CAWELO GROUNDWATER SUSTAINABILITY AGENCY

Cawelo GSA Groundwater Sustainability Plan REVIEW DRAFT

August 29, 2019

2490 Mariner Square Loop, Suite 215 Alameda, CA 94501 510.747.6920 www.toddgroundwater.com

PROFESSIONAL CERTIFICATION

Table of Contents

Executive Summary ...... 1 1. Introduction ...... 1 1.1. Purpose of the Groundwater Sustainability Plan ...... 1 1.2. Agency Information (REG. § 354.6) ...... 1 1.3. GSP Organization ...... 4 2. Cawelo GSA Plan Area ...... 5 2.1. Description of the Plan Area ...... 5 2.2. Water Resources Management ...... 10 2.3. Water Resources Monitoring ...... 13 2.4. Land Use ...... 21 2.5. General Plans ...... 22 2.6. Well Permitting...... 24 2.7. Regulatory Framework of Oil Field Operations ...... 25 2.8. Notice and Communication ...... 28 3 Basin Setting ...... 29 3.1 Hydrogeologic Conceptual Model (Reg. § 354.14) ...... 29 3.2 Current and Historical Groundwater Conditions (Reg. § 354.16) ...... 49 3.3 Management Areas ...... 66 3.4 Data and Knowledge Gaps ...... 66 4 Water Budget ...... 68 4.1 Water Budget Approach ...... 68 4.2 Study Period ...... 69 4.3 Historical and Current Water Budget ...... 70 4.4 C2VSimFG-Kern Model Water Budget Analysis...... 82 4.5 Change in Groundwater Storage ...... 85 4.6 Projected Water Budgets ...... 88 4.7 Projected Water Budget Results using C2VSimFG-Kern ...... 95 4.8 Data and Knowledge Gaps for the Water Budget Analysis ...... 95 5 Sustainability Goal and Undesireable Results ...... 97 5.1 Sustainability Goal ...... 97 5.2 Approach to Undesirable Results ...... 98 5.3 Chronic Lowering of Groundwater Levels ...... 98 5.4 Reduction of Groundwater Storage ...... 101 5.5 Seawater Intrusion ...... 102 5.6 Land Subsidence ...... 103 5.7 Degraded Water Quality ...... 105 5.8 Depletions of Interconnected Surface Water ...... 106

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA i TODD GROUNDWATER 6 Monitoring Network ...... 107 6.1 Monitoring Network Objectives ...... 107 6.2 Existing Monitoring Programs ...... 110 6.3 Groundwater Level Monitoring Networks ...... 122 6.4 Groundwater Storage Monitoring Networks ...... 123 6.5 Groundwater Quality Monitoring Networks ...... 124 6.6 Land subsidence Monitoring Networks ...... 126 6.7 Surface Water Monitoring Networks ...... 127 6.8 Representative Regional Monitoring (Reg. § 354.36) ...... 129 6.9 Assessment and Improvement of Monitoring Network (Reg. § 354.38) ...... 132 6.10 Reporting Monitoring Data to the Department (Reg. § 354.40) ...... 134 7 Minimum Thresholds, Measurable Objectives and Interim Milestones ...... 135 7.1 Sustainable Management Criteria ...... 135 7.2 Chronic Lowering of Groundwater Levels ...... 136 7.3 Reduction of Groundwater Storage ...... 139 7.4 Land Subsidence ...... 141 7.5 Seawater Intrusion ...... 144 7.6 Degraded Water Quality ...... 144 7.7 Depletions of Interconnected Surface Water ...... 147 7.8 Coordination with Kern County Subbasin GSAs ...... 147 8 Projects, Management Actions and Adaptive Management ...... 149 8.1 Overview of Projects and Management Actions ...... 149 8.2 Projects ...... 149 8.3 Management Actions ...... 159 8.4 Sustainability Assessment ...... 162 8.5 Projected Water Budget Results using C2VSimFG-Kern ...... 164 9 Plan Implementation ...... 166 9.1 Schedule for Implementation...... 166 9.2 Annual Reporting ...... 166 9.3 Periodic Evaluations ...... 166 10 References and Technical Studies ...... 167

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA ii TODD GROUNDWATER List of Tables

Table 3-1 Summary of Wells on Cross Sections Table 3-2 Oilfields and Adjustments to Subbasin Bottom in the Cawelo GSA Area Table 3-3 Well Completion Analysis using Available Data for the Cawelo GSA Table 3-4 Summary Statistics of Select Groundwater Quality Constituents Table 3-5 NCCAG-Mapped Natural Communities Polygons and Acres in the Cawelo GSA Table 4-1 Summary of Imported/Exported Water Deliveries (Acre-Feet per Water Year) Table 4-2 Summary of Groundwater Pumping (Acre-Feet per Water Year) Table 4-3 Summary of Surface Water Flows (Acre-Feet per Water Year) Table 4-4 Summary of Precipitation (Acre-Feet per Water Year Table 4-5 Summary of Evapotranspiration (Acre-Feet per Water Year Table 4-6 Summary of Percolation to Groundwater (Acre-Feet per Water Year) Table 4-7 Summary of Managed Aquifer Recharge (Acre-Feet per Water Year) Table 4-8 Summary of Natural Stream Recharge (Acre-Feet per Water Year) Table 4-9 Summary of Precipitation Percolation (Acre-Feet per Water Year) Table 4-10 Surface Water Budget Summary (Acre-Feet per Water Year). Table 4-11 Groundwater Budget Summary (Acre-Feet per Water Year) Table 4-12 Historical and Current Groundwater Budget from C2VSimFG-Kern for the Cawelo GSA Table 4-13 Net Subsurface Flows In/Out of Cawelo GSA Table 4-14 Method Comparison, Change in Groundwater Storage, Cawelo GSA. Table 4-15 Native Yield estimation for the Cawelo GSA Table 4-16 Historical hydrology for each simulation period Table 4-17 Data used to estimate State Water Project deliveries for future scenarios Table 4-18 Projected Future Surface Water Budget Summary for Baseline, 2030 Climate and 2070 Climate Change Conditions over 50-year Hydrologic Period (Acre-Feet per Water Year) Table 4-19 Projected Future Groundwater Budget Summary for Baseline, 2030 Climate Change and 2070 Climate Change Conditions over 50-year Hydrologic Period (Acre-Feet per Water Year) Table 4-20 Future Baseline Groundwater Budget Summary Comparison (Acre-Feet per Water Year) Table 6-1 Select Guidelines for Density of Monitoring Wells Table 6-2 Monitoring Well Network in the Cawelo GSA Table 6-3 Construction Information for Monitoring Well Network Table 7-1 Groundwater Level Minimum Thresholds, Measurable Objectives, Recent Groundwater Elevations, and Interim Milestones for Representative Wells Table 7-2 Groundwater Level Minimum Thresholds, Measurable Objectives, Recent Groundwater Elevations, and Interim Milestones for Land Subsidence at Representative Wells Table 8-1 Proposed SGMA Projects and Management Actions for the Cawelo GSA Table 8-2 Projected Benefit of Proposed Projects and Management Actions over Implementation and Planning Period Table 8-3 Future Baseline Groundwater Budget Summary Comparison (Acre-Feet per Water Year

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA iii TODD GROUNDWATER List of Figures (following text)

Figure 1-1 Kern County Groundwater Subbasin, Adjacent Basins, and Cawelo GSA Figure 1-2 Original and Final Cawelo GSA Boundary Figure 2-1 Cawelo GSA and Neighboring Jurisdictional Areas Figure 2-2 GSAs in Kern County Subbasin Figure 2-3 General Plan Areas within Cawelo GSA Figure 2-4 Water Purveyors within Cawelo GSA Figure 2-5 Cawelo GSA Water Supply Features Figure 2-6 Well Density Maps for a) Domestic, b) Production and c) Public Supply Figure 2-7 Land Use 2015 Figure 2-8 Important Farmland Figure 2-9 Agricultural Preserves Figure 3-1 Ground Surface Elevations Figure 3-2 Geologic Map Figure 3-3 Surface Geologic Units Figure 3-4 Soil Textures Figure 3-5 1983-2017 Annual Precipitation Figure 3-6 Surface Water Bodies Figure 3-7 Cross Section Transects Figure 3-8 Cross Section A-A’ Figure 3-9 Cross Section B-B’ Figure 3-10 Kern County Subbasin Cross Section with Oil Fields Figure 3-11 Oil Field Administrative Boundaries and Productive Limits Figure 3-12 Oil Field Aquifer Exemptions Figure 3-13 Regional Cross Section Locations Figure 3-14 Regional Hydrostratigraphic Cross Section Figure 3-15 Base of Fresh Water Figure 3-16 Depth to Base of USDW Figure 3-17 Conceptual Approach Bottom of the Subbasin in the Plan Area Figure 3-18 Depth to Base of Fresh Groundwater with Exempt Aquifers Figure 3-19 Depth to Base of USDW with Exempt Aquifers Figure 3-20 Area Where Groundwater Absent Above Basin Bottom Figure 3-21 Representative Hydrographs Figure 3-22 Groundwater Elevation Contours Spring 1998 Figure 3-23 Groundwater Elevation Contours Spring 2013 Figure 3-24 Groundwater Elevation Contours Spring 2017 Figure 3-25 Environmental Cleanup Sites Figure 3-26 Total Dissolved Solids Median Concentration Figure 3-27 Nitrate Median Concentration Figure 3-28 Pesticides in Groundwater Figure 3-29 Arsenic Median Concentration

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA iv TODD GROUNDWATER Figure 3-30 Boron Median Concentration Figure 3-31 Concepts of Land Subsidence Figure 3-32 Historical Subsidence 1926-1970 Figure 3-33 Subsidence 2007-2011 Figure 3-34 Recent Subsidence May 31, 2015 – December 31, 2016 Figure 3-35 Historic Low Groundwater Levels in Cawelo GSA Figure 3-36 Natural Communities and Wetlands within Cawelo GSA Figure 3-37 Groundwater Elevation Profiles Along Section A-A’ Figure 4-1 Checkbook Method Historical Surface Water Budget for Cawelo GSA Figure 4-2 Checkbook Method Historical Groundwater Budget for Cawelo GSA Figure 4-3 Cawelo GSA C2VSimFG-Kern Water Budget Area Figure 4-4 C2VSimFG-Kern Historical Water Budget for Cawelo GSA Figure 4-5 C2VSimFG-Kern Average Annual Water Budget for Cawelo GSA Figure 4-6 C2VSimFG-Kern Change in Groundwater S for Cawelo GSA Figure 4-7 Projected Future Change in Groundwater Storage for Cawelo GSA Figure 6-1 Wells with Water Level Data Figure 6-2 Famoso and Cawelo Coalition Water Quality Network Figure 6-3 Monitoring Well Network Figure 7-1 Relationship between Sustainability Management Criteria Figure 7-2 Representative Monitoring for the Cawelo GSA Figure 7-3 Average Change in Groundwater Levels in the Cawelo GSA Figure 7-4 Average Groundwater Level Change Compared to Change in Groundwater Storage Figure 7-5 Neighboring GSA and Water District Areas Figure 8-1 Projected Future Change in Groundwater Storage for Baseline Conditions Figure 8-2 Projected Future Change in Groundwater Storage for 2030 Climate Conditions Figure 8-3 Projected Future Change in Groundwater Storage for 2070 Climate Conditions Figure 8-4 T27S/R26E-12H (RMW-167) Baseline & 2030 Projected Future Groundwater Levels Figure 8-5 T27S/R26E-4R (RMW-168) Baseline & 2030 Projected Future Groundwater Levels Figure 8-6 T28S/R27E-28L (RMW-169) Baseline & 2030 Projected Future Groundwater Levels Figure 8-7 T26S/R26E-24R (RMW-170) Baseline & 2030 Projected Future Groundwater Levels Figure 8-8 T28S/R26E-11M (RMW-171) Baseline & 2030 Projected Future Groundwater Levels Figure 8-9 T28S/R27E-6C (RMW-172) Baseline & 2030 Projected Future Groundwater Levels Figure 8-10 T27S/R26E-33C2 (RMW-173) Baseline & 2030 Projected Future Groundwater Levels Figure 8-11 T27S/R26E-12H (RMW-167) Baseline & 2070 Projected Future Groundwater Levels Figure 8-12 T27S/R26E-4R (RMW-168) Baseline & 2070 Projected Future Groundwater Levels Figure 8-13 T28S/R27E-28L (RMW-169) Baseline & 2070 Projected Future Groundwater Levels Figure 8-14 T26S/R26E-24R (RMW-170) Baseline & 2070 Projected Future Groundwater Levels Figure 8-15 T28S/R26E-11M (RMW-171) Baseline & 2070 Projected Future Groundwater Levels Figure 8-16 T28S/R27E-6C (RMW-172) Baseline & 2070 Projected Future Groundwater Levels Figure 8-17 T27S/R26E-33C2 (RMW-173) Baseline & 2070 Projected Future Groundwater Levels Figure 9-1 Cawelo GSA GSP Implementation Schedule

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA v TODD GROUNDWATER Appendices

Appendix A Notice of Decision to become a Groundwater Sustainability Agency Appendix B GSP Preparation Checklist Appendix C Selected General Plan Goals, Policies, and Implementation Measures Appendix D Cawelo GSA Outreach Plan Appendix E Historical and Current Water Budgets – Checkbook Method Appendix F Historical and Current Water Budgets – C2VSimFG-Kern Method Appendix G Projected Future Water Budgets – Baseline and Climate Change Appendix H Projected Future Water Budgets – Sustainability Assessment of Proposed SGMA Projects and Management Actions

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA vi TODD GROUNDWATER List of Acronyms

AF Acre-Feet AFY Acre-Feet per Year As Arsenic AWMP Agricultural Water Management Plan BMPs Best Management Practices BTEX Benzene, Toluene, Ethylbenzene, and Xylene bgs Below ground surface BVWSD Buena Vista Water Storage District CASGEM California Statewide Groundwater Elevation Monitoring CCR California Code of Regulations CDFA California Department of Food and Agriculture CDFW California Department of Fish & Wildlife CDMG California Division of Mines and Geology (now California Geological Survey) CEQA California Environmental Quality Act CFR Code of Federal Regulations cfs cubic feet per second CGPS Continuous Global Positioning System CGQMP Comprehensive Groundwater Quality Management Plan CGS California Geological Survey (formerly California Division of Mines and Geology) CIMIS California Irrigation Management Information System CSU California State University CVRWQCB Central Valley Regional Water Quality Control Board, also referred to as Central Valley Water Board CVC Cross Valley Canal CVP Central Valley Project CV-SALTS Central Valley—Salinity Alternative for Long-Term Sustainability CWD Cawelo Water District CWDC Cawelo Water District Coalition CWSC California Water Science Center C2VSim California Central Valley Groundwater-Surface Water Simulation C2VSimFG-Kern California Central Valley Groundwater-Surface Water Simulation Model Kern County Update for the Kern County and White Wolf Subbasin DBCP 1,2-Dibromo 3-chloropropane (also Dibromochloropropane) DDW Division of Drinking Water, SWRCB DEM Digital Elevation Map DO Dissolved Oxygen DOGGR California Division of Oil, Gas, and Geothermal Resources DOT Department of Transportation DPLA Division of Planning and Local Assistance DPR Department of Pesticide Regulation DQO Data Quality Objective DTSC Department of Toxic Substances Control DTW Depth to Water DWR California Department of Water Resources EC Electrical Conductivity EHS Environmental Health Services

