Cawelo Groundwater Sustainability Agency (CGSA) Workshop ...

Cawelo Water District17207 Industrial Farm Road,

Bakersfield, CA 93308

Cawelo Groundwater Sustainability Agency (CGSA)Workshop ‐ Groundwater Sustainability Plan

August 5, 2019 ‐Workshop #4

Groundwater Sustainability PlanConsultant

Today’s Workshop Agenda

1. Introductions2. SGMA and Cawelo GSA Updates3. Draft Groundwater Budget4. Draft Sustainable Yield5. Groundwater Monitoring Network6. Measurable Objectives and Minimum Thresholds7. Management Actions for Sustainability8. Questions & Discussion

1. Introductions

• General Manager – David Ansolabehere• Board of Directors• CGSA & CWD Staff• Legal Counsel• Consultants

o Todd Groundwatero Hamilton Resource Economics

• There are 10 other GSAs in the Kern County Subbasin

1. Buena Vista WSD2. Cawelo GSA3. Greenfield County4. Henry Miller WD5. KGA GSA6. Kern River GSA7. McFarland GSA8. Olcese GSA9. Pioneer GSA10. Semitropic WSD11. West Kern WD

Kern County Subbasin GSAsDWR 5‐022.14 Feb 2019

2. SGMA & Cawelo GSA Updates

• Kern Groundwater Authority GSA is Largest in our Subbasin• The KGA was formed under a Joint Powers Agreement and has 16 members

1. Arvin Community Services District2. Arvin‐Edison Water Storage District3. Cawelo Water District (Cawelo GSA)4. City of Shafter5. Kern County Water Agency6. Kern‐Tulare Water District7. Kern Water Bank Authority8. North Kern Water Storage District9. Rosedale‐Rio Bravo Water Storage District10. Semitropic Water Storage District (GSA)11. Shafter‐Wasco Irrigation District12. Southern San Joaquin Municipal Utility District13. Tejon‐Castaic Water District14. West Kern Water District (GSA)15. Westside District Water Authority16. Wheeler Ridge‐Maricopa Water Storage District

• The KGA is developing an umbrella Groundwater Sustainability Plan (GSP) to cover the KGA GSA area and its members. Each KGA member will have it’s own member section in the umbrella GSP.

• Coordination occurring within KGA and its members


• Other GSAs • Other GSAs are developing their own independent GSPs

1. Buena Vista WSD2. Greenfield County3. Henry Miller WD4. Kern River GSA5. McFarland GSA6. Olcese GSA

• The KGA GSA and other GSA are required to coordinate their GSPs and submit a coordination agreement

• Some key coordination elements are water budget methodologies, minimum groundwater thresholds, monitoring networks, and data management.

• SGMA Coverage for Non‐Districted Areas• Kern County has withdrawn from the KGA and is no longer managing non‐districted areas (“white land”

areas)

• At this time, some lands have obtain SGMA coverage by agreeing to be managed by a nearby water district or management group. There remain many white land areas that have not obtained similar coverage


• KGA and Member GSP Schedule • Currently – All KGA Member administrative draft GSPs/Sections are due to the KGA• Currently – KGA is reviewing drafts and rolling up for umbrella GSP• August 28, 2019 – KGA Board of Directors to conduct internal review of Member GSPs/Sections for

inclusion into the KGA Umbrella GSP• August 30 to November 29, 2019 – Post Umbrella GSP for Public Review & Comment process

• December 20, 2019 – Final responses to comments

• January 10, 2020 – Final member GSPs/sections due to KGA

• January 17, 2020 – Final KGA Umbrella GSP complete

• January 22, 2020 – KGA Board approval to submit Umbrella GSP to DWR

• January 31, 2020 – All GSPs for the Kern Subbasin due to DWR

• Cawelo GSA GSP Schedule• Today’s Workshop• August 8, 2019 ‐ Cawelo GSA Board of Directors to review and authorize updated administrative draft,

the continued participation in the KGA GSP process, and make draft available to the public• Update as necessary, for KGA August 28 review and public comment


• Cawelo GSA has modified GSA boundary to include certain non‐districted lands

• Boundary modification also transferred industrial land at the south end to KRGSA


• Full Cawelo GSA Area is 62,616 Acres

• Water District area within the GSA is 44,017 Acres

• Eastern Extension Area is 18,600 Acres

• Industrial area transferred is 1,707 Acres

Note: Cawelo GSA and Cawelo Water District are two distinct and separate entities

• SGMA requires a basin level groundwater model & a water budget for surface and groundwater supplies

• Todd Groundwater was contracted through the KRGSA to develop the model for the entire basin

• Used DWR’s C2VSim model that covers the Central Valley and refined it to better fit the conditions of the southern end of the valley

• The model only represents volumes of water entering and leaving the basin system and indicates the change in aquifer storage. It does not consider or determines who “owns” the water.

