eki technical presentation: gsp development and...
TRANSCRIPT
EKI TECHNICAL PRESENTATION:GSP DEVELOPMENT AND PRELIMINARY
FINDINGS FOR THE BASIN SETTING
WHITE WOLF GSA PUBLIC WORKSHOP #1
4 JUNE 2019
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SUSTAINABLE GROUNDWATER MANAGEMENT ACT (SGMA)
Signed into CA Law on September 16, 2014 Contained in these bills: SB 1168 & SB 1319
(Pavley); AB 1739 (Dickinson)
“Requires governments and water agencies of high and medium priority basins to halt groundwater overdraft and bring groundwater basins into balanced levels of pumping and recharge”(1)
(1) DWR, 2018. https://water.ca.gov/Programs/Groundwater-Management/SGMA-Groundwater-Management 2
Basin Boundary Modification July 2016 – DWR approved Basin Boundary Modification request forming the White Wolf Subbasin
GSA Formation May 2017 – AEWSD, Kern County, TCWD, and WRMWSD submitted GSA notification to DWR
CASGEM Compliance June 2017 –White Wolf GSA submitted CASGEM notification to DWR
GSP Development – Deadline: January 31, 2022 June 2018 – Initial Notification to prepare a GSP submitted to DWR June 2018 –White Wolf GSA adopts Stakeholder Communication and Engagement Plan December 2018 – Entered into a Prop 1 SGWP Grant Agreement with DWR June 2019 – Draft finding for the “Basin Setting” presented at Public Workshop
Demonstrate Groundwater Sustainability – January 31, 2042
SGMA COMPLIANCE TIMELINE20
19
201
8
2
017
2
016
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WHITE WOLF GSA AEWSD, Kern County, TCWD,
and WRMWSD coordinated to become the White Wolf GSA via a Joint Powers Agreement (JPA) on 9 May 2017
White Wolf GSA is the exclusive GSA for the White Wolf Subbasin
White Wolf GSA is producing one GSP
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BASIN BOUNDARY MODIFICATION
In 2016 the GSA entities petitioned DWR to revise Kern County Subbasin boundaries to create a separate White Wolf Subbasin (WWB)
Basin boundary modification request approved by DWR in July 2016 and the California Water commission in October 2016
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After the creation of the new WWB, the GSA entities petitioned DWR to downgrade the WWB from critical overdraft status
DWR released final prioritization on 4 January 2019 – WWB is Medium Priority
WWB now has two more years to comply with SGMA
GSP due January 31, 2022
DOWNGRADE FROM CRITICAL OVERDRAFT STATUS
Data Source: Statewide Map of SGMA 2019 Basin Prioritization Results (draft, subject to change)https://water.ca.gov/Programs/Groundwater-Management/Basin-Prioritization
Kern CountySubbasin
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KEY SGMA REQUIREMENTS – GSP DEVELOPMENT Notice and Communication
Data Management System (DMS)
Description of Plan Area
Hydrogeological Conceptual Model (HCM)
Groundwater Conditions Assessment
Water Budget
Sustainable Management Criteria (SMCs)
Monitoring Network
Projects & Management Actions (P&MAs)* 23-CCR Sections 352.6 , 354.8-20;www.water.ca.gov/groundwater/sgm/gsp.cfm
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White Wolf GSA adopted and is implementing a Stakeholder Communication & Engagement Plan (SCEP)
Venues for public engagement include: White Wolf GSA Board Meetings (first Tuesday
of every third month)
Public Workshops
White Wolf GSA actively coordinates with neighboring Kern Groundwater Authority (KGA) in the Kern Subbasin
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STAKEHOLDER ENGAGEMENT & COORDINATION
http://whitewolfgsa.org/
Surveys sent out to Basin stakeholders
20 surveys returned
Most stakeholders are familiar with SGMA and are currently engaged in groundwater management activities/discussions
11 stakeholders willing to share data
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STAKEHOLDER SURVEY FEEDBACK
Yes90%
No10%
FAMILIARITY WITH SGMA
Yes55%
No20%
Occasionally20%
No answer5%
CURRENT ENGAGEMENT WITH GW MANAGEMENT
Sent data requests to stakeholders willing to share data
Received 6 responses containing well location and construction information, pump test results, geophysical data, water level data, and water quality data for 34 wells
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STAKEHOLDER DATA REQUESTS
338 wells in the DMS
204 wells with water level data (1919-2018)
219 wells with water quality data
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DATA MANAGEMENT SYSTEM (DMS)
Land use maps show main basin floor as primarily irrigated agriculture and uplands area as undeveloped grazing and conservation lands
Identifies Grapevine Development as a major change in land use
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DRAFT PLAN AREA KEY FINDINGS
Defines one principal aquifer: Shallow Alluvium, Kern River Formation, and Chanac Formation
Santa Margarita Formation defined as the unpumped aquifer
