eki technical presentation #11 - water...

Draft – For discussion purposes only

EKI TECHNICAL PRESENTATION #11COSUMNES SUBBASIN GSP DEVELOPMENT

18 SEPTEMBER 2019COSUMNES SUBBASIN WORKING GROUP / TAC MEETING

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AGENDA ITEM #1 GROUNDWATER SUSTAINABILITY PLAN UPDATES GSP updates Three-month look-ahead

Groundwater Modeling Coordination with CoSANA

TSS Grant Applications

Basin Setting: Groundwater Conditions

Data Gaps Filling Update

Prop 68

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Updated Draft TM#3: Numerical Groundwater Model Evaluations

and Recommendations

Draft TM #6: GW Conditions & HCM

Finalize decision recommendation on

numerical groundwater modelTHREE MONTH LOOK AHEAD

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Provide feedback on TM #6

Provide detailed information on currently

monitored wells


UPCOMING DEADLINESTask 8: Evaluate Numerical Groundwater Model options

EKI: Conduct the evaluation of numerical groundwater model options and prepare associated work products (Update Draft TM #3 – Numerical Groundwater Model Evaluations and Recommendations – due 9/19/2019).

WG: Make final decision regarding the numerical groundwater model by 10/16/2019.

Task 13: Assess Groundwater Conditions & Develop HCM

EKI: Develop the Groundwater Conditions Assessment and Hydrogeologic Conceptual model and associated interim work products (Draft TM #6 – Groundwater Conditions and Hydrogeologic Conceptual Model – due 11/30/2019).

WG: Review and provide feedback on TM #6 by 12/18/2019.

Task 16: Assess Existing Monitoring Programs & Develop SGMA Network

EKI: Assess existing monitoring programs and propose a SGMA compliant monitoring network, and prepare the associated interim work products (Draft TM #9 - Summary of Monitoring Network Assessment and Preliminary Monitoring Plan – due 1/31/2020).

GSAs: Provide detailed information as to which wells are currently monitored, their specific monitoring objectives, and availability for incorporation into the SGMA required network by 12/31/2019.

WG: Review and provide feedback on TM #9 by 2/19/2020.

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CoSANA COORDINATION Sharepoint site created to facilitate information

exchange with EKI.

Model mesh finalized incorporating Working Group recommendations and uploaded to Sharepoint site.

EKI uploaded reported municipal pumpage data (City of Galt and Camanche Village) to Sharepoint site for processing into model input data sets.

EKI plans to also upload in the near future:

- Diversion data (for surface water routing and recharge calculations).

- Geologic formation data (top and bottom elevations for model layering).

CoSANA development schedule updated as follows:

- Input data sets completed 12/31/19.

- Historical calibration 3/31/20.

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REVISED DRAFT RANKING - WEIGHTED CRITERIA (9/18/19)

1/16/199/18/19

0 0 0 5

5

2

3017 17 17

Originalrecommendation (1/16/19) was a “Nested” Model

Updatedrecommendation (as of 9/18/19) is the Regional CoSANA Model

CoSANA


TSS GRANT APPLICATIONS

OHWD GSA application is being reviewed by DWR.

Amador County GMA GSA

First well completed at “Bamert” site and included in DMS.

Second well planned for construction at “Carbondale” Site.

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Amador County GMA TSS Well Locations

OHWDTSS Well Location


ESJ SUBBASIN 9/11/2019 MEETING SUMMARY

Draft GSP comments have been received

Comments will be released to the public in October

Comments will broken into three categories based on level of consideration

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ESJ SUBBASIN 9/11/2019 MEETING SUMMARY

ESJ GSP Adoption Timeline


AGENDA ITEM #2 GROUNDWATER SUSTAINABILITY PLAN UPDATES

Basin Setting

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Hydrogeological Conceptual ModelWater Budget Groundwater Conditions+ +


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HCM REVIEW (1 OF 2)Regional Setting: Single Principal Aquifer

Data category Single aquifer characteristics

Well depths Wells are screened at variable depths throughout the basin.

Groundwater quality There is no visual relationship between ionic composition and formation/depth.

Well uses Most well uses occur across the basin and at all depth intervals.