• The KGA GSA and other GSAs are also developing and reviewing their water budgets using a checkbook accounting method

• Variability in current data, unknowns, and data gaps only allow for best estimates for initial planning

3. Draft Groundwater Budget

• Cawelo GSA is also developing its groundwater model & water budget for surface and groundwater supplies

• Contracted with Todd Groundwater to develop the Cawelo GSP which includes the C2VSim model portion for the Cawelo GSA area

• The Cawelo model uses historical data provided by Cawelo Water District and model outputs are specific to the water district and Cawelo GSA area.

• Model uses data from the 1995 to 2015 historic period because it represents typical hydrological conditions

• Model makes many assumptions using data and information that need to be further refined for the local area

• The model provides water budget information but Cawelo GSA is also developing and reviewing their water budgets using a checkbook accounting method


• C2Vsim Historical budget based on water years 1995 through 2014.



Imported WaterET

Ag Pumping

Rain

Exported Water

Percolation to GW

Managed GW

Recharge/Banking

Stream Recharge

Urban Pumping

Stream Out

Rain Percolation

Water Budget at the Surface

Stream In

Agricultural, Urban and Undeveloped

3. Draft Groundwater BudgetWater Budget at the Surface


Ag Pumping

Percolation to GW

Managed GW

Recharge/Banking

Stream Recharge

Urban Pumping

Rain Percolation

Groundwater Budget

Agricultural, Urban and Undeveloped

3. Draft Groundwater BudgetGroundwater Budget

3. Draft Groundwater Budget• 3rd Groundwater Budget Method – Checkbook Coordination with KGA and other GSAs

• General Kern County Subbasin Assumptions for Native Yield & Precipitation• Insufficient data to understand native groundwater sources• Insufficient data to properly apply precipitation to the subbasin area• For initial plan submittals, attempt to coordinate Native Yield range of 0.15 to 0.30 Af/Acre• For initial plan submittals, attempt to coordinate average precipitation values at 0.20 Af/acre

3. Draft Groundwater BudgetGroundwater Budget Summary

Source

Annual GW Storage Change

(Acre‐ft) Comments

C2Vsim Water Budget

Cawelo GSA Checkbook Water Budget

Coordinated Budget with KGA & GSA

‐9,576 AF / Year

‐10,813 AF / Year

‐6,829 AF / Year

There is a subsurface flow balance component that is part of the calculation. Typical Native Yield components are integrated in other sources.

Two part budget that balances the surface water budget with GW pumping and precipitation, then uses that information to determine the GW balance. Typical Native Yield components are integrated in other sources.

Simple high level budget coordinated with KGA and other GSAs. GW return flow estimates are eliminated and surface waters are applied directly to offset the ET Demand. Native Yield & precipitation are estimated.

3. Draft Groundwater Budget• Draft groundwater budget projections are required out to another 50 years after 2020

using 2030 and 2070 climate change estimates.• Current water supplies projected to decrease due to climate and availability of Kern

River• Surface Supplies Projected to decrease from 91,644 to 81,616 Af per year (11%) by

year 2030• ET estimated to increase by 3% but acres farmed can be variable

4. Draft Sustainable Yield (Safe Yield)• The maximum annual volume of water that can be extracted from groundwater supplies

without causing undesirable results• Chronic lowering of GW levels• Significant and unreasonable reduction of groundwater storage• Significant and unreasonable degraded water quality• Significant and unreasonable land subsidence• Significant and unreasonable seawater intrusion• Depletion of interconnected surface waters

• Cawelo GSA’s goal is to manage groundwater levels at or above historical low GW levels• Management actions to create zero or positive groundwater storage change• Examine the 3 Water Budgets and corresponding deficits

4. Draft Sustainable Yield (Safe Yield)• Examine the 3 Water Budgets and corresponding deficits• Sustainable Yield = (Total Groundwater Extractions – Annual GW Deficit)

• Sustainable Yield includes native groundwater sources or Native Yield. This includes any precipitation infiltration, storm and small watershed infiltration. Share of subbasinsubsurface flows not accounted

• Balance of Sustainable Yield are return flows and banking from CWD operations

5. Groundwater Monitoring Network• SGMA Best Management Practices recommend a well monitoring network with a well

density of 4 wells for the Cawelo GSA area• Cawelo Water District has an extensive well monitoring network • Wells evaluated for appropriate GW monitoring for Cawelo GSA activities and

surrounding areas• Use wells that are also part of other groundwater monitoring programs such as ILRP• Wells were further evaluated for monitoring the Measurable Objectives and Minimum

Thresholds• Seven (7) wells selected for monitoring network and in the process of securing an 8th

well for the Kern River Field area

5. Groundwater Monitoring Network

6. Measurable Objectives and Minimum Thresholds• Measurable objectives are quantitative goals that reflect Cawelo GSA’s desired

groundwater conditions and allow the GSA to achieve sustainability in 20 years• During the recent drought, the groundwater levels reached historical lows but groundwater

supplies have begun to recover

• As a result of recent GW lows, several landowners had to lower their pumps for proper submergence, but there was no apparent impact to water quality, and there are indication of some land subsidence

• Draft water budgets indicate there is a groundwater deficit and minor long‐term chronic lowering of water levels, but reasonable management actions are available to overcome a deficit of this magnitude

• The goal for the Cawelo GSA or the Measurable Objective is to maintain GW levels at or above the historical lows

6. Measurable Objectives and Minimum Thresholds

6. Measurable Objectives and Minimum Thresholds• When setting Sustainable Management Criteria, need to consider Sustainability

Indicators, Undesirable Results and Minimum Thresholds• Minimum Thresholds are limits that when exceeded potentially cause undesirable

results• Undesirable Results occur when any of the Sustainability Indicators become significant

and unreasonable• Can use groundwater levels as a proxy indicator for undesirable results

• Chronic lowering of groundwater levels• Depletion of groundwater storage• Degradation of groundwater quality• Land subsidence

• There is no apparent correlation between changing groundwater levels and water quality in the Cawelo area. Difficult to use GW levels as a proxy for undesirable water quality impacts

• Need quantitative measure to determine undesirable results

6. Measurable Objectives and Minimum Thresholds• Chronic lowering of groundwater levels

• The demand on the groundwater basin in the Cawelo GSA area is primarily agriculture with some domestic and industrial uses

• Chronic lowering of water levels potentially lead to the need to drill deeper groundwater wells

• Examine typical well construction depths

• Depletion of groundwater storage• Need to maintain sufficient groundwater storage, depletion of groundwater storage is

directly related to chronic lowering of GW levels• Maintain sufficient GW storage (GW levels) to accommodate extended drought period

• Degradation of GW quality• Not suitable to use GW level as a proxy. Further evaluate setting potential WQ indicator

such as salinity that is appropriate for GSA area

• Land Subsidence• There is data indicating subsidence has occurred in localized area in and around the GSA

area but there is insufficient data.• Participate at a basin wide monitoring effort to determine subsidence impacts to critical

infrastructure and then evaluate potential undesirable results for the Cawelo GSA area


• To determine GW levels as a proxy for undesirable results, use recent GW level data and project potential GW levels to the year 2040

• Use water levels from 2006 to 2016. This includes the most recent drought and saw GW levels at historical lows. Consider this the worse case scenario.

• Examine known GW level records for the Cawelo Water District and use average trend lines for the whole district area, the north of Poso Creek area and south of Poso Creek area to project GW levels to 2040 under the worse case scenario.


District Ave. Decrease:8.1 Ft/year

Water Level Decrease:161 Ft at 2040

North Ave. Decrease:7.81 Ft/year


South Ave. Decrease:8.4 Ft/year


• Using worse case scenario it is estimated that:• 5% of Ag wells – Bottom of screens would dewater• 40% of domestic wells – Bottom of screens would dewater• 0% of municipal wells – Bottom of screens would dewater

• Domestic water use is critical factor when State considers sustainable GW use. Dewatering 40% of domestic wells would constitute an undesirable result

• Examine using a 10 year GW storage criteria and its impact on chronic lower of GW levels and that impact to domestic wells

• Use same projection criteria, drought conditions are drawing on groundwater storage



District Ave. Decrease:8.1 Ft/year

Water Drop:81 Ft at 2030

North Ave. Decrease:7.81 Ft/year


South Ave. Decrease:8.4 Ft/year


• Using worse case scenario projected to 10 years:• Average water level drop is 81 feet• Estimated that less than 5% of all wells – Bottom of screens would dewater

• From the historical groundwater lows at each of the monitoring well locations, use the 10 year projected GW level decrease to set Minimum Threshold.


6. Measurable Objectives and Minimum Thresholds• The Cawelo GSA area is considered

to be causing Undesirable Results when at least 3 wells have simultaneously exceeded their corresponding Minimum Thresholds for 3 consecutive years

• This could also apply to the MTs for potential water quality levels

• Currently water levels are above Measurable Objectives, but process for implementing projects has already begun and will continue in anticipation of future conditions

• Local projects, management actions and adaptive management is necessary and required to meet sustainability targets and for groundwater overdraft mitigation

• Current GW overdraft conditions indicate an annual average of ‐10,813 Af• Projected overdraft conditions using 2030 climate change conditions

indicate ‐23,803 Af• Projected overdraft conditions under 2070 climate change conditions

indicate ‐28,803 Af

• Management actions were necessary for current conditions but projections indicate a significant portfolio of projects or management actions is necessary.

6. Management Actions for Sustainability

• Potential projects and management actions to be implement by the Water District or privately by landowners

• The Cawelo GSA is not providing a water supply to landowners but is managing GW supplies per the GSP and SGMA, in cooperation with CWD

• District to immediately begin the process to implement supply projects• Evaluate status as approaching 2030 then begin demand reduction projects

6. Management Actions for Sustainability

Questions, comments and discussion?

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