
5.3.3.Summary statistics
The data used for this and the following analysis is primarily from the State Water Quality Assessment and Monitoring Program (SWAMP). Summary statistics of available data for each parameter in a WRP area will be defined. These include basic statistics such as range (minimum, maximum), central tendency (mean, median) and variability (standard deviation, interquartile range, coefficient of variation). These statistics help define basic patterns of water quality degradation.
5.3.4.Data analysis
Analysing water quality data is a crucial step in diagnosing issues and their causes. Basic analysis involved examining relationships between parameters, temperature and season, location and hydrology. Data analysis is used to help understand the nature of ecological problems, their interdependencies, seasonal variances, relationship to flow regimes and spatial relationships. Data analysis was based on routine sampling conducted between 2010 and 2015.
5.3.5.Spatial and GIS
Existing spatial information relevant to the causes of water quality degradation for each parameter has been compiled into ArcGIS geodatabases. Initial maps have been produced with relevant spatial information and land use are determined through the CSI process for each WRP area. The spatial information may be refined during the CSI process.
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5.3.6.Local and expert knowledge
For each WRP area, meetings were held with the technical working group comprised of representatives from partner agencies and other invited experts. These meetings facilitated input of local knowledge and expert opinion to the WQMP. In general, these meetings occurred on a one-on-one or organisational basis. This approach was chosen to allow more freedom for people to speak and explore ideas. Information from these meetings was used to refine the scope of water quality degradation, conceptual diagrams, GIS mapping, and to guide further exploration. They also help define conclusions reached for the causes of water quality degradation and most relevant and fit-for-purpose information to include in this report and the WQMP.
5.4. Murray Lower Darling WRPA Risk Assessment Risk assessments are the first steps in the development of a water resource plan for each surface water and groundwater planning area in the Murray Darling Basin. Risk assessments and associated water resource plans must be prepared having regard to current and future risks to the condition and continued availability of water resources in a water resource plan area, and outline strategies to address those risks.
The risk assessment approach compiles the best available information to highlight the range of potential risks that may be present. Where a risk is highlighted as medium or high, it does not necessarily imply that existing rules in the water sharing plan require change or are inadequate, but rather, that further detailed investigation may be required. The risk assessment also highlights where existing plan rules may already be mitigating the risk.
The risk to the health of water dependent ecosystems was assessed by identifying the risk, quantifying the impact based on instream values (consequence) and determining the probability of that consequence occurring (likelihood).
The consequence of poor water quality was determined using the HEVAE (High Ecological Value Aquatic Ecosystems) instream value. For each monitoring station, a reach was defined as 25 km upstream and downstream of the site. This was chosen as a conservative estimate of the spatial representativeness of water quality data and movement of instream biota within the river channel. The consequence decision support tree was then used to define the final consequence score using the HEVAE instream values within each reach area. For detailed description of the risk assessment process and outputs, refer to the Risk Assessment for the Murray Lower Darling Water Resource Plan Area (SW8) (DoIW 2018b).
The calculation method for the likelihood scores varied between water quality attributes. The likelihood scores for total nitrogen, total phosphorus, dissolved oxygen, pH and turbidity were the frequency that the Basin Plan water quality target was exceeded, based on monthly sampling data for the five year period, 2010 to 2015.
Continuous electrical conductivity data, rather than discrete monthly data, was used to assess risks from poor salinity. In the NSW Murray and Lower Darling Rivers, there are no End-of-Valley salinity targets. For this reason, the default ANZECC guideline for lowland slightly disturbed ecosystem value of 300 µS/cm was used to assess the suitability for water dependent ecosystems. The likelihood of water being unsuitable for irrigation was calculated using the frequency that the 95th percentile of the daily mean electrical conductivity exceeded the Basin Plan irrigation infrastructure operator target of 833 µS/cm for the 10 year period from 2005 to 2015.
Water temperature risk was based on the presence of a dam classified as having a severe, moderate or low cold water pollution status, according to Preece (2004).
The objective for recreational water quality is to achieve a low risk to human health from water quality threats posed by exposure through ingestion, inhalation or contact during recreational use. Blue-green algae were chosen as the indicator for risk to recreational water quality because of the potential for some species to impact on human health. The risk of water being unsuitable for recreational use considered the frequency of high concentrations of potentially toxic algal blooms (likelihood), compared to the degree of recreational usage of the water body where the sample was taken (consequence).
New South Wales currently manages the risk of human exposure to blue-green algal blooms through a coordinated regional approach with the Regional Algal Coordination Committees (RACC). State-wide and regional contingency plans and guidelines have been developed to provide methodologies on the
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management of algal blooms (NSW Office of Water 2014). The objective of the guidelines is to provide a risk assessment framework to assist with the effective management response to freshwater, estuarine and marine algal blooms. They aim to minimise the impact of algal blooms, by providing adequate warning to the public ensuring their health and safety in recreational situations and for stock and domestic use.
Under the current management of algal blooms, the level of human exposure to a bloom can be reduced by management practices such as issuing algal alerts. Alert levels have been developed and are used to determine the actions that need to be undertaken with respect to an algal incident. These alerts have been adopted from the National Health and Medical Research Council algal bloom response guidelines (NHMRC 2008). The risk to a site with a high recreational usage may be reduced by the management strategy of placing algal warning signs at the site and informing users of the risks and dangers. Therefore the initial risk assessment outcomes were reviewed and an adjustment in the consequence values made to reflect the application of these arrangements.
Pathogens, pesticides, heavy metals and other toxic contaminants are not monitored regularly in the Murray Lower Darling WRPA, so were not included in the risk assessment.
6. Results
6.1. Water quality index (WaQI)
6.1.1.Water-dependent ecosystems
The Water Quality Index (WaQI) score for each parameter, and the overall score for each site, was calculated for the 2010 to 2015 water quality data set. There were five sites rated as poor: the Tooma River at Warbrook, Wakool River at Stoney Crossing and Kyalite and the Darling River at Weir 32 and Burtundy. The Edward River at Deniliquin, Murray River at Barham and Euston Weir were rated as fair with all other sites, good. The results from the WaQI are shown in Table 12 and summarised in Figure 6.
Table 12: Water quality index scores for the Murray and Lower Darling WRPA 2010-2015 water quality data
Station Name Rating WaQI Total N Total P Turbidity pH DO
Murray River at Indi Bridge Good 88 93 86 67 100 100
Tooma River at Warbrook Poor 54 55 35 21 96 80
Murray River at Jingellic Good 80 89 74 46 100 96
Murray River at Albury (Union Bridge) Good 85 91 90 93 87 66
Murray River downstream Yarrawonga Weir Good 81 85 82 76 76 85
Edward River at Deniliquin Fair 63 85 43 25 89 79
Wakool River at Stoney Crossing Poor 53 50 27 50 93 49
Wakool River at Kyalite Poor 47 55 27 19 94 51
Murray River at Barham Fair 61 72 51 23 92 82
Murray River upstream Euston Weir Fair 77 77 79 67 89 72
Murray River at Merbein Pump Station Good 80 81 82 68 90 78
Darling River at Menindee Weir 32 Poor 26 17 7 18 65 56
Darling River at Burtundy Poor 30 18 9 24 71 65
Murray River at Lock 8* Good 92 100 90 84 100 85
* NOTE: There is only two years of water quality data for the Murray River at Lock 8. Monitoring commenced at this site in July 2013.
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Figure 6: Murray Lower Darling WRPA water quality index scores
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6.1.2.Water temperature
In the Murray River catchment upstream of Hume Dam there is a continuous water temperature data set for two sites. The Murray River at Biggera is approximately 150 km upstream of Hume Dam, and Murray River at Jingellic is 40 km above full supply level. The monthly 20th and 80th percentiles were calculated using the Murray River at Jingellic hourly water temperature data. The Biggera site was not included due to the distance upstream and the difference in altitude. The monthly median temperature downstream of Hume Dam was calculated using the hourly water temperature data from the Murray River at Heywoods gauging station. Figure 7 compares the monthly median temperature at the downstream Hume Dam site to the percentiles of the reference site. The thermal pollution WaQI score, using the difference between the reference site and downstream data was 42, which is a poor rating.
The water temperature data in Figure 8 is the daily minimum water temperature at the site upstream and three sites downstream of Hume Dam. The Murray River at Heywoods (409016) is approximately 1.2 km below the outlet. Further downstream it is 26 km to Albury (409001) and 134 km to Corowa (409002). The Murray River reaches the impoundment of Lake Mulwala approximately 200 km from Hume Dam.
Jul-2009 Nov-2010 Apr-2012 Aug-2013 Dec-2014 May-2016
0
5
10
15
20
25
30
Wate
r T
em
pera
ture
(°C
)
Reference 20%ile
Reference 80%ile
Downstream Hume median
Figure 7: Water temperature downstream of Hume Dam compared to estimated 20th and 80th percentile of natural temperature
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Jul-2009 Nov-2010 Apr-2012 Aug-2013 Dec-2014 May-2016
0
5
10
15
20
25
30
Min
imum
daily w
ate
r te
mpera
ture
(°C
)
Murray at Jingellic
Murray at Heywoods
Murray at Albury
Murray at Corowa
Figure 8: Minimum daily water temperature in the Murray River upstream and downstream of Hume Dam
6.1.3.Dissolved oxygen
There are numerous continuous dissolved oxygen sensors installed in the Murray Lower Darling WRPA as an early warning for possible hypoxic events and to assist in the delivery of environmental water during an event. Figure 9 illustrates that dissolved oxygen in the Darling River was generally suitable to maintain ecological process and support aquatic life. The red line shows the Basin Plan dissolved oxygen target for managing water flows (50% saturation). In 2012 and 2016, major flooding resulted in hypoxic blackwater events in the mid Murray River catchment, with dissolved oxygen concentrations dropping to critical levels in the Edward, Wakool and Niemure Rivers (Figure 10).
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Apr-2012 Oct-2012 May-2013 Nov-2013 Jun-2014 Dec-2014 Jul-2015 Jan-2016 Aug-2016 Mar-2017
0
50
100
150
200
250
Dis
solv
ed o
xygen (
% s
atu
ration)
Figure 9: Dissolved oxygen in the Darling River at Burtundy from 2012 to 2017
Apr-2012
Oct-2012
May-2013
Nov-2013
Jun-2014
Dec-2014
Jul-2015
Jan-2016
Aug-2016
Mar-2017
Sep-2017
0
25
50
75
100
125
150
Dis
solv
ed o
xygen (
% s
atu
ration)
Muray River at Barham
Edward River at Moulamein
Wakool River at Stoney Crossing
Niemure River at Barham-Moulamein Road
Figure 10: Dissolved oxygen in the mid Murray River and Edward-Wakool system from 2012 to 2017
6.1.4.Irrigation
The agriculture and irrigation salinity target is for the 95th percentile of the daily mean electrical conductivity, over a 10 year period, not to exceed 833 µS/cm. This target applies at sites where water is extracted by an irrigation infrastructure operator for the purpose of irrigation. The 95th percentile of the 2005 to 2015 electrical conductivity data set and results of the WaQI are shown in Table 13.
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Table 13: Water quality index scores for the Murray Lower Darling WRPA 2005-2015 continuous electrical conductivity data
Station Number Station Name 95th
percentile WaQI Rating
409002 Murray River at Corowa 76 100 Excellent
409025 Murray River downstream Yarrawonga Weir 69 100 Excellent
409215 Murray River at Barmah 70 100 Excellent
409005 Murray River at Barham 132 100 Excellent
409023 Edward River downstream Stevens Weir 111 100 Excellent
409202 Murray River at Tocumwal 65 100 Excellent
409204 Murray River at Swan Hill 212 100 Excellent
414216 Murray River downstream Mildura Weir 218 100 Excellent
414217 Murray River at Curlwaa 224 100 Excellent
425017 Darling River at Wentworth 471 100 Excellent
A4260501 Murray River upstream Lock 9 305 100 Excellent
The mean daily electrical conductivity in the Edward and Murray Rivers fluctuates throughout the year, though results do not exceed the agriculture and irrigation salinity target (Figure 11). As the target is not exceeded, the risk of any impacts to soil and crop health is minimal. The Wakool River at Stoney Crossing had very high electrical conductivity results between 2007 and 2010, reaching a peak of 6 339 µS/cm in November 2008. Comparing electrical conductivity and mean daily flow (Figure 12) illustrates the impact of increased flows after 2010, diluting salts in the Wakool River.
May-2005 Oct-2006 Feb-2008 Jul-2009 Nov-2010 Apr-2012 Aug-2013 Dec-2014
0
100
200
300
400
500
600
Mean d
aily e
lectr
ical conductivity (
µS
/cm
)
Murray River at Corowa
Murray River at Swan Hill
Edward River at Leiwah
Murray River US Lock 9
Figure 11: Mean daily electrical conductivity (µS/cm) at selected sites in the Murray valley from 2005 to 2015
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Apr-2008 Mar-2009 Mar-2010 Feb-2011 Feb-2012 Jan-2013 Jan-2014 Dec-2014
0
1000
2000
3000
4000
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Figure 12: Mean daily electrical conductivity (µS/cm) and mean daily flow (ML/day) in the Wakool River at Stoney Crossing from 2007 to 2015
High electrical conductivity results were recorded in the Darling River at Burtundy during low and cease to flow periods when salts become further concentrated by evaporation (Figure 13). Electrical conductivity results exceed the Basin Plan agriculture and irrigation salinity target (833 µS/cm) and the target for managing water flows in the Darling River (830 µS/cm). The spike in electrical conductivity of over 3 400 µS/cm in August 2016 coincided with the recommencement of flows following an extended period of no flow. Electrical conductivity in the Murray River at Lock 6 did not exceed the flow management target of 580 µS/cm (Figure 14).
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Figure 13: Mean daily electrical conductivity (µS/cm) and mean daily flow (ML/day) in the Darling River at Burtundy from 2005 to 2017 (red line indicates 833 µS/cm irrigation salinity target)
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Figure 14: Mean daily electrical conductivity (µS/cm) and mean daily flow (ML/day) in the Murray River at Lock 6 from 2008 to 2017 (red line indicates 580 µS/cm flow target)
6.1.5.Recreation
Blue-green algae biovolume data are used to assign recreational alerts based on the National Health and Medical Research Council guidelines. At the red alert level (4 mm3/L), waters are not suitable for recreational
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use, and exceed the Basin Plan target. There were major algal blooms in the Murray River in 2009, 2010 and 2016. However, as there were no major algal blooms in the Murray River between 2010 and 2015, the result was excellent WaQI scores for all sites.
In March 2009, high concentrations of cyanobacteria were detected by routine monitoring in Lake Hume. Following the detection of the bloom, additional downstream monitoring indicated that cyanobacteria was present in the Murray River for a distance of 1 000 km, including associated tributaries of Gulpa Creek, Edward River and Wakool River. The potentially toxic taxa Anabaena circinalis (Dolichospermum circinale), Cylindrospermopsis raciborskii and Microcystis flos-aquae were detected at the majority of the sampling sites during March and April 2009. The algal biovolumes in the Murray River in late March, ranged from 5 to 9 mm3/L. Biovolumes had decreased to below 4 mm3/L by late April/early May 2009.
An unusual bloom of Chrysosporum ovalisporum occurred in the Murray River from mid-February to early June 2016. At its greatest extent in April and May, it extended from Lake Hume to Lock 8 and throughout the Edward, Wakool and Niemur River distributary system, a combined river length of about 2 360 km. It also extended into distributary systems in Victoria. Bloom densities at times exceeded 40 mm3/L, and C. ovalisporum usually comprised >99% of the total bloom biovolume at most locations sampled.
The potentially toxic blue-green algae biovolume data from selected locations, displayed in Figure 15 for the Upper Murray and Figure 16 for the Edward-Wakool system, extends from January to July 2016, and highlights the extent and severity of the bloom. The red line is the National Health and Medical Research Council (2008) recreational use guideline.
Murray River at Albury
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Figure 15: Potentially toxic algal biovolume (mm3/L) at selected sites in the Murray River from January to July 2016
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Edward River at Deniliquin
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Figure 16: Harmful algal blooms at selected sites in the Edward Wakool River system from January to July 2016
6.2. Literature review A literature search was undertaken to gather information from the published literature relevant to water quality in the Murray Lower Darling WRPA. Following is a summary of relevant information with more detailed information listed in Appendix C.
Habitat condition is degraded across much of the Murray Darling Basin. Loss of riparian vegetation and increased sand and gravel bed load are the principal components causing degradation. The most marked degradation is in the mid slopes (Norris et al. 2001). Riparian vegetation is important as a carbon source, its shading reduces solar radiation, limiting in-channel autotrophic production (Kelleway et al. 2010) and as a source of large woody debris to protect against erosion and restore river health (Erskine et al. 2012). The most impacted areas are in the Edward - Wakool system, Lower Murray River and Darling River near Menindee Lakes, with some long reaches of less than 20% native woody riparian vegetation. Inversely, in the upper Murray catchment there are long reaches with greater than 80% cover (DoIW 2018b).
Parts of the Murray River are extremely impaired, with 43% of the Murray-Riverina area and 19% of the Darling River substantially modified. Parts of the Murray River may have lost over 80% of the biota likely to have occurred there (Norris et al. 2001). Water temperature, flows, habitat and food resource (prey size and availability) all impair fish recruitment. Flow magnitude and water temperature appear to have the largest effect in determining larval fish composition (Rolls et al. 2013). It is suggested that a lack of prey and food resources may be one reason why there is not a strong response to managed flow events (Rolls et al. 2013). In the Great Darling Anabranch, the fish community is dominated by carp as there is little habitat available for native fish, except during floods (Thoms et al. 2000). Water quality has also been found to have an effect on river red gum survival (Kingsford 2000).