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA vii TODD GROUNDWATER ELAP Environmental Laboratory Accreditation Program EOR Enhanced Oil Recovery ESA European Space Agency ET Evapotranspiration ETo Reference Evapotranspiration EWMP Efficient Water Management Practices ft Feet ft/day Feet per Day FEMA Federal Emergency Management Agency GAMA Groundwater Ambient Monitoring and Assessment GAR Groundwater Quality Assessment Report GDE Groundwater Dependent Ecosystem GICIMA Groundwater Information Center Interactive Map GIS Geographic Information System gpd/ft Gallons per Day per Foot gpm Gallons per Minute GPS Global Positioning System GQTMP Groundwater Quality Trend Monitoring Program GSA Groundwater Sustainability Agency gse Ground surface elevation GSP Groundwater Sustainability Plan GWE Groundwater Elevation GWMP Groundwater Management Plan HCM Hydrogeologic Conceptual Model ID Identification IDC Independent Demand Calculator IFI Important Farmlands Inventory ILRP Irrigated Lands Regulatory Program IM Interim Milestones InSAR Interferometric Synthetic Aperture Radar IRWMP Integrated Regional Water Management Plan ITRC Irrigation Training and Research Center JPL Jet Propulsion Laboratory KCWA Kern County Water Agency KGA Kern Groundwater Authority KRGSA Kern River Groundwater Sustainability Agency LLNL Lawrence Livermore Nation Laboratory LUST Leaking Underground Storage Tank m Meters mgd Million Gallons per Day mg/L Milligrams per Liter or Parts per Million (ppm) msl Mean Sea Level MAR Managed Aquifer Recharge MCL Maximum Contaminant Level METRIC Mapping EvapoTranspiration at high Resolution with Internalized Calibration MO Measurable Objective MOU Memorandum of Understanding MPEP Management Practices Evaluation Program

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA viii TODD GROUNDWATER MT Minimum Threshold MWC Mutual Water Company M&I Municipal and Industrial N Nitrogen NaCl Sodium Chloride NASA National Aeronautics and Space Administration NCCAG Natural Communities Commonly Associated with Groundwater NCDC National Climatic Data Center NED National Elevation Dataset NEHRP National Earthquake Hazards Reduction Program NIST National Institute of Standards and Technology NKWSD North Kern Water Storage District NL Notification Level NOAA National Oceanic and Atmospheric Administration NO2 or NO2 Nitrite NO3 or NO3 Nitrate NPDES National Pollutant Discharge Elimination System NRCS Natural Resources Conservation Service NSF National Science Foundation NWIS National Water Information System OPS Office of Pipeline Safety PAH Polynuclear Aromatic Hydrocarbons Pb Lead PBO Plate Boundary Observation PHMSA Pipeline and Hazardous Material Safety Administration Plan Groundwater Sustainability Plan ppm Parts per million PRC Public Resources Code QAPP Quality Assurance and Project Plan QA/QC Quality Assurance/Quality Control RCRA Resource Conservation and Recovery Act RMP Regional Monitoring Program RMS Representative Monitoring Sites ROD Record of Decision RPE Reference Point Elevation RRBWSD Rosedale Rio Bravo Water Storage District RTK Real-Time-Kinematic RWD Report of Waste Discharge RWMG Regional Water Management Group RWQCB Regional Water Quality Control Board SB4 Senate Bill 4 SCS Soil Conservation Service SDWA Safe Drinking Water Act SDWIS State Drinking Water Information System Se Selenium SGMA Sustainable Groundwater Management Act SJRRP San Joaquin River Restoration Program SMCL Secondary Maximum Contaminant Level

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA ix TODD GROUNDWATER SNMP Salt and Nitrate Management Plan SSJMUD Southern San Joaquin Municipal Utilities District SSURGO Soil Survey Geographic Database SWID Shafter-Wasco Irrigation District SWMP Surface Water Monitoring Plan SWP State Water Project SWPPP Storm Water Pollution Prevention Plan SWRCB State Water Resources Control Board SWSD Semitropic Water Storage District TCP 1,2,3-Trichloropropane TDS Total Dissolved Solids TLB Tulare Lake Basin TNC The Nature Conservancy TOC Total Organic Carbon TSS Total Suspended Solids UC University of California UIC Underground Injection Control USBR U.S. Bureau of Reclamation USDW Underground Source of Drinking Water USEPA U.S. Environmental Protection Agency USGS U.S. Geological Survey UST Permitted Underground Storage Tank UWMP Urban Water Management Plan VWDC Valley Waste Disposal Company WDL Water Data Library WDR Waste Discharge Requirements WQCP Water Quality Control Plan WSR Water Supply Report WY Water Year, October 1 through September 30 µg/L Micrograms per liter or parts per billion (ppb) µmho/cm Micromhos per centimeter ° Degrees (Direction or Bearing) °F Degrees Fahrenheit

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA x TODD GROUNDWATER EXECUTIVE SUMMARY

(Reg. § 354.4) Placeholder.

To be added for the Final GSP.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA ES-1 TODD GROUNDWATER

1. INTRODUCTION

In 2014, the State of California passed the Sustainable Groundwater Management Act (SGMA) that provides local agencies with a framework for managing groundwater basins in a sustainable manner. SGMA requires high priority basins, as defined by the California Department of Water Resources (DWR), to develop Groundwater Sustainability Plans by January 31, 2020 and achieve sustainability by the year 2040.

The Cawelo Water District (CWD or District) is a local agency in the Kern County Subbasin area, DWR Bulletin 118, 5-022.14, and has established the Cawelo Groundwater Sustainability Agency (Cawelo GSA) to develop a local Groundwater Sustainability Plan (GSP or Plan) that is tailored to the resources and needs of the Plan area. DWR has designated the Kern County Subbasin as critically overdrafted and a high priority basin. This document, along with the included tables, figures and attachments is the proposed GSP for the Cawelo GSA.

The District is a member of the Kern Groundwater Authority (KGA) which has formed its own Groundwater Sustainability Agency (GSA) and will develop a Plan that covers the KGA plan area and its members’ corresponding coverage areas. The KGA GSA Plan is referred to as the “Umbrella Plan” and each of the individual KGA members will provide their respective GPS that will are referred to as a “Chapter” within the Umbrella Plan.

It is the intent that this document be included as a Chapter in the KGA Umbrella Plan.

1.1. PURPOSE OF THE GROUNDWATER SUSTAINABILITY PLAN

The purpose of the Cawelo GSP is to assess water resources and land use conditions within the Cawelo GSA and to implement management activities to achieve long-term groundwater sustainability within the SGMA framework. . Several GSPs by multiple Groundwater Sustainability Agencies (GSA) have been developed by multiple GSAs within the Kern County Subbasin. This GSP was developed in conjunction with the other Kern County Groundwater GSPs through a single coordination agreement that covers the entire basin. The coordination agreement is included in the KGA Umbrella GSP (GEI, 2019).

1.2. AGENCY INFORMATION (REG. § 354.6)

Cawelo Water District (CWD) has actively managed groundwater since its inception in 1965. This management, focused on conjunctive use of groundwater and surface water sources, was formalized in 1994 through adoption of its Groundwater Management Plan (GWMP), subsequently updated in 2007, and December 2013.

SGMA also empowers local agencies to form a GSA for managing groundwater resources in a sustainable manner. Accordingly, the Cawelo GSA was formed to continue groundwater management within its portion of the Kern County Groundwater Subbasin (Figure 1-1) with the goal of achieving sustainability in accordance with SGMA. Cawelo GSA was formed through the following process:

• A properly noticed public hearing was held by CWD on Thursday May 18, 2017 to determine whether to become a GSA.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 1 TODD GROUNDWATER • The Cawelo Board of Directors subsequently adopted Resolution No. 688 on May 18, 2017 to form a GSA. • On June 12, 2017, CWD submitted to the California Department of Water Resources (DWR) a Notice of Decision to become a Groundwater Sustainability Agency, along with required information including a boundary map of the GSA and a list of interested parties. • After the 90-day review period, Cawelo GSA became an exclusive groundwater sustainability agency. • On January 10, 2019, the Cawelo GSA Board of Directors approved the expansion of the original Cawelo GSA boundary to incorporate two additional general areas. One of the additional areas is adjacent and to the east of the original GSA boundaries. The second additional area is located further to the southeast and is land in the general area of the Kern River oilfield. (Figure 1-2). The two additional areas are herein referred to as the Eastern Extension Area of the Cawelo GSA. • Effective April 09, 2019, the Cawelo Water District and the County of Kern executed a Joint Powers Agreement for the Purpose of Expanding the Cawelo Groundwater Sustainability Agency Pursuant to the Sustainable Groundwater Management Act. This agreement provides for the authority to manage the Eastern Extension Area lands pursuant to SGMA. • In May of 2019, in cooperation with neighboring GSAs, the Cawelo GSA submitted a request to DWR to modify the Cawelo GSA coverage area. • On June 14, 2019, DWR approved the current Cawelo GSA coverage area.

1.2.1. Agency Point of Contact

The point of contact for the Cawelo GSA is:

David Hampton, Assistant General Manager Cawelo Groundwater Sustainability Agency 17207 Industrial Farm Rd., Bakersfield, CA 93308 661-393-6072 [email protected]

As required by GSP Regulations §354.6 and SGMA §10723.8, the Notice of Decision to become a Groundwater Sustainability Agency is included in Appendix A. This includes the resolution, list of interested parties, and a preliminary service area boundary map.

1.2.2. Organization and Management Structure

The CWD has been approved as of September 10, 2017 to be the exclusive GSA for the portion of the Kern County Subbasin (No. 5-22.14) within the Cawelo GSA boundaries. On June 14, 2019, the modifications to the GSA boundary to include the Eastern Extension Area was approved. The CWD, organized as a California Water District, is governed by a five-person Board of Directors that elects a president from its members and appoints a secretary. The CWD Board of Directors (Board) also serves as the Board of Directors for the Cawelo GSA. The Board meets monthly at its office, located at 17207 Industrial Farm Road, Bakersfield, California. Meetings are announced, and agenda are posted on the CWD website (www.cawelowd.org); the meetings are open to the public. The Board (except as

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 2 TODD GROUNDWATER otherwise specifically provided in the California Water Code) manages and conducts the business and affairs of the CWD and Cawelo GSA. The vote of a majority of the directors present at any meeting attended by a quorum is necessary to determine any proposition or resolution presented. The Board is supported by operations staff and by administrative staff, including the Assistant General Manager who is the GSA Point of Contact (see above).

The Cawelo GSA welcomes public participation in the ongoing planning and development activities supporting the GSP process. Public meetings regarding development of the GSP are being conducted to encourage public participation and to provide educational outreach. Meeting notices are provided to the list of interested parties that is maintained pursuant to Water Code Section 10723.2. Additionally, GSP development information and meeting notices are posted to the Cawelo GSA website.

CWD is a member of the Kern Groundwater Authority (KGA), which provides a forum for local policy makers, stakeholders, and the public to monitor, report and discuss groundwater activities and issues. The KGA is an exclusive GSA for their defined coverage area and is currently the largest GSA in the Kern County Subbasin 5-022.14. Information on the KGA and its monthly meetings (open to the public) are posted on its website (www.kerngwa.com). CWD is signatory to the KGA Joint Powers Agreement (included in the KGA Umbrella GSP (GEI, 2019)) that supports implementation of SGMA within the Kern County Subbasin and coordinates preparation of GSPs. Cawelo GSA participates actively with the Kern Groundwater Authority and its members and meets with other local GSAs.

1.2.3. Legal Authority of the GSA

The CWD is a public agency overlying a portion of the Kern County Subbasin. The CWD is a California Water District formed on February 16, 1965, under the provisions of California Water Code Division 13 for the purpose of obtaining a supplemental or partial water supply for irrigation; therefore, it is qualified to form a GSA.

As stated in Water Code §10732, the Cawelo GSA has the power to develop and implement SGMA, including a GSP. The GSA can adopt standards for measuring and reporting water use, develop and implement policies designed to reduce or eliminate overdraft within the boundaries of the GSA, develop and implement conservation best management practices, and develop and implement metering, monitoring and reporting related to groundwater pumping.

On January 10, 2019, the Cawelo GSA Board of Directors approved the expansion of the original Cawelo GSA boundary to incorporate two additional general areas. One of the additional areas is adjacent and to the east of the original GSA boundaries. The second additional area is located further to the southeast and is land in the general area of the Kern River oilfield (Figure 1-2). The CWD and the County of Kern executed a Joint Powers Agreement for the Purpose of Expanding the Cawelo Groundwater Sustainability Agency Pursuant to the Sustainable Groundwater Management Act. This agreement provides for the authority to manage the additional areas outside the CWD boundaries.

1.2.4. GSP Development Costs and Funding Sources

The Cawelo GSA approach to costs includes a Cawelo GSA component that is focused on local conditions and issues and a regional effort through the KGA that supports regional coordination. In January 2018, Cawelo GSA contracted with Todd Groundwater to develop the Cawelo GSP for the initial area, with a contract amount for $484,394. The scope of work was expanded to include the Eastern Extension Area for an additional contract amount not to exceed $146,583 for a total of $630,977. In addition, specific

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 3 TODD GROUNDWATER costs for general SGMA related basin efforts are shared among KGA members; these include administrative services, technical assistance, groundwater modeling, and model peer review. The cost allocation for Cawelo GSA, based on the Special Activities Agreement, is 5.413 percent (KGA, 2018). The estimated expenditures for Cawelo GSA’s share of the general basin efforts to complete the GSP are $360,000.

The total costs for Cawelo GSA, SGMA related support, and GSP development is estimated to be $990K through January 31, 2020 which includes SGMA and GSA activities during the 2017 and 2018 years. Currently, the CWD is funding the related SGMA cost for the main GSA area. The Cawelo GSA is currently considering land based assessment fees and water pumping toll charges that will reimburse the CWD for related expenditures.

1.3. GSP ORGANIZATION

This GSP is organized generally to follow the Groundwater Sustainability Plan (GSP) Annotated Outline provided by DWR as one of its Guidance Documents. Major sections include:

• Executive Summary • Introduction (including Agency Information) • Plan Area • Basin Setting • Sustainable Management Criteria • Monitoring Networks • Projects and Management Actions • Plan Implementation A Preparation Checklist demonstrating compliance with SGMA is included in Appendix B.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 4 TODD GROUNDWATER 2. CAWELO GSA PLAN AREA

The following sections, consistent with GSP Regulations §354.8, provide general agency information, a description of the Plan Area, and land use planning for the Cawelo GSA. For the Eastern Extension Area of the Cawelo GSA, the plan area primarily consists of addressing SGMA issues related to the operations at the Kern River, Kern Front, and Poso Creek Oil Fields.

2.1. DESCRIPTION OF THE PLAN AREA

The Kern County Subbasin and the Cawelo GSA are located within Kern County. The following provides a general description of the Cawelo GSA Plan Area.

2.1.1. Geographic Area

The Cawelo GSA area encompasses about 98 square miles, or 63,000 acres, in Kern County (Figure 2-1) and is mostly highly-developed agriculture on prime farmland. Cawelo GSA is bounded by four water districts that include:

• North Kern Water Storage District to the west, • Kern-Tulare Water District to the north, • Southern San Joaquin Municipal Utilities District to the northwest, and • Improvement District #4 to the south.

Cawelo GSA is generally located between U.S. Highway 99 on the west and State Highway 65 on the east, with the Eastern Extension Area of the Cawelo GSA located east and southeast of State Highway 65. A small area of the City of Shafter city limits extends into the Cawelo GSA. The City of Bakersfield city limit extends along the southwestern boundary of Cawelo GSA, and the City of McFarland is located about two miles the northwest (Figure 2-1). The Eastern Extension Area is largely in the foothills that are oil field operations and undeveloped land. The cities of Oildale and Bakersfield lie to the south and west of the Eastern Extension Area Small areas of Oildale and Bakersfield city limits extend into the Eastern Extension Area (Figure 2-1).