Well yields Well yields vary by within two physiographic subareas and not by depth.

Cross-sections Borehole data and existing cross sections confirm no regional barriers to flow.

Data confirms that the Basin can be represented as a single Principal Aquifer.

Note: No barriers to flowSource: DWR, 1974, Evaluation of Ground Water Resources: Sacramento County, Bulletin 118-3.


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HCM REVIEW (2 OF 2)Regional Setting: Physiographic subareas

EKI recommends delineated subbasin into two physiographic subareas: the “Basin Plain” and “Basin Foothills”:

Basin Plain

BasinFoothills

Category Basin Plain Basin Foothills

Geomorphic providence

Delta, low alluvial plain and fans, dissected uplands

Dissected uplands and transition to Sierra Nevada

Topography Uniformly gentle slope to the west

Influenced by tectonics, greater topographic variation

Alluvial sediment thickness

Mehrten Formation > 50 ft thick Mehrten Formation < 50 ft thick, or absent

Water supply well construction

Screened primarily in Laguna and/or Mehrten Formations

Screened primarily in Valley Springs and/or Ione Formations

Well yield Average specific capacity 90 gpm/ft, ~30x greater than Basin Foothills

Average specific capacity = 3 gpm/ft, ~30x less than Basin Plain

Depth to water Smooth variations generally increasing from west to east

Substantial variability even within wells near one another

Groundwater Quality Primarily Na-Mg-HCO3 and Ca—Mg-HCO3 water types; brackish water exists within deeper Tertiary formations

No distinct water type; base of fresh water generally coincides with basement rock


§354.16. Groundwater Conditions

Each Plan shall provide a description of current and historical groundwater conditions in the basin, including data from January 1, 2015, to current conditions, based on the best available information….

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GROUNDWATER CONDITIONS (GWC) (1 OF 21)


These topics will be presented at the

October Cosumnes WG Meeting

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GWC CHECK LIST (2 OF 21)

Check List/Status Required GC Components

Groundwater data: elevation contour maps

Groundwater data: long-term hydrographs

Graph of annual/cumulative storage change

Maps and cross-sections of the seawater intrusion front for each principal aquifer

Groundwater quality issues including map of known contamination sites and plumes

The extent, cumulative total, and annual rate of land subsidence

Interconnected surface water systems and quantity and timing of depletions

Groundwater Dependent Ecosystems within the basin.


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GWC CHECK LIST (3 OF 21)Approximately 10 ft Difference Between Spring and Fall 2018 Water Levels in the Basin Plain

Spring 2018 Fall 2018


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GWC CHECK LIST (4 OF 21)Groundwater Elevations in the Basin Plain Declined on Average More Than15 feet between 1999 and 2018

Fall 1999 Fall 2018


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GWC CHECK LIST (5 OF 21)Long-term Hydrographs Confirm Declining Water Levels in the Basin Plain


GWC CHECK LIST (6 OF 21)Measured Water Level Trends in Plain and Foothill Areas Are Different

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Statistically significant trends based on ten years or more of measured water levels in wells during 1999-2018

Downward trend in Plain- Representative trend -0.5 ft/yr

- Downward trends range from -0.4 ft/yr to -1.1 ft/yr

No consistent trend in Foothills- 5 upward

- 2 downward

- 2 flat (“0” trend)

Basin Foothills

BasinPlain


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GWC CHECK LIST (7 OF 21)Estimated 42,900 AFY Decrease in Basin Plain Storage Based onthe Observed 1999-2018 Water Level Decline

Area weighted water level change = -15.6 ft (-0.78 ft/yr)

Area of Basin Plain = 131,000 acres

Approximate average thickness of Basin Plain = 1,400 ft

Specific Storage (Ss)= 0.0003 per ft

Basin Foothills

BasinPlain


STORAGE CHANGE ESTIMATE COMPARISONS (8 OF 21)

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-80,000 AFY-150,000 AFY-22,000 AFY

-6,000 AFY

-29,000 AFY

-130,000 AFY

Water Balance based Water Budget

Water Level based Water Budget (assuming most basin storage change occurs in Sacramento County)

Range of uncertainty

Range of uncertainty

-42,900 AFY

Average Annual Storage Change 1999-2018 (from groundwater elevation maps)


GWC CHECK LIST (9 OF 21)Seawater Intrusion SGMA Regulations

Defined by § 351(af). The advancement of seawater from any source that results in water quality degradation.