Where river channels have already been impacted by regulated flows, complex surfaces such as benches may have already been lost, so restoring more natural flows at these levels of channel, may have little immediate impact on nutrient processing (Woodward et al. 2015). Low level benches will need to be ‘rebuilt’ before environmental flows can increase connectivity.
Discharge temperatures from Hume Dam during spring and summer may be depressed by more than 5°C relative to the temperature in the surface layer of the reservoir (Sherman 2005). Two options proposed by
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Sherman (2005) for mitigation of cold water pollution include: construction of a multi-level offtake, or deployment of a submerged curtain. The submerged curtain option was expected to produce the greatest discharge temperature. Increased discharge temperatures appear to be achievable and are expected to reduce the stress currently impacting Murray cod populations during crucial post-spawning periods (Sherman et al. 2007).
Developing ecologically effective environmental flow regimes is a challenge for river managers globally, and in many regulated rivers, sufficient water is rarely available to ensure that environmental flow releases are fully effective (Dyer and Thoms 2006). Estimates are that climate change my reduce water yield in the Upper Murray River (18% by 2030 and 43% by 2070), the Murray-Riverina (21% by 2030 and 48% by 2070) and Darling River (26% by 2030 and 57% by 2070) (Austin et al. 2010).
Nutrient and sediment loads from the Australian Alps are largely unmodified. Most of the loads are generated in the upland and mid-slope areas, while most of the impact is felt in lowland rivers, weir pools and reservoirs where the sediment is stored (Norris et al. 2001). In the long-term, management needs to focus on reducing sediment supply, but the greatest short-term benefits will come from managing the lowland sediment and nutrient stores.
Flow releases from Menindee Lakes were assessed for their ability to either suppress bloom development, or to mitigate pre-existing blooms in the Darling River. A discharge of 300 ML/day (flow velocity of 0.03 m/s) was found to be sufficient to prevent prolonged periods of persistent thermal stratification, which also suppressed the development of Anabaena circinalis blooms (Mitrovic et al. 2011). Mitrovic et al. (2011) also found a flow release of 3 000 ML/day was effective at removing an established cyanobacterial bloom, with total cyanobacterial numbers declining from over 100 000 to 1 000 cells/mL within a week. In two summers without blooms, higher flows and decreased light availability prevented bloom development. As well as flushing algae downstream, greater discharges increased turbidity, which diminished the growth of cyanobacteria through reduced light availability (Mitrovic et al. 2011).
6.3. Lower Darling flow release and water quality event The cessation of water releases from Menindee Lakes to the lower Darling in December 2015 was a contingency measure to protect water supply to Broken Hill during an unprecedented low inflow period. The result was remnant pools in the lower Darling River would decline in both water quality and quantity, with water retreating to standing pools during 2016. The water quality in the remnant pools used for water supply was surveyed in April 2016 and was found to be generally poor with high electrical conductivity readings up to 3 500 µS/cm and high algae concentrations.
There are numerous risks involved when returning flows to a river that has stopped flowing, sometimes referred to as ‘re-starting’ a river:
As poor quality water is flushed downstream, it may be unusable for some water user enterprises;
Water with low or zero dissolved oxygen often sits on the bottom of stagnant pools. The flushing of this water can cause fish kills in pools downstream;
Some elements are released at harmful concentrations from river sediments under zero oxygen conditions. These could have toxic effects on plants and soil if used for irrigation;
Denser saline water can flow along or sit on the bottom of pools, leaving the fresher water sitting on top, and
The water in stagnant pools can have high nutrient concentrations, triggering potentially toxic blue-green algal blooms downstream.
Rainfall in May/June 2016 brought inflows to Menindee Lakes, allowing releases to the lower Darling River to resume. The aim was to release a large volume 'flush' from Lake Wetherell to eject poor quality water from the standing pools, and flush it into the Murray River. The initial intention was to flush the poor quality water past Burtundy, to provide some relief for water users on the Darling River. This would result in poor quality water passing the water users around Ellerslie and Tapio and mixing with the better quality water in this stretch of river that is supplied by the weir pool behind Lock 10.
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The initial flush volume suggested as necessary was far greater than could be contemplated at that time. The forecast inflows to Menindee Lakes were limited, and would be set aside mostly to extend the water supply security for Broken Hill and to provide longevity of low flow in the lower Darling River. At the time, the Menindee system was still well below 10% storage capacity. A budget of 35 000 ML was made available for release, with a commencement date of 28 July 2016.
In 2004, the lower Darling River received the return of flows after a period of drought. The release started at a flow rate of 40 ML/day and increased to 200 ML/day over a period of weeks. The Darling River at the time was a series of pools, and being summer, these pools were thermally stratified, resulting in the water in the bottom of pools having low dissolved oxygen. The flushing of this deoxygenated water from the pools resulted in fish-kills downstream. The 2016 release was undertaken at the end of winter, when the pools were not stratified, and a larger volume was released to dilute the poorer quality water, ensuring the water was mixed through the profile, reducing the risk to aquatic ecosystems.
There was an additional confounding factor influencing the timing of the 2016 release. There were concerns about the poor quality of the water to be released from Lake Wetherell. The inflows to Lake Wetherell at the time were carrying high salinity loads from the upper Darling River. Monitoring near the main weir showed the electrical conductivity in May 2016 had increased to over 2 000 µS/cm (Figure 17). The inflows were held in Lake Wetherell for a short period, to enable some dilution and mixing of the inflows with water within the storage. Water quality profile data was collected from Lake Wetherell by WaterNSW to determine when the release should commence. At the start of the release on 28 July, inflows of lower salinity water had diluted the electrical conductivity in Lake Wetherell to 1 200 µS/cm. By 5 September, the electrical conductivity was 337 µS/cm.
To further mitigate risk during the release:
The quality of the flows were monitored prior to and as they progressed down the Darling River. The main aim of the sampling program was to collect water samples from the head of the flow as it progressed down the Darling River to enable notification of water users of the quality of the water. In addition, information on the quality of the water in the tail of the flow was also needed, to enable water users to determine when the water was safe for use in their enterprise;
Water users were notified of the quality of the water throughout the release so they could make informed decisions about their enterprises;
Releasing water into the lower Darling and flushing remnant pools in winter, at a time of lower risk, may alleviate water use and environmental issues in the coming summer;
The release was being managed by multiple agencies including, DoI Water, WaterNSW and DPI Fisheries to maximise beneficial outcomes and minimise risks, and
It was acknowledged that there may be a need for contingency sampling in the event of reported fish kills at sites as advised by NSW DPI Fisheries Officers. These were to be coordinated between the various agencies if/when the situation arose.
The electrical conductivity in Weir 32 was approximately 2 000 µS/cm prior to the release. The arrival of the release saw the conductivity drop rapidly to 1 000 µS/cm and then continue to decrease with time. The progression of the head of the flow down the Darling River flushed the saline water from the standing pools, resulting in the electrical conductivity increasing to over 3 600 µS/cm at Pooncarie and 3 500 µS/cm at Burtundy. The electrical conductivity declined rapidly as the first flush passed each of the gauging stations (Weir 32, Pooncarie and Burtundy) (Figure 18). The flow data from the Darling River at Burtundy shows that once the river was flowing, subsequent flows did not result in increased electrical conductivity.
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Feb-2008 Jul-2009 Nov-2010 Apr-2012 Aug-2013 Dec-2014 May-2016
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Figure 17: Electrical conductivity (µS/cm) in Lake Wetherell compared to inflows from the Darling River at Wilcannia gauging stations
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Figure 18: Continuous electrical conductivity (µS/cm) at Darling River gauging stations
The quality of the water in the Wentworth weir pool became an issue once the head of the flow entered the upper reaches near Ellerslie. The electrical conductivity at Ellerslie increased from 153 µS/cm on 5 July, to 2 755 µS/cm on 22 August. Similarly, the pH increased from 7.09 to 8.52 and the sodium adsorption ratio from 1.53 to 9.00. A sodium adsorption ratio of greater than 6 has increased effect on all soils and starts to reduce growth of most crops and pasture plants (NSW DPI 2014). The change in the quality of the water in the Wentworth weir pool directly impacted water users in the area.
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Due to the volume of water flowing down the Murray River at the time (32 000 ML/day), there were concerns that the saline water would sit on the bottom of deeper holes in the Wentworth weir pool and not be flushed out of the Darling River, impacting on irrigation enterprises. In response to this, a second release was proposed. An additional profile monitoring program was commenced on 31 August by WaterNSW, to track the movement of the poor quality water through the Wentworth weir pool. The electrical conductivity results in the following tables have been highlighted to indicate the progression of the denser saline water Through the weir pool. Results less than 1 000 µS/cm are green, between 1 000 and 2 900 µS/cm are amber and greater than 2 900 µS/cm are red. Tables 14 to 19 track the movement in the saline water down the Darling and into the Murray River. Distances are measured upstream from the junction of the Darling and Murray Rivers. Samples from the Murray River were collected on the NSW/Lock chamber side of the river.
It took 25 days for the head of the saline first flush from the initial release to travel from Lake Wetherell to the upper reaches of the Wentworth Weir pool near Ellerslie. The highly saline first flush then moved slowly through the weir pool, taking 24 days to commence merging into the Murray River. The salt plume, being denser than fresh water, made its way along the bed of the weir pool. It was a further 28 days before the saline water had been fully dispersed from the Darling River into the Murray River.
Table 14: Electrical conductivity profiles upstream of Darling and Murray Rivers junction – 31 August
Depth (m) 19 km 22 km 39 km
0.5 143 160 3041
1.0 143 160 3026
2.0 144 164 3001
3.0 141 786 3028
4.0 135 896 3187
5.0 132 918 3283
Table 15: Electrical conductivity profiles upstream of Darling and Murray Rivers junction – 7 September
Depth (m) 4 km 8 km 14 km 18 km 20 km 24 km 30 km 38 km 42 km 46 km 52 km
0.5 116 131 173 202 289 517 1900 1976 1858 1847
1.0 117 132 167 175 202 309 839 1903 1978 1858 1847
2.0 121 131 160 176 316 1329 1984 2120 2007 1901 1847
3.0 127 132 304 780 1721 2584 2527 2400 2291 1870
4.0 128 582 2099 1940 2667 2938 2980 2840 3192 3117 2138
5.0 129 680 2236 2497 2967 2983
Table 16: Electrical conductivity profiles upstream of Darling and Murray Rivers junction – 12 September
Depth (m) Murray
River
U/S
Junction
1 km 3 km 9 km 14 km 20 km 28 km 32 km 36 km 44 km
0.5 116 132 121 277 317 676 1472 1909 1961 1765
1.0 116 132 121 152 273 419 703 2005 1992 1958 1772
2.0 117 133 133 163 368 804 968 2568 2046 2003 1788
3.0 117 133 321 448 1803 2333 2534 2819 2409 2266 2552
4.0 118 133 594 1128 2216 2526 2654 2691 2391 3105
5.0 119 132 622 1350 2234 2679
Table 17: Electrical conductivity profiles upstream of Darling and Murray Rivers junction – 19 September
Depth (m) Murray
River
U/S
Junction
3 km 8 km 12 km 16 km 20 km 26 km 30 km 34 km 40 km
0.5 415 907 1690 2122 2006 1805 1468 1150 1078 1019 988
1.0 366 961 1714 2122 2006 1808 1465 1149 1080 1019 988
2.0 379 972 1715 2123 2007 1808 1476 1149 1080 1020 988
3.0 423 1262 1718 2127 2007 1811 1486 1150 1080 1021 988
4.0 457 1437 1722 2193 2007 1815 1491 1151 1080 1021 988
5.0 462 1654 1981 2008 1820 1499 1080 1021
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Table 18: Electrical conductivity profiles upstream of Darling and Murray Rivers junction – 26 September
Depth (m) Murray
River
U/S
Junction
Wentworth
boat ramp
3 km 8 km 12 km 16 km 20 km 22 km
0.5 288 713 252 1111 1012 954 878 865 853
1.0 339 742 302 1115 1013 954 878 866 855
2.0 355 782 1006 1122 1014 955 879 864 855
3.0 373 803 1182 1130 1044 953 883 864 855
4.0 388 914 1295 1123 1082 956 886 864 892
5.0 395 1023 1417 1608 943 865
Table 19: Electrical conductivity profiles from Lock 10 and Darling River at Wentworth – 13 October
Depth (m) Wentworth
boat ramp
10 km 20 km 30 km 40 km 50 km 60 km
0.5 384 464 516 475 449 405 367
1.0 394 464 516 475 449 405 367
2.0 443 464 516 475 450 405 367
3.0 581 464 516 475 450 405 367
4.0 638 465 516 475 450 405 367
5.0 640 465 516 475 449
Monitoring of additional sites within the Lock 10 weir pool showed that when the saline water from the Darling River was able to push into the Murray River, it largely stuck to the lock chamber side of the weir (NSW bank). The results of profiles collected approximately 1.2 km downstream of Lock 10 showed that the electrical conductivity was slightly higher mid river and on the NSW side than closer to the Victorian bank, but generally the results indicate the waters were well mixed and would not impact downstream water users.
Recommendations for future releases include:
Salinity and hydrology:
Hydraulic modelling of the Murray and Darling River to better understand the movement of the salt slug captured in the Lock 10 Weir pool.
Risk management and stakeholder communication:
Prior survey and event monitoring of the Darling River, Lake Wetherell and Wentworth Weir pool;
Functional arrangements and roles of WaterNSW and DoI Water; operational and customer service, and
Discussion of utilisation of block banks and manipulation of Lock 10. Governance of the Water Management Act and subordinate Policies:
Governance of water release decisions;
Regulatory instruments (works approval), and
Implementation of Lower Darling Water Sharing Plan rules. Basin Plan Implementation – Water Quality Management Plans (and WRPs):
First flush flows and ecological objectives;
Water quality targets when managing flows, and
Water quality objectives and measures.
6.4. Summary statistics Boxplots have been used to show general water quality trends across the valley, and to display monitoring site variability within the Murray and Lower Darling WRPA. The boxplots in Figure 16 show the annual 25th, 50th
and 75th percentile values, with error bars indicating the 10th and 90th percentile values for each water quality attribute at each site. There are numerous plots within Figure 19; A) total nitrogen, B) total phosphorus, C) turbidity, D) total suspended solids, E) dissolved oxygen, F) pH and G) electrical conductivity. Summary statistics for the key water quality parameters at each monitoring site have been displayed as tables in Appendix D. Additional detail for each individual site is shown in Appendix E.
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The two sites located on the Darling River at Weir 32 and Burtundy had the highest nutrient concentrations and highest turbidity, followed by the Wakool River at Stoney Crossing and Kyalite. In the regulated Murray River there was a slight increase in nutrient concentration and turbidity between Albury and Lock 8, reflecting the impact of the cumulative effects of land use, soil disturbance and human activity on water quality. The concentrations of nutrients detected are not limiting to algal growth.
Dissolved oxygen levels fluctuate between sites in response to local drivers. In most cases, the site median was between 80 and 100% saturation. The highest readings were in the Murray River at Lock 8 and the lowest dissolved oxygen readings were in the Darling River at Weir 32 and Burtundy. The pH in the Darling River was slightly elevated (basic), but not to the extent where it would impact on the health of aquatic ecosystems or agricultural enterprises.
The electrical conductivity in the Murray River was generally low. The release of water from Hume Dam provides dilution flows to the Murray River, and the operation of salt interception schemes help manage salt inputs from saline groundwater. The Wakool River at Stoney Crossing had very high electrical conductivity results during periods of low or zero flow between 2007 and 2010. Electrical conductivity did not increase markedly with distance down the Murray River to Barham, but there was a slight increase between Barham and Lock 8. The annual median electrical conductivity and salt loads are summarised in Tables 28 to 30 in Appendix D.
Draftsman plots for each site have been developed to assess the relationships between water quality parameters. These figures are shown in Appendix E. Sites generally showed a positive correlation between total nitrogen, total phosphorus and turbidity, indicating similar transport mechanisms for the three parameters. This suggests that nutrients are mostly transported in the river system bound to particulate matter. The highest total nitrogen and total phosphorus concentrations tend to coincide with increased flow. This indicates that the majority of the nutrients are derived from diffuse sources rather than point sources. In addition, there are occasional high readings during low flow, indicating a mixture of nutrient sources, such as livestock access or release of nutrients from bed sediments at some sites. In contrast to nutrients and turbidity, electrical conductivity was negatively correlated to flow and decreased as salts are diluted by increased flow.
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Figure 19: Water quality data for water quality parameters by site
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6.4.1.Total annual flow
Many water quality attributes are strongly correlated to river flow conditions. Flow during the 2010 to 2015 data period was characterised by high flows in 2010 and 2011, and low flow from 2013 to 2015. The storage capacity of Hume Dam was less than 20% in April 2010. Following heavy rainfall between August and October, Hume Dam filled to 100% capacity. There were no major inflows from 2013 to 2015. Figure 20 illustrates the total annual flow at selected gauging stations from the upland, midland and lowland areas. The use of total annual flow gives a general indication of river flow conditions. No attempt has been made to assess individual results against flow at the time of sampling, or the timing of sampling in relation to high or low flow events. The general trend at most sites were higher nutrient and turbidity results during the wetter years and lower concentrations during the dryer years.