The Cawelo GSA is located in the north-central portion of the Kern County Subbasin of the San Joaquin Valley Groundwater Basin as defined by DWR (DWR Basin 5-22.14). Figure 1-1 shows the boundaries of the Cawelo GSA within the larger Kern County Subbasin. Cawelo GSA is located completely within the Kern County Subbasin and does not directly border any other subbasin. As shown on Figure 1-1, there are four subbasins adjacent to the Kern County Subbasin:

• Kettleman Plain Subbasin (DWR Basin 5-22.10) • Tulare Lake Subbasin (DWR Basin 5-22.12) • Tule Subbasin (DWR Basin 5-22.13) • White Wolf Subbasin (DWR Basin 5-22.18)

The Cawelo GSA is one of eleven GSAs that have been formed in the Kern County Subbasin. Figure 2-2 shows the boundaries of all GSAs in the Kern County Subbasin in relation to the location of the Cawelo GSA. The other GSAs defined for the Kern County Subbasin are:

• Buena Vista Water Storage District GSA

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 5 TODD GROUNDWATER • Greenfield County Water District GSA • Henry Miller Water District GSA • Kern River GSA • Kern Groundwater Authority GSA • McFarland GSA • Olcese GSA • Pioneer GSA • Semitropic Water Storage District GSA • West Kern Water District GSA

2.1.2. Jurisdictional Agencies

The area of the Cawelo GSA coincides with the area of the CWD, who manages the area as an exclusive GSA. The Eastern Extension Area of the Cawelo GSA extends to the east beyond the area of the Cawelo Water District. No areas are managed for which the Cawelo GSA is not the exclusive GSA. No adjudicated areas exist in the Kern County Subbasin and no Alternative Plans were submitted.

Through the Kern County Planning & Community Development Department, Kern County has jurisdiction for land use planning for unincorporated areas. The County also has responsibility for well permitting through its Department of Public Health. The City of Shafter and Metropolitan Bakersfield are local jurisdictions with land use planning authority within parts of the Cawelo GSA. The City of Shafter General Plan planning area overlaps small areas along the western boundary of Cawelo GSA (Figure 2-3). The City of Shafter is a groundwater dependent and a disadvantaged community. The City of Bakersfield is adjacent to part of the Cawelo GSA southern boundary, and portions of the Metropolitan Bakersfield General Plan planning area overlap the Cawelo GSA (Figure 2-3). The City of Oildale that is adjacent to the southern boundary of the Eastern Extension Area is also a disadvantaged community. Additional discussion of these general plans is provided in Section 2.5.

Two water purveyors provide water supply to small portions of the Cawelo GSA (Figure 2-4). The City of Shafter Water Department’s service area overlaps a small portion of the Cawelo GSA western boundary (Shafter, 2016). However, the parcels located in both the City and Cawelo GSA are largely open land with some storage and warehousing land use. The Oildale Mutual Water Company (Oildale MWC) provides water supply to industrial areas in the southern end of Cawelo. For other areas within the Cawelo GSA, domestic and industrial water supply is met from private groundwater wells.

Review of the DWR Water Management Planning Tool (2018) reveals the nearby presence of several Bakersfield Cactus ecological reserves administered by the California Department of Fish & Wildlife (CDFW); however, none overlie the Cawelo GSA, but one area is adjacent to the Cawelo GSA (Figure 2-1). No other state or federal agencies are known to administer land in the Cawelo GSA, such as military installations, United States Forest Service lands, other federal lands, or state parks. However, several small parcels that are managed by the Bureau of Land Management are located within the Eastern Extension Area of the Cawelo GSA. No tribal lands are documented in the DWR Water Management Planning Tool or are known to exist in the Cawelo GSA. Poso Creek, which crosses CWD, drains toward the Kern National Wildlife Refuge about 25 miles west of Cawelo GSA.

Oil and gas field operations are required to comply with an array of federal, state and local regulatory requirements. The United States Environmental Protection Agency (EPA) must review and approve aquifer exemption requests in accordance with the regulatory criteria in 40 CFR 146.4. The California

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 6 TODD GROUNDWATER Division of Oil, Gas, and Geothermal Resources (DOGGR) regulate production of oil, gas, and geothermal resources, including standards for well design and construction standards, surface production equipment and pipeline requirements, and well abandonment procedures and guidelines. (California Code of Regulations, Title 14, Division 2, Chapter 4). EPA has also granted DOGGR primacy over the Underground Injection Control program for Class II wells.

2.1.3. Water Supply

Water supply for the Cawelo GSA is from groundwater, local surface water from Poso Creek, imported water (State Water Project, Kern River and Federal Central Valley Project), treated-produced water, and conjunctive use programs. The water supply production and use in the Eastern Extension Area of the Cawelo GSA is relatively low compared to the CWD portion of the Cawelo GSA.

Groundwater. Groundwater in the Cawelo GSA is pumped from the underlying Kern County Subbasin, which is one of the largest in the state, covering approximately 2,800 square miles and containing more than 40,000,000 acre-feet (AF) of groundwater in storage (DWR, 2006; 2016c). The local aquifer system is replenished by percolation of overlying surface water and precipitation, groundwater inflow originating primarily from the uplands to the east, agricultural irrigation return flow, and CWD groundwater recharge and water banking programs.

Most groundwater pumping within CWD is attributable to on-farm pumping, with some pumping for rural domestic and commercial uses. CWD maintains and operates 16 deep wells to supplement deliveries of surface water as needed (CWD, 2015b). In years when the availability of imported surface water is limited, local landowners pump groundwater from privately-owned wells consistent with CWD’s conjunctive management strategy.

Imported Water. The primary source of surface supply for CWD is its allocation of State Water Project (SWP) water through the Kern County Water Agency (KCWA), the local SWP contractor. SWP water is diverted from the California Aqueduct and conveyed through the Cross Valley Canal and delivered to CWD via the Beardsley-Lerdo Canal (Figure 2-5). CWD has a contract for 38,200 AF per year (AFY) with KCWA but does not receive the full amount due to shortages in SWP supplies. Water supplies available from the SWP are governed by watershed precipitation, snow melt runoff and other regulatory factors. Accordingly, CWD receives an annual allocation. SWP allocations are variable, with frequent shortages, and can be quite limited in a dry year such as 2014. In a year when the SWP water supply is less than the total CWD contract amount, each water user is allocated a pro-rated share of the total. Historically, CWD has received an annual Article 21 allocation of approximately 6,800 AF; however, due to restrictions on pumping water from the Delta, Article 21 water has become less available to CWD and other districts over time (CWD, 2015b).

Water from the Central Valley Project (CVP), operated by the U.S. Bureau of Reclamation (USBR), used within the Cawelo GSA is Section 215 water, which is a temporary supply of CVP water made available in large water supply years. While CWD is not a long-term CVP contractor, the USBR at times has made annual contracts available to non-CVP contractors for purchase and diversion of Section 215 supplies. These are generally un-storable and unmanaged flood flows of short duration and their availability depends on hydrologic conditions of the San Joaquin River and diversions from the Friant-Kern Canal. Given recent completion of the Calloway-to-Lerdo Intertie and the Friant-Kern Canal connection (Figure 2-5), CWD is now capable of receiving CVP Section 215 deliveries and other exchanges.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 7 TODD GROUNDWATER In previous years, CWD purchased, on average, about 27,000 AFY of Kern River water from the City of Bakersfield that was delivered to CWD via the Lerdo Canal (Figure 2-5). The basic delivery schedule under this contract, which is no longer a reliable supply, called for 2,700 AF per month to be delivered during March and April, and 5,400 AF per month during May through August. The contract also made available for sale “miscellaneous water” which occasionally was available in addition to the contract amount. CWD has been in discussions with the City of Bakersfield to reach a new agreement for the diversion of Kern River water (CWD, 2015b).

Surface Water. Poso Creek traverses the Cawelo GSA about midway between the District’s northern and southern boundaries (Figure 2-5). Poso Creek originates in the Southern Sierra Nevada and flows westward across CWD. CWD currently monitors Poso Creek at Trenton Weir near State Highway 65. The annual flow at this site has exceeded 120,000 AF, but many years it has little to no flow. While flows are variable, some CWD landowners do occasionally exercise their riparian rights to divert water from Poso Creek.

In 2000, CWD was issued a permit to divert water from Poso Creek for beneficial use at a rate of approximately 110 cubic feet per second (cfs), with the volume limited to 30,000 AF between November 1 and June 14 of the following year. An agreement between CWD, North Kern Water Storage District, and Semitropic Water Storage District allocated the first 135 cfs of Poso Creek flow (as measured at the State Highway 65 gaging station) to CWD.

The Kern River flows within and along the southern boundary of the Eastern Extension Areas of the Cawelo GSA (Figure 2-5). The Kern River originates in the Southern Sierra Nevada and flows westward across the southern portion of the Eastern Extension Area. Several stream flow gages are located on the Kern River; the United States Geological Survey (USGS) operates several gages upstream of the City of Bakersfield and flow data on the River has been collected since the 1890s.

Treated Produced Water. “Produced Water” refers to water entrained in oil as oil is extracted from the ground. “Treated Produced Water” refers to water removed from the extracted oil, which is subsequently treated for beneficial reuse or reinjection. CWD purchases up to 36,000 AFY of treated produced water from local oil extraction operations including Chevron and CRC official Name? (formerly Valley Water Management Company). The treated produced water is pumped to CWD Reservoir B through a separate pipeline from the Kern River and Kern Front Oilfields . This water is treated to conform with the Central Valley Regional Water Quality Control Board’s (CVRWQCB) waste discharge requirements and is blended with water from other sources before delivery to the CWD’s water users where it is used for both irrigation and groundwater recharge in banking projects. Supplies from this source are dependent on local oil production, because the water is entrained in oil as it is produced. In recent years, the total delivery of treated produced water has ranged between 20,000 and 37,000 AF. The volume of treated produced water will fluctuate with oil production and long-term availability cannot be predicted.

Conjunctive Use Programs. CWD has based its irrigation distribution system on conjunctive management of its surface water and groundwater resources. Surplus surface water supplies are available for direct groundwater recharge within the District. CWD operates over 400 acres of spreading basins; the largest spreading site, the Famoso Project Basins, encompass about 370 acres along Poso Creek near Highway 99 (Figure 2-4). The Poso Creek Basin, with over 30 acres, is along Poso Creek just west of Highway 65. Other CWD reservoirs, used for operational storage, also contribute some recharge

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 8 TODD GROUNDWATER (CWD, 2015b). CWD maintains and operates 16 deep wells for recovering this groundwater recharge to supplement deliveries of surface water for beneficial uses as needed.

CWD also operates a long-term “In-Lieu Water Banking Program” that allows “banking partners” to store “surplus” water in CWD and to recover their water when needed. Water banking involves the regulation of surplus surface water supplies, by placing the water into groundwater storage for subsequent recovery. The storage is achieved through either indirect or direct recharge. Indirect recharge is based on the delivery of surface water in-lieu of pumping groundwater (CWD, 2015b).

2.1.4. Canals, Conveyance and Infrastructure

The Cawelo Water District (CWD) is primarily irrigated agriculture and the Eastern Extension Area is predominantly oil fields. The CWD supplies imported water for beneficial uses such as irrigation and groundwater banking. Sources of imported water include Kern River water, SWP, CVP, and treat produced water. Irrigation return flows and infiltration from water conveyance systems account for one half of groundwater inflows using the checkbook method. CWD receives imported surface water conveyed by a network of canals, pipelines, pump stations and reservoirs (CWD, 2007). The CWD shares the following facilities (Figure 2-5) with other water districts.

• Beardsley Canal • Part of the Lerdo Canal • Part of the Calloway Canal • Calloway to Lerdo Intertie • Cross Valley Canal to Calloway Canal Intertie - • Cross Valley Canal

CWD’s major water distribution infrastructure includes six pump stations with associated discharge pipelines, an irrigation distribution system, five reservoirs, and recharge basins (CWD 2015). These facilities and capacities are listed below:

• Pump Stations and Discharge Pipelines o Pump Station and Conduit A CVC Extension to Beardsley Canal (165.0 cfs) o Pump Station and Conduit B Lerdo Canal to Reservoir B ( 212.0 cfs) o Pump Station and Conduit C North of Poso Service Area (120.0 cfs) o Pump Station and Conduit D Lerdo Canal to Pump Station E and F (130.0 cfs) o Pump Station and Conduit E Western Service Area (80.0 cfs) o Pump Station and Conduit F Famoso Service Area (30.0 cfs)

• Irrigation Distribution System o 6.5 miles of lined canals (250.0 cfs) o 53 miles of main and lateral pipeline (various capacities)

• Reservoirs o Reservoir B (140 AF) o Robertson Reservoir (120 AF) o Poso Reservoir (400 AF) o Reservoir C (125 AF) o Reservoir E (49 AF)

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 9 TODD GROUNDWATER • Recharge Basins: o Famoso Groundwater Banking Project Basins (374 AF) (K/J, 2011) o East Poso Water from the State Water Project is delivered from the State aqueduct to the Cross Valley Canal, then to the Beardsley Canal which becomes the Lerdo Canal, then to Pump Station B, Reservoir B, and to CWD’s service area (GEI, 2007). Central Valley Project (CVP) water flows from the Friant-Kern Canal through the Cross Valley Canal Extension, the Beardsley and Lerdo canals, then to Pump Station B, Reservoir B, and CWD’s service area (CWD, 2007). Kern River water from the City of Bakersfield is diverted to the Beardsley and Lerdo canals and to Reservoir B. Treated produced water from both Chevron USA Inc. and CRC is delivered by pipeline to CWD’s Reservoir B. Historically, CWD received treated produced water from Shaefer Oil Company which was delivered by pipeline to Reservoir C.

2.1.5. Water Well Density

The density of water supply wells in and around Cawelo GSA is based on the DWR Well Completion Report Map Application tool for domestic, production and public supply wells (Figure 2-6a, 2-6b and 2-6c). As indicated, the density of supply wells is relatively low in Cawelo GSA, ranging from zero to ten wells per section except for a small area straddling the southeastern boundary of the Eastern Extension Area. Wells in this section are domestic wells (Figure 2-6a) and have a density of 26 to 30 wells. The general low density of wells in the Cawelo GSA reflects the prevailing agricultural land uses and scarcity of residences and businesses, all of which depend on groundwater.

2.2. WATER RESOURCES MANAGEMENT

Water resources management have a long history in the Cawelo GSA area. Management programs are conducted by local water agencies at regional and local scales. This section provides a brief overview of these programs.

2.2.1. CWD Water Management Plans

CWD has developed several local water management plans in accordance with state and local regulations. These plans are summarized below.

Agricultural Water Management Plan, December 2015. The Agricultural Water Management Plan (AWMP) (CWD, 2015b) involves planning and operations to provide an adequate, reliable and acceptable agricultural water supply for the landowners of CWD. CWD’s water supplies are defined as water that is delivered to CWD water management facilities for the purposes of agricultural, groundwater recharge, transfer and exchange, or irrigation water uses. Agricultural water supply, primarily for crop irrigation, includes water delivered to CWD’s service area landowners from both surface water and groundwater sources. The AWMP describes CWD, its service area, water management facilities and operations, and water shortage policies and drought plan. It also documents water use (agricultural, groundwater recharge, transfers and exchanges, etc.), describes the quantity and quality of water sources (State Water Project, Kern River, Central Valley Project, treated produced Water, Poso Creek, and groundwater), and assesses future water supply reliability, including analysis of climate change effects. The implementation of Efficient Water Management Practices (EWMPs) are addressed, as are water measurement practices.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 10 TODD GROUNDWATER Comprehensive Groundwater Quality Management Plan, May 2015. This plan (CWD Coalition, 2015a) is responsive to the RWQCB’s General Order No. R5‐2013‐0120 (Waste Discharge Requirements General Order for Growers within the Tulare Lake Basin Area that are Members of a Third‐Party Group; herein General Order) and describes the CWD Coalition area and upstream supplemental coverage area. It identifies nitrate as the constituent of concern for the plan, describes the physical setting, and establishes objectives. The management strategy involves determination of nitrate sources, and if agriculture is a source, identifies education and outreach programs to improve irrigation and nutrient practices, along with an implementation plan and procedures for monitoring and reporting.