Currently defines the “bottom of the Basin” as the depth of the deepest groundwater extractions (approximately 2,200 ft bgs)
Wells installed below that depth will have to demonstrate that they will not create impacts
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DRAFT BASIN SETTING KEY FINDINGS - HCM
Groundwater flow directions are generally to the northwest across the White Wolf Fault and into the Kern Subbasin
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DRAFT BASIN SETTING KEY FINDINGS – WATER LEVELS
Groundwater level trends: Lowest prior to the 1970s
Recovery starting around 1975 after surface water imports begin, by 2007 levels had recovered much of the decline
Decline again due to severe drought from 2012-2016
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DRAFT BASIN SETTING KEY FINDINGS – WATER LEVELS
DRAFT BASIN SETTING KEY FINDINGS – WATER LEVELS
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Water quality conditions based on data collected between 2012-2016 38% of well samples had constituents that
exceed MCLs / SMCLs: Nitrate
TDS
Arsenic
Selenium
Sulfate
Manganese
Iron
Boron was detected at levels that may restrict groundwater use for irrigation for common crops in 35% of wells
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DRAFT BASIN SETTING KEY FINDINGS – WATER QUALITY
Nitrate
TDS
Historical subsidence occurred in northern part of WWB and near Aqueduct
Recent subsidence mapping shows little deformation (within the range of error)
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DRAFT BASIN SETTING KEY FINDINGS - SUBSIDENCE
Groundwater storage in the Basin has increased by ~5,200 AFY between 1995-2014
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DRAFT BASIN SETTING KEY FINDINGS – GW STORAGE
Analytical spreadsheet model developed to quantify historical (WY 1994-2014) and current (WY 2015) conditions
Model-calculated water levels generally match the observed
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DRAFT BASIN SETTING KEY FINDINGS – WATER BUDGETEXTERNAL WATER BUDGET DOMAIN
HISTORICAL WATER BUDGET RESULTS – ANALYTICAL MODEL (WY 1994-2014)
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Land Surface Agricultural LandUrban Land
Groundwater Basin
Change in Storage5,200
Atmosphere
Groundwater Inflow
0
Vadose Zone
Imported Water
Deliveries74,108
Agricultural Pumping22,305
Direct Precipitation
78,380
Evapo-transpiration
143,281
Consumptive Use
1,587
Deep Percolation:Effective Precipitation 3,463Surface Water Infiltration 8,197Applied Water Infiltration 23,061
Pumping:Private 17,636District 4,669
Water Budget Domain
Inflow to water budget zone
Outflow from water budget zone
Flow between subdomainUnits: AFY
Groundwater Outflow
7,104
Natural Surface
Water Flows8,416
Basin is not in a condition of critical overdraft
Sustainable yield estimate = historical pumping + change in storage
Sustainable yield estimated to be about 27,500 AFY
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DRAFT BASIN SETTING KEY FINDINGS – WATER BUDGET
1995-2014 Historical Water Budget
Pumping 22,300 AFY
Change in Storage 5,200 AFY
Sustainable Yield 27,500 AFY
Assuming no interconnected surface water: Depth to groundwater in the principal
aquifer is well below land surface
Most streams in Basin are ephemeral (i.e., mostly dry with infrequent storm flows)
GDEs appear to be mapped in riparian areas
Springs Fault area may be an area we have to address GDEs
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DRAFT BASIN SETTING KEY FINDINGS - GDEs
WWB decided to participate in KGA’s groundwater model efforts for the Kern Subbasin
Model is not calibrated and results are not proving reliable for the WWB
White Wolf GSA considering doing its own model for GSP development and basin management
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GROUNDWATER MODELING COORDINATION
Uncertainty in distinguishing water transmitting and storage properties (hydraulic conductivity, specific yield, and specific storage) between geologic formations
Uncertainty in water transmitting and storage properties and groundwater flow across the White Wolf Fault
Uncertainty about well construction details, well use, and status for many wells
Uncertainty about well data received from stakeholders being correctly assigned to wells
Unknown well locations for the Tut Brothers public water system wells
Uncertainty in the reliability of groundwater flow model in its existing form
Limited available data associated with potential GDEs
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PRELIMINARY DATA GAPS
§351. Defines “Data gap” as a lack of information that significantly affects the understanding of the basin setting or evaluation of the efficacy of Plan implementation, and could limit theability to assess whether a basin is being sustainably managed.