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Figure 20: Annual flow (ML/year) at selected gauging stations
6.5. Risk assessment The impact of the quality of the water in the Murray and Darling Rivers on the health of water dependent ecosystems was assessed by identifying the risk. This was achieved by quantifying the impact based on instream values (consequence) and determining the probability of that consequence occurring (likelihood). Tables 20 to 24 list the sites with medium or high risk scores in the Murray Lower Darling risk assessment for each parameter. The Murray River at Barham had a high risk for turbidity, total phosphorus and total nitrogen. The Tooma River at Warbrook, Edward River at Deniliquin, Wakool River at Kyalite, Darling River at Burtundy and Murray River at Lock 8 were also a high risk for turbidity.
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Table 20: Sites with high and medium risk to the health of water dependent ecosystems from turbidity
Station Name Consequence Likelihood Level of Risk
Tooma River at Warbrook Medium High High
Murray River at Jingellic Medium Medium Medium
Edward River at Deniliquin High High High
Wakool River at Kyalite High High High
Murray River at Barham Very high High High
Murray River upstream Euston Weir High Medium Medium
Darling River at Menindee Weir 32 Low High Medium
Darling River at Burtundy Medium High High
Murray River at Lock 8 Medium High High
Table 21: Sites with high and medium risk to the health of water dependent ecosystems from total phosphorus
Station Name Consequence Likelihood Level of Risk
Tooma River at Warbrook Medium Medium Medium
Edward River at Deniliquin High Medium Medium
Wakool River at Kyalite High Medium Medium
Murray River at Barham Very high Medium High
Murray River upstream Euston Weir High Medium Medium
Darling River at Burtundy Medium Medium Medium
Murray River at Lock 8 Medium Medium Medium
Table 22: Sites with high and medium risk to the health of water dependent ecosystems from total nitrogen
Station Name Consequence Likelihood Level of Risk
Tooma River at Warbrook Medium Medium Medium
Wakool River at Kyalite High Medium Medium
Murray River at Barham Very high Medium High
Daring River at Burtundy Medium Medium Medium
Murray River at Lock 8 Medium Medium Medium
Table 23: Sites with high and medium risk to the health of water dependent ecosystems from pH
Station Name Consequence Likelihood Level of Risk
Murray River at Barham Very high Low Medium
Darling River at Burtundy Medium Medium Medium
Table 24: Sites with high and medium risk to the health of water dependent ecosystems from dissolved oxygen
Station Name Consequence Likelihood Level of Risk
Murray River at Union Bridge (Albury) Medium Medium Medium
Wakool River at Kyalite High Medium Medium
Murray River at Barham Very high Low Medium
Darling River at Burtundy Medium Medium Medium
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There was a medium risk to water dependent ecosystems from salinity in the Murray River at Barham and Lock 8. The highest value at Lock 8 across the five year period was 572 µS/cm. The risk to all irrigation infrastructure operators throughout the WRP area from salinity, was low.
There was a high risk to water dependent ecosystems from thermal pollution from Hume Dam and a medium risk to water dependent ecosystem from Khancoban Dam. Most inflow to Khancoban Dam is transferred from Island Bend Pondage, Lake Eucumbene and Lake Jindabyne.
Numerous sites were routinely monitored for blue-green algae between 2010 and 2015. When algal blooms occur, the level of human exposure can be reduced by implementing management practices such as issuing algal alerts. The risk at a site with a high recreational usage can be reduced by the management strategies of erecting algal warning signs and informing users of the risks and dangers. The risk assessment consequence values reflect the implementation of these arrangements. The risk outcome for Lake Hume, Lake Wetherell and Lake Pamamaroo was medium.
7. Discussion Water quality attributes in the Murray Lower Darling WRPA are strongly correlated to flow. High flow from rainfall and runoff can result in higher turbidity, nutrients and possibly pesticides and pathogens, but lower electrical conductivity. The Basin Plan water quality targets were developed using data collected from 1991 through to 2009, to try and incorporate a spread of climatic and flow conditions (Tiller and Newall 2010). It was noted that although the time period covered a range of conditions, the data used was primarily collected at base or low flow, and generally missed high flow and flood events. It should be noted that as the Basin Plan targets refer to low flow conditions, targets for flow dependent attributes are likely to be exceeded in wetter years. There was a general trend of higher nutrient and turbidity results in the wetter years from 2010 to 2012, with many very high results collected in these years and annual medians exceeding the Basin Plan targets.
Where there was inadequate reference site data or locally derived guidelines for a zone during the development of the Basin Plan, the target was based on the ANZECC Guidelines (2000) for slightly modified waterways (Tiller and Newall 2010). This has had significant implications for the reporting of water quality condition in the Darling River; with the illogical scenario of more stringent targets in lower reaches compared to upstream catchments. For example, the turbidity target decreases from 230 NTU in the Darling upper zone to 50 NTU in the middle lower zone. The targets should account for the trend of increasing sediment loads and nutrient concentrations with distance down the catchment. Tiller and Newall (2010) identified the middle and lower zones of the Darling River as a ‘hot spot’ in terms of turbidity and nutrients and suggested the proposed targets may be too low and need refinement.
In the Basin Plan, the middle and lower reaches of the Darling River are combined into one zone. It could be expected that the water retention time in Menindee Lakes would allow the settling of particulate matter, resulting in reduced turbidity, total phosphorus and total nitrogen in the river downstream of the lakes. An assessment by Mawhinney and Muschal (2015) found this does not appear to be the case. The large shallow lakes that make up the Menindee Lakes system are exposed to the wind and are well mixed. The re-suspension of fine sediments from the bottom maintains high turbidity in the lakes. This turbid water is then released downstream. For this reason it appears appropriate to use the same targets in the middle and lower zones of the Darling River.
Water quality application zone boundaries were reviewed by Mawhinney and Muschal (2015) and one major change in the Murray WRPA was recommended. In the Central Murray zone (cMum), the smaller regulated Edward - Wakool Rivers function as lowland rivers, especially when compared to the Murray River at Albury and downstream of Yarrawonga Weir. A change to the central Murray River zone boundary was suggested so that the Edward - Wakool Rivers (and Billabong Creek in the Murrumbidgee WRPA) are separated from the Murray River, which could retain the existing central Murray targets.
7.1. Elevated levels of salinity Assessment of the discrete electrical conductivity data has shown the highest salinity results are in the Darling River and the Wakool River during zero and low flow periods. Electrical conductivity levels are low in the
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Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
Murray River with regulated flows from Hume Dam diluting salt, keeping electrical conductivity low. The 95th
percentile of the daily mean electrical conductivity did not exceeded the 833 µS/cm target for irrigation at any of the irrigation infrastructure operator offtakes on the Murray and Lower Darling Rivers. The highest was at the bottom of the system downstream of Mildura Weir and at Lock 9 with a 95th percentile of 218 and 305 µS/cm respectively. At these sites, the risk of crop damage and increased soil salinity is low.
Brock et al. (2005) showed that aquatic plant germination and species richness in wetlands decreases when salinities increase above 300 mg/L (500 µS/cm). The electrical conductivity in the Murray River is rarely above this level, and unlikely to impact on species diversity. It was found that increased salinity (up to 5 000 mg/L) had no effects on the Darling Anabranch, with no change in community structure.
The median data from the unregulated catchments shows a gradual increase in electrical conductivity following the commencement of heavy rainfall across the catchment in 2010. McGeoch et al. (2017) hypothesised that an episodic decline in salinity in NSW rivers during the 2000’s may have been due to extended drought conditions. Long periods of low rainfall can cause a drop in shallow groundwater levels, resulting in a disconnection between saline groundwater and fresher surface water, causing the observed lower salinity levels in streams. The return of wetter conditions in 2010 would have recharged shallow water tables, increasing the contribution of groundwater to low flows, raising the electrical conductivity. In all cases the median electrical conductivity had started to decline in 2014/2015 following the return of dryer conditions. Future monitoring will show whether recent salinity observations in unregulated catchments persist at current levels or decrease as shallow saline groundwater aquifers decline.
Electrical conductivity increases very slightly with distance down the Murray River. Parsons et al. (2008) found the Murray River varies between being a losing stream and a gaining stream as it progresses down the catchment. The electrical conductivity of surface water in the lowlands area is generally considered excellent for irrigation purposes, but can be high in the lower Wakool River during low flow periods. The mean daily electrical conductivity in the Murray River fluctuates throughout the year, though results do not exceed the agriculture and irrigation salinity target, keeping the risk of impacts on soil and crop health low.
Maintaining low flow in unregulated catchments and ensuring that freshes are available to the environment, helps to break up stratification, provide dilution flows and prevent saline water from sitting on the bottom of pools. This will maintain the health of the river and the continued use of the water for productive purposes. Water released from Hume Dam has a low electrical conductivity and dilutes saline inflows from unregulated tributaries, ensuring water is suitable for irrigation and the protection of water dependent ecosystems. Generally the river systems in the upper catchment remain relatively fresh. However salinity in the lower Murray (the Mallee region), in particular below the South Australian border, can approach critical levels. The operation of numerous salt interception schemes in the Lower Murray by both NSW and Victorian agencies reduce salt inputs to the Murray River from saline groundwater. There is a delicate balance in the interface between the groundwater regime and the river regime.
Salinity mitigation is currently achieved through the diversion of irrigation drainage waters or groundwater interception. Investigations have identified historical poor irrigation practices combined with poor location of irrigation developments as a major contributor of additional salt to the Murray River. Improved irrigation practices offer opportunities for both irrigators and natural resource managers. Significant effort has been made to foster improved irrigation practices through research and practical on-farm education. Irrigators have been able to reduce water consumption, resulting in reduced recharge (root zone drainage) to the groundwater system. Groundwater modelling suggests that the irrigation induced salt accessions throughout the Mallee region could reduce substantially, putting off the need for further salinity mitigation investments (Newman 2010).
The cessation of water releases from Menindee Lakes into the Lower Darling River results in water retreating to standing pools. The water in these remnant pools generally has a high electrical conductivity as salts are further concentrated by evaporation. The electrical conductivity of the flows into Menindee Lakes is highly variable, depending on climatic conditions in the upper catchment. High salt loads can result in increased electrical conductivity within Lake Wetherell, adding further complexity to the management of salinity in the Lower Darling. When releases are recommenced, saline water is flushed downstream from the standing pools, where it impacts on water users in the Wentworth weir pool. Monitoring in 2016 has shown that it can take over 50 days for saline water to pass through the weir pool and completely disperse into the Murray River.
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Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
A salinity assessment needs to consider land salinity, salt load and stream electrical conductivity in an integrated framework to determine the hazard of a landscape. The Murray Lower Darling salinity technical report (DoIW 2018c) uses the Hydrogeological Landscapes (HGL) framework to undertake an assessment, as well as determine the likely cause and identify solutions. In addition, salinity modelling was used to assess catchment behaviour, define problem areas and quantify impacts. The use of discrete and continuous long term salinity data in these modelling frameworks increased both the accuracy and utility of the salinity models. The salinity assessment in the Murray and Lower Darling valley salinity technical report will inform and give support to the WQMP and identify water, land and vegetation measures to increase productivity and environmental sustainability.
7.2. Elevated levels of suspended matter The draftsman plots show there was generally a linear relationship between turbidity and total suspended solids in the Murray Lower Darling WRPA. Turbidity and suspended sediments were closely related to discharge, with most sites displaying a positive correlation to flow. The lowest turbidity results were in the Murray River upstream of Hume Dam. A large portion of the upper catchment area is National Park, with more than 80% cover by native woody vegetation helping to reduce soil erosion.
Turbidity only increased slightly with distance down the Murray River in response to the cumulative impacts from activities upstream. The Tooma River at Warbrook, Edward River at Deniliquin, Wakool River at Kyalite, Darling River at Burtundy and Murray River at Barham and Lock 8 were all rated as having a high risk to water dependent ecosystems from turbidity in the risk assessment. The highest median turbidity was in the Darling River at Weir 32 and Burtundy. The alluvial soils of the Darling River have a high clay content, which increases their susceptibility to resuspension within the water column. In addition, the very fine clay particles are able to remain in suspension during low and zero flow, maintaining high turbidity readings.
High levels of turbidity are influenced by a number of factors including the wide spread conversion of land for cropping and irrigation, bank and riparian condition, and the presence of carp. Stock trampling causes removal of groundcover, pugging, destabilising soils and erosion of stream banks, which can all lead to increased turbidity (Wilson et al. 2008; Holmes et al. 2009). Carp can contribute to turbidity by stirring up sediments when feeding, uprooting aquatic vegetation, and increasing bank destabilisation (Koehn 2004). Carp are common throughout most of the WRPA.
Rapidly ascending and descending limbs of the hydrograph during irrigation releases, and draw down of water levels in weir pools, can be responsible for channel erosion through bank slumping and bank erosion in the regulated river. To minimise bank degradation, the Murray and Lower Darling water sharing plan lists rates of water level rise and fall, and rates of drawdown in weir pools.
Sites in the Darling River exceeded the turbidity target most years. When the Basin Plan water quality targets were developed, there was insufficient reference data available to develop water quality targets for the middle and lower zones of the Darling River, therefore the default trigger values of the National Water Quality Guidelines (ANZECC and ARMCANZ 2000) were used as the Basin Plan water quality targets. This has resulted in the illogical scenario of water quality targets in the lower reaches of the Darling being more stringent than the upstream reaches. The Basin Plan water quality targets for the Darling upper zone could be applied across the whole Darling River until more appropriate water quality targets are developed.
River Styles® recovery potential (Figure 19) is synonymous with geomorphic condition. Recovery potential represents geomorphic stability and can indicate the capacity of a stream to return to good condition or to a realistic rehabilitated condition (Brierley and Fryirs 2005). Streams rated as having conservation or rapid recovery potential are likely to be the most stable and in a good condition, whereas streams with low recovery potential may never recover to a natural condition or may continue to decline quickly without intervention (Cook and Schneider 2006).
The highest priorities for intervention action are the strategic recovery potential reaches. These are reaches of river that may be sensitive to disturbance, triggering impacts that can have off-site effects. Particular emphasis should be placed on reaches or point-impacts (nick-points), where disturbances may threaten the integrity of remnant or refuge reaches. Figure 21 identifies large portions of the Murray River between Hume Dam and Euston as strategic recovery potential reaches. The Darling Anabranch is also a conservation reach. Proactive
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management strategies in these areas are the most effective means of river conservation, leading to improvements in water quality.
There is a short reach of low and moderate recovery potential on the Murray River downstream of Hume Dam. A threat to the recovery potential of this section of the Murray River is the lack of sediment delivered from the upper catchment. Hume Dam acts as a large sediment trap, restricting the movement of sediment down the catchment. As well as providing more suitable conditions within the dam for the production of harmful algal blooms, the reduced sediment load restricts the development of low level benches and bars in the Murray River downstream of Hume Dam, reducing river complexity and the recovery potential.
The Murray catchment upstream of Hume Dam has an extensive network of tributaries identified as conservation reaches. The majority of this area is National Park and State Forest and remains densely vegetated. The recovery potential is decreased in areas cleared for grazing.
There are long reaches in the mid catchment including the Edward River, Wakool River, Niemur River and Merran Creek with low to moderate recovery potential, suggesting sparse riparian vegetation, erosion of the stream bed and stream bank and low instream geomorphic diversity. These reaches are likely sources of suspended sediment.
In the unregulated catchments, land and vegetation management are the key drivers for sediment entering waterways. The principal factor generating high sediment loads (and associated nutrients) is loss of vegetation in the catchment and/or the riparian zone, leading to increased hillslope, gully and bank erosion and increased suspended sediment loads in the river. The main sources of sediment are gully erosion in degraded areas and hillslope erosion where cover is seasonally low through grazing or tillage of cropped lands (National Land and Water Resources Audit 2001). The implementation of flow rules in these catchments will have little impact on reducing sediment inputs. In the regulated system, reducing the extent of bank erosion and slumping may be possible through a more natural, gradual rising and falling limb of water releases from Hume Dam.
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Map produced by NSW Industry | Lands & Water | Water December 2018
Data sources: DPI Fisheries,NSW Industry | Lands & Water | Water; Office of Environment and Heritage
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Figure 21: River styles recovery potential in the Murray and Lower Darling Rivers catchment
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Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
7.3. Elevated levels of nutrients The highest nitrogen and phosphorus concentrations in the Murray Lower Darling WRPA are in the Darling River at Weir 32 and Burtundy, while the lower results were in the unregulated Murray River upstream of Hume Dam. Nitrogen and phosphorus concentrations generally followed similar trends, indicating similar transport processes are driving both parameters. Nutrient concentrations are generally driven by runoff and erosion during rainfall events, with higher concentrations at high flow.
There are areas of high soil nutrient concentrations in the upper catchment (Figures 22 and 23), which may be contributing to the high nutrient concentrations found in the Tooma River at Warbrook. Soil erosivity and nutrient transport may be exacerbated by the historical conversion of forested land to grazing, particularly clearing in the riparian zone. The Murray River at Barham was rated as a high risk to water dependent ecosystems for total phosphorus and total nitrogen, largely in response to a very high consequence score.
Concentrations of total nitrogen and total phosphorus in the Darling River, above the Basin Plan target, resulted in low WaQI scores for Weir 32 (26) and Burtundy (30). Total phosphorus was deemed to be a medium risk to aquatic ecosystems. The Darling middle, lower zone is a priority area to develop local targets to determine if the low WaQI score at these sites are due to poor water quality, or as a consequence of an inappropriate water quality target. In a similar scenario to turbidity, the nutrient targets decrease between the upper Darling zone and the middle lower Darling zone. Total nitrogen decreases from 900 to 500 µg/L and total phosphorus from 250 to 50 µg/L. The National Water Quality Management Strategy recommends and provides guidance for the development of regional and local targets. New South Wales has not developed targets beyond the default trigger values of the ANZECC Guidelines (2000), and therefore required to use the Basin Plan water quality targets for reporting, or commit to the development of regional or location specific guidelines.