CWD Groundwater Management Plan, 2007. The Groundwater Management Plan (CWD, 2007) describes the powers of CWD as a Water Replenishment District, establishes management goals and objectives, and documents water supply and groundwater conditions. The Plan also documents monitoring programs and protocols for groundwater, surface water, and subsidence monitoring. Groundwater management activities are described, including then-current CWD facilities and programs under development such as the Poso Creek Diversion Project, Famoso Water Banking Project, and other conjunctive use, banking, and transfer programs. Groundwater quality protection programs are described, as are groundwater sustainability programs.

2.2.2. Regional Water Management Plans

Several regional water management programs that include the Cawelo GSA area are briefly summarized below.

Water Quality Control Plan for the Tulare Lake Basin 4, 2018. The Tulare Lake Basin Water Quality Control Plan, or Basin Plan (CRWQCB, 2018), comprises the drainage area of the San Joaquin Valley south of the San Joaquin River including all of the Kern County Subbasin. The Basin Plan consists of designated beneficial uses to be protected, water quality objectives to protect those uses, and a program of implementation needed for achieving the objectives in accordance with the California Water Code, Section 13050(j).

Beneficial uses, together with their corresponding water quality objectives, meet both state and federal requirements for water quality control (40 CFR Parts 130 and 131). California's basin plans establish standards for groundwater in addition to surface waters. The designated beneficial uses for groundwater in Cawelo GSA include:

• Agricultural Supply • Municipal and Domestic Supply, and • Industrial Service and Process Supply.

The designated beneficial uses of surface water from Poso Creek include:

• Agricultural Supply • Water Recreation • Warm water fish habitat, Freshwater and Wildlife Habitat, and • Groundwater Recharge and Freshwater Replenishment.

Integrated Regional Water Management Plan, 2014. The Poso Creek Integrated Regional Water Management Plan (IRWMP) 2014 Update (Poso Creek RWMG, 2014) provides a framework for regional

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 11 TODD GROUNDWATER coordination of groundwater and surface water management activities and for implementation of the measures necessary to meet those objectives. The IRWMP describes the region, provides goals and objectives, and identifies and evaluates projects and programs, including assessment of climate change. An overarching conclusion of the IRWMP is that imported surface water supplies have been largely unreliable on an annual basis and will likely remain so in the future; this situation has led to increased groundwater pumping and groundwater level declines. These need to be addressed proactively, or economic, environmental, and social burdens will be felt by groundwater users--agricultural, environmental, municipal, community, and domestic.

With this situation in mind, the Poso Creek Regional Water Management Group (RWMG), which includes CWD, has actively identified and evaluated programs and projects and has sought state and federal funding. The 2014 Update provides a summary of accomplishments since the 2006 establishment of the RWMG. The regional approach taken by the RWMG has led to the successful completion of approximately $82 million in planning, project (structural), and program (non-structural) implementation activities to enhance water resources management and thereby mitigate the actual and anticipated reductions to surface water supplies delivered to the region. These efforts have helped to increase water use effectiveness in the region through greater absorption and groundwater recharge and have helped to alleviate some of the water resources issues that are otherwise unresolvable and unmanageable under an individualized district planning focus.

Kern Storm Water Resource Plan, 2016. The Kern Storm Water Resource Plan was developed for the benefit of the Kern and Poso Creek Integrated Regional Water Management (IRWM) groups and encompasses their combined boundaries (Provost & Pritchard, 2016). The Plan includes a comprehensive review and description of watersheds located within the Plan boundaries. It describes both surface and groundwater resources, water suppliers, and watershed priorities. Following the State Water Resources Control Board (SWRCB) Guidelines, natural habitat, existing water bodies, open space and watershed processes were reviewed and presented. The Plan addresses how water quality standards will be complied with and includes provision for modification of stream channels or lake beds and provides requirements for monitoring, data collection and management. It summarizes evaluation of 12 specific project proposals.

2.2.3. Urban Water Management Plans

While land use in the Cawelo GSA is predominantly agricultural, a small area of it is overlapped by the water supply services areas of the City of Shafter and Oildale MWC (Figure 2-4). Each of these has prepared an Urban Water Management Plan (UWMP) (Shafter, 2016; Dee Jaspar, 2016) in accordance with the Urban Water Management Planning Act.

A UWMP is a long-term planning tool that provides information regarding an urban water supplier’s existing and projected sources of water supply, existing and projected water demands, water service reliability, water conservation and demand management measures, and water shortage contingency planning. The UWMPs determine per capita water use, establish water use reduction goals, and document performance.

City of Shafter Urban Water Management Plan, 2015. The City of Shafter relies solely on groundwater for its supply and has experienced long-term groundwater level declines. The City generally has responded with construction of new wells or deepening of existing wells. In addition, the City has implemented water conservation efforts, including its ongoing metering program. For wastewater

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 12 TODD GROUNDWATER treatment, the City has a Joint Powers Agreement with North of the River Sanitation District. While the City currently does not use recycled water for its water system applications, a portion of its treated effluent is used for crop irrigation and recharged.

Oildale MWC Urban Water Management Plan, 2015. The Oildale MWC service area includes a portion of southern CWD and Southeast Shafter. The latter area is currently agricultural land expected to be developed for urban uses. Oildale MWC has access to imported water from KCWA and uses groundwater; in addition, local wastewater is recycled by North of the River Sanitation District through direct percolation or indirect recharge through delivery for agricultural use. Water demands in Southeast Shafter are anticipated to be met with groundwater.

2.3. WATER RESOURCES MONITORING

Water resources monitoring and management have a long history in the Cawelo GSA area. Monitoring and management programs are conducted by water agencies at regional and local scales, ranging from federal and state programs (e.g., National Oceanic and Atmospheric Administration (NOAA) and California Statewide Groundwater Elevation Monitoring (CASGEM) programs, respectively) and regional plans (e.g., Integrated Regional Water Management Plans) to water system monitoring by local entities such as CWD and Oildale MWC. Water resource monitoring programs for the Cawelo GSA are summarized below.

2.3.1. Water Supply Monitoring

Climate. Long-term climate data are available from the Bakersfield Airport climate station (NOAA, 2018) for approximately the last 50 years, from water year 1965 to water year 2017. A portion of the Bakersfield Airport overlies the southern area of the Cawelo GSA. The California Irrigation Management Information System (CIMIS) was developed by DWR to collect climate data relevant to agricultural operations. The closest active CIMIS station to Cawelo is the Shafter Station #5 located at a former USDA Cotton Research facility on Shafter Avenue. The station’s record began June 1, 1982, with a one-year gap in 2012-2013, and currently is active. CIMIS Station #138, located at Famoso, is currently inactive but historical data are available from April 9, 1997 to December 29, 2015. Information on CIMIS stations and CIMIS data are available online (CIMIS, 2018). Precipitation and temperatures are also monitored at the CWD office located within CWD with precipitation data beginning in 1996.

Imported water deliveries. CWD monitors irrigation water deliveries throughout the its distribution system, CWD has installed meters on all pumping plants and canal and pipeline turnouts that are read daily (CWD, 2015b). CWD monitors the flow and volumes of water received from oil extraction operations for irrigation and delivery. CWD also monitors the flow into its Famoso and Poso Creek recharge basins.

Regionally, KCWA (the contractor for SWP water) regularly accounts for and reports its SWP supplies for Kern County in its Report on Water Conditions. KCWA monitors daily all turnouts from the California Aqueduct and all turnouts along the Cross Valley Canal (KCWA, 2001).

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 13 TODD GROUNDWATER 2.3.2. Groundwater Conditions Monitoring

CWD established a groundwater monitoring program that includes monitoring of groundwater levels, groundwater quality, imported surface water, Poso Creek gaging, and conjunctive use operations. Additional data are available from local, state, and federal agencies.

Wells and groundwater pumping. CWD operates 18 wells and pumping for these wells has been tabulated monthly since initiation of pumping for each well since 1990. Estimates of pumping from privately-owned wells are not reported to CWD unless the water is pumped into the CWD system for conveyance and delivery. Although infrequent, water pumped from certain private wells is used for CWD purposes through an agreement with the private well owner (CWD, 2015b).

Groundwater levels. CWD commenced a Groundwater Monitoring Program in the fall of 1979, and currently measures groundwater levels in approximately 250 wells on a semi-annual basis (CWD, 2015b).

CWD is the local CASGEM monitoring entity; the program includes regular measurement of seven wells. CASGEM data are available from CWD and from DWR’s Groundwater Information Center Interactive Map (GICIMA), a database that collects and stores groundwater elevations and depth-to-water measurements. No data have been collected by USGS.

2.3.3. Water Quality Monitoring

CWD maintains extensive water quality monitoring that reflects distinct programs that monitor water quality for groundwater, surface water, imported water, and treated-produced water. The availability of water quality data from state and local sources are summarized below.

CWD Water Quality Monitoring. CWD conducts groundwater monitoring programs to satisfy the requirements of previously existing WDR permits that authorize CWD to receive treated produced waters for the purposes of irrigation and groundwater recharge. Water samples are collected annually from designated wells and analyzed for constituents of concern including nitrate, salinity, and arsenic. This information is compiled and reported to the Regional Board per the requirements of the WDRs (CWD Coalition, 2015).

Annual sampling is conducted of CWD-owned and some private wells (CWD, 2016 AWMP Table 38). Groundwater pumped from CWD deep wells is sampled in years of heavy use—typically during years of reduced surface water supplies.

CWD actively monitors imported surface water quality. Most monitoring locations are at District pumping stations where the principal surface water supplies from the SWP and Kern River are imported to CWD. Samples are collected and analyzed at each of Pump Stations “A” and “B” on a monthly basis. In addition, DWR regularly monitors the water quality at several locations along the California Aqueduct. The United States Bureau of Reclamation also conducts routine water quality testing along the Friant‐ Kern Canal.

Treated oilfield water is sampled monthly at Reservoir B for agricultural suitability (CWD, 2015b). Water quality reports for this source of supply are prepared by the treated oilfield producers and provided to the CVRWQCB to illustrate compliance with regulations and guidelines contained in their respective discharge permits.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 14 TODD GROUNDWATER Irrigated Lands Regulatory Program (ILRP). The Irrigated Lands Regulatory Program (ILRP) of the Regional Water Quality Control Board (RWQCB) regulates discharges from irrigated lands. The ILRP focuses on priority water quality issues, such as pesticides and toxicity, nutrients, and sediments. The Cawelo Water District Coalition (CWDC) monitors surface water and groundwater quality associated with agricultural activities (CWD, 2015b) under this program. Additional details of the ILRP relevant for the Cawelo GSA are outlined in section 2.3.4 Irrigated Lands Regulatory Program.

State-Wide Groundwater Quality Monitoring. State-wide sources of groundwater quality data include the DWR’s Water Data Library (WDL), GeoTracker/GAMA program, and SWRCB Division of Drinking Water data. DWR’s WDL is a repository for groundwater quality data. Samples are collected from a variety of well types including irrigation, stock, domestic, and some public supply wells. WDL has groundwater quality data from 43 wells in the Cawelo GSA; these data have been included in the CWD database.

2.3.4. Irrigated Lands Regulatory Program

2.3.4.1. Background The Irrigated Lands Regulatory Program (ILRP) was established in 2003 by the Central Valley Water Board with the Waste Discharge Requirements for discharges from irrigated lands. The ILRP provides requirements for discharging waste from irrigated agriculture to surface water. The ILRP also required completion of an environmental impact report for the long-tern ILRP to protect California groundwater and surface waters. The general goals of the long-term ILRP are to provide the highest reasonable quality of state waters and safe and reliable drinking water. The objectives of the ILRP are established to meet the water quality goals. The State of California Central Valley Regional Water Quality Control Board (CVRWQCB) adopted the Waste Discharge Requirements General Order for Growers within the Tulare Lake Basin Area that are Members of a Third-Party Group, Order R5-2013-0120 (General Order) on September 19, 2013 replacing the Ag Waiver Program (General Order R5-2006-0053).

Requirements for evaluating and protecting surface water quality are established by the General Order and include:

• Surface Water Monitoring Plan (SWMP) with a Quality Assurance and Project Plan (QAPP), • 2019 Pesticide Monitoring Plan, and • Sediment Discharge and Erosion Assessment Report.

Requirements for evaluating and protecting groundwater quality established by the General Order include:

• Groundwater Quality Assessment Report (GAR), • Comprehensive Groundwater Quality Management Plan (CGQMP), • Groundwater Quality Trend Monitoring Program (GQTMP), and • Management Practices Evaluation Program (MPEP).

Cawelo Water District Coalition (CWDC) is the third-party representing the growers in the CWD for compliance with the General Order and Revising Order R5-2014_0143 (Revising Order). The CWDC was authorized to act as the third-party group representative on April 25, 2014 and assist irrigated agriculture within the CDWC with compliance of the ILRP.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 15 TODD GROUNDWATER Members of Third-Party Groups such as the CWDC are expected to comply with the General Order and conduct water quality monitoring and implement water quality management practices to comply with surface and groundwater receiving limitations established in the General Order. Management practices include sediment discharge and erosion prevention and irrigation and nitrogen management. At a minimum, water quality management practices required for individual members are:

• “Minimize waste discharge offsite in surfaces water, • Minimize percolation of waste to groundwater, and • Protect wellheads from surface water intrusion (General Order R5-2013-0120).”

Waste discharges from irrigated lands include irrigation return flows, tailwater, drainage water, subsurface (tile) drains, stormwater runoff, and aerial drift and overspraying of pesticides. Potential discharge pathways to groundwater include percolation through the subsurface, backflow of waste into wells, discharge into unproductive wells and dry wells, and leaching from tailwater ponds or sedimentation basins. The General Order applies to any discharge waste that could reach surface or groundwaters of California.

2.3.4.2. Surface Water

2.3.4.2.1. Surface Water Monitoring Plan The purpose of the Surface Water Monitoring Plan (SWMP) is to obtain data and evaluate the impact of irrigated agriculture on surface-water quality in the CWDC area and determine if existing or new agricultural management practices comply with surface water receiving limitations defined by the General Order (CWDC, 2014). The CWDC SWMP was reviewed on December 29, 2014. Revisions to the SWMP are required. The description of the SWMP that follows is from the 2014 version of the SWMP (CVRWQCB, 2014).

Seven miles of the Poso Creek channel are in the CWDC area. The irrigated agriculture in the CWDC is the first area of irrigated agriculture are that could impact the quality of Poso Creek waters. Agricultural lands front the north and south sides of Poso Creek for several miles and have potential for surface runoff to reach the channel. Water quality monitoring of this section of Poso Creek provides data to evaluate the impact of agricultural management practices on Poso Creek waters (CWDC, 2014).

Monitoring is performed at Poso Creek at Highway 65 and Poso Creek at Highway 99 monitoring stations, which replace the Poso Creek at Zerker Road monitoring station. The Poso Creek at Highway 65 monitoring station is located where Poso Creek begins to pass through irrigated agriculture. The station is about 0.7 miles east of irrigated agriculture defined by the eastern boundary of the CWDC area. Water quality at this monitoring station provides a baseline for Poso Creek waters entering the CWDC area. The Poso Creek at U.S. Highway 99 monitoring station is located at the west boundary of the CWDC area and is used to monitor for potential impacts from irrigated agriculture in the CWDC area. Data collected from the Highway 99 monitoring station is compared with data from the Highway 65 monitoring station. Both monitoring stations are core monitoring sites with assessment monitoring occurring every three years (CWDC 2014).

Sediment toxicity testing is performed twice a year for Poso Creek, which is an intermittent stream. Storm runoff sampling and testing is required for two storm runoff events. The sampling of storm runoff flows occurs three days after the flow event begins and there should be no flow for the prior thirty days. For periods of continuous flow in Poso Creek, precipitation will be monitored to determine when a

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 16 TODD GROUNDWATER secondary storm runoff event is occurring. Flow is to increase by 50 percent or more to be identified as a storm runoff event and sampling will occur on the third day of the flow event (CWDC, 2014).

Field measurements of flow, conductivity, temperature, pH, and dissolved oxygen are measured at the time of sample collection. Water samples are analyzed for E. Coli, total organic carbon (TOC), CaCo3, total suspended solids (TSS), turbidity, ammonia, nitrogen (NO3 and NO2), orthophosphate, nine metals (including As, Pb, and Se), and thirty pesticides. Both water and sediment samples are evaluated for toxicity. Water samples are evaluated for parameters and sediments are tested for one parameter. Sediment samples are tested for TOC, grain size, and nine pesticides. Results and evaluations are submitted through Quarterly and Annual Monitoring Reports and Exceedance Reports (CWDC, 2014).

Protocols and procedures for sampling and testing are defined in the Quality Assurance Project Plan (QAPP) under the SWMP. Sample collection includes photo documentation and collection of field conditions at all monitoring events. Documentation of field conditions includes recording the time, weather observations, water and sediment characteristics, and any other observations of interest to the sampling event. Water and sediment sampling and analysis protocols are defined in the QAPP (CWDC, 2014).

2.3.4.3. Groundwater

2.3.4.3.1. Groundwater Quality Assessment Report The CWDC prepared a Groundwater Quality Assessment Report (GAR) (CWDC, 2015) to comply with Section VIII.E of the General Order and include the following components:

• “Assess all available, applicable, and relevant data and information to determine the high and low vulnerability areas where discharges from irrigated lands may result in groundwater quality degradation; • Establish priorities for implementation of monitoring and associated studies within high vulnerability areas; • Provide a basis for establishing workplans and priorities to evaluate the effectiveness of agricultural management practices to protect groundwater quality; and • Provide a basis for establishing groundwater quality management plans in high vulnerability areas and priorities for implementation of those plans.”

The CWDC GAR (2015) was conditionally approved on April 13, 2016 by the CVRWQCB. CVRWQCB requested that additional data and information be obtained, evaluated, and included in the CWDC conceptual hydrogeologic model. The updated hydrogeologic conceptual model and other information contained in the GAR was used for the development of the MPEP, GQTMP, and GQMP (CVRWQCB, 2016).

2.3.4.3.2. Fertilizer Nitrogen application is a primary concern identified in the General Order. In the CWD area, irrigation is relatively expensive as water is pumped uphill for distribution to growers. High efficiency irrigation allows for effective and reduced cost nitrogen management practices. In 2015, most growers in the CWD used pressurized irrigation systems with less than 1 percent using flood or row irrigation methods. Nitrogen, phosphorus, and potassium are commonly applied to crops through fertigation. Fertigation, liquid fertilizer mixed with irrigation water, is used with drip and micro-sprinklers. Typical annual

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 17 TODD GROUNDWATER applications rates for nitrogen for citrus, almonds, pistachios and vineyards are 80 to 125 lbs/acre, 200 to 275 lbs/acre, 125 to 150 lbs/acre, and 30 to 50 lbs/acre, respectively (CWDC, 2015).

2.3.4.3.3. Groundwater Level and Quality Monitoring Groundwater quality monitoring is performed to monitor the use of treated produced water for irrigation and groundwater recharge. Sampling is performed annually, and the samples are analyzed for an array of constituents including nitrate, salinity, and arsenic. Nitrate and salinity levels in groundwater can be indicators of potential impacts on groundwater quality due to irrigation.

Depth to groundwater, percolation rates in the vadose zone, irrigation efficiencies are significant factors. Transport rates of nitrate through percolation in areas of low irrigation efficiencies for alluvial fans of the eastern San Joaquin Valley are approximately 14.8 feet per year and higher for higher irrigation efficiencies (Botros, 2012). The average depth to groundwater in the CWDC ranges from 300 to 600 feet depending on hydrologic conditions and location. Nitrate migration to groundwater could take 20 to 30 years (CWDC GAR, 2015). The CWDC obtains groundwater level measurements from 150 to 250 wells.

2.3.4.3.4. High Vulnerability Areas High vulnerability areas are at risk of discharges from irrigated lands potentially resulting in groundwater quality degradation. High vulnerability ranking is based on regional or localized trends of nitrate concentrations with high exceedances (NO3 > 45 mg/L as NO3) in the groundwater with some consideration of depth to groundwater, irrigation practices, historical trend of nitrate levels, proximity to urban, rural, or disadvantaged communities, salinity, soil permeability and areas of high vulnerability outside the CWDC boundary. Boundary lines around high vulnerability area are along parcel boundaries (CDWC GAR, 2015). High vulnerability areas are prioritized as High, Medium, or Low for purposes of groundwater quality monitoring and agricultural management plans. The prioritization ratings are based on proximity to urban and rural communities, significant NO3 exceedances, crop types, irrigation systems, and soil permeability (CDWC GAR, 2015).

2.3.4.3.5. Comprehensive Groundwater Quality Management Plan The Comprehensive Groundwater Quality Management Plan (CGQMP) was completed May 11, 2015 and is required for high vulnerability areas identified in the CWDC GAR and locations of documented water quality exceedances. The purpose of the CGQMP is to evaluate the impact of irrigated agriculture on groundwater quality and reduce potential impacts to groundwater quality (CWDC CGQMP, 2015). The CWDC CGQMP is designed to determine potential sources of NO3 in groundwater and evaluate if current irrigated agricultural practices are contributing. Potential sources of NO3 identified by the CGQMP are non-irrigated agriculture and irrigated agriculture. If current irrigated agricultural practices are contributing or it is not clear, the CGQMP will address implementation of a program promoting irrigation and nutrient management practices that focuses on improving groundwater quality through further evaluation of irrigated agricultural practices and outreach and education programs (CWDC CGQMP, 2015).

On August 9, 2017, the CVRWQCB reviewed the CGQMP and identified portions of the plan requiring modification to comply with the General Order including establishing performance goals and a timeline for implementation of management practices. CWDC area growers are required to implement wellhead protection, destruction of abandoned wells, and establish nitrogen accountability (CVRWQCB, 2017).

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 18 TODD GROUNDWATER 2.3.4.3.6. Groundwater Quality Trend Monitoring Program The General Order states that the overall objectives of the Groundwater Quality Trend Monitoring Program (GQTMP) are to “… determine current water quality conditions of groundwater relevant to irrigated agriculture and develop long-term groundwater quality information that can be used to evaluate the regional effects of irrigated agricultural practices.” The CWDC submitted a Groundwater Quality Trend Workplan on April 19, 2017. The first review was completed on March 7, 2018 with the revised Workplan submitted on May 14, 2018. Conditional approval of the revised Workplan occurred on June 28, 2018. The required Addendum with a time extension request was submitted on July 31, 2018 and approval of the revisions to the Workplan and time extension request was given on August 20, 2018.

CWDC has been collecting groundwater quality data for over twenty years as part of requirements for receiving treated produced water for irrigation and groundwater recharge and for monitoring groundwater levels (Orders R5-2012-0058 and R5-2012-0059). The CWDC groundwater monitoring program has been incorporated into the GQTMP to continue collection of water quality data, determination of long-term trends in water quality, and evaluation of regional effects of irrigated agriculture on groundwater quality. Key requirements of the GQTMP include the following:

• Establish a monitoring network covering High and Low Vulnerability areas including use of shallow wells and rational for well selection. • Collect and evaluate sufficient data to identify trends and report in the annual Monitoring Report.

The General Order requires, at a minimum, groundwater samples be analyzed for the following water quality parameters.

Annual Monitoring Constituents of Concern: • Conductivity • pH • Dissolved Oxygen • Temperature • Nitrate as Nitrogen

Five Year Monitoring Constituents of Concern: • Total Dissolved Solids • General minerals o Anions: carbonate, bicarbonate, chloride, and sulfate o Cations: boron, calcium, sodium, magnesium, and potassium The CVRWQCB has additionally identified pesticides and metals to be constituents of concern that may impact groundwater quality through irrigated agricultural practices (CVRWQCB, 2017).

The proposed monitoring network will consist of 19 locations for a well density of 1 well per 3.7 square miles. Water samples will be obtained during the summer when wells are providing water for agricultural irrigation. Samples will be collected after two well casing volumes have been pumped (agricultural production wells) or two pump column volumes (domestic wells). Sample collection will follow the best practices and protocols of the water analysis industry. Static water levels will be measured in the spring and fall each year.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 19 TODD GROUNDWATER 2.3.4.3.7. Management Practices Evaluations Program The General Order states that the goal of the Management Practices Evaluations Program (MPEP) is to “…evaluate the effectiveness of irrigated agricultural practices with regard to groundwater quality.” The CWDC is part of a joint MPEP program with seven coalitions representing irrigated agriculture south of Fresno. Technical partners for the Southern San Joaquin Valley (Tulare Lake Basin) MPEP are the USDA NRCS, CDFA, UC and CSU. The combined coalitions are working with the State of California, Regional Boards, and technical partners to develop this program (Cawelo Water District, 2019).

2.3.5. Surface Water Monitoring

CWD Surface Water Monitoring. Poso Creek traverses the Cawelo GSA about midway between the District’s northern and southern boundaries (Figure 2-5). Several streamflow gages are located on Poso Creek; the U.S. Geological Survey (USGS) and Kern County have operated a gage from July 1959 to present at Coffee Canyon, 10 miles northeast of Oildale. CWD currently monitors Poso Creek at Trenton Weir near State Highway 65. The annual flow at this site has exceeded 120,000 AF, but many years it has little to no flow. While flows are variable, some CWD landowners do occasionally exercise their riparian rights to divert water from Poso Creek. The Kern River flow along and within the southern border of the Eastern Extension Area of the Cawelo GSA. Discharge on the Kern River is measured at several locations upstream of the GSA.

Surface Water Quality Monitoring Plan, 2014. CWD Coalition has prepared a Surface Water Monitoring Plan (CWD, 2014) in response to the RWQCB’s General Order No. R5‐2013‐0120 (Waste Discharge Requirements General Order for Growers within the Tulare Lake Basin Area that are Members of a Third‐Party Group; herein General Order).

Surface water quality monitoring of Poso Creek occurs at Highway 65 Monitoring Station and the Poso Creek at U.S. Highway 99 Monitoring Stations. Sampling occurs when water is present and flowing during a monthly sampling event. Consistent with RWQCB requirements, the surface water monitoring parameters include field measurements, drinking water parameters (such as E. Coli and Total Organic Carbon), general physical parameters, metals, nutrients, pesticides, and water toxicity for designated species. These parameters are provided in Appendix B of the CWD Surface Water Monitoring Plan (CWD, 2014). The Quality Assurance and Project Plan for sample collection and laboratory analysis is included as part of the SWMP in its Appendix C.

2.3.6. Land subsidence Monitoring

Subsidence has been documented in Kern County through a series of key studies by the USGS and DWR. The studies are cited in the CWD GWMP, which recommends continued use of regional subsidence reporting to track subsidence. The U.S. Bureau of Reclamation monitors two multi-port monitoring wells in NKWSD (and other monitoring points outside of the Plan Area) to track the ongoing potential for subsidence-related problems.

2.3.7. Underground Injection Control

The disposal of treated produced water typically occurs in injection wells or percolation ponds. Much of the treated produced water from the Eastern Extension is recycled and used in the CWD area of the GSA.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 20 TODD GROUNDWATER Under the Safe Drinking Water Act, the federal underground injection control (UIC) program was created to protect underground sources of drinking water from oil and gas production (Class II). The UIC program includes the injection of oil and gas production fluids through wells into geologic formations for enhanced oil recovery (EOR) or produced water disposal. The UIC program only permits the injection in aquifers that do not quality as underground sources of drinking water, which is defined by federal regulations.

In California, DOGGR has the authority from the USEPA to implement the Class II UIC program. Operators of UIC wells must have a permit from DOGGR prior to injecting fluids for EOR of disposal of produced water. An aquifer may become exempt from the UIC permitting processes only after a proposal from DOGGR is forwarded to the USEPA for approval. The process for exemption has stringent requirements in both the federal and state regulations to protect underground sources of drinking water and other beneficial uses of the water.

2.3.8. Incorporation of Existing Monitoring into GSP.

Existing monitoring procedures and locations will be maintained to assure historical consistency. The monitoring program for the GSP is described in Section 5.

2.4. LAND USE

This section presents land use in the Cawelo GSA and summarizes the goals, objectives, policies, and implementation measures of the General Plan for Kern County, which encompasses the entire area, and the general plans for the Metropolitan Bakersfield Area and City of Shafter, which overlap portions of the Cawelo GSA (Figure 2-3).

2.4.1. Current Cawelo GSA Land Use

Agriculture is the main land use in the Cawelo GSA and is characterized primarily by perennial crops (e.g., citrus, vines, pistachios and almonds), some annual crops (e.g., grains and potatoes), and fallow land. Other land uses include semi-agricultural land, industrial, and rural commercial land. Land use in the Eastern Extension Area of the Cawelo GSA consists of primarily oil field operations, undeveloped land with minor amounts of agriculture, and other uses. Figure 2-7 provides an overview of land uses in the Cawelo GSA that shows the dominance of local agriculture.

2.4.2. Land Use Mapping

CWD (encompassing 45,305 acres) has tracked land use annually since 1980. Land use is tabulated in terms of permanent crops (e.g., vineyards, citrus and subtropical fruits, deciduous fruit, nut trees), other irrigated crops (e.g., cotton, alfalfa, pasture, potato, grain, vegetables and melons), irrigable non-farmed (e.g., non-irrigated, fallow, undeveloped, abandoned), and non-agricultural including residential, commercial, County airport, and Poso Creek. Agricultural crop data are combined with estimated crop demand and leaching requirements to estimate applied water needs (CWD, 2015b).

The Kern County Department of Agriculture and Measurement Standards compiles annual local crop production information. These records are based on the calendar year and have been published annually since 1930 and are currently available through 2016. These reports show all crops grown county wide, including harvested acres, production per acre, total production, unit value, and total value

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 21 TODD GROUNDWATER for each crop. The reports also include livestock and poultry product reports and pest prevention and control.

The Division of Planning and Local Assistance (DPLA) of California DWR’s San Joaquin District has conducted more than 250 land-use surveys of all or parts of every county within the San Joaquin District area. The data are gathered using aerial photography and extensive field visits and include agricultural land uses and lesser detailed urban and native vegetation land uses. There are currently land-use survey maps available for Kern County in 1990, 1998, and 2006 in a single, countywide, shapefile format.

2.4.3. Important Farmlands Inventory

The California Department of Conservation, Farmland Mapping and Monitoring Program identifies lands that have agricultural value and maintains a statewide map in its Important Farmlands Inventory (IFI). The distribution of IFI designated lands in the Cawelo GSA are shown on Figure 2-8. IFI classifies land based upon its productive capabilities, which is based on many characteristics, including fertility, slope, texture, drainage, depth, salt content and availability of water for irrigation. Farmland categories are based on their suitability for agriculture:

• Prime Farmland. This land has the best combination of physical and chemical characteristics for crop production. When treated and managed, its soil quality, growing season, and irrigation supply produce sustained high crop yields. • Unique Farmland. This land does not meet the criteria for Prime Farmland or Farmland of Statewide Importance but has produced specific crops with high economic value. • Farmland of Statewide Importance. This is land that does not qualify as Prime Farmland but has a good combination of irrigation and physical and chemical characteristics for crop production. • Farmland of Local Importance. This land is either currently producing crops or has the capability to produce crops but does not meet the criteria of the categories above. • Grazing Land. This is land with vegetation that is suitable for grazing livestock.

Agricultural Preserves and agricultural lands protected under the Williamson Act encompass most of CWD (Figure 2-9). The Williamson Act (California Land Conservation Act of 1965, Section 51200) was adopted to encourage preservation of the state’s agricultural lands and to discourage its conversion to urban uses. This Act established an agricultural preserve contract procedure through which any county or city would levy taxes on Agricultural Preserve contract land at a lower rate using a scale based on the actual use of the land for agricultural purposes, as opposed to its unrestricted market value. In return, the owners guarantee that these properties would remain under agricultural production for a ten-year period. This contract is renewed automatically unless a Notice of Non-Renewal is filed by the owner. In this manner, each agricultural preserve contract (at any given date) is always operable at least nine years into the future. While contracts can be cancelled earlier than the ten-year period (with specific approvals and fees), the Williamson Act stabilizes agricultural land uses.

2.5. GENERAL PLANS

This section summarizes the goals, objectives, policies, and implementation measures of the principal land use plans for the Cawelo GSA. The General Plan for Kern County encompasses the entire GSA area

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 22 TODD GROUNDWATER whereas the Metropolitan Bakersfield Area and City of Shafter general plans overlap small portions of the Cawelo GSA (Figure 2-3)..

2.5.1. Kern County General Plan

The general Land Use Planning Designations of the Kern County General Plan (Kern County Planning Department, 2009) are shown on Figure 2-7. As illustrated, the Cawelo GSA is predominantly zoned as Intensive Agriculture with some Extensive Agriculture, but also includes public utilities, industrial, commercial, and mineral and petroleum land uses.

As of 2018, the Kern County General Plan is being updated; this process (initiated in October 2016) is anticipated to extend to 2019. As part of this effort, the water element for the update considers reliable long-term water supply, water quality, watershed and groundwater protection, and conservation. The General Plan Update contains policies that reflect future growth and goals.

Consistent with the California Government Code, portions of the Land Use, Open Space, and Conservation elements were developed in coordination with KCWA and other local water agencies. Groundwater management is addressed in four sections of the Land Use, Open Space, and Conservation Element: Physical and Environmental Constraints, Public Facilities and Services, Resource, and General Provisions. For each, the relevant goals, policies, and implementation measures are summarized in Appendix C - Table 2-1. This table is a summary and may not include all General Plan policies relevant to the GSP; accordingly, specific issues will likely involve consultation with Planning Department staff.

2.5.2. Metropolitan Bakersfield General Plan

The Metropolitan Bakersfield General Plan (Bakersfield, 2002) overlaps the southern edge of the Cawelo GSA (Figure 2-3). Zoning designations include agricultural, industrial, and commercial land uses.

The General Plan was adopted in December 2002 and was most recently updated in January 2016 per Resolution Nos. 018-16, 019-16, and 020-16. Two sections are most relevant to the GSP: The Water Resources section of the Conservation Element and the Water Distribution section of the Public Services and Facilities Element. Appendix C - Table 2-2 summarizes goals, policies, and implementation measures for these sections. As a summary, this table may not include all General Plan policies relevant to the GSP; accordingly, specific issues will likely involve consultation with Planning Department staff.

The Water Resources section of the Conservation Element recognizes three long-standing issues:

• The conservation and effective utilization of planning area water resources is complicated by multi-jurisdiction control over such resources. • There are portions of the planning area which are water deficient and/or in which there are problems with water quality. • Water transport, groundwater recharge needs, recreational usage of water resources, and the preservation and enhancement of water-related natural habitat all compete for the usage of scarce water resources in the planning area.

These issues are addressed through the Goals, Policies, and Implementation Measures summarized in the Water Resources section of Appendix C - Table 2-2. Similarly, the Public Services and Facilities Element includes a Water Distribution Section that addresses the following water distribution issues:

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 23 TODD GROUNDWATER • Provision of adequate water service to the planning area. • Coordination of water purveyors and water rights holders.

Sections on Sewer Service and Stormwater in the 2002 Metropolitan Bakersfield General Plan are oriented toward wastewater and water disposal, but do not address water recycling or recharge.

2.5.3. City of Shafter General Plan

The City of Shafter General Plan area overlaps portions of the Cawelo GSA (Figure 2-3). Zoning designations include agricultural, commercial, and residential land use designations. As a matter of perspective, the draft City of Shafter General Plan (Shafter, 2005) states that one of its objectives is to “Recognize and retain commercial agriculture as a desirable land use and as a major segment of the community’s identity and economic base.”

The General Plan includes two sections with relevance to the GSP: Water Facilities and Environmental Management Program. Key objectives and policies are summarized in Appendix C - Table 2-3; again, as a summary, this table may not include all relevant General Plan policies and specific issues will likely involve consultation with Planning Department staff.

2.6. WELL PERMITTING

Permitting of new or replacement water supply wells in Kern County is administered by the Kern County Public Health Services Department through the Environmental Health Services (EHS) Water Well Program. The Kern County Ordinance Code, Chapter 14, provides for the design, construction, repair, and reconstruction of agricultural wells, domestic wells, cathodic protection wells, industrial wells, monitoring wells, observation wells, geothermal heat exchange wells, and test wells in such a manner that the groundwater of the county will not be contaminated or polluted, and that water obtained for beneficial uses will not jeopardize the health and safety or welfare of the people of Kern County.

Well permitting policies, procedures, and guidelines are presented on the EHS website for Water Wells & Small Water Systems and in the Water Well Permits Policy Manual; links are provided below:

• http://kernpublichealth.com/water/water-wells-small-water-systems/ • http://kernpublichealth.com/wp- content/uploads/2016/03/EHSWellPolicyManual_2008_09_11_08.pdf

The Manual presents the procedures to obtain, complete and apply for a water well permit. To summarize, the application is reviewed by EHS staff to determine if an annular seal is required based on location and groundwater quality. One or more site inspections is conducted by EHS staff. Water quality testing is required to be submitted and will be reviewed by EHS.

Water well permit applications are required to be sent to KCWA under certain conditions. These conditions include location of the proposed well within the extent of Corcoran Clay or shallow groundwater. They also include location within a one-mile radius of:

• a public drinking water supply well • sphere of influence of any Kern County municipality • established or proposed groundwater recharge/recovery facility

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 24 TODD GROUNDWATER • proposed dairy or feedlot operation • biosolids composting, disposal, or land application area • known or suspected hazardous waste site • active or inactive sanitary landfill, burn dump, or hazardous materials facility • known area of poor water quality • active or proposed fruit or vegetable processing facility.

All water well destruction permit applications will be reviewed by KCWA and any water district having jurisdiction for the site. The Water Well Permits Policy Manual also specifies approved sealing materials for well construction and well destruction.

The Kern County EHS also has established Standards and Rules and Regulations for Land Development that address sewage disposal, water supply, and preservation of environmental health (Kern County EHS, 2010). Chapter III, Water Supply, lists requirements for domestic water supply systems that mandate documentation of an adequate supply, provision of water quality meeting drinking water standards, and compliance with water well drilling standards, setbacks, and the Kern County Zoning Ordinance. Kern County Policy 40 encourages utilization of community water systems rather than the reliance on individual wells.

2.7. REGULATORY FRAMEWORK OF OIL FIELD OPERATIONS

The oil field operations in the Eastern Extension Area of the Cawelo GSA must comply with a regulatory framework that includes federal, state, and county level regulations. These regulations have direct and indirect implications for the Cawelo GSP and the sustainability of groundwater and groundwater quality, including groundwater monitoring plans and water management plans. The following sections outline the regulatory setting.

2.7.1. Underground Injection Control (UIC) Program In California, wells that inject fluids associated with oil and natural gas production operations (Class II injection wells) are regulated DOGGR under its Underground Injection Control (UIC) Program. The UIC Program regulates injection operations that include waterflood, steamflood, cyclic steam, water disposal, gas storage, and other enhanced oil recovery projects. The requirements of DOGGR’s UIC Program are found in the Public Resources Code (PRC), the Safe Drinking Water Act (SDWA), and in the other state and federal regulations. The UIC Program has several main features, include the permitting, inspection, and enforcement, mechanical integrity testing, plugging and abandonment oversight, data management, and public outreach (BSK, 2015).

The State of California was delegated primary responsibility for implementing the Class II UIC Program of the federal SDWA in 1983. The USEPA audited DOGGR Class II UIC primacy program in 2011 and identified substantial implementation deficiencies (USEPA, 2019). In 2012, USPA review of DOGGR aquifer exemptions raised questions about the alignment of injection wells with EPA-approved exemption boundaries. In 2014, EPA increased its oversight efforts with DOGGR, which culminated in California’s 2015 Corrective Action Plan to be in compliance before the deadline of February 2017 (USEPA, 2019). The USEPA Region 9 worked closely with DOGGR and the State Water Resources Control Board to implement the Correction Action Plan and the full compliance of DOGGR’s Class II UIC program with the SDWA. As part of the compliance, DOGGR carefully reviewed their inventory of injection wells, completed a review of thousands of injection wells into non-exempt aquifers, and shut-in about 60 injection wells in 2014 and 2015 due to their potential to impact groundwater quality (USEPA, 2019).

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 25 TODD GROUNDWATER 2.7.2. Aquifer Exemptions DOGGR evaluates aquifer exemption requests from oil and gas operators. Aquifer exemption requests are initiated by operators, reviewed by DOGGR and Water Board and submitted for approval to USEPA. In 2017, DOGGR submitted a letter to USEPA on its Class II UIC program compliance efforts, including their efforts focused on aquifer exemption proposals. The USEPA responded to the DOGGR letter generally concurring with the State’s proposed plans for ongoing work (USEPA, 2019).

An aquifer exemption is an action by USEPA to remove an aquifer or portion of an aquifer from protection as an underground source of drinking water (USDW) under the SDWA. Federal Underground Injection Control (UIC) regulations allow USEPA to exempt aquifers that do not currently serve as a source of drinking water and will not serve as a source of drinking water in the future, based on specific criteria (USEPA, 2019). An aquifer exemption allows the underground source of water to be used by energy and mining companies for oil or mineral extraction or disposal purposes in compliance with USEPA’s UIC requirements. Underground sources of drinking water surrounding the exempted areas continue to be protected by the SDWA (USEPA, 2019). Federal regulations define an underground source of drinking water as an aquifer that supplies a public water system or contains a sufficient quantity of groundwater to supply a public water system, or currently supplies drinking water for human consumption or contains fewer than 10,000 mg/L total dissolved solids (TDS) (USEPA, 2019).

The federal regulatory criteria in 40 CFR 146.4 establishes the USEPA as responsible for the final review and approval of all aquifer exemption requests. For the USEPA to approve an aquifer exemption, the Agency must first find that the application has demonstrated that the aquifer of the portion of the aquifer sought for exemption does not currently served as a source of drinking water. The second exemption criteria that the aquifer cannot now, and will not in the future, serve as a source of drinking water, or that the TDS of the groundwater is more than 3,000 and less than 10,000 mg/L and is not reasonably expected to supply a public water system. California’s drinking water limit for TDS (secondary Maximum Contaminant Level) is 1,000 mg/L. The USEPA’s regulatory definition of an Underground Source of Drinking Water (USDW) is less than 10,000 mg/L (USEPA, 2019).

The 40 CFR 146.4(b) describe four potential reasons that the aquifer cannot and will not in the future serve as a source of drinking water. These reasons include that the aquifer is mineral, hydrocarbon, or geothermal energy production, or can be demonstrated as part of a permit application to contain minerals or hydrocarbons that are expected to be commercially producible. The other reasons relate to the practicality and cost of accessing and treating the water for human consumption (USEPA, 2019).

2.7.3. Senate Bill 4 and Senate Bill 1281 Senate Bill 4 (SB4) was signed into law on September 20, 2013 and complements existing rules that require some of the strongest well construction standards in the U.S. (BSK, 2015). SB4 enacts further safeguards to public health and safety and the environment regarding the oil field practices (BSK, 2015).

2.7.3.1. Area Groundwater Monitoring As required by SB4, the State Water Resources Control Board has implemented an Oil and Gas Groundwater Monitoring Program in order to protect all waters designated for any beneficial use, while prioritizing the monitoring of groundwater that is or has the potential to be a source of drinking water (SWRCB, 2019). The Model Criteria for Groundwater Monitoring as Model Criteria) was established July 7, 2015 (SWRCB, 2015) and is composed of three components:

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 26 TODD GROUNDWATER • Area-Specific Monitoring, • Designated Contractor Sampling, and • Regional Groundwater Monitoring.

The details of the monitoring program are in the Model Criteria document (SWRCB, 2015). Oil field operators are required to monitor groundwater near oil and gas production activities that have potential to degrade waters suitable for beneficial use. Area-specific monitoring does not apply to groundwater monitoring programs approved and permitted by DOGGR prior to July 2015 (SWRCB, 2015). Operators are required to report data and results from groundwater monitoring and sampling activities to the SWB and upload all data and reports to GeoTracker.

2.7.3.2. Regional Groundwater Monitoring The State Water Board has established a regional groundwater monitoring program for protected waters with a priority to monitor potential sources of drinking water known as the California State Water Resources Control Board’s Regional Monitoring Program of Water Quality in Areas of Oil and Gas Production (Regional Monitoring Program). The Regional Monitoring Program focuses on monitoring for potential impacts from oil & gas production activities (SWRCB, 2015).

The Regional Monitoring Program is being conducted in a phased approach, with the first phase anticipated to take approximately five years. The U.S. Geological Survey (USGS) is the technical lead on implementing the Regional Monitoring Program, which is funded through a contract with the SWRCB. The USGS has summarized in a January 22, 2018 memo (Landon and Taylor, 2018) the objectives, sample collection and analysis protocols, quality-assurance procedures, approaches, and reporting procedures uses for the SWRCB Regional Monitoring Program in areas of oil and gas production. Additional details about the USGS activities related to the Regional Monitoring Program are outlined on the USGS California, Oil, Gas, and Groundwater (COGG) Program website (USGS, 2019).

2.7.4. National Pollutants Discharge Elimination System (NPDES) The California Regional Water Quality Control Board (RWQCB) implements and enforces general permits that are issued under the National Pollutant Discharge Elimination System (NPDES). The NPDES issues general permits for Storm Water Discharge Associated with Construction Activity (General Permit) Water Quality Order 99-08-DWQ that applies to projects that disturb one or more acres of soil. The general permit requires the following general measures to be implemented during construction activity:

• Elimination or reduction of non-stormwater discharges to storm water systems and other water of the U.S. • Development and implementation of a Storm Water Pollution Prevention Plan (SWPPP) prepared by a Qualified SWPPP Developer identifying Best Management Practices (BMPs) that the discharger will use to protect storm water runoff and incorporate visual, chemical, and sediment monitoring programs. • Inspections of storm water control structures and pollution prevention measures.

2.7.5. Kern County Zoning Ordinance The Kern County Zoning Ordinance Chapter 19-98 covers oil and gas production activities in Kern County. The purpose of the ordinance is to promote the economic recovery of oil, gas, and other hydrocarbon substances in a manner compatible with surrounding land uses and protection of the public health and safety by establishing reasonable limitations, safeguards, and controls on exploration,

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 27 TODD GROUNDWATER drilling and production of hydrocarbon resources (BSK, 2015). Chapter 19-98 includes the current procedures and standards that apply to all exploration drilling and production activities related to oil, gas, and other hydrocarbon substances in unincorporated Kern County. The procedures and standards include section 19.98.20 Unrestricted Drilling, 19.98.030 Drilling by Ministerial Permit, 19.98.040 Drilling by Conditional Use Permit, 19.98.050 Development Standards and Conditions, 19.98.070 Permit Revocation and Modification, and other information about oil and gas operations in Kern County (BSK, 2015).

2.8. NOTICE AND COMMUNICATION

The Cawelo Groundwater Sustainability Agency is committed to working with the local stakeholders to develop a Groundwater Sustainability Plan (GSP) that will lead to long-term groundwater sustainability and support active and flourishing industries. Stakeholder involvement is vital and the CGSA will provide many workshops and outreach events to solicit stakeholder input.

The CGSA regular Board Meetings are held at 8:30 am every second Thursday of each month. The meetings are located at the CWD office at 17207 Industrial Farm Road, Bakersfield, CA 93308. Information is available through the Cawelo GSA web page located at: https://www.cawelowd.org/cawelo-gsa/.

The importance of groundwater as a source of supply for water purveyors, various land uses, and other beneficial uses is presented in Section 2.1.3. Recognizing the importance of communication, multiple and diverse agencies and interested parties have been identified. These are listed in the Cawelo GSA Outreach Plan, which is included as Appendix D.

The Outreach Plan in Appendix D also provides an overview of outreach to the public by means of regular and special Cawelo GSA Board meetings, quarterly public meetings, and the Cawelo GSA website. These will inform the public about the GSP development and implementation process and encourage active involvement by interested parties. Targeted outreach also is planned, as is basin-wide coordination among GSAs. The Outreach Plan also summarizes the Cawelo GSA decision-making process.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 28 TODD GROUNDWATER 3 BASIN SETTING

This section summarizes Cawelo GSA’s basin setting, which includes the hydrogeologic conceptual model, groundwater conditions and groundwater budget. The basin setting of the Plan Area provides the foundation on which to evaluate sustainability criteria and develop the Cawelo GSA GSP. As provided in the GSP regulations, the basin setting is based on three related analyses including: 1. Hydrogeologic Conceptual Model (HCM) - describes the groundwater basin including its physical conditions and setting, surface features and hydrology, lateral sides and bottom, and the aquifers and aquitards that control groundwater storage and movement. 2. Groundwater Conditions - provides an understanding of groundwater occurrence and flow, groundwater levels, including trends and fluctuations, groundwater quantity and quality, and interconnected surface water, if any. 3. Water Budgets - provide an accounting of inflows and outflows of the groundwater system including an analysis of historical and current conditions. The water budget analysis also provides a baseline on which to project the water budget analysis into the future using projected water supplies and reasonable estimates of land use and water demand. Projected future water budgets are analyzed with various management actions and projects – as described in Section 9 of this GSP – to determine how best to achieve and maintain sustainability goals for the future. The HCM and Groundwater Conditions are addressed in Section 3 and the Water Budgets are presented in Section 4. In addition, the Cawelo GSA is an active participant with the Kern Groundwater Agency (KGA) and is actively coordinating with several basinwide activities. The KGA is developing regional information on the hydrogeologic conceptual model and groundwater conditions across the entire subbasin to provide a large coordinated, basinwide GSP that covers about 70 percent of the subbasin. In addition, a basinwide modeling task is being used to develop basinwide water budgets using the regional DWR Central Valley model, C2VSim, that has been updated with local groundwater data provided by the various Kern County Subbasin GSAs. The Cawelo GSA is coordinating with these regional efforts and the Cawelo GSP does not intend to duplicate or replace detailed regional information being developed by others; however, an abbreviated description of the regional setting is provided for context of the local Plan Area analyses.

3.1 HYDROGEOLOGIC CONCEPTUAL MODEL (REG. § 354.14)

The Cawelo GSA is located near the northeastern margins of the Kern County Subbasin. The groundwater basin beneath the Cawelo GSA consists of unconsolidated to consolidated alluvial sediments, and most of the groundwater supply occurs in the unconsolidated alluvium and underlying semi-consolidated Kern River Formation, which crops out in the eastern areas of the Cawelo GSA. These aquifers were deposited in fluvial and alluvial fan environments associated with the Kern River and other ancestral drainageways (Robbins, 2014). The regional geologic and structural setting, along with a more complete description of the hydrogeologic conceptual model, is provided in the following sections.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 29 TODD GROUNDWATER 3.1.1 Physical Setting

The Cawelo GSA is located in the northeastern area of the Kern County Subbasin. The following provides a summary of the physical setting in the vicinity of the Cawelo GSA.

3.1.1.1 Topography A Digital Elevation Map (DEM) of the topography based on the United States Geological Society (USGS) National Elevation Dataset (NED) is illustrated on Figure 3-1. The Cawelo GSA extends from the edge of the Sierra Nevada foothills to the San Joaquin Valley floor. Most of the Cawelo GSA is characterized by a gently westward-sloping plain ranging in altitude from 600 feet on its east margin to 375 feet in the west and southwest. In large part, this plain represents a surface of aggradation immediately underlain by deposits of Recent age laid down by the westward-flowing streams. The eastern areas of the Cawelo GSA are located in the dissected foothill belt that separates the Sierra Nevada from the valley plain. The dissected belt is in marked contrast to the valley plain with respect to physiography, land use and farming practices that separates the highly productive vineyards, citrus groves, and cultivated fields on the valley plain from the low-yield dry farms and parched ranges of the largely undeveloped foothills. Poso Creek, with headwaters in the Sierra Nevada, cuts from west to east across the dissected foothill belt onto the valley floor in the central portion of the GSA. Little Creek, a smaller creek, flows into the north-central portion of the GSA approximately 4.5 miles north of Poso Creek. A short stretch of the Kern River crosses the southeastern Cawelo GSA. The Kern River exits the dissected uplands southeast of the Cawelo GSA at an elevation of about 420 feet, forming the apex of the alluvial fan. The alluvial fan surface has a slope of about 7 to 8 feet per mile.

3.1.1.2 Surface Geology A regional geologic map shown on Figure 3-2 illustrates the age and composition of surficial deposits in the Subbasin (Page, 1986). Most of the Subbasin is covered with continental deposits of Quaternary age and is flanked by Miocene and pre-Miocene marine sedimentary units and basement rocks on the eastern and western margins of the valley. These deposits are part of the San Joaquin Valley, a structural trough approximately 200 miles long and 70 miles wide filled with up to 32,000 feet of marine and continental sediments deposited by periods of oceanic inundation and erosion of the surrounding mountains. Cawelo GSA overlies Tertiary to Holocene continental rocks and deposits composed of a heterogeneous mix of generally poorly sorted clay, silt, sand and gravel (Page, 1986). Surface geologic units have been compiled statewide on the Geologic Map of California by the California Geological Survey (CGS, formerly Division of Mines and Geology) (CGS, 2000); a portion of this map is shown on Figure 3-3. This geologic map has been modified slightly from GIS data of the Geologic Map of California developed by the California Division of Mines and Geology (CDMG, 2000). Some older units outside of the groundwater basin have been combined on Figure 3-3 for simplicity, but most geologic unit labels have been preserved from the source. As shown by the yellow shading, most of Cawelo GSA is covered by alluvial deposits of Pleistocene and Holocene age (Quaternary Period, labeled Q). The dissected foothill areas in the eastern Cawelo GSA are underlain by older alluvial deposits of Miocene to Pliocene age (labeled QPc) composed of sandstone and conglomerate originating from the Sierra Nevada mountains (Figure 3-3). The dissected foothill belt of Tertiary and Quaternary marine and continental rocks that separates the Sierra Nevada from the alluvial deposits of the valley plain (Lofgren and Klausing, 1973).

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 30 TODD GROUNDWATER 3.1.1.3 Soils The soils of the Cawelo GSA formed on continental deposits of loosely consolidated and poorly bedded sediments made up of sands, gravels, silts, and clays. Small intermittent streams that historically flowed from the western foothills formed thick deposits of alluvium. More recent alluvium was deposited by Poso Creek. Soil textures from the Soil Survey Geographic (SSURGO) database for Kern County, developed by the U.S. Department of Agriculture, Natural Resources Conservation Service, are illustrated on Figure 3-4. This map covers most of the GSA except for areas along the southern boundary. Soil textures are color- coded and listed in the legend by decreasing grain size (texture). As shown on the soil texture map, sandy loam is present throughout most of the GSA, with areas of fine sandy loam along Poso Creek and in the southern GSA, and areas of loam in the central and northwestern GSA. Clay loam is present at the edge of the foothills in the northeastern area of the Cawelo GSA. Figure 3-4 also illustrates the recharge basins within the GSA that are located along Poso Creek and west of the Cawelo GSA boundary. The recharge basins are in areas of coarse-grained soils (sandy loam and loam).

3.1.2 Hydrologic Setting

The local hydrologic setting is dominated by the Kern River, which provides significant water supply to the Cawelo GSA. Poso Creek also provides additional water supplies to the Subbasin. Deep percolation of precipitation and local stormwater runoff provide additional natural water sources. These surface water supplies are augmented with imported water, supported by associated infrastructure of diversions, conveyance, treatment, and delivery. All of these supplies are actively managed in the Cawelo GSA to optimize conjunctive use and groundwater recharge. Details of the local hydrologic setting are provided below.

3.1.2.1 Climate The climate is characterized by hot, dry summers and cool, moist winters. The mean annual temperature is 65 °F and summer highs frequently exceed 100 °F. On average, about 70 percent of the precipitation occurs in December through March. The long-term average precipitation from 1938 through 2017 at the Bakersfield Field Meadows Airport station is approximately 6 inches per year (NOAA, 2018). CWD has maintained a precipitation gauge within the Cawelo GSA since 1982. The average rainfall at this station from 1982 to 2017 is 7.1 inches. Annual precipitation ranges from 3.1 inches in WY 2014 to 18.75 inches in WY 1998. The differences in rainfall totals between the Shafter CIMIS station and the CWD gauge provide an indication of the range of spatial variability of rainfall across the region.

Annual precipitation – displayed by Water Year (WY) - is shown on Figure 3-5, covering a 35-year period from WY 1983 to WY 2017. The precipitation data are from CIMIS Station #5 in Shafter. Data in water years 2005, 2012, and 2013 are from the NOAA Bakersfield Airport climate station because the CIMIS Station #5 data are incomplete in these years. As shown on the figure, annual precipitation is highly variable, ranging from 2.2 inches in WY 2014 to 15.8 inches in WY 1998. Average annual precipitation during the period is 6.29 inches. Figure 3-5 shows that the wettest water years in the last 35 years are associated with precipitation totals above 10 inches per year; using this definition, wet years occurred in WYs 1983, 1995, 1998, and 2011. The driest water years, with precipitation less than 4 inches per year, occurred in WYs 1984, 1990, 2007, 2008, 2013 and 2014.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 31 TODD GROUNDWATER Each Water Year shown on Figure 3-5 is color-coded based on the San Joaquin Valley water year hydrologic classification indices (CDEC, 2018): wet (blue), above normal (light blue), below normal (yellow), dry (orange), and critically dry (magenta). The San Joaquin Valley water year indices do not always correlate with precipitation measured at the Bakersfield airport station because they are based on runoff in the Stanislaus, Tuolumne, Merced, and San Joaquin Rivers, all north of Kern County. Based on a discussion with DWR, these hydrologic classifications are the best available information for Kern County because DWR does not calculate runoff indices for the Tulare Basin (DWR, personal communication, 2018).

The Cawelo GSA is also characterized by relatively high referenced evapotranspiration rates. From 1983 to 2017, reference evapotranspiration (ETo) averaged at the Shafter CIMIS station, located about 10 miles east of the Cawelo GSA, averaged about 57 inches per year. Monthly averages range from an ETo of 1.3 inches in January to 8.2 inches in July (CIMIS, 2018). These rates indicate that much of the local precipitation would be evaporated (or transpired by local vegetation), with relatively small amounts contributing to deep percolation and recharge.

3.1.2.1 Rivers and Streams Figure 3-6 illustrates the surface water bodies within and adjacent to the Cawelo GSA. Surface water bodies within the GSA include Little Creek, Poso Creek, Lerdo Canal, Cawelo’s Distribution Canal and recharge facilities along Poso Creek. Additionally, the Kern River flow within and along the southern boundary of the Eastern Extension Area of the Cawelo GSA (Figure 3-6). Friant-Kern Canal and Calloway Canal are immediately to the west of the GSA, Poso Canal is to the east of the GSA along Little Creek, and Beardsley Canal is the southern extension of Lerdo Canal. Given the depth to groundwater, there are no known active springs, seeps, or groundwater-supported wetlands in the Cawelo GSA. Poso Creek is the most significant surface water body within the Cawelo GSA. Poso Creek is an intermittent stream that crosses the central region of the Cawelo GSA from east to west over approximately seven miles. Its watershed originates in the Greenhorn Mountains of the South Sierra Nevada Mountain Range at an elevation of approximately 8,000 feet (CWD, 2007). Poso Creek has several tributaries including Angel Creek, Cedar Creek, Little Poso Creek, Rattlesnake Creek, and Little Creek (CWDC, 2014). There are two stream gages on Poso Creek, at Coffee Canyon and Trenton Weir upstream of State Highway 65 (CWD, 2007). The Coffee Canyon gage has a record of streamflow from 1959 to present, recorded by the USGS until 1985 and Kern County Water Agency since 1985 (CWD, 2007). The Trenton Weir has a streamflow record since 1982 and is monitored by Cawelo Water District (CWD, 2007). The Kern River crosses a small portion of the southeastern Cawelo GSA (see Figures 3-6). The Kern River is about 165 miles long and drains snowmelt and runoff from a watershed of approximately 2,400 square miles (City of Bakersfield, 2012b). Since 1953, flows in the river have been regulated at Isabella dam, about 25 miles upstream of where it enters the Kern County Subbasin (Figure 1-1).

The Kern River is a major water resource for the Kern County Subbasin. Kern River flow is monitored at two permanent stream gage stations, First Point and Second Point. A Kern River Index is established for runoff between April and July, representing a percentage of the long-term average flow for those months. Kern River flows are highly variable with peak flow rates ranging between a wet year high flow (14,038 cfs), an average year flow (3,355 cfs), and a dry year flow (373 cfs).

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 32 TODD GROUNDWATER 3.1.2.2 Surface Water Canals, Conveyance and Infrastructure The Cawelo Water District (CWD) is primarily irrigated agriculture and the eastern extension area is predominantly oil fields or undeveloped lands. The CWD supplies imported water for beneficial uses such as irrigation and groundwater banking. Sources of imported water include Kern River water, SWP, CVP, and treated produced water. Irrigation return flows and infiltration from water conveyance systems account for approximately one half of groundwater inflows using the checkbook method1. Cawelo Water District receives imported surface water conveyed by a network of canals, pipelines, pump stations and reservoirs (CWD, 2007).

Imported surface water is delivered to CWD via a series of canals and pipelines (Figure 3-6). Water from the State Water Project is delivered from the California Aqueduct to the Cross Valley Canal, then to North Kern’s Beardsley Canal which becomes the Lerdo Canal, then to Pump Station B, CWD’s Reservoir B, and to the CWD service area (GEI, 2007). Central Valley Project (CVP) water flows from the Friant-Kern Canal through the Cross Valley Canal Extension, the Beardsley and Lerdo canals, Pump Station B, Reservoir B, and then to the CWD service area (CWD, 2007). Kern River water from the City of Bakersfield is diverted to the Beardsley and Lerdo canals and to Reservoir B. Treated produced water from both Chevron USA Inc. and Valley Waste Disposal Company is delivered by pipeline to Reservoir B. Treated produced water from Shaefer Oil Company flows to Reservoir C (CWD, 2007).

3.1.2.3 Recharge Areas Groundwater recharge is achieved through either indirect or direct recharge. Indirect recharge is based on the delivery of surface water in-lieu of pumping groundwater. Direct recharge is based on the surface spreading and percolation of precipitation and applied water supplies in basins or ponds. The Cawelo GSA has over 400 acres of spreading ponds along Poso Creek that are used for groundwater recharge (CWD, 2015). The biggest spreading site, encompassing approximately 370 acres, is the Famoso Project Basins (Figure 3-6). Water banking involves the regulation of surplus surface water supplies, by placing the water into groundwater storage for subsequent recovery. Cawelo GSA has two banking partners, Zone 7 Water Agency and Dudley Ridge Water District (CWD, 2015) that employ indirect recharge by delivering surface water in lieu of pumped groundwater to satisfy irrigation water requirements. The In-Lieu Water Banking Program provides up to 120,000 acre-feet of groundwater storage capacity for a banking partner(s) with an annual recharge and recovery capacity of approximately 1,500 to 5,500 acre-feet per year. Figure 3-4 highlights the occurrence of the more permeable soils discussed in Section 3.1.1.3, where surface water is readily recharged. The occurrence of these higher permeability soils and sediments along Poso Creek, including unconsolidated alluvial deposits of sand and gravel, illustrate why the channel is used for managed recharge by CWD. Although soil textures in the northern part of the Cawelo GSA are finer-grained, local sand lenses allow for some infiltration of surface water (and groundwater return flows) applied for crop irrigation (see areas of intensive agricultural shown on Figure 2-9).

1 The checkbook method is an analysis of the water budget (described in Section 4-2) that involves a detailed accounting of inflows and outflows, although not addressing subsurface flows.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 33 TODD GROUNDWATER 3.1.3 Regional Geologic and Structural Setting

A regional basin setting describing the regional geologic setting has been developed by KGA to support GSP development for KGA members (GEI, 2019). The focus is on the area encompassed within the jurisdiction of the Kern Groundwater Authority, its participating members, and collaborators. The following provides a highlights key features of the regional geologic setting relevant to the Cawelo GSA.

3.1.3.1 Kern County Subbasin The Kern County Subbasin encompasses a surface area of 1,792,000 acres (2,800 square miles) and has approximately 40,000,000 acre-feet (AF) of groundwater storage with another 10,000,000 AF of storage capacity, including areas where water levels have declined (DWR, 2006; Page, 1986). The Kern County Subbasin consists of the upper portion of a deep structural trough between the crystalline rocks of the Sierra Nevada and the basement rocks of the Coast Ranges. The deeper portions of the trough contain mostly Miocene and older marine sedimentary units. The upper tough has been infilled over time with mostly Late Miocene and younger continental sediments. Continental sediments comprise up to approximately 3,400 feet of the material along the Kern River near the town of Tupman (western side of the valley), and the base of the fill is over 18,000 feet deep (Davis et al., 1959).

3.1.3.2 Geologic Units A regional geologic map shown on Figure 3-2 illustrates the age and composition of surficial deposits in the Subbasin (Page, 1986). As shown, most of the Subbasin is covered with continental deposits of Quaternary age and is flanked by Miocene and pre-Miocene marine sedimentary units and basement rocks on the eastern and western margins of the valley. A brief description of the geologic units in the Kern County Subbasin is provided below.

The Tulare Formation is Plio-Pleistocene in age, and in conjunction with the Kern River Formation (Mio- Pliocene to possibly early Pleistocene), represents west-east facies change across the subbasin. The Tulare and Kern River formations are moderately to highly permeable and are major freshwater sources within the Kern County Subbasin (Page, 1986; SWSD, 2012). In the central and eastern part of the basin, the Tulare Formation was deposited in a fluvial-lacustrine environment, while the west side has lacustrine claystones, fan-delta deposits, debris-flow dominated alluvial-fan deposits, and paleosols representing an arid to semiarid setting (Nilsen and Campbell, 1996).

The Corcoran Clay occurs laterally in the north subbasin (about 34 miles wide in extent) from Delano to Lost Hills and narrows to the south just to the west of the Kern River banking facilities to about 3.5 miles wide. Within the central area of the subbasin between the Kern River and Highway 46, the depth to the Corcoran Clay varies from 300 to 450 feet. Further north to the county line, the depth varies from 200 to 750 feet. The Corcoran Clay, most notably the modified E-clay (Page, 1986) is generally very fine grained; however, isolated, coarser zones are possible, particularly where the clay is less than 20 feet thick. The Corcoran Clay does not exist under the Kern Alluvial Fan (Kern Fan), where the shallow unconfined layers are separated from deeper layers by an intermediate zone of interbedded sands and silts which retard vertical groundwater flow and create an increase in semi-confinement with depth. The Corcoran Clay is also not present in the eastern/northeastern part of the subbasin from the cities of McFarland and Bakersfield, to Edison (Faunt et al., 2009).

The Kern River Formation includes from 500 to 2,000 feet of poorly sorted, lenticular deposits of clay, silt, sand, and gravel derived from the Sierra Nevada. The Kern River Formation crops out along the eastern margin of the Kern County Subbasin and reaches its maximum thickness of 2,600 feet in the

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 34 TODD GROUNDWATER subsurface west of mapped outcrops (Bartow and Pittman, 1983). The formation consists mostly of poorly sorted fluvial sandstone and conglomerate with interbeds of siltstone or mudstone that becomes finer grained northward and westward. Some of the thicker siltstone or mudstone interbeds may represent deposits of small ephemeral lakes or ponds (Bartow, 1983). The Kern River Formation is coarsest in its easternmost exposures, generally the area south of the Kern River, where the composition includes a cobble conglomerate with boulders near the base and pebbly sandstone. (Bartow and Pittman, 1983). Two oil-producing zones occur in the lower part of the formation where oil is believed to have migrated to the Kern River Formation from older marine sediments (Bartow and Pittman, 1983).

Older alluvium and terrace deposits overlie the Tulare and Kern River formations. These deposits also make up a portion of the regional aquifer system. They are composed of up to 250 feet of Pleistocene- age lenticular deposits of clay, silt, sand, and gravel that are loosely consolidated to cemented. These deposits are moderately to highly permeable and yield sufficient water to wells. They are often indistinguishable from the underlying Tulare and Kern River formations (DWR, 2006).

The Holocene-age younger alluvium and flood basin deposits vary in character and thickness in the subbasin. Along the eastern and southern subbasin margins, these younger deposits consist of up to 150 feet of interstratified and discontinuous beds of clay, silt, sand, and gravel. In the southwestern portion of the subbasin, the deposits are finer-grained and less permeable as they grade into fine- grained flood basin deposits underlying the historic lakebeds of Buena Vista and Kern lakes in the southern portion of the subbasin. The flood basin deposits consist of silt, silty clay, sandy clay, and clay interbedded with poorly permeable sand layers. These flood basin deposits are difficult to distinguish from underlying fine-grained older alluvium (Page, 1986; DWR, 2006).

The Kern River Formation unconformably overlies the Chanac Formation and may be contemporaneous with the Etchegoin, San Joaquin, and the Tulare formations (Bartow, 1983 and 1991); however, Graham and others (1988) concluded that the Kern River Formation predates the Corcoran Clay, which has a basal age of about 725,000 years. Radiometric dating of a volcanic ash layer near the top of the Kern River Formation at the Kern River oilfield may agree with the aforementioned basal age; however, others dated this ash bed at 6 million years which would place the Kern River Formation solely in the Miocene (Scheirer et al., 2007). Nevertheless, the gradational relationship between the Kern River Formation and seemingly younger units such as the Etchegoin, San Joaquin, and Tulare formations would have to be reexamined.

The Mio-Pliocene Etchegoin Formation varies considerably, ranging from clay and silt to sand, gravel, and sandstone. It ranges in thickness from a few tens of feet to more than 2,000 feet. The 90 to 170 foot thick Macoma claystone (shale) member of the Etchegoin Formation is a low permeability blue- green shale that serves as the cap rock for oil accumulation. The Macoma serves to vertically isolate the overlying freshwater zones within Kern River Formations from the underlying oil reservoirs. the Pliocene-age non-marine Chanac Formation is a 350 to 450 foot thick sequence of brown to gray, fine to coarse grained, poorly sorted sands with interbedded siltstones, mudstones that were deposited as lenticular braided streams and floodplains.

The origin of the Miocene Olcese Sand and Santa Margarita Sandstone varies from continental to marine going from east to west across the subbasin (Scheirer, et al, 2007). The Miocene Olcese Sand ranges up to 600 feet in thickness and consists of unconsolidated medium- to coarse-grained sand containing a few pebble and siltstone beds. The Santa Margarita Sandstone ranges in thickness from 200 to 600 feet

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 35 TODD GROUNDWATER and consists of coarse-grained sand (DWR 2006), and includes an upper bed of fine, silty, well sorted gray sand, and a lower bed of brownish-gray and brown fossiliferous micaceous sandy siltstone. The Round Mountain Silt is an aquitard that separates the Miocene Olcese Sand from the Santa Margarita Sandstone and acts as a confining unit for the Miocene Olcese Sand (KTWD, 2016). This silt unit consists mostly of a gray and brown siltstone that contains beds of diatomite and silty sand (Page, 1986), and ranges in thickness from 0 to about 200 feet.

Deeper formations are generally considered to be below the base of the groundwater basin and are primarily associated with the oil fields. The Jewett Sand is a unit of silty sand to sandy shale and the Freeman Silt is a siltstone. These units do not outcrop in Kern County. The Vedder Sand is principally a subsurface unit that is widespread in the southeastern San Joaquin Valley (Richardson, 1966) and may reach a thickness of more than 300 m locally. It crops out in a narrow belt north of Poso Creek, where it is composed principally of light gray well-sorted fine- to medium-grained sandstone, locally cemented with silica. The Famoso-Walker Formation consists of an arkosic sandstone/conglomerate and green sandy claystone; however, in the Cawelo GSA area it is predominantly a green sandy claystone.

3.1.3.3 Geologic Structure and Faulting Geologic faults are also shown on the CGS map on Figure 3-3. As indicated on the figure, most of the faulting occurs close to the subbasin margins east of Cawelo GSA. These faults characteristically trend north to north-northwest; however, an apparently conjugate set trends generally north-northeast. Many of the faults extend to the surface, except within the southwestern part of the area, which is overlain by alluvial deposits. Vertical separations along most of these faults are on the order of tens of feet (Castle, 1983).

These are generally high-angle faults that cut through much of the sedimentary section. The Kern Front fault, which defines the east edge of the Kern Front oil field, and several faults along the east margin of the Premier area of the Poso Creek field, are known to cut deposits younger than the Kern River Formation. Figure 3-3 shows the surface traces of the mapped faults in the region. The Kern Front and Premier (Poso Creek) faults are known to have sustained historical rupturing. The Kern Front fault dips about 60° W at the north end of the Kern Front oil field, but it steepens to about 80° W. near its southern terminus (Castle, 1983). The dips along the historically active faults on the east side of the Premier area are less certain, but subsurface projections suggest that they too dip steeply to the west. The structural and depositional setting of the Cawelo GSA is influenced by the Bakersfield Arch, a deep geologic structure of basement rocks that dips towards the northwest below the Cawelo GSA. This arch and northwesterly dip of basement rocks created a deep trough for infill of sediments (depocenter), mostly during the Neogene period (Miocene and younger) (Bartow, 1991).

3.1.4 Principal Aquifers and Aquitards

The older alluvium and the underlying Kern River Formation form the principal aquifer body in the Kern County Groundwater Basin (DWR, 2006). Groundwater is present under unconfined conditions in the eastern Kern County Basin, beneath the Cawelo GSA. Collectively, these formations are considered the Principal Aquifer for groundwater management purposes.

3.1.4.1 Principal Aquifers Groundwater pumping in the Cawelo GSA primarily occurs within the upper 1,500 feet of the aquifer system, consisting primarily of the Quaternary alluvium by possibly including some of the Kern River Formation. The Kern River Formation, older alluvium and younger alluvium deposits are similar and

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 36 TODD GROUNDWATER difficult to distinguish from one another (GEI Consultants, Inc., 2018). Therefore, combining these units into single designation of the principal aquifer system is appropriate for the Cawelo GSA because most production wells are screened in both units, the two units are difficult to differentiate on subsurface logs, and the two formations appear to be hydraulically connected without an intervening, regionally extensive aquitard.

The surficial distribution of younger alluvial deposits is shown in Figures 3-3 and includes younger alluvium presently being deposited along the Kern River and Poso Creek. The shallow alluvial deposits are not easily differentiated in the subsurface except for slope angles on the older and younger surfaces and the presence of paleo-soils (Dale, et al., 1966). In the Cawelo GSA, these younger alluvial deposits are generally unsaturated with possible localized perched zones along Poso Creek that are not connected to the regional groundwater basin aquifer. The gently sloping areas of the Cawelo GSA are underlain by unconsolidated continental deposits derived from the Sierra Nevada. These continental deposits range in age from late Pliocene to the present, and are, in general, correlative with the Tulare Formation and younger deposits to the west, with the upper part of the Kern River Series of Diepenbrock (1933) to the south. The unconsolidated continental deposits form a westward-thickening wedge that ranges to over 2,000 feet in thickness. The unconsolidated continental deposits are composed of lenticular deposits of clay, silt, sand, and gravel that are loosely consolidated to cemented. These deposits are moderately to highly permeable and yield sufficient water to wells. The Corcoran Clay Member of the Tulare Formation is not present in the Cawelo GSA. The lacustrine and flood plain clay layers are less continuous so as not to form a regional confining layer in the GSA. The aquifer system is generally unconfined throughout becoming more semi-confined with depth. The Kern River Formation crops out on the eastern margin of the valley as shown in Figure 3-2. As shown in Cross Section A-A’ (Figure 3-62), the Kern River Formation ranges from 500 to 2,600 feet thick and overlies the marine Etchegoin and Chanac formations. The Kern River Formation is described (Bartow, 1983) as Pliocene/Upper Miocene nonmarine, semi-consolidated, coarse-grained and pebbly sandstone and conglomerate, containing beds and lenses of siltstone and mudstone; it generally is coarser with decreasing depth and to the east, indicating a source in Sierran granites. Most coarse- grained units are south of the Kern River. The dissected foothill areas of the eastern Cawelo GSA are underlain by older unconsolidated continental deposits and the Kern River Formation. The older alluvium consists mostly of the reduced flood-plain and lacustrine deposits, and lacustrine clay deposits.

Several wells near the foothills and a few deep wells in the valley derive fresh water from the Etchegoin; however, its depth is more than 3,000 feet beneath most of the valley and is limited to deep well production (Page, 1986). The Miocene Olcese Sand and Santa Margarita Sandstone are current sources of drinking water in the northeastern portion of the subbasin where they occur as confined aquifers (KTWD, 2016).

3.1.4.2 Hydrogeologic Framework To illustrate these relationships, three geologic cross sections were developed within Cawelo GSA to identify textures and aquifers in the GSA. The orientation of the cross sections and the location of wells used for the cross sections are shown on Figure 3-7. The wells are summarized in Table 3-1. Cross

2 Cross section transects are shown on Figure 3-7.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 37 TODD GROUNDWATