Lake Independence Phosphorus TMDL Critique Stephanie Koerner & Zach Tauer BBE 4535 Fall 2011.
Lower Wild Rice River Turbidity: TMDL Critique
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Transcript of Lower Wild Rice River Turbidity: TMDL Critique
Lower Wild Rice River Turbidity:TMDL CritiqueBrent Mason, Mackenzie
Consoer, Rebekah Perkins
BBE 5543November 8, 2011
Outline
TMDL OverviewWatershed BackgroundWater Quality StandardsLoading CapacityMonitoring and ImplementationConclusion
TMDL OverviewClean Water Act Section 303 (d) requirements:
Every 2 years states publish a list of “impaired” waters TMDL report must be developed for all waters on the
impaired waters list
TMDL Requirements: Provides a calculation of the maximum amount of a
pollutant that a water body can receive and still meet water quality standards
Sums the loads of a single pollutant from all point and non point sources
Watershed BackgroundWild Rice River watershed: Encompasses just over 1 million acres Flows Across 5 Minnesota counties Lies within three eco-regions Impaired for Turbidity from the confluence of the
South Branch of the Wild Rice River to the Red River
Impaired section of River is 30.58 miles in length and is located entirely within Norman County.
Wild Rice River Watershed Location
Wild Rice River Watershed
Wild Rice River Watershed Characteristics
Lower reach of Wild Rice River lies within the Lake Plain from Glacial Lake Agassiz
Extremely Flat with level deposits of lake sediment Lower Wild Rice River is contained by low banks
and has high sinuosity Soils tend to be clays with low permeability and low
internal drainage Cropland dominates the land use of the Lower
Wild Rice River Upland is heavily drained by both ditch and tile
systems
Wild Rice River Land Use Chart
Wild Rice River Watershed Land Use
Water Quality Standards
Designated Beneficial Use: Water body is classified as both 2B and 3B water Chose class 2 waters: aquatic life and recreation **Higher standards
Turbidity: 25 NTU standard for natural water bodies Surrogate measurement for Total Suspended
Solids (TSS) and Suspended Sediment Concentration (SSC)
Turbidity Overview Clarity of water Caused by sediment, micro-
organisms, dissolved material, and organic matter
Measurement of amount of light scattered
Measured with dimensionless unit of NTU
Blocks sunlight that fish and plants thrive on
Degrades aesthetic appeal of water body Lenntech.com
Fishschooled.blogspot.com
Numeric Water Quality Target Turbidity is dimensionless and cannot be used
to determine sediment loads Relationship between Turbidity and SSC
needed to be derived Using paired turbidity and SSC data, simple
regression analysis was used to create a relationship between the two variables
Using this relationship: 25 NTU = 38 mg/L SSC
Turbidity vs. SSC Relationship
o Majority of samples are at low flows and low turbidity
o Limited amount of data
Major Assumptions Major inconsistencies between turbidity meters Turbidity relationship only based on one year of
data and primarily at one location**Depending on how the make up of the sediment changes throughout this watershed, this relationship can vary greatly
The majority of the data was taken during low flows or winter months
Loading Capacity: Duration Curve Approach
Loading Capacity: Duration Curve Approach -Only 2 sites
-Underrepresented Low Flow Zone
Point Sources: Wasteload Allocation
TMDL = WLA + LA + MOS + RC
o Four Identified Potential Sources:1. Municipal Wastewater Treatment Facilities (WWTFs)2. Construction Activities3. Industrial Facilities4. Concentrated Animal Feeding Operations (CAFOs)
Note: No MS4 permit requirements (stormwater)
o All Require NPDES/SDS permit
o Assumed Full Permit Compliance
o Minor contributors to turbidity impairment
Point Sources: Wasteload Allocation
1. Municipal Wastewater Treatment Facilities (WWTFs)o NPDES/SDS permit = 45
mg/l TSSo Assume TSS values
comparable to SSCo Similar is stream with
high fine material (Gray et al, 2000)
o Lower Wild Rice ~90% fine material (Macek-Rowland and Dressler, 2002)
o Seasonal Discharge Windowso April-June and Sept-Dec o Assumes coincides with
High Flows
1.5 tons/day for each flow zone, except low flows
Low Flow Allocation Exception Loading Capacity for LOW FLOW ZONE very small Permitted WWTF loads exceed total daily loading at
low flows**Not possible because it is a component of total loads
Concentration – based on allocation to sources for low flow zone
Allocation = (flow contribution from a given source) x (45 mg/L TSS, the permit limit)
Point Sources: Wasteload Allocation2. Construction Activities
o WLA=estimated % of disturbed land= 0.17%
o MPCA stormwater permit records
3. Industrial Facilitieso 2 located in watershedo No accessible acreage datao Assumed same as Construction
Activities (0.17%)
4. Concentrated Animal Feeding Operations (CAFOs)o 2 located in watershedo WLA=0 discharge, in accordance with
permit
Construction Activities + Industrial Facilities + CAFOs=.17% + .17% + 0% = 0.32% of TMDL within each Flow Zone
Non Point Sources: Load Allocation
o No NPDES/SDS Permit Requirements
o Major Load Contributors, occurs mostly at HIGH FLOWS
o LA = Total Load Capacity-WLA-MOS
o Primary Drivers in Wild Rice River Watershedo Upland Soil Erosiono Stream-Bank Erosion
o Relative contributions?
o Natural Processes
TMDL = WLA + LA + MOS + RC
magazine.noaa.gov
Margin of Safety
Margin of Safety (allocation uncertainty)o Four highest flow zones
o Accounted for flow variability within each flow zoneo Median flow-Minimum flow within each zone (standard
calculation)o Low Flow Zone
o Implicit MOS used (built into TMDL allocations)o Conservative assumptions
o Discharge periods = High flows o Discharging below permit limits
TMDL = WLA + LA + MOS + RC
Reserve Capacity
Reserve Capacity (future loading uncertainty)o Population Growth
o 4/10 cities declineo 6/10 cities increase from 1.9% to 7.5%
o WWTFs operating below loading limits, no planned expansiono RC = 0
TMDL = WLA + LA + MOS + RC
Loading Allocations
High Moist Mid Dry0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Lower Wild Rice River Suspended Sediment Loading Allocations
WLA (Permitted WWTFs) WLA (Construction/Industrial Stormwater)LA MOS
Flow Zone
Tota
l Dai
ly L
oadi
ng A
lloca
tion
Major Assumptions/Critiques
Flow Zone Sample Representation NPDES/SDS permit compliance Assume TSS values comparable to SSC Seasonal Discharge Windows Coincide High Flow Land Disturbance % = Loading Allocation % Natural Background Insignificant RC = 0
Wild Rice River Monitoring Plan
Current Monitoring Activities Red River Basin Watch USGS flow monitoring and sediment analysis MPCA milestone and condition monitoring
Future Monitoring Plans Future monitoring is being developed by the
Wild Rice Watershed District with the assistance of its Flood Damage Reduction Team
Implementation Strategy
Restoration Plan under development: Focus of plan: Identify sources of
sediment spatially Funding for Implementation: Existing
programs (Clean Water Legacy, Conservation Reserve Program, etc.)
Soil and Water Conservation District: Encourage the funding of programs that will reduce non point sources of turbidity
Tools to Achieve Reductions Best Management Practices (BMPs) Filter Strips Riparian Buffers Grassed Waterways Cover Crops Conservation Tillage
Critique of Reduction Plan
Requires collaborative effort by many individuals and organizations
Assumes land use practices do not change significantly
Restoration costs are estimated to be in the tens of millions of dollars
Restoration tools suggested will occupy many acres of valuable farmland.
Conclusion Turbidity and SSC were monitored Numeric standard of 38 mg/L derived Load duration curve developed to
evaluate load exceedences Monitoring and implementation plans
being developed Many assumptions were made but few
assumptions had a significant impact on overall load calculations
Questions?