The land use in the Darling catchment is dominated by grazing, with some cropping and irrigation of the lower reaches near Wentworth. Apart from floodplain areas closely associated with the river, most of the soils have low soil nutrient concentrations. This suggests that the bulk of the nutrients are delivered from upstream catchments rather than local sources. Access of livestock to the river may also be a source of nutrients and turbidity.
The fertile soils associated with cropping and irrigation in the lower Murray are a potential source of excess nutrients, though there was not a marked increase in nutrient concentrations with distance downstream. Nutrient impacts can be ameliorated, possibly through a process of assimilation by the river, through phytoplankton uptake and deposition, uptake by benthic organisms or by adsorption onto the sediment of the river bed (Caitcheon et al. 1999).
As for sediment, land and vegetation management are the key drivers for nutrients entering waterways in unregulated rivers. The implementation of flow rules upstream of Hume Dam will have little impact on nutrient management. In the regulated system, reducing the extent of eutrophication caused by bank slumping is possible through a more natural, gradual rising and falling limb of water releases.
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Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
Map produced by NSW Industry I Lands & Water 22 August 2018
! Towns
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Soil Total Nitrogen 0-5cm
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Low : 0.030852
Data Sources:
NSW Industry I Lands & Water I Water.
Office of Environment and Heritage.
Murray Darling Basin Authority.
Geoscience Australia.
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Figure 22: Soil total nitrogen for the Murray and Lower Darling Rivers catchment
Map produced by NSW Industry I Lands & Water 22 August 2018
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NSW Industry I Lands & Water I Water.
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Murray Darling Basin Authority.
Geoscience Australia.
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Figure 23: Soil total phosphorus for the Murray and Lower Darling Rivers catchment
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7.4. Elevated levels of cyanobacteria Harmful algal blooms have been a regular occurrence in the Murray valley in recent years with extensive blooms in 2009, 2010 and 2016. A number of factors can contribute to the formation of an algal bloom. Nutrient rich inflows, combined with warm, still, clear water during summer, provide ideal conditions for algal growth. Phosphorus and nitrogen concentrations are generally not limiting to algal growth in the Murray Lower Darling WRPA. Harmful algal blooms do occur, but not to the extent indicated by the nutrient concentrations. This highlights that other factors such as flow, turbidity and light availability are also limiting.
The Murray River is highly regulated and subsequently has a range of impediments, creating weir pools. When Hume Dam storage levels fall below six per cent, blooms in the Murray River have been shown to be more likely to occur. It is felt this is a consequence of reduced releases producing lower velocity flow in the river and/or algal blooms in Hume Dam itself, seeding the river (Baldwin et al 2008, 2009). Lake Mulwala has also been found to seed the river downstream with algae, once a bloom develops. The release of large volumes of water for irrigation over summer results in turbulent, high velocity water which is not suitable for algal growth. High flow releases have generally not been an available management option during algal blooms in the Murray River, as they have occurred during periods of prolonged drought. In all cases it has been a matter of waiting for cooler weather, rain, increased run-off or strong winds to cause the blue-green algae to dissipate, or for the bloom to disperse naturally with time.
Red alerts for recreational use are also common in Menindee Lakes and in the lower Darling River. A discharge of 300 ML/day from Menindee Lakes was found to be sufficient to prevent prolonged periods of persistent thermal stratification, which also suppressed the development of algal blooms. Mitrovic et al. (2011) also found a flow release of 3 000 ML/day was effective at removing an established cyanobacterial bloom. As well as flushing algae downstream, greater discharges increased turbidity, which diminished the growth of cyanobacteria through reduced light availability.
Seeding by Hume Dam was determined to be the major cause of the 2009 bloom. A similar situation occurred downstream of Lake Mulwala, with algal rich water released into the Murray River downstream and diverted into the Mulwala Main Canal. As both Lake Hume and Lake Mulwala were infested with cyanobacteria, there was no clean, non-infested water available to provide flushing flows downstream. Blooms in the mid-section of the Murray River downstream of Torrumbarry Weir through to Euston Weir may have developed in-situ, as a result of the low flow conditions and low water levels increasing residence times in this section of the river.
A combination of nutrients, sunlight, high water temperature, minimal rainfall and still water were proposed as the likely causes of the 2016 bloom, in addition to the release of algal infested water from Lakes Hume and Mulwala (Bowling et al. 2016). The 2016 bloom was unique in that the species composition was comprised predominately of Chrysosporum ovalisporum. The optimal water temperatures for this species are normally 25 to 30°C, but river temperatures during the bloom were not generally this high. Blooms containing C. ovalisporum have been recorded in NSW previously, but these have been small, and the species was not dominant. Most reported blooms of this species have produced the toxin cylindrospermopsin, but the Murray bloom appeared to have been non-toxin producing. Reviews of meteorological, hydrological and water quality data did not provide any obvious reason why this species bloomed at this particular time (Bowling et al. 2016).
Similar to the 2009 bloom, the release of water from upstream to flush algae from the system was not an option due to the lack of clean, non-infested water available to provide flushing flows, and the large extent and severity of the bloom.
Nutrient management in the catchment area of Hume Dam is essential to reduce the risk of algal blooms within the dam. When algal blooms do occur, the level of human exposure can be reduced by implementing the established algal management framework. The NSW Algal Management Strategy and implementation of the Murray and Sunraysia Regional Algal Contingency Plans, are instrumental in ensuring the public health aspects are met. The Murray Regional Algal Coordinating Committee is administered by WaterNSW and includes representatives from NSW Health, NSW Department of Industry Water, Victorian Department of Environment, Land and Water Planning, NSW Office of Environment and Heritage, NSW Department of Primary Industries, Local Land Services, Murray Irrigation Limited, Goulburn-Murray Water, Lower Murray Water, NSW Local Government and the MDBA. The risk at a site with a high recreational usage can be
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reduced via implementing the management strategies of erecting algal warning signs and informing users of the health risks, dangers and symptoms of ingesting or coming into contact with blue-green algae.
7.5. Water temperature outside natural ranges Preece (2004) characterised storages across New South Wales according to their level of impact due to thermal (cold water) pollution. Hume Dam was identified as likely to cause severe cold water pollution in the Murray River, largely due to discharges in the order of 20 000 ML/day during summer. The outlet works of Hume Dam comprise intakes at 30 to 34 m below full storage level. Walker (1980) found the water temperature downstream of Hume Dam to be approximately 3°C lower than upstream of the storage. Due to the large releases, cold water pollution will generally persist for 200 km to the headwaters of Lake Mulwala (Walker 1980).
During most summers, the water temperature downstream of Hume Dam was close to the 20% percentile of the upstream reference site at Jingellic. An impact can be observed in 2012 and 2013. The water temperature downstream is 3 to 5°C colder than the upstream reference site during the summer months. The cold water impact decreases with distance downstream, but is still evident at the Corowa gauging station. It is expected that impacts would extend to Lake Mulwala. Hume Dam filled to 100% following heavy rainfall in 2010 and remained above 90% capacity for most of 2011 and 2012. The greater depth of water above the offtakes results in increased cold water pollution. The impact is not as prononuced during the 2014 to 2016 summer releases. As the storage volume and the depth of water above the outlets decreased over the following years, the impact was not as pronounced.
The thermal pollution WaQI score, using the difference between the reference site and downstream data was 42, which is a poor rating. In addition to cold water pollution, the poor WaQI rating was also a consequence of warmer water released during winter.
Cold water pollution can hinder ecological responses in the Murray River downstream of Hume Dam. The issue of thermal pollution cannot be mitigated in the Murray WRPA through the use of flow rules in the WRP, environmental flows or by making adjustments to release patterns. Major infrastructure works, such as a multi-level offtake or thermal curtain are required.
7.6. Dissolved oxygen outside natural ranges The dissolved oxygen levels at most sites was within the target range for the majority of the data period. During low and cease to flow periods, dissolved oxygen levels become unpredictable and fluctuate from very high to very low. These variations are primarily driven by the response of instream biota in these rivers. High organic carbon, nutrients and water temperatures result in increased microbial respiration. High turbidity and suspended sediment reduces light availability, and likely reduces primary production. The lowest annual median dissolved oxygen results were in the Darling River at Weir 32 and Burtundy. A combination of low flow, high turbidity and warm water temperature can result in low dissolved oxygen levels at these sites.
The Murray River downstream of Yarrawonga Weir monitoring site is located approximately 250 metres downstream of the weir. The release of water from Yarrawonga Weir could result in low dissolved oxygen results downstream. As the annual median was above 100% saturation most years, suggests this is not the case. Similarly the Murray River at Lock 8 monitorinf sites is located downstream of the weir. The progression of water through the weir, and possible aquatic plant growth within the weirs appears to oxygenate the water.
Maintaining low and base flows through cease and commence to pump rules and protection of small freshes in unregulated catchments assist in flushing or turning over stratified pools. This breaks down the stratification and prevents water on the bottom of pools becoming anoxic and unsuitable for aquatic fauna. In addition, flows help prevent excessive algal and aquatic macrophyte growth which can result in supersaturated oxygen conditions.
The Murray is a controlled river. The regulation of flows via dams, weirs and locks reduces the frequency of flooding in return for better security for town water supply and agriculture. The retention of peak winter/spring flows in Lake Hume for later water delivery reduces the frequency of floodwater breaking the banks, and flowing onto the floodplain. Numerous dry years preceding 2010 meant that regular flooding of the valley had
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been further reduced. During the spring and summer of 2010-2011, there were several large flow events that led to widespread flooding of the floodplain, some of which had experienced little recent inundation. This resulted in a large-scale hypoxic blackwater event in the southern Murray–Darling Basin that affected over 2 000 km of river channels and persisted for six months (Whitworth et al. 2012). Further flooding in August 2016 led to an additional hypoxic blackwater event.
Hypoxic (no oxygen) blackwater is a natural feature of lowland river systems, and occurs during flooding when organic material (sticks, leaves, bark and grass) is broken down in the flood water, or is washed off the floodplain, and into the river. The breakdown of this material by bacteria can lead to a sudden decrease in the oxygen available to fish and other organisms. The critical minimum level for dissolved oxygen varies between fish species, their size and their physical condition. The larger the fish, the more oxygen they require. As a general guide, native fish and other large aquatic organisms require at least 2 mg/L of dissolved oxygen in water to survive, but may begin to suffer at levels below 4 to 5 mg/L (Gerhke 1988). The black appearance of the water is due to the release of dissolved carbon compounds, including tannins, as the organic matter decays. Large blackwater events can lead to fish kills and ecosystem collapse (Whitworth et al. 2012).
The extent of the impact that hypoxic blackwater events have on a river is also affected by water temperature. At high water temperatures, there is naturally less dissolved oxygen in the water, and the breakdown of carbon occurs more quickly, making hypoxia more likely to occur. In cooler weather, organic carbon can stimulate productivity in the food chain, but the dissolved oxygen is not consumed so quickly that the water becomes hypoxic. The impact of a hypoxic blackwater event on the river ecosystem can change as the flood water moves downstream. Often the effects of an event can be less severe as flows progress down the catchment.
Hypoxic blackwater events can be particularly severe in the Edward-Wakool system. This system is downstream of both the Barmah-Millewa Forest and Koondrook-Perricoota Forest. During flood events, the Wakool River receives water with high dissolved carbon that is returned from both of these floodplain forests, in addition to carbon entering the river from localised overbank flooding within the Edward-Wakool system.
It is not possible, nor desirable, to prevent hypoxic blackwater events from occurring, as they usually extend over a large area. Hypoxic blackwater events on this scale have occurred in the past, and will continue to occur in the future. It is distressing that these events occur, resulting in the loss of fish and other aquatic life. The impacts of these events on the environment are harmful, but are usually short-term, as the river water re-oxygenates again as the flooding subsides. Naturally occurring events such as these underpin the broad health of rivers. They provide nutrients to drive the overall production of our river and wetland systems. In the longer term, native fish, water birds and other organisms will benefit from the increased production in the river, boosting food supplies and supporting breeding cycles.
It may be possible to reduce the duration and/or severity of hypoxic blackwater events through more frequent flushing of forests and floodplains in winter and early spring, when water temperatures are lower. This will help remove some of the carbon load, so the carbon inputs during subsequent floods will be lower and more likely to result in good outcomes for river ecosystems.
The dilution of blackwater returning to the river from the floodplain, using better quality water released from upstream, has proven to be a successful management approach. These releases provide refuge areas of higher dissolved oxygen for native fish and other aquatic species to congregate until the blackwater event has passed. The Murray Lower Darling Environmental Water Advisory Group (MLD EWAG) in consultation with the Technical Advisory Group determines when and how environmental water is to be released to try and achieve a specific ecological goal or to avoid/mitigate environmental risks wherever possible. The groups also try to predict the likelihood and severity of an event occurring, monitor to detect if an event is occurring and its extent and then respond with the available strategies to help mitigate the effects. The MLD EWAG includes representatives from Local Land Services, Forestry Corporation of NSW, Department of Primary Industries, the Centre for Freshwater Ecosystems, recreational fishing groups, landholder representatives, Murray-Darling Wetlands Working Group, Murray Lower Darling Rivers Indigenous Nations, Office of Environment and Heritage and WaterNSW. The group also includes observers from the Commonwealth Environmental Water Holder and Murray-Darling Basin Authority.
The volume of environmental water available in Lake Hume is not sufficient to flush organic material from the entire floodplain. Instead, environmental water can be used to produce the small floods to flush material from lower areas. Studies undertaken by the Murray Darling Freshwater Research Centre suggest delivering
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environmental flows to forest areas in winter or early spring, when water temperatures are lower and the risk of triggering a hypoxic blackwater event is reduced.
Recommendations to improve prediction and management of hypoxic events (DPIW 2013) include:
Development of a monitoring plan ahead of expected hypoxic events;
Better hydrological knowledge of floodplain returns, with a combination of time series flow data at points along the river, better ratings data from escapes and adequate gaugings at major floodplain escapes during events;
Comprehensive dissolved oxygen time series monitoring;
Comprehensive dissolved organic carbon monitoring before, during and following events, and
Increased use of existing blackwater models to enable better validation and enhance prediction.
The Basin Plan dissolved oxygen target ranges were designed specifically to be applied to monthly data, and provide an indication of any issues. Monitoring of dissolved oxygen is currently conducted monthly, however it does not capture the full diurnal variation. To fully capture dissolved oxygen dynamics, continuous monitoring during a range of hydrologic and seasonal conditions is required. Dissolved oxygen sensors have been installed at key gauging stations in the Murray and Lower Darling catchment as a tool to better monitor blackwater events. The use of continuous data may prove more beneficial for assessing dissolved oxygen concentrations than single monthly readings. Watson et al. (2009) suggests that when dissolved oxygen concentrations drop below 5 mg/L (or 50% saturation) in lowland rivers, there is a substantial increased risk to fish health. This target has been applied in the Basin Plan for managing water flows (Section 9.14 (5)). It was proposed by Tiller and Newall (2010) that the assessment of continuous data against this proposed trigger level may prove more beneficial for dissolved oxygen data analysis and give a better assessment of the oxygen regime.
7.7. Elevated levels of pesticides and other contaminants Historically, monitoring of pesticide residues in rivers has not been undertaken in the Murray and Lower Darling Rivers. With the agricultural industry becoming increasingly reliant on chemical use for weed and pest control, it is expected that the residues of some chemicals may be present in waterways. The detection of residues of herbicides used in dryland agriculture in other valleys has shown a need for natural filters such as grassed waterways, natural grasslands or vegetated buffer strips to reduce chemical concentrations in runoff and aerial drift.
There are no current monitoring data on the presence of toxicants in this water resource plan area. Pollution from mining and industrial activities is controlled through environmental protection licences under the Protection of the Environmental Operations Act 1997 (POEO Act).
7.8. pH outside natural ranges Soil pH increases with distance down the Murray River catchment (Figure 24), but this is not reflected to the same extent in the water quality results. There was a slight increase in the annual median with distance downstream, with the highest results in the Murray River at Merbein Pump Station. The soils in the Darling River catchment are alkaline which could be causing the high pH results at Weir 32 and Burtundy, above the Basin Plan upper limits. The pH in the Darling River sites was also correlated to dissolved oxygen, suggesting elevated pH could be driven by primary productivity, such as increased algal growth.
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Map produced by NSW Industry I Lands & Water 22 August 2018
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Geoscience Australia.
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Figure 24: Soil pH for the Murray and Lower Darling Rivers catchment
7.9. Elevated pathogen counts There are no current data on the extent of pathogens in the Murray Lower Darling WRPA. It is expected that with ongoing inputs of human and animal waste, and access of stock and animals to rivers and streams, that pathogens would be present in waterways. Higher counts would be expected following rainfall and runoff flushing contaminants into the rivers, and during the warmer summer months. Similarly, high counts may be common during low flows in areas with point source pollution. There is an unknown risk from the high prevalence of septic systems across the catchment. As for other pollutants, pathogens cannot be managed through water planning.
7.10. Knowledge gaps Dissolved oxygen
Dissolved oxygen is currently not monitored immediately downstream of Hume Dam. It is anticipated that water drawn through the low level outlets would have very low dissolved oxygen levels. It is not known if turbulence from the process of releasing the water from Hume Dam re-oxygenates the water as it enters the river. Or, how far downstream the water needs to flow before it becomes oxygenated to a level suitable for aquatic organisms.