Groundwater Conditions § 354.16 (c). Maps and cross-sections of the seawater intrusion front for each principal aquifer.

Minimum Thresholds § 354.28 (3). Defined by chloride concentration isocontour for each principal aquifer and supported by: (A) Maps and cross-sections of the chloride concentration isocontour. (B) Describe how the threshold considers current and projected sea levels.

Monitoring Network § 354.34 (3). Utilize chloride concentrations, or measurements convertible to chloride concentrations, so

that the current and projected rate and extent of seawater intrusion may be calculated.

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GWC CHECK LIST (10 OF 21)Maps and Cross-sections Indicate Seawater Intrusion is Not Occurring Chloride concentrations can reveal the influence

of marine water sources- 250 mg/L is secondary MCL- 500 mg/L used by some coastal agencies to map

the seawater intrusion front

Base of fresh water determined by TDS shallows near the Delta

Recent (2015-2019)

Base of Fresh Water (determined by TDS concentrations > 2,000 mg/L).

A

A’

Basin FoothillsBasin Plains


GWC CHECK LIST (11 OF 21)Arsenic and Nitrate are the OnlyConstituents that ExceedPrimary MCLs

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Water quality issues that most impact the beneficial uses of the water include constituent concentrations which:1. Exceed established Maximum

Contamination Limits (MCL)

2. Exceed established water quality objectives (WQO)

3. Known groundwater contamination sites and plumes

Constituent Primary MCL

(mg/L)

Secondary MCL

(mg/L)

WQO(mg/L)

# of Wells Exceeding

MCL/WQO

Arsenic 0.01 -- -- 21

Fluoride 2 -- -- 0

Lead 0.015 -- -- 12

Nitrate as N 10 -- -- 6

Selenium 0.05 -- -- 0

TDS -- 500 -- 17

Chloride -- 250 -- 4

Sulfate -- 250 -- 3

Iron -- 0.3 -- 30

Manganese -- 0.05 -- 48

Boron -- -- 0.5 1

Sodium -- -- 20 50

Note: Bold constituents are evaluated in the following slides.


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GWC CHECK LIST (12 OF 21)Historical and Recent Arsenic Concentrations Distributionis Similar (based on available data)

Recent (2015-2019) Historical (Pre-2015)


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GWC CHECK LIST (13 OF 21)All Samples from the Laguna Formation Exceed the Arsenic MCL

VictorMehrten Ione

ValleySprings Laguna Victor Mehrten IoneValley

Springs Laguna

only MWs

only MWs

only MWs

only MWs

Recent (2015-2019): Historical (Pre-2015):

MCL 0.01 mg/L

Arsenic levels in drinking water that exceed the MCL are a significant human health concern as arsenic ingestion has been associated with an increased risk of cancer and other chronic health effects.

Additional work needs to be done to assess relationship of Arsenic concentrations to water levels trends, if any.


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GWC CHECK LIST (14 OF 21)Historical and Recent Nitrate as NitrogenConcentrations Distribution is Similar (based on available data)


Maximum Nitrate as N Concentration (mg/L)


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GWC CHECK LIST (15 OF 21)High Nitrate (as N) Concentrations Observed in Monitoring Wells Screened in the Victor and Valley Springs Formations.

only MWs

only MWs

only MWs

Victor Mehrten IoneValley Springs Laguna Victor Mehrten IoneValley

Springs Laguna


MCL 10 mg/L

Nitrate concentrations in drinking water that exceed the MCL are a significant health concern for pregnant women and infants as high concentrations can cause methemoglobinemia (“blue baby syndrome”).

Additional work needs to be done to assess relationship of Nitrate concentrations to depth and water levels trends, if any.