POTENTIAL DATA GAP FILLING ACTIVITIES Conduct aquifer pumping tests to improve characterization of aquifer and fault
properties Consider applying for a Technical Support Services Grant to support well installation
and/or video logging Conduct additional outreach and field inspection to determine well construction
details of existing wells for potential use as monitoring wells Further attempts at stakeholder and public water systems outreach to accurately
locate well(s) Begin drafting coordination agreements with well owners for future monitoring Conduct additional model development / refinement Conduct field surveys for GDEs
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KEY TAKEAWAYS White Wolf GSA is preparing one GSP: Grapevine Development is a significant future land use change
One Principal Aquifer, extending to depths of approximately 2,200 feet bgs
Historically, groundwater level were lowest prior to the1970s, began to recover around 1975 after surface water imports begin, peak around 2007, and decline again due to severe drought from 2012-2016
Basin is not in critical overdraft: Average change in storage +5,200 AFY (WY1994-2014)
Irrigated areas of the Basin show high nitrate concentrations
Recent subsidence is minimal; historical subsidence has occurred near the Aqueduct
Limited reliability and data associated with groundwater flow modeling and potential GDEs requires future work
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SUSTAINABILITY CRITERIA(1)
Sustainability indicators (SIs) are the six effects that, when significant and unreasonable, become undesirable results
Minimum thresholds (MTs) are the quantitative values representing groundwater conditions at a representative monitoring site that, when exceeded, may cause an undesirable result(s)
Measurable Objectives (MOs) are quantitative goals that reflect the basin’s desired groundwater conditions and allow the GSA to achieve the sustainability goal within 20 years
Interim Milestone (IM) is a target value representing measurable groundwater conditions, in increments of five years, set by an Agency as part of a Plan
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Margin of Operational Flexibility
(1) DWR, 2017. Draft Sustainable Management Criteria BMP; Union of Concerned Scientists, 2017.
SUSTAINABILITY INDICATORS OF POTENTIAL CONCERN
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Land Subsidence
Seawater Intrusion
DWR CWP 2013Winter et al 1998
Water Quality Degradation
Lowering of GW Levels
Reduction of GW Storage
Surface Water Depletion
Low Concern High Concern
SIGNIFICANCE TO WHITE WOLF SUBBASIN
Sustainable Management Criteria (SMC) are the heart of the GSP
Development of SMC is a data-driven process (also guilty until proven innocent)
Scale and coordination are critical to defining Sustainability Indicators and Undesirable Results
SMCs can be iteratively adjusted in future years
State intervention can happen before 2042 if GSP is deemed inadequate or basin is underperforming relative to interim milestones
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NEXT STEPS
Assess monitoring network
Identify key data gaps and begin planning for data gaps filling efforts
Coordinate with KGA on projected future modeling
Begin Sustainability Planning
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White Wolf GSA Board Meetings First Tuesday of every third month
(Mar, Jun, Sep, & Dec) at 1 PM at the WRMWSD Headquarters
Public Workshops
White Wolf GSA Website: http://whitewolfgsa.org/
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OPPORTUNITIES FOR ENGAGEMENT
QUESTIONS?
Anona Dutton, P.G., C.Hg.
650-292-9100
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www.ekiconsult.comBurlingame, CA | Los Angeles, CA
Oakland, CA | Centennial, CO
http://whitewolfgsa.org/