Water temperature
Clearing of vegetation in the riparian zone and poor geomorphic condition can lead to increased sunlight reaching the water surface, resulting in increased water temperatures. The extent and scale of this form of increased thermal pollution is unknown.
Event based monitoring
The current surface water quality monitoring program targets low and base flow conditions with limited, high flow event based monitoring. High velocity water is generally required to transport large concentrations and loads of suspended sediment and associated nutrients, pesticides and pathogens. Suspended solids and
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nutrients tend to increase during high river flow, when particulate matter is washed from the catchment, bank erosion contributes material and/or bed sediments are resuspended in the water column. The high velocity water in the upper catchment is capable of carrying greater quantities of sediment and nutrients. As the stream bed flattens out across the floodplain, these nutrient rich suspended particles fall out of suspension and are deposited on the floodplain and into river sediments. For streams upstream of Hume Dam, this material is deposited in the dam, settling out of the water column and providing a source of nutrients to sustain algal blooms. The deposition of sediment in the dam results in less material for instream bar and bench formation downstream.
Hazard mapping
Spatial modelling to develop hazard mapping, utilising the range of data sets available such as, riparian vegetation cover and geomorphic condition, and overlaying soil erosion risk areas, soil nitrogen and soil phosphorus, could identify key areas most likely to contribute to poor water quality and guide the implementation of management decisions. In addition, the mapping and identification of high priority refuge pools would assist in the monitoring and delivery of water to maintain water quality suitable for water depended ecosystems during extended dry periods.
Additional water quality monitoring sites
The current New South Wales surface water quality monitoring program has been in operation since 2007. It was established and designed to meet the objectives and data requirements at the time. A revision of the state wide water quality monitoring program is required to better meet the requirements of the Basin Plan and to fill identified information gaps.
Agricultural chemical, toxicants and pathogen data
There are no current data on the concentrations of agricultural chemicals in the creeks and rivers of the Murray Lower Darling WRPA. As large quantities of insecticides and herbicides are used in the catchment, and the main transport mechanisms for their movement in the environment still exist, it is assumed that there is a risk that chemical residues are present in waterways. Without monitoring data, we cannot determine which chemicals are present, when, or the concentrations. Similarly, it is only assumed that there are pathogens present in the waterways.
Development of local water quality targets
It has been identified that some of the Basin Plan water quality targets may not be appropriate for some parameters, in some zones. The Middle and Lower Darling zone is the highest priority for target development, along with assessment of the suggested boundary change to remove the Edward–Wakool system from the central Murray zone. Time frames do not allow for the development of local targets before the completion of the WQMP, but they will be incorporated as a long-term strategy in the plan.
8. Conclusion The quality of the water in a river or stream is a reflection of underlying climate and geology and the multiple activities occurring in a catchment area. There are numerous factors contributing to the observed results, many of which are outside the influence of flow management and therefore cannot be addressed through water planning alone.
In unregulated catchments, greater emphasis must be focused on preventing pollutants such as sediment and nutrients from entering waterways through land, soil and vegetation management. As sediment is a major transport mechanism for many pollutants, practices such as maintaining groundcover, vegetated buffer strips and good agronomic practices together with management of riparian vegetation to reduce stream bank erosion provide simple and effective means to improve water quality. Land and vegetation management does not only address water quality issues in the rivers but also harmful algal blooms in Hume Dam, Menindee Lakes and the Murray River.
In the regulated system, issues of dissolved oxygen, contribution of sediment and nutrients through bank slumping, dissolved organic carbon and to a lesser degree, cold water pollution can be addressed through the implementation of flow rules.
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There are opportunities for government agencies, including NSW Local Land Services (LLS), Office of Environment and Heritage (OEH), DPI Fisheries and DPI Agriculture to work closely with Department of Industry, Water in managing external constraints through complementary measures. Collaboration between natural resource management groups to examine alignment of priorities has been a continued focus of NSW Government (NRC 2010). Alignment of natural resource management continues to be identified as a priority for LLS (Local Land Services 2016) and for the management of environmental water and water quality in New South Wales (OEH 2014). Alignment of priorities for river management will assist in strengthening the outcomes of mitigation measures.
The information and data analysis from this report will support the development of the Murray Lower Darling Water Quality Management Plan (WQMP). Based on the water quality data and information available, water quality objectives for the Murray Lower Darling WRPA will be formulated where there are flow ‘levers’ available to water managers. The WQMP will consider the impacts of wider natural resource and land management on water quality within the Murray Lower Darling water resource plan area. It will provide a framework to protect and maintain water quality that is ‘fit for purpose’ for a range of outcomes. These uses and activities may include irrigation of crops, maintaining a healthy environment, recreational fishing or cultural and spiritual links to Country for Aboriginal communities.
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Appendix A. Water quality monitoring site locations Table 25: Location of water quality monitoring stations in the Murray Lower Darling WRPA
Station Number
Station Name Latitude Longitude
Routine water quality
401556 Murray River at Indi Bridge -36.235100 148.035100
401003 Tooma River at Warbrook -36.044600 148.037900
401201 Murray River at Jingellic -35.929200 147.704100
409001 Murray River at Albury (Union Bridge) -36.091800 146.906800
409025 Murray River d/s Yarrawonga Weir -36.010100 145.997110
409003 Edward River at Deniliquin -35.529700 144.965700
409013 Wakool River at Stoney Crossing -35.037680 143.570500
409034 Wakool River at Kyalite -34.949701 143.481024
409005 Murray River at Barham -35.630400 144.123500
414209 Murray River upstream Euston Weir -34.599700 142.758600
414206 Murray River at Merbein Pump Station -34.173343 142.082577
425012 Darling River at Menindee Weir 32 -32.436903 142.379985
425007 Darling River at Burtundy -33.743683 142.270868
42610001 Murray River at Lock 8 -34.128507 141.399365
Blue-green algae
409001 Murray River at Albury (Union Bridge) -36.091800 146.906800
409026 Mulwala Canal at Offtake -35.982100 146.010700
409025 Murray River d/s Yarrawonga Weir -36.010100 145.997110
409202 Murray River at Tocumwal -35.812820 145.559113
40910089 Murray River at Picnic Point -35.854443 144.998876
40910087 Murray River at Moama (Echuca) -35.120392 144.755067
409005 Murray River at Barham -35.630400 144.123500
41310021 Murray River at Mount Dispersion -34.591176 142.471563
409003 Edward River at Deniliquin -35.529700 144.965700
40910090 Edward River at Old Morago -35.379874 144.653815
409014 Edward River at Moulamein -35.089900 144.033100
409015 Gulpa Ck at Mathoura -35.815147 144.917951
409045 Wakool River at Wakool-Barham Road -35.510500 144.209900
409034 Wakool River at Kyalite -34.949701 143.481024
Continuous electrical conductivity
409016 Murray River downstream Hume Dam (Heywoods) -36.099100 147.024000
409002 Murray River at Corowa -36.007200 146.395300
409025 Murray River downstream Yarrawonga Weir -36.010100 145.997110
409029 Mulwala Canal at Edward River -35.564500 145.008300
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409005 Murray River at Barham -35.630400 144.123500
409008 Edward River at Offtake -35.847900 144.997900
409003 Edward River at Deniliquin -35.530000 144.965700
409023 Edward River downstream Stevens Weir -35.434400 144.758600
409035 Edward River at Leiwah -34.988800 143.622800
409013 Wakool River at Stoney Crossing -35.037680 143.570500
409207 Murray River at Torrumbarry -35.942583 144.464667
409214 Murray River at Pental Island Pumps -35.423556 143.764778
409204 Murray River at Swan Hill 35.327639 143.564167
414203 Murray River at Euston -34.600250 142.758194
414216 Murray River downstream Mildura Weir -34.168139 142.160083
425012 Darling River at Weir 32 -32.436903 142.379985
425005 Darling River at Pooncarie -33.386400 142.567800
425007 Darling River at Burtundy -33.746417 142.268278
A4260501 Murray River at Lock 9 -34.191613 141.595565
Continuous water temperature
401012 Murray River at Biggara -36.319200 148.051900
401013 Jingellic Creek at Jingellic -35.895800 147.692700
401201A Murray River at Jingellic -35.929200 147.704100
409016 Murray River downstream Hume Dam (Heywooods) -36.099100 147.024000
409017 Murray River at Doctors Point -36.112300 146.939900
409001 Murray River at Albury (Union Bridge) -36.091400 146.907000
409037 Murray River at Howlong -35.976400 146.619600
409002 Murray River at Corowa -36.007200 146.395300
409025 Murray River downstream Yarrawonga Weir -36.011400 145.994000
409008 Edward River at Offtake -35.847900 144.997900
Continuous dissolved oxygen
409005 Murray River at Barham -35.630400 144.123500
409047 Edward River at Toonalook -35.642800 144.959600
409003 Edward River at Deniliquin -35.530000 144.965700
409014 Edward River at Moulamein -35.089900 144.033100
409062 Wakool River at Gee Gee Bridge -35.329000 143.932200
409013 Wakool River at Stoney Crossing -35.037600 143.570200
409048 Niemur River at Barham – Moulamein Road -35.273900 144.159500
409086 Niemur River at Mallan School -35.135100 143.800100
409044 Little Merran Creek at Franklins Bridge -35.521400 144.051700
409036 Merran Creek upstream Wakool River Junction -35.107400 143.582600
409111 Barber Creek at Sandy Bridge Road -35.506862 144.078137
425007 Darling River at Burtundy -33.746417 142.268278
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Appendix B. Water quality index (WaQI) method A water quality index is a tool to communicate complex and technical water quality data in a simple and consistent way. It is useful for presenting information with different units (e.g. µg/L and % saturation) or characteristics (e.g. turbidity in a montane vs lowland river) on a common scale. It can also be used as a reporting tool for evaluation of changes in water quality over the life of a water quality management or water sharing plan.
For water quality management plans (WQMP) the WaQI is calculated as an overall integrated index (for five to eight parameters) and for each water quality parameter individually. These calculations are performed independently.
The overall WaQI for the WQMP includes total nitrogen, total phosphorus, turbidity, dissolved oxygen and pH. It is based on the exceedance of water quality targets as prescribed in Schedule 11 of The Basin Plan. Blue-green algae, salinity and temperature are calculated as individual parameters. To calculate the index a minimum of 30 samples is required across a five year period with a minimum of four samples in any one year.
The outcome provides a number between 1 and 100 that is categorised according to the following:
The index for both the overall score or, for an individual parameter is calculated as:
√𝐹12 + 𝐹22
𝑊𝑎𝑄𝐼 = ( )1.41421
Where F1 (frequency), the frequency of the number of failed tests per total tests, is:
𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑓𝑎𝑖𝑙𝑒𝑑 𝑡𝑒𝑠𝑡𝑠 𝐹1 = ( ) × 100
𝑇𝑜𝑡𝑎𝑙 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑡𝑒𝑠𝑡𝑠
And where F2 (amplitude), the amplitude is the amount a value exceeded he target, is:
𝐹2 = (𝑛𝑠𝑒 ÷ [0.01𝑛𝑠𝑒 + 0.01])
Where nse (the normalised sum of excursions) is:
𝑛∑𝑖=1 𝑒𝑥𝑐𝑢𝑟𝑠𝑖𝑜𝑛 𝑖 𝑛𝑠𝑒 = ( )
𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑡𝑒𝑠𝑡𝑠
And where the excursion is:
𝐹𝑎𝑖𝑙𝑒𝑑 𝑡𝑒𝑠𝑡 𝑣𝑎𝑙𝑢𝑒 𝑖 𝐸𝑥𝑐𝑢𝑟𝑠𝑖𝑜𝑛 = (
𝑇𝑒𝑠𝑡 𝑜𝑏𝑗𝑒𝑐𝑡𝑖𝑣𝑒 )
or
𝑇𝑒𝑠𝑡 𝑜𝑏𝑗𝑒𝑐𝑡𝑖𝑣𝑒 𝐸𝑥𝑐𝑢𝑟𝑠𝑖𝑜𝑛 = ( )
𝐹𝑎𝑖𝑙𝑒𝑑 𝑡𝑒𝑠𝑡 𝑣𝑎𝑙𝑢𝑒 𝑖
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How was the method determined?
A literature review of existing water quality index methods, purposes and reviews was conducted in 2015. There is extensive literature (over 500 papers), and a wide range of existing methods (more than 100) of calculating water quality indices. A number of individual index methods as well as key text and review papers (e.g Abbasi and Abbasi 2012; Achterberg 2014; Bauer et al. 2013; Brown et al. 1970; Cude 2001; Dinius 1987; Hurley et al. 2012; Lumb et al. 2011; Srebotnjak et al. 2012; Terrado et al. 2010; Van Oost et al. 2007) were reviewed to determine an appropriate index for NSW that is robust and meets our requirements.
The Canadian Council of Ministers of the Environment (CCME) water quality index (Roulet and Moore 2006) was chosen as method on which to base the WaQI. The key questions that were considered when making this decision were:
Has it been tested and accepted in peer review literature?
How widely is it used?
Can it be used without requiring calibration to biogeographically distinct regions?
Is it flexible, and can it be used with continuous data or toxicants if required?
Has it been tested against ecological indices (e.g. macroinvertebrates)?
Can it be easily presented and understood for reporting?
The method has been modified to remove a subindex that included the number of failed parameters. The subindex was excluded as only five to seven parameters will be used to calculate the NSW WaQI. In comparison, the CCME WQI is designed for up to +30 parameters.
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Appendix C. Literature Review A Web of Science search was undertaken that always included ‘NSW’ and then one of the following ‘Murray River’, ‘Darling River’, ‘Edward River’, ‘Wakool River’, ‘Hume Dam’, or ‘Dartmouth Dam’. This search was supplemented with a search using the Google Scholar database and the terms ‘Murray’, ‘Darling’, ‘river’ and ‘NSW’. The output is summarised in Table 26.
Table 26: Review of published literature
References Subcatchment Description
Korbel and
Hose 2015
Alluvial Found water quality appeared to have relatively little influence on stygofauna.
Some influence on microbial communities. Water flow and habitat appeared
most important for stygofauna.
Macdonald et
al. 2012
Lowlands Flooding supports recruitment for weeds. Recruitment reduced by presence of
other vegetation. Hotter constant temperatures reduced germination.
Fluctuation and colder temperatures increases germination.
Kingsford 2000 Wetlands Water quality has had an effect on river red gum survival. Also studied the
Macquarie, Barmah, Millewa and Moira Marshes and Chowilla floodplain.
Brock et al. Narran Lakes, Tested response to zooplankton hatching and seed germination to different
2005 Gwydir
wetlands,
Macquarie
Marshes,
Billybung
Lagoon, Lake
Cowal, Great
Cumbung
Swamp, Darling
anabranch
salinities in a range of wetlands. Salinity increases in soils when damp but not
when flooded. Aquatic plant germination and species richness decreased
significantly with increasing salinity. These decreases started immediately
between the lowest treatments of <300 to 1000 mg/L. Similar for zooplankton
hatching, Macquarie Marshes had significant declines above <300 mg/L,
Narran Lakes and Gwydir had declines above 1000 mg/L. Community structure
changed above 1000 mg L Increased salinity however had no effects on Lake
Cowal, Darling Anabranch and Great Cumbung Swamp (ie up to 5000 mg/L
treatment). There was no change in community structure.
Kelleway et al.
2010
Wetlands Carbon sources supporting consumers are varied and appear related to spatial
distribution of primary producers. Highlights the importance of riparian
vegetation as a carbon source, its influence on shading and decreases in in-
channel solar radiation limiting in-channel autotrophic production.
Norris et al. Murray and Habitat condition is degraded across much of the basin. Loss of riparian
2001 Lower Darling
(and all of Basin)
vegetation and increased sand and gravel bed load are the principal
components causing degradation. Most marked degradation is in the mid
slopes.
Nutrient and sediment loads from the Australian Alps are largely unmodified. Most of the loads are generated in the upland and mid-slope areas while most of the impact is felt in lowland rivers, weir pools and reservoirs where the sediment is stored. In the long-term, management needs to focus on reducing sediment supply, but the greatest short-term benefits will come from managing the lowland sediment and nutrient stores.
Parts of the Murray River are extremely impaired, with 43% of the Murray
Riverina area and 19% of the Darling River substantially modified. Parts of the
Murray River may have lost over 80%of the biota likely to have occurred there.
Rolls et al.
2013
Lowlands,
midlands
Temperature, flows, habitat and food resource (prey size and availability) all
impair fish recruitment. Flow magnitude and water temperature appeared to
have the largest effect in determining larval fish composition. Hypothesised that
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a lack of prey and resources may be one of the reasons why there is not a
strong response to managed flow events.
Erskine et al.
2012
Lowlands Studies the importance of in-stream woody debris to protect against erosion
and restore river health.
Austin et al.
2010
Murray and
Darling (and all
of Basin)
Estimates that climate change my reduce water yield in the Upper Murray River
by over 18% by 2030 and 43% by 2070, the Murray-Riverina by over 21% by
2030 and 48% by 2070, and Darling River by over 26% by 2030 and 57% by
2070. These numbers are based on the higher resolution model of two
scenarios tested. This scenario is overly optimistic and assumes wide spread
change in energy production industry towards less emissions intensive.
Woodward et Midlands Examined carbon and nutrient inputs from banks under different flow heights.
al. 2015 Where river channels have already been impacted by regulated flows, complex
surfaces may have been lost, so restoring more natural flows at these levels of
channel, may have little immediate impact on nutrient processing. Low level
benches will need to be ‘rebuilt’ before environmental flows can increase connectivity.
NSW DPI, 2006 Weir review,
Murray River
Detailed review of weirs in the Murray River catchment providing a
comprehensive overview of each structure including operational details, system
hydrology, ecological considerations, and the preferred remediation option of
NSW DPI for improving fish passage at the weir.
Ryan et al. Murray River High concentrations of cyanobacteria were detected by routine monitoring in
2009 Lake Hume in March 2009, resulting in the issuing of a red alert for recreational
use. Following the detection of the bloom in Lake Hume, additional
downstream monitoring indicated that cyanobacteria was present in the Murray
River for a distance of 1 000 km, including associated tributaries of Gulpa
Creek, Edward River and Wakool River.
Sherman 2005 Hume Dam Discharge temperatures from Hume Dam during spring and summer may be
depressed by more than 5°C relative to the temperature in the surface layer of
the reservoir. Hume Dam receives water from Dartmouth Dam via the Mitta
Mitta River and from the Snowy Hydro Scheme via the River Murray. Both of
these sources may deliver unseasonably cold inflows to Hume Dam.
Two options proposed for mitigation of cold water pollution: construction of a multi-level offtake or deployment of a submerged curtain. The submerged curtain option was expected to produce the greatest discharge temperature.
Sherman et al
2007
Hume Dam Mitigation of cold water pollution through the introduction of selective
withdrawal capabilities to access near-surface water is predicted to increase
discharge temperatures during the crucial spring-early summer post-spawning
period by 4–6°C for normal operating conditions. No improvement in discharge
temperature was predicted for drought conditions characterised by relatively
low storage levels in early spring. The predicted temperature increase using
selective withdrawal increased the predicted average minimum female
population abundance by 30–300%. Increased discharge temperatures appear
to be achievable and are expected to reduce the stress currently impacting
Murray cod populations during crucial post-spawning periods. This provides
evidence that mitigation of this problem may assist in rehabilitating Murray cod
populations in the Murray River downstream of Hume Dam.
Whitworth et al
2012
Southern Murray
Darling Basin
After a decade long drought in south-eastern Australia, a series of spring and
summer flood events in 2010–2011 resulted in a large-scale hypoxic
blackwater event in the southern Murray–Darling Basin that affected over
2000 km of river channels and persisted for six months. Inundation of both
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forested and agricultural floodplains that had not been flooded for over a
decade mobilised large stores of reactive carbon. Altered flow seasonality, due
to a combination of climatic effects and river regulation, not only increased the
risk of hypoxic blackwater generation, but also shifted the proportion of
bioavailable carbon that was returned to the river channels. Hypolimnetic weir
discharge also contributed to hypoxia at some sites.
Mitrovic et al.
2011
Lower Darling Flow releases from the regulated Menindee Lakes System were assessed for
their ability to either suppress bloom development or to mitigate pre-existing
blooms over this period in the Darling River at Weir 32. A discharge of
300 ML/day (flow velocity of 0.03 m/s) was found to be sufficient to prevent
prolonged periods of persistent thermal stratification, which also suppressed
the development of Anabaena circinalis blooms. A flow release of 3000 ML/day
was effective at removing an established cyanobacterial bloom, and total
cyanobacterial numbers declined from over 100 000 to 1 000 cells/mL within a
week.
In two summers without blooms, higher flows and decreased light availability
prevented the development of cyanobacterial blooms. Flow releases were
effective at mitigating cyanobacterial growth through either the suppression of
persistent thermal stratification or through dilution and translocation of cells.
Greater discharges also increased turbidity, which diminished the growth of
cyanobacteria through reduced light availability under the mixed conditions,
which also reduced the ability for surface migration through buoyancy
regulation.
Bowling et al.
2016
Murray River An unusual bloom of Chrysosporum ovalisporum occurred in the Murray River
from mid-February to early June 2016. At its greatest extent in April and May it
extended along the river from Lake Hume to Lock 8 and also throughout the
Edward, Wakool and Niemur River distributary system, a combined river length
of about 2360 km. It also extended into distributary systems in Victoria. Bloom
densities at times exceeded 40 mm3/L, and C. ovalisporum usually comprised
>99% of the total bloom biovolume at most locations sampled. The origins of
the bloom were most likely Lakes Hume and Mulwala on the upper Murray
River, with cyanobacterial infested water released from them contaminating the
river systems downstream.
Thoms et al. Darling River In the Great Darling Anabranch, the fish community is dominated by carp as
2000 there is little habitat available for native fish except during floods. Riparian
vegetation is in poor condition as a result of clearing in the past. Grazing has
affected the regeneration of vegetation on the floodplain to some extent.
Parsons et al.
2008
Murray Darling
Basin
Generally the river systems in the upper Murray remain relatively fresh.
However salinity in the lower Murray (the Mallee region), in particular below the
South Australian border, can approach critical levels. There is a delicate
balance in the interface between the groundwater regime and the river regime.
The river varies between being a losing stream and a gaining stream.
Gilligan and Carp abundance in the upper Murray River was relatively low compared to
Rayner 2007 other Murray-Darling Basin catchments in NSW. Except for Lake Hume itself
and wetlands on the upper Murray floodplain, carp are unlikely to have a
substantial impact on turbidity and sediment re-suspension given the low
proportion of muddy substrates susceptible to re-suspension. Low carp
abundances in upstream areas are linked to unsuitable habitat and water
quality conditions (colder winter temperatures).
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Appendix D. Water quality summary statistics Table 27: Water quality summary statistics for the Murray Lower Darling WRPA 2007-2015 water quality data
Total Nitrogen (mg/L)
Total Phosphorus (mg/L)
Site Name N Mean Std Dev Std Error Min Q10 Q25 Median Q75 Q90 Max
Murray River at Indi Bridge 88 0.206 0.205 0.022 0.060 0.110 0.130 0.165 0.215 0.290 1.900
Tooma River at Warbrook 88 0.425 0.308 0.033 0.170 0.240 0.285 0.350 0.450 0.640 2.600
Murray River at Jingellic 89 0.260 0.122 0.013 0.130 0.160 0.190 0.220 0.330 0.390 0.940
Murray River at Union Bridge 86 0.361 0.111 0.012 0.140 0.250 0.280 0.350 0.430 0.520 0.710
Murray River d/s Yarrawonga Weir 88 0.384 0.210 0.022 0.190 0.230 0.280 0.320 0.450 0.550 1.900
Edward River at Deniliquin 87 0.389 0.155 0.017 0.200 0.250 0.290 0.340 0.450 0.570 0.980
Wakool River at Stoney Crossing 86 0.614 0.258 0.028 0.300 0.420 0.480 0.555 0.650 0.770 2.100
Wakool River at Kyalite 84 0.550 0.282 0.031 0.220 0.320 0.385 0.480 0.615 0.780 2.000
Murray River at Barham 82 0.447 0.277 0.031 0.140 0.250 0.280 0.325 0.510 0.820 1.600
Murray River u/s Euston Weir 83 0.662 0.385 0.042 0.170 0.320 0.390 0.550 0.790 1.300 1.800
Murray River at Merbein Pump Station 77 0.486 0.311 0.035 0.130 0.220 0.300 0.390 0.590 0.960 1.600
Darling River at Menindee Weir 32 76 1.232 0.427 0.049 0.530 0.690 0.930 1.200 1.500 1.800 3.000
Darling River at Burtundy 82 1.119 0.371 0.041 0.430 0.730 0.840 1.000 1.300 1.600 2.300
Murray River at Lock 8 23 0.462 0.156 0.032 0.280 0.290 0.350 0.420 0.540 0.640 0.880
Site Name N Mean Std Dev Std Error Min Q10 Q25 Median Q75 Q90 Max
Murray River at Indi Bridge 88 0.025 0.034 0.004 0.007 0.012 0.015 0.020 0.026 0.031 0.323
Tooma River at Warbrook 88 0.055 0.050 0.005 0.016 0.027 0.036 0.045 0.055 0.072 0.404
Murray River at Jingellic 89 0.029 0.019 0.002 0.010 0.016 0.020 0.025 0.034 0.045 0.170
Murray River at Union Bridge 86 0.028 0.011 0.001 0.010 0.018 0.021 0.025 0.031 0.043 0.064
Murray River d/s Yarrawonga Weir 88 0.036 0.019 0.002 0.010 0.021 0.027 0.032 0.037 0.054 0.166
Edward River at Deniliquin 87 0.049 0.027 0.003 0.018 0.030 0.030 0.042 0.055 0.071 0.180
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Wakool River at Stoney Crossing 86 0.061 0.048 0.005 0.020 0.030 0.040 0.054 0.072 0.091 0.420
Wakool River at Kyalite 84 0.068 0.053 0.006 0.030 0.030 0.040 0.054 0.075 0.101 0.430
Murray River at Barham 83 0.048 0.030 0.003 0.010 0.020 0.030 0.040 0.059 0.090 0.160
Murray River u/s Euston Weir 94 0.058 0.044 0.005 0.010 0.030 0.035 0.045 0.060 0.090 0.291
Murray River at Merbein Pump Station 90 0.048 0.039 0.004 0.010 0.020 0.020 0.039 0.051 0.090 0.230
Darling River at Menindee Weir 32 89 0.275 0.137 0.015 0.060 0.090 0.169 0.280 0.352 0.434 0.886
Darling River at Burtundy 95 0.260 0.139 0.014 0.010 0.060 0.120 0.270 0.375 0.430 0.510
Murray River at Lock 8 23 0.062 0.032 0.007 0.019 0.033 0.039 0.056 0.077 0.105 0.145
Turbidity (NTU)
Site Name N Mean Std Dev Std Error Min Q10 Q25 Median Q75 Q90 Max
Murray River at Indi Bridge 94 7.3 19 2.0 1.0 3.0 3.0 4.0 7.0 10 188
Tooma River at Warbrook 94 27 105 11 2.0 6.0 9.0 12 17 24 1000
Murray River at Jingellic 95 13 34 3.4 3.0 4.0 5.0 7.0 11 16 329
Murray River at Union Bridge 93 9.1 4.5 0.5 3.0 5.0 6.0 8.0 10 14 31
Murray River d/s Yarrawonga Weir 89 16 8.5 0.9 5.0 9.0 10 14 19 29 57
Edward River at Deniliquin 94 32 11 1.2 13 20 25 30 37 44 85
Wakool River at Stoney Crossing 89 41 24 2.5 7.0 9.0 20 39 56 68 127
Wakool River at Kyalite 94 52 25 2.6 6.0 29 36 50 64 77 164
Murray River at Barham 95 33 19 2.0 5.0 14 19 28 41 57 104
Murray River u/s Euston Weir 90 33 19 2.0 7.0 13 19 27 45 57 110
Murray River at Merbein Pump Station 80 31 31 3.5 0.8 10 14 23 37 63 250
Darling River at Menindee Weir 32 87 199 160 17 12 36 97 165 264 405 895
Darling River at Burtundy 93 208 198 20 9.0 19 86 148 287 451 1198
Murray River at Lock 8 24 36 20 4.2 14 14 17 30 53 69 74
Total Suspended Solids (mg/L)
Site Name N Mean Std Dev Std Error Min Q10 Q25 Median Q75 Q90 Max
Murray River at Indi Bridge 92 10 19 1.9 5.0 5.0 5.0 6.0 10 14 170
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Tooma River at Warbrook 92 25 61 6.4 5.0 5.0 8.0 14 24 31 570
Murray River at Jingellic 93 12 18 1.9 5.0 5.0 5.5 9.0 13 20 170
Murray River at Union Bridge 90 8.9 4.8 0.5 5.0 5.0 5.0 7.4 11 14 27
Murray River d/s Yarrawonga Weir 88 14 7.1 0.8 5.0 6.5 10 14 17 23 56
Edward River at Deniliquin 92 35 14 1.4 12 20 26 32 42 53 87
Wakool River at Stoney Crossing 91 24 15 1.5 7.5 10 13 20 28 39 81
Wakool River at Kyalite 87 28 14 1.5 9.0 17 20 25 32 43 97
Murray River at Barham 88 35 25 2.7 7.0 14 20 30 40 59 180
Murray River u/s Euston Weir 46 26 21 3.1 5.0 10 14 19 31 52 110
Murray River at Merbein Pump Station 40 21 16 2.5 7.0 9 11 16 25 42 80
Darling River at Menindee Weir 32 4 20 7.9 4.0 12 12 14 18 26 30 30
Darling River at Burtundy 44 69 84 13 10 18 25 43 76 120 410
Murray River at Lock 8 23 17 6.5 1.4 6.0 11 12 17 19 26 36
Dissolved Oxygen (% saturation)
Site Name N Mean Std Dev Std Error Min Q10 Q25 Median Q75 Q90 Max
Murray River at Indi Bridge 92 97 3.8 0.4 84 91 95 97 99 101 106
Tooma River at Warbrook 94 90 5.4 0.6 74 81 86 90 94 96 99
Murray River at Jingellic 91 91 4.7 0.5 72 85 89 91 95 97 101
Murray River at Union Bridge 92 89 11 1.2 50 74 83 93 96 100 106
Murray River d/s Yarrawonga Weir 88 101 7.8 0.8 76 91 97 101 106 111 120
Edward River at Deniliquin 95 93 13 1.3 36 83 91 97 100 103 110
Wakool River at Stoney Crossing 87 90 17 1.8 23 77 84 92 98 104 122
Wakool River at Kyalite 93 86 18 1.9 2.0 77 83 90 96 100 108
Murray River at Barham 95 94 15 1.5 23 86 94 98 101 103 110
Murray River u/s Euston Weir 66 91 17 2.1 7.7 83 90 95 98 102 114
Murray River at Merbein Pump Station 86 99 16 1.7 18 91 96 101 106 112 131
Darling River at Menindee Weir 32 92 86 18 1.9 50 62 75 86 96 108 163
Darling River at Burtundy 93 90 21 2.1 47 69 79 91 96 110 191
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Murray River at Lock 8 24 106 5 1.0 98 100 104 105 110 111 116
pH
Site Name N Mean Std Dev Std Error Min Q10 Q25 Median Q75 Q90 Max
Murray River at Indi Bridge 93 7.01 0.26 0.03 6.40 6.60 6.80 7.00 7.20 7.30 7.50
Tooma River at Warbrook 94 6.96 0.29 0.03 6.10 6.60 6.80 7.00 7.10 7.30 7.60
Murray River at Jingellic 93 6.97 0.31 0.03 6.30 6.50 6.80 7.00 7.10 7.30 7.70
Murray River at Union Bridge 93 7.11 0.40 0.04 6.10 6.60 6.90 7.10 7.40 7.50 8.70
Murray River d/s Yarrawonga Weir 89 7.29 0.53 0.06 5.90 6.70 7.00 7.30 7.50 7.90 8.70
Edward River at Deniliquin 96 6.94 0.38 0.04 6.00 6.50 6.70 6.90 7.20 7.50 7.90
Wakool River at Stoney Crossing 88 7.16 0.39 0.04 6.40 6.70 6.90 7.10 7.40 7.79 8.30
Wakool River at Kyalite 93 7.08 0.33 0.03 6.20 6.60 6.90 7.10 7.29 7.50 8.10
Murray River at Barham 95 7.15 0.40 0.04 6.00 6.70 6.90 7.20 7.40 7.60 8.50
Murray River u/s Euston Weir 91 7.33 0.39 0.04 6.30 6.89 7.03 7.40 7.60 7.80 8.10
Murray River at Merbein Pump Station 86 7.51 0.41 0.04 6.48 7.00 7.24 7.50 7.70 8.10 8.60
Darling River at Menindee Weir 32 91 7.73 0.76 0.08 6.21 6.72 7.10 7.76 8.34 8.70 9.26
Darling River at Burtundy 93 8.04 0.61 0.06 6.70 7.28 7.70 7.96 8.33 9.00 9.50
Murray River at Lock 8 24 7.43 0.32 0.07 6.50 7.10 7.25 7.45 7.55 7.90 8.00
Electrical Conductivity (µS/cm)
Site Name N Mean Std Dev Std Error Min Q10 Q25 Median Q75 Q90 Max
Murray River at Indi Bridge 89 43 9.3 1.0 20 30 39 43 49 55 61
Tooma River at Warbrook 89 66 11 1.2 31 53 61 66 71 79 98
Murray River at Jingellic 90 40 7.6 0.8 26 30 35 40 46 51 58
Murray River at Union Bridge 89 50 7.7 0.8 34 41 45 52 57 61 67
Murray River d/s Yarrawonga Weir 89 56 6.9 0.7 38 46 51 56 62 64 72
Edward River at Deniliquin 88 66 29 3.1 44 48 56 60 67 78 287
Wakool River at Stoney Crossing 87 805 1311 141 67 98 138 203 660 2990 5330
Wakool River at Kyalite 84 160 144 16 55 85 98 130 166 202 1070
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Murray River at Barham 83 78 18 1.9 52 60 65 77 87 96 149
Murray River u/s Euston Weir 94 120 39 4.0 75 83 92 109 134 178 314
Murray River at Merbein Pump Station 90 150 43 4.5 76 103 122 141 168 211 295
Darling River at Menindee Weir 32 89 538 402 43 116 242 318 417 512 1200 2057
Darling River at Burtundy 95 512 290 30 168 255 327 417 574 884 1780
Murray River at Lock 8 23 166 54 11 94 112 135 158 187 227 309
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Table 28: Electrical conductivity in the Darling River at Burtundy and Murray River at Lock 6 for purposes of long term salinity planning
Year
Darling River at Burtundy
Salinity (EC µS/cm) Salt Load (t/year)
Murray River at Lock 6
Salinity (EC µS/cm) Salt Load (t/year)
Median
(50%ile)
Peak (80%ile) Total Median (50%ile) Peak (80%ile) Total
2008-2009 401 564 67228 249 292 178297
2009-2010 394 406 323 199 229 198061
2010-2011 325 359 557195 211 266 2116801
2011-2012 335 390 549513 194 253 1238268
2012-2013 483 530 401276 303 360 847017
2013-2014 520 577 75310 223 289 436997
2014-2015 846 916 11797 182 197 319856
2015-2016 1293 1627 321 170 197 241029
2016-2017 517 921 143829 222 285 1101578
Mean 200755 741989
Table 29: Electrical conductivity in Edward and Wakool Rivers for purposes of long term salinity planning
Edward River at Leiwah Wakool River at Stoney Crossing
Year Salinity (EC µS/cm) Salt Load (t/year)
Salinity (EC µS/cm) Salt Load (t/year)
Median
(50%ile)
Peak (80%ile) Total Median (50%ile) Peak (80%ile) Total
2001-2002 89 183 27796 503 680 44343
2002-2003 65 85 19619 335 515 34750
2003-2004 79 98 26331 328 443 37282
2004-2005 67 81 21452 280 333 32444
2005-2006 69 88 33943 233 437 33551
2006-2007 64 87 19219 380 517 25503
2007-2008 89 122 9446 1682 4102 13582
2008-2009 65 78 9853 3461 5042 26224
2009-2010 64 76 14971 776 1482 20235
2010-2011 120 157 133869 133 369 216204
2011-2012 142 177 98994 170 268 60557
2012-2013 126 152 54892 169 281 56631
2013-2014 107 136 40236 153 222 25525
2014-2015 83 99 33406 135 185 20436
Mean 38859 46233
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Table 30: Electrical conductivity in the mid Murray River for purposes of long term salinity planning
Year
Murray River at Barham
Salinity (EC µS/cm) Salt Load (t/year)
Murray River at Euston
Salinity (EC µS/cm) Salt Load (t/year)
Median (50%ile) Peak (80%ile) Total Median (50%ile) Peak (80%ile) Total
2001-2002 82 121 87210 199 265 238168
2002-2003 63 95 78053 114 165 171529
2003-2004 78 88 126799 115 135 202836
2004-2005 78 90 112267 115 130 189509
2005-2006 75 92 123916 111 126 218957
2006-2007 65 76 67549 96 124 119219
2007-2008 71 81 68160 95 132 94665
2008-2009 58 65 50091 79 116 89567
2009-2010 59 68 57377 88 104 98480
2010-2011 104 137 454724 156 187 1124117
2011-2012 98 127 300864 130 152 621889
2012-2013 87 97 210862 119 134 429305
2013-2014 81 95 151461 97 128 240270
2014-2015 82 90 157099 88 110 220858
Mean 146174 289955
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Appendix E. Draftsman plots and Box plots by site The mean daily discharge, turbidity, total nitrogen, total phosphorus and total suspended solids data in the draftsman plots has been natural log transformed to normalise the distribution of the data. Some outlying data points have been removed from the data sets to maintain focus on the core data.