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GWC CHECK LIST (16 OF 21)Historical Lead Concentrations Exceeded the MCL;whereas Recent Concentrations Do Not

Recent (2015-2019) Historical (Pre-2015)


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GWC CHECK LIST (17 OF 21)All Exceedances of the Lead MCL occurred Historically in Victor Formation Monitoring Wells

Mehrten IoneLaguna Victor Mehrten IoneValley

Springs Laguna

only MWs

only MWsonly

MWs


MCL 0.015 mg/L

Lead is a toxic metal that can be harmful to human health in drinking water at low exposure levels and can bioaccumulate in the body over time.

There has been no exceedances since 2015, however much fewer samples have been collected.

Additional work needs to be done to assess relationships of Lead concentrations to depth and water levels trends, if any.


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GWC CHECK LIST (18 OF 21)Most Known ContaminationSites are Closed LUST Sites

GeoTracker Site #

LUST Cleanup – Case Open 4

LUST Cleanup – Case Closed 31

Permitted USTs 9

Cleanup Program 5

DTSC Cleanup 13

Land Disposal 7

Military Cleanup 1



GWC CHECK LIST (19 OF 21)Subsidence SGMA Regulations Subsidence is the vertical displacement of ground surface caused by tectonic

activity, groundwater withdrawals, natural gas and oil extractions, and oxidization of organic matter.

Groundwater Conditions § 354.16 (e)

- The extent, cumulative total, and annual rate of land subsidence, including maps depicting total subsidence.

Minimum Thresholds § 354.28 (c)(5)

- The minimum threshold for land subsidence shall be the rate and extent of subsidence that substantially interferes with surface land uses and may lead to undesirable results supported by the following:

(A) Identification of land uses and property interests that have been affected or are likely to be affected by land subsidence in the basin.

(B) Maps and graphs showing the extent and rate of land subsidence that defines the minimum threshold and measurable objectives.

Monitoring Network § 354.34 (c)(5)

- Identify the rate and extent of land subsidence, which may be measured by extensometers, surveying, remote sensing technology, or other appropriate method.

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GWC CHECK LIST (20 OF 21)Inferometric Synthetic Aperture Radar(InSAR) Map from NASA JPL showsfairly small and uniform distribution ofland surface change.

Image for period March 2015 to March 2016

Average vertical displacement in the Cosumnes subbasin was -0.6 inches (-0.05 ft)

Source: SGMA data viewer https://sgma.water.ca.gov/webgis/?appid=SGMADataViewer#landsub


https://sgma.water.ca.gov/webgis/?appid=SGMADataViewer#landsub


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GWC CHECK LIST (21 OF 21)Total and Annual Rate of Historical MeasuredLand Subsidence was Small

UNAVCO GPS station P275 located in the Cosumnes Subbasin:

Vertical displacement recorded from July 2006 to present

Vertical displacement rate during that time period was 2.34 mm/yr

From July 2006 to present vertical displacement was -30.8 mm (-0.1 ft)

Source: https://www.unavco.org/instrumentation/networks/status/pbo/overview/P275


https://www.unavco.org/instrumentation/networks/status/pbo/overview/P275


BASIN SETTING PREPARATION TIMELINE

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Present HCM at August Cosumnes WG Meeting

Present GC at September Cosumnes WG Meeting

Present Preliminary WB at July Cosumnes WG Meeting

TM #6: Groundwater Conditions and Hydrogeologic Conceptual Model 11/30/2019 Feedback on TM #6

Present GDE & GW/SW interaction portion of the GC at October Cosumnes

WG Meeting


DATA GAP FILLING NEAR COMPLETIONTask Percent

Complete

Mine and Process DWR Well Completion Reports for construction data 100%

Aquifer Parameters- Calculate and evaluate specific capacity data- Compile values from other studies - Analyze lithologic logs and available lithologic data sets to extrapolate parameter values

across Basin

75%

Identify, assemble, and analyze GW/SW data 40%

Download and compile relevant eWRIMS diversion data 100%

Assemble climate and land use data to estimate recharge and agricultural groundwater use (pumping)

100%

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DWR is hosting a Sustainable Groundwater Management (SGM) Grant Program Planning Round 3 Grant Solicitation Applicant Assistance Webinar today

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PROP 68 GRANT APPLICATION (1 OF 9)


Attachments to Application:

1. Board Resolution

2. Eligibility

3. Work Plan

4. Budget

5. Schedule

6. Disadvantaged Areas documentation to support cost share reduction waiver, if applicable

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Board Resolution Applicant must adopt a

Resolution authorizing the grant application submittal

Need to decide applicant

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PROP 68 GRANT APPLICATION (4 OF 9)Eligibility Requirement Needs

Applicant GSA or member agency of a GSA

Agricultural Water Management Plan (AWMP)

If the applicant is an agricultural water supplier, must have an adopted 2015 AWMP verified as complete by DWR

CASGEM Compliance Must demonstrate the applicant met DWR’s CASGEM program requirements

Climate Change Must demonstrate project will address risks to water supply and water infrastructure arising from climate change

Groundwater Management Plan (GWMP)

Must have either (1) an adopted GWMP that complies with Water Code § 10753.7 before January 1, 2015, or (2) participate or consent to be subject to a GWMP, basin-wide management plan, or other Integrated Regional Water Management (IRWM) Program or plan that meets the requirements of Water Code § 10753.7.

Surface Water Diverter Compliance

If applicant is a surface water diverter, must have submitted surface water diversion reports to SWRCB

Sustainable Water Use and Demand Reduction

If applicant is an urban water supplier, must have a gallons per capita per day reduction targets with the end goal of a 20% reduction by 2020

Urban Water Management Plan (UWMP)

If applicant is an urban water supplier, must have an adopted UWMP verified as complete by DWR

Water Metering Compliance If applicant is an urban water supplier, must demonstrate they meet water meter requirements per Water Code § 525 et seq.


Work PlanA. Project

Description

B. Project Benefits

C. Technical Expertise

D. Project DetailsA. Scope of Work

B. Deliverables

E. Project Support

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Category (a) Grant Administration

Task 1 – Quarterly reporting and invoicing

Task 2 – Project management

Category (b) Stakeholder Engagement / Outreach

Task 1 – Surface water ecosystem working group

Category (c) GSP Development

Task 1 – GDEs identification/verification

Task 2 – Geophysical studies

Task 3 – Install monitoring wells

Task 4 – Isotopic recharge study

Task 5 – Model refinements

Category (d) Monitoring / Assessment

Task 1 – Shallow monitoring well installation

Task 2 – Install meters on agricultural and residential wells


PROP 68 GRANT APPLICATION (6 OF 9)Work Plan

Specific Needs from Working Group: Demonstration of GSA coordination

Description of decision-making processes

Describe and provide documentation of any communication with beneficial users of groundwater in the basin that may potentially be affected by implementation of the project, including, but not limited to DACs, agricultural water users, municipal water users, wildlife refuges, or other stakeholders – Letters of Support:

- DACs and/or SDACs

- Tribes

- Other GSAs surrounding and within the Basin

- Stakeholders

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Estimated costs need to be refined.

Task Relative Cost

1. GDEs Identification/Verification $85,000

2. Geophysical studies $210,000

3. Install monitoring wells $180,000

4. Isotopic Recharge Study $125,000

5. Install and monitor meters on agricultural and residential water wells $75,000

6. Model Refinements $200,000

Subtotal (Grant and SAFCA Match) $875,000Water Forum Match $125,000

Total $1,000,000

Estimated costs need to be refined.



Schedule – Subject to Revision

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Category Timeline

(a) Grant Administration Mar 2020 – April 2022

(b) Stakeholder Engagement / Outreach Mar 2020 – May 2021

(c) GSP Development Mar 2020 – May 2021

(d) Monitoring / Assessment Mar 2020 – May 2021


Prop 68 Grant Application Schedule:

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11/1/19: Application due to DWR by 1 pm

9/20/19: EKI sends information request to

Working Group

10/9/19: EKI sends Draft Application to Working

Group

10/23/19: Letters of Support & Board

Resolution due to EKI

10/25/19: Submit Application to DWR

10/18/19: Working Group Comments on Draft

Application due to EKI

10/2/19: Working Group information

due to EKI9/8/19: Notice to Proceed

eki technical presentation #11 - water...

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