The box plots show the annual 25th, 50th and 75th percentile values, with error bars indicating the maximum and minimum values for each parameter. The data set extends from 2007 to 2015, and displays within site variability. In each figure there are numerous plots with A) total nitrogen, B) total phosphorus, C) turbidity, D) total suspended solids, E) dissolved oxygen, F) pH, G) electrical conductivity measured during monthly sampling and H) continuous electrical conductivity (where measured). Red lines indicate the Basin Plan water quality targets (and target ranges) from Schedule 11 of the Basin Plan for the appropriate zone. Total suspended solids have a lower detection limit of 5 mg/L.
Monitoring at the Murray River at Lock 8 commenced in July 2013, in response to the identification of a water quality data gap in the Lower Murray zone. There is insufficient data to show meaningful correlations in the draftsman plots and boxplots.
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Murray River at Indi Bridge There was a positive correlation between total nitrogen and total phosphorus, indicating that both nutrients are transported via similar mechanisms. Nutrients were correlated to turbidity, but not to flow. Electrical conductvity had a slight negative correlation to flow.
The majority of total nitrogen and total phosphorus results were less than the respective Basin Plan targets, even during years of high flow. The annual median turbidity exceeded the target every year from 2009 to 2015. Dissolved oxygen and pH are both within the desired range. The electrical conductivity is very low with and annual median less than 50 µS/cm. Following the flooding in 2010, there was a slight increase in electrical conductivity from 2011 to 2014, and then decreasd again in 2014-2015. The increase is likely in response to the wetting up of the catchment in 2010, resulting in increased baseflow contributions from slightly more saline groundwater.
5.0 6.0 7.0 8.0
5.0
6.5
8.0
LnQ
85
95
10
5
DO
20
40
60
EC
0.0
50
.20
LnTN
6.4
6.8
7.2
pH
0.0
10
.03
LnTP
1.8
2.2
2.6
3.0
LnTSS
1.0
2.0
LnNTU
5.0 6.0 7.0 8.0
51
52
5
85 90 95 100 20 30 40 50 600.05 0.15 0.25 6.4 6.8 7.2 0.01 0.02 0.03 0.04 1.8 2.2 2.6 3.0 1.0 1.5 2.0 2.5 5 10 15 20 25
51
52
5
TEMP
Murray River at Indi Bridge
Figure 25: Draftsman plots for Murray River at Indi Bridge
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2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0.0
0.1
0.2
0.3
0.4T
N (
mg/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0.00
0.01
0.02
0.03
0.04
TP
(m
g/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
5
10
15
Turb
idity (
NT
U)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
5
10
15
20
TS
S (
mg/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
80
90
100
110
120
DO
(%
sat)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
6.5
7.0
7.5
8.0
pH
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
25
50
75
EC
(µS
/cm
)
A) B)
C) D)
E) F)
G)
Figure 26: Water quality data for Murray River at Indi Bridge
NSW Department of Industry | PUBXX/YYYY | 80
Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
Tooma River at Warbrook The draftsman plots show a positive correlation between total nitrogen, total phosphorus and turbidity, with only total nitrogen and turbidity showing a positive correlation with flow. There was no correlation between electrical conductivity and flow.
The annual median turbidity and total phosphorus exceed the Basin Plan target every year, with total nitrogen exceeding the target in the high flow years from 2010-2012 and in 2013-2014. Total phosphorus results did not fluctuate in response to high flow years which is consistent with the draftsman plots for this site. The annual median dissolved oxygen was stable throughout the sampling period, with most results between 85 and 95% saturation. Some dissolved oxygen results during low flows dropped below the Basin Plan lower limit. The pH was mostly within the Basin Plan upper and lower limits. Electrical conductivity was low and generally stable, with the annual median fluctuating between 50 and 75 µS/cm. There was a slight increase in electrical conductivity in 2012-2013, but results had returned to a more normal level by 2014-2015.
4 5 6 7 8
45
67
8
LnQ
75
85
95
DO
30
50
70
90
EC
0.2
0.4
0.6
LnTN
6.5
7.0
7.5
pH
0.0
20
.06
0.1
0
LnTP
2.0
3.0
4.0
LnTSS
1.0
2.0
3.0
4.0
LnNTU
4 5 6 7 8
51
52
5
75 80 85 90 95 30 50 70 90 0.2 0.4 0.6 6.5 7.0 7.5 0.02 0.06 0.10 2.0 2.5 3.0 3.5 4.01.0 2.0 3.0 4.0 5 10 15 20 25
51
52
5
TEMP
Tooma River at Warbrook
Figure 27: Draftsman plots for Tooma River at Warbrook
NSW Department of Industry | PUBXX/YYYY | 81
Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0.00
0.25
0.50
0.75
1.00T
N (
mg/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0.000
0.025
0.050
0.075
0.100
0.125
TP
(m
g/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
20
40
60
80
Turb
idity (
NT
U)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
20
40
60
80
TS
S (
mg/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
80
90
100
110
120
DO
(%
sat)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
6.5
7.0
7.5
8.0
pH
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
25
50
75
100
125
EC
(µS
/cm
)
A) B)
C) D)
E) F)
G)
Figure 28: Water quality data for Tooma River at Warbrook
NSW Department of Industry | PUBXX/YYYY | 82
Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
Murray River at Jingellic There were strong correlations between total nitrogen, total phosphorus and turbidity, indicating transport by similar mechanisms. All three parameters were corrleated to flow. Electrical conductivity did not show a clear correlation to flow.
Total nitrogen, total phosphorus and turbidity all increased during the higher flow years from 2010 to 2012. The annual median turbidity exceeded the Basin Plan target every year. Total phosphorus exceeded the target from 2010 to 2012 while total nitrogen did not exceede the target. The majority of the dissolved oxygen results remained above the lower limit of 85% saturation and pH varied from year to year within the upper and lower range. Electrical conductivity was generally less than 50 µS/cm with a very small increase following the flooding in 2010.
7.0 8.0 9.0
7.0
8.0
9.0
LnQ
75
85
95
DO
25
35
45
55
EC
0.2
0.4
LnTN
6.4
7.0
7.6
pH
0.0
20
.06
LnTP
2.0
3.0
LnTSS
1.5
2.5
3.5
LnNTU
7.0 8.0 9.0
51
02
0
75 85 95 25 35 45 55 0.2 0.3 0.4 0.5 6.4 6.8 7.2 7.6 0.02 0.04 0.06 0.08 2.0 2.5 3.0 3.5 1.5 2.5 3.5 5 10 15 20 25
51
02
0
TEMP
Murray River at Jingellic
Figure 29: Draftsman plots for Murray River at Jingellic
NSW Department of Industry | PUBXX/YYYY | 83
Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0.0
0.2
0.4
0.6T
N (
mg/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0.000
0.025
0.050
0.075
TP
(m
g/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
10
20
30
Turb
idity (
NT
U)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
20
40
60
TS
S (
mg/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
80
90
100
110
120
DO
(%
sat)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
6.5
7.0
7.5
8.0
pH
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
25
50
75
EC
(µS
/cm
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
25
50
75
EC
(µS
/cm
)
A) B)
C) D)
E) F)
G) H)
Figure 30: Water quality data for Murray River at Jingellic
NSW Department of Industry | PUBXX/YYYY | 84
Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
Murray River at Albury (Union Bridge) The Murray River at Albury site is located approximately 26 km downstream of Hume Dam. The quality of the water at this site is impacted by the quality and quantity of the water in Hume Dam. When stratified, the bottom waters of large storages can become anoxic, resulting in the release of nutrients and metals from the reservoir sediments.
There were positive correlations between total nitrogen, total phosphorus and turbidity, indicating transport by similar mechanisms. Total nitrogen showed a slight positive correlation to flow, while total phosphorus and turbidity did not. Electrical conductivity was not correlated to flow, due to the stabilising influence of releases from Hume Dam. Some low dissolved oxygen results were recorded during high flows.
Total nitrogen, total phosphorus and turbidity annual medians were all highest during the high flow year of 2010-2011. The annual median total phosphorus and turbidity did not exceed the Basin Plan target. Total nitrogen exceded the target in 2010-2011. The annual median dissolved oxygen was above the lower limit all years except for 2010-2011. The flooding and inundation of high banks and floodplains in 2010 may have resulted in decreased dissolved oxygen. The pH fluctuated between the upper and lower limits, and would not post a threat to aquatic ecosystems. Despite the release of low salinity water from Hume Dam, there was some fluctuation in electrical conductivity between years. Similar to the unregulated catchments, electrical conductivity increased between 2010 and 2012 in response to flooding and the subsequent recharge of shallow groundwater. From 2012 to 2015, electrical conductivity decreased to lower levels.
7 8 9 10
78
91
0
LnQ
50
70
90
DO
35
45
55
65
EC
0.2
0.4
LnTN
6.0
7.0
8.0
pH
0.0
10
.04
LnTP
2.0
2.5
3.0
LnTSS
1.5
2.5
3.5
LnNTU
7 8 9 10
51
02
0
50 70 90 35 45 55 65 0.2 0.3 0.4 0.5 6.0 7.0 8.0 0.01 0.03 0.05 2.0 2.5 3.0 1.5 2.0 2.5 3.0 3.55 10 15 20 25
51
02
0
TEMP
Murray River at Albury
Figure 31: Draftsman plots for Murray River at Albury
NSW Department of Industry | PUBXX/YYYY | 85
Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0.1
0.2
0.3
0.4
0.5
0.6T
N (
mg/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0.00
0.02
0.04
0.06
0.08
TP
(m
g/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
5
10
15
20
25
Turb
idity (
NT
U)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
5
10
15
20
25
TS
S (
mg/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
40
60
80
100
120
DO
(%
sat)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
6.5
7.0
7.5
8.0
pH
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
20
40
60
80
EC
(µS
/cm
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
20
40
60
80
EC
(µS
/cm
)
A) B)
C) D)
E) F)
G) H)
Figure 32: Water quality data for Murray River at Albury
NSW Department of Industry | PUBXX/YYYY | 86
Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
Murray River downstream Yarrawonga Weir There were strong correlations between total nitrogen, total phosphorus and turbidity, indicating transport by similar mechanisms. All three parameters were correlated to flow, suggesting nutrients were transported attached to soil particles during high flow events. There was not a correlation between flow and electrical conductivity. The release of low salinity water from Hume Dam and minimal saline inputs downstream keeps the electrical conductivity at this site low.
Total nitrogen, total phosphorus and turbidity annual medians were all highest during the high flow year of 2010-2011, with the annual medians exceeding the Basin Plan targets. Dissolved oxygen fluctuated between the upper and lower limits. The monitoring site is located approximately 250 metres downstream of Yarrawonga Weir. The release water from Yarrawonga Weir could result in low dissolved oxygen results downstream. As the annual median was above 100% saturation most years, suggests this is not the case. The annual median pH was within the target range all years except for 2012-2013. The electrical conductivity shows a similar trend to the Albury site which is located approximately 70 kms upstream. Electrical conductivity increased between 2010 and 2012 in response to flooding and the subsequent recharge of shallow groundwater. From 2012 to 2015, the return of dryer years saw electrical conductivity decrease to lower levels.
8 9 10 11
89
10
LnQ
80
10
01
20
DO
40
50
60
70
EC
0.2
0.4
0.6
LnTN
6.0
7.0
8.0
pH
0.0
20
.06
LnTP
2.0
2.5
3.0
LnTSS
2.0
3.0
4.0
LnNTU
8 9 10 11
10
20
80 90 100 120 40 50 60 70 0.2 0.3 0.4 0.5 0.6 6.0 7.0 8.0 0.02 0.04 0.06 0.08 2.0 2.5 3.0 2.0 2.5 3.0 3.5 4.0 10 15 20 25
10
20
TEMP
Murray River downstream Yarrawonga Weir
Figure 33: Draftsman plots for Murray River downstream Yarrawonga Weir
NSW Department of Industry | PUBXX/YYYY | 87
Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0.00
0.25
0.50
0.75
1.00
1.25T
N (
mg/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0.000
0.025
0.050
0.075
0.100
TP
(m
g/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
10
20
30
40
Turb
idity (
NT
U)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
10
20
30
TS
S (
mg/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
80
90
100
110
120
DO
(%
sat)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
0155.5
6.0
6.5
7.0
7.5
8.0
8.5
pH
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
20
40
60
80
EC
(µS
/cm
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
20
40
60
80
EC
(µS
/cm
)
A) B)
C) D)
E) F)
G) H)
Figure 34: Water quality data for Murray River downstream Yarrawonga Weir
NSW Department of Industry | PUBXX/YYYY | 88
Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
Edward River at Deniliquin The Edward River at Deniliquin had zero flow for most of the 2007 to 2015 period resulting in poor correlations between water quality attributes and flow. Total nitrogen and total phosphorus were strongly correlated to each other, indicating similar transport mechanisms. Nutrients were not as strongly correlated to turbidity.
The highest nutrient results were in 2010-2011 when higher flows were returned to the Edward River. Turbidity was slightly higher, but not to the same degree as nutrients. Total nitrogen exceeded the Basin Plan target in 2010-2011. Total nitrogen exceeded the target from 2010 to 2014, while turbidity exceeded the target every year. The annual median dissolved oxygen was within the desired range every year except for 2010-2011. Flooding and wide spread inundation of the floodplain resulted in a hypoxic blackwater event in the Edward River. The annual median pH was within the upper and lower limits all years. Flows in the Edward River are highly regulated, receiving diversions from the Murray River. As the electrical conductivity does not fluctuate greatly from year to year, suggests there is little surface water groundwater interaction.
0 2 4 6 8 10
02
46
8
LnQ
40
80
DO
60
10
0
EC
0.2
0.4
0.6
LnTN
6.0
7.0 pH
0.0
50
.15
LnTP
2.5
3.5
4.5
LnTSS
3.0
4.0
LnNTU
0 2 4 6 8 10
10
20
40 60 80 100 60 80 100 0.2 0.4 0.6 6.0 6.5 7.0 7.5 0.05 0.10 0.15 2.5 3.0 3.5 4.0 4.5 3.0 3.5 4.0 4.5 10 15 20 25
10
20
TEMP
Edward River at Deniliquin
Figure 35: Draftsman plots for Edward River at Deniliquin
NSW Department of Industry | PUBXX/YYYY | 89
Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0.00
0.25
0.50
0.75
1.00T
N (
mg/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0.00
0.05
0.10
0.15
0.20
TP
(m
g/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
20
40
60
Turb
idity (
NT
U)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
20
40
60
80
TS
S (
mg/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
40
60
80
100
120
DO
(%
sat)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
6.0
6.5
7.0
7.5
8.0
pH
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
50
100
150
200
EC
(µS
/cm
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
50
100
150
200
EC
(µS
/cm
)
A) B)
C) D)
E) F)
G) H)
Figure 36: Water quality data for Edward River at Deniliquin
NSW Department of Industry | PUBXX/YYYY | 90
Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
Wakool River at Stoney Crossing Total nitrogen and total phosphorus were strongly correlated to each other, indicating similar transport mechanisms. Nutrients were not as strongly correlated to turbidity. Similar to the Edward River at Deniliquin, the Wakool River had zero flow for most of the 2007 to 2010 period, resulting in poor correlations between some water quality attributes and flow. Electrical conductivity was strongly correlated to flow with very high results during periods of no or low flow, and low results when salts were diluted by regulated flows.
The highest nutrient results were in 2010-2011, when higher flows were returned to the Wakool River. Total nitrogen, total phosphorus and turbidity annual medians exceeded the Basin Plan targets most years. The annual median dissolved oxygen was within the desired range most years. Flooding and widespread inundation of the floodplain in 2010-2011 resulted in a hypoxic blackwater event in the Wakool River. The electrical conductivity boxplots highlight the very high results from 2007 to 2010 during low flow. This indicates surface water and groundwater connectivity at this site, with highly saline groundwater contributing to base flow. The arrival of regulated flows, with low electrical conductivity, diluted the salts.
0 2 4 6 8 10
04
8
LnQ
04
08
01
20
DO
02
00
05
00
0
EC
0.3
0.5
0.7
LnTN
6.5
7.5
pH
0.0
20
.06
0.1
0
LnTP
2.5
3.5
LnTSS
2.0
3.0
4.0
LnNTU
0 2 4 6 8 10
10
20
0 20 60 100 0 2000 4000 0.3 0.5 0.7 6.5 7.0 7.5 8.0 0.02 0.06 0.10 2.5 3.0 3.5 4.0 2.0 3.0 4.0 10 15 20 25
10
20
TEMP
Wakool River at Stoney Crossing
Figure 37: Draftsman plots for Wakool River at Stoney Crossing
NSW Department of Industry | PUBXX/YYYY | 91
Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0.0
0.5
1.0
1.5
2.0T
N (
mg/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0.00
0.05
0.10
0.15
0.20
0.25
TP
(m
g/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
20
40
60
80
100
Turb
idity (
NT
U)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
20
40
60
80
TS
S (
mg/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
20
40
60
80
100
120
DO
(%
sat)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
0156.0
6.5
7.0
7.5
8.0
pH
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
1000
2000
3000
4000
5000
6000
EC
(µS
/cm
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
1000
2000
3000
4000
5000
6000
EC
(µS
/cm
)
A) B)
C) D)
E) F)
G) H)
Figure 38: Water quality data for Wakool River at Stoney Crossing
NSW Department of Industry | PUBXX/YYYY | 92
Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
Wakool River at Kyalite There is now flow data available for the Wakool at Kyalite monitoring site. The Kyalite site is located approximately 20 kms downstream of the Stoney Crossing site. The Edward River, which receives flows from Billabong Creek from the Murrumbidgee WRPA, joins the Wakool River between the two sites.
Total nitrogen and total phosphorus were strongly correlated to each other, indicating similar transport mechanisms. Nutrients were not as strongly correlated to turbidity.
The highest nutrient results were in 2010-2011, when higher flows were returned to the Wakool River. Total phosphorus and turbidity annual medians exceeded the Basin Plan targets most years. The annual median dissolved oxygen was close to or below the lower limit most years. Flooding and widespread inundation of the floodplain in 2010-2011 resulted in a hypoxic blackwater event in the Wakool River. The electrical conductivity boxplots highlight the very high results from 2007 to 2010 during low flow. This indicates surface water and groundwater connectivity at this site, with highly saline groundwater contributing to base flow. The pH fluctuated from year to year, but generally remained within the desired range.
0 20 40 60 80 100
04
08
0
DO
10
03
00
EC
0.2
0.4
0.6
0.8
LnTN
6.5
7.5
pH
0.0
40
.08
0.1
2
LnTP
2.5
3.5
4.5
LnTSS
2.0
3.0
4.0
5.0
LnNTU
0 20 40 60 80 100
10
20
30
100 200 300 400 0.2 0.4 0.6 0.8 6.5 7.0 7.5 8.0 0.04 0.08 0.12 2.5 3.0 3.5 4.0 4.5 2.0 3.0 4.0 5.0 10 15 20 25 30
10
20
30
TEMP
Wakool River at Kyalite
Figure 39: Draftsman plots for Wakool River at Kyalite
NSW Department of Industry | PUBXX/YYYY | 93
Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0.00
0.25
0.50
0.75
1.00
1.25
1.50T
N (
mg/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0.00
0.05
0.10
0.15
TP
(m
g/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
20
40
60
80
100
Turb
idity (
NT
U)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
20
40
60
80
100
TS
S (
mg/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
20
40
60
80
100
120
DO
(%
sat)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
6.0
6.5
7.0
7.5
8.0
pH
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
250
500
750
1000
1250
EC
(µS
/cm
)
A) B)
C) D)
E) F)
G)
Figure 40: Water quality data for Wakool River at Kyalite
NSW Department of Industry | PUBXX/YYYY | 94
Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
Murray River at Barham There were strong correlations between total nitrogen, total phosphorus and turbidity, indicating transport by similar mechanisms. All three parameters were correlated to flow, suggesting nutrients were transported attached to soil particles during high flow events. There was not a correlation between flow and electrical conductivity. The lowest dissolved results were during high flow events.
As for many sites, the highest nutrient results were in 2010-2011, when higher flows were returned to the Murray River. Turbidity annual medians exceeded the Basin Plan targets most years. The annual median dissolved oxygen was within the desired range all years except for 2010-2011. Flooding and widespread inundation of the floodplain in 2010-2011 resulted in a hypoxic blackwater event in the Murray River. The pH fluctuated from year to year, but generally remained within the desired range. The electrical conductivity was stable, due to the release of low salinity water from Hume Dam.
7.5 8.5 9.5
7.5
8.5
9.5
LnQ
20
60
10
0
DO
60
10
01
40
EC
0.0
0.4
0.8
LnTN
6.0
7.0
8.0
pH
0.0
20
.08
0.1
4
LnTP
2.0
3.5
5.0
LnTSS
2.0
3.0
4.0
LnNTU
7.5 8.5 9.5
10
20
20 40 60 80 100 60 80 120 0.0 0.4 0.8 6.0 7.0 8.0 0.02 0.06 0.10 0.142.0 3.0 4.0 5.0 2.0 3.0 4.0 10 15 20 25
10
20
TEMP
Murray River at Barham
Figure 41: Draftsman plots for Murray River at Barham
NSW Department of Industry | PUBXX/YYYY | 95
Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0.00
0.25
0.50
0.75
1.00
1.25T
N (
mg/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0.00
0.05
0.10
0.15
TP
(m
g/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
25
50
75
100
Turb
idity (
NT
U)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
25
50
75
100
125
TS
S (
mg/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
20
40
60
80
100
120
DO
(%
sat)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
6.0
6.5
7.0
7.5
8.0
pH
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
50
100
150
200
EC
(µS
/cm
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
50
100
150
200
EC
(µS
/cm
)
A) B)
C) D)
E) F)
G) H)
Figure 42: Water quality data for Murray River at Barham
NSW Department of Industry | PUBXX/YYYY | 96
Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
Murray River upstream Euston Weir Total suspended soilds was added to the monitoring program for Euston Weir in 2011.
There was a strong positive correlation between total nitrogen and total phosphorus indicating similar transport mecahisms. Total phosphorus was positively correlated to turbidity, while total nitrogen was not. Nutrients and turbidity were both correlated to flow.
Total nitrogen and total phosphorus concentrations were highest during the high flows in 2010-2011, but were less than the Basin Target most years. Turbidity readings increased in 2010-2011, and remained high until 2014-2015. Water quality samples at this site are collected on the upstream side of the weir from within the weir pool. There may be some settling of heavier particles in the upper reaches of the weir pool, leaving the finer clay particles in suspension. The annual median dissolved oxygen was within the desired range most years, except for 2010-2011. Flooding and widespread inundation of the floodplain in 2010-2011 resulted in a hypoxic blackwater event in the Murray River. The pH fluctuated from year to year, but generally remained within the desired range. The electrical conductivity increased in 2010-2011. Flooding may have flushed salts into the Murray River from smaller tributaries and from the soil surface. Recharge of the groundwater by flooding may have reconected the shallow saline aquifers with the river, increasing saline inputs. Electrical conductivity decreased in subsequent years due to the release of low salinity water from Hume Dam. Euston Weir is upstream of the salt interception schemes located in the Mildura area.
7.5 8.5 9.5 10.5
7.5
9.0
10
.5
LnQ
20
60
10
0
DO
10
02
00
30
0
EC
0.2
0.6
1.0
LnTN
6.5
7.5
pH
0.0
50
.15
LnTP
2.0
3.0
4.0
LnTSS
2.0
3.0
4.0
LnNTU
7.5 8.5 9.5 10.5
10
20
20 40 60 80 100 200 300 0.2 0.4 0.6 0.8 1.0 6.5 7.0 7.5 8.0 0.05 0.10 0.15 2.0 3.0 4.0 2.0 3.0 4.0 10 15 20 25
10
20
TEMP
Murray River upstream Euston Weir
Figure 43: Draftsman plots for Murray River upstream Euston Weir
NSW Department of Industry | PUBXX/YYYY | 97
Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0.0
0.5
1.0
1.5
2.0T
N (
mg/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0.00
0.05
0.10
0.15
0.20
TP
(m
g/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
20
40
60
80
100
Turb
idity (
NT
U)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
20
40
60
80
100
TS
S (
mg/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
20
40
60
80
100
120
DO
(%
sat)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
0156.0
6.5
7.0
7.5
8.0
8.5
pH
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
50
100
150
200
250
EC
(µS
/cm
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
50
100
150
200
250
EC
(µS
/cm
)
A) B)
C) D)
E) F)
G) H)
Figure 44: Water quality data for Murray River upstream Euston Weir
NSW Department of Industry | PUBXX/YYYY | 98
Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
Murray River at Merbein Pump Station Total suspended soilds was added to the monitoring program for Merbein Pump Station 2011.
There was a strong positive correlation between total nitrogen and total phosphorus, indicating similar transport mecahisms. Nutrients had a stronger correlation to flow than to turbidity. Turbidity was not correlated to flow.
As for many sites, total nitrogen, total phosphorus concentrations and turbidity were highest during the high flows in 2010-2011, exceeding the Basin Plan target. Annual medians for these three atributes did not exceed the target values other years. The annual median dissolved oxygen was within the desired range most years, except for 2010-2011 during the hypoxic blackwater event in the Murray River. The pH fluctuated from year to year, but generally remained within the desired range. Electrical conductivity was low with minor fluctuations between years.
7.5 8.5 9.5 10.5
7.5
9.0
10
.5
LnQ
20
60
10
0
DO
10
02
00
30
0
EC
0.2
0.6
LnTN
6.5
7.5
8.5
pH
0.0
20
.08
LnTP
2.0
3.0
4.0
LnTSS
12
34
5
LnNTU
7.5 8.5 9.5 10.5
10
20
30
20 60 100 100 200 300 0.2 0.4 0.6 0.8 6.5 7.0 7.5 8.0 8.5 0.02 0.06 0.10 2.0 2.5 3.0 3.5 4.0 1 2 3 4 5 10 15 20 25 30
10
20
30
TEMP
Murray River at Merbein Pump Station
Figure 45: Draftsman plots for Murray River at Merbein Pump Station
NSW Department of Industry | PUBXX/YYYY | 99
Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0.0
0.5
1.0
1.5
2.0T
N (
mg/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0.00
0.05
0.10
0.15
0.20
0.25
TP
(m
g/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
50
100
150
200
Turb
idity (
NT
U)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
20
40
60
80
TS
S (
mg/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
20
40
60
80
100
120
DO
(%
sat)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
6.0
6.5
7.0
7.5
8.0
8.5
pH
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
50
100
150
200
250
EC
(µS
/cm
)
A) B)
C) D)
E) F)
G)
Figure 46: Water quality data for Murray River at Merbein Pump Station
NSW Department of Industry | PUBXX/YYYY | 100
Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
Darling River at Weir 32 Analysis of total suspended solids was added to the parameter list for this site in 2014.
There was a positive correlation between total phosphorus and turbidity, and a slight correlation between total nitrogen and total phosphorus. Dissolved oxygen and pH were positively correlated, suggesting algal growth in the weir pool could be increasing both parameters. The highest electrical conductivity results were measured during low and zero flows, when salts can become concentrated in the weir pool by evaporation. Electrical conductivity was also negatively correlated to turbidity.
The total nitrogen and total phosphorus concentrations did not fluctuate greatly from year to year in response to changes in flow, as occurred in monitoring sites on the Murray River. Weir 32 is located approximately 40 km downstream of Lake Wetherell. The process of flows from the upper Darling catchment, passing through Menindee Lakes, appears to have a smoothing effect on nutrient concentrations. Nutrient concentrations exceeded the Basin Plan targets every year. The annual median turbidity exceeded the target most years, except for 2007-2008 and 2014-2015 when electrical conductivity was high. High concentrations of salt can cause soil particles to settle out of the water column, resulting in lower turbidity. The alluvial soils of the Darling River have a high clay content which increases their susceptibility to resuspension within the water column. In addition, the very fine particles are able to remain in suspension, even during low or zero flow periods. The low dissolved oxygen results from 2010 to 2012 coincide with the highest turbidity results. High turbidity, reducing light penetration into the water column, inhibiting aquatic plant growth, could be causing the lower dissolved oxygen results.
0 2 4 6 8 10
02
46
8
LnQ
60
10
01
40
DO
50
01
50
0
EC
0.4
0.8
1.2
LnTN
6.5
7.5
8.5
pH
0.1
0.3
0.5
LnTP
34
56
LnNTU
0 2 4 6 8 10
10
20
60 80 120 160 500 1000 1500 20000.4 0.6 0.8 1.0 1.2 1.4 6.5 7.5 8.5 0.1 0.3 0.5 3 4 5 6 10 15 20 25
10
20
TEMP
Darling River upstream Weir 32
Figure 47: Draftsman plots for Darling River at Weir 32
NSW Department of Industry | PUBXX/YYYY | 101
Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0.0
0.5
1.0
1.5
2.0
2.5
3.0T
N (
mg/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0.00
0.25
0.50
0.75
1.00
TP
(m
g/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
200
400
600
Turb
idity (
NT
U)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
200
400
600
TS
S (
mg/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
40
60
80
100
120
140
DO
(%
sat)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
0156.5
7.0
7.5
8.0
8.5
9.0
9.5
pH
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
500
1000
1500
2000
2500
EC
(µS
/cm
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
500
1000
1500
2000
2500
EC
(µS
/cm
)
A) B)
C) D)
E) F)
G) H)
Figure 48: Water quality data for Darling River at Weir 32
NSW Department of Industry | PUBXX/YYYY | 102
Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
Darling River at Burtundy Analysis of total suspended solids was added to the parameter list for this site in 2011.
There was a positive correlation between total phosphorus and turbidity, and between both parameters and flow. Total nitrogen does not appear to be correlated to total phosphorus, turbidity or flow. Dissolved oxygen and pH were positively correlated, suggesting algal growth in the weir pool could be increasing both parameters. The highest electrical conductivity results were measured during low and zero flows, when salts can become concentrated by evaporation. Electrical conductivity was also negatively correlated to turbidity.
There were similar water quality trends visible at the Burtundy site, as at Weir 32. Nutrient concentrations exceeded the Basin Plan targets every year. The annual median turbidity exceeded the target most years, except for 2007-2008 and 2014-2015 when electrical conductivity was high. The low dissolved oxygen results from 2010 to 2012 coincide with the highest turbidity results. Electrical conductivity results increased between 2010 and 2015.
0 2 4 6 8 10
04
8
LnQ
50
10
0 DO
50
01
50
0
EC
0.4
0.8
1.2
LnTN
7.0
8.0
9.0
pH
0.0
0.2
0.4
LnTP
34
56
LnTSS
34
56
7
LnNTU
0 2 4 6 8 10
10
20
30
50 100 150 500 1000 1500 0.4 0.6 0.8 1.0 1.2 7.0 8.0 9.0 0.0 0.1 0.2 0.3 0.4 3 4 5 6 3 4 5 6 7 10 15 20 25 30
10
20
30
TEMP
Darling River at Burtundy
Figure 49: Draftsman plots for Darling River at Burtundy
NSW Department of Industry | PUBXX/YYYY | 103
Water quality technical report for Murray Lower Darling surface water resource plan area (SW8)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0.0
0.5
1.0
1.5
2.0
2.5T
N (
mg/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0.0
0.1
0.2
0.3
0.4
0.5
TP
(m
g/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
100
200
300
400
500
600
700
Turb
idity (
NT
U)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
100
200
300
400
500
TS
S (
mg/L
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
40
60
80
100
120
140
160
DO
(%
sat)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
0156.5
7.0
7.5
8.0
8.5
9.0
9.5
pH
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
250
500
750
1000
1250
1500
EC
(µS
/cm
)
2007/2
008
2008/2
009
2009/2
010
2010/2
011
2011/2
012
2012/2
013
2013/2
014
2014/2
015
0
200
400
600
800
1000
EC
(µS
/cm
)
A) B)
C) D)
E) F)
G) H)
Figure 50: Water quality data for Darling River at Burtundy
NSW Department of Industry | PUBXX/YYYY | 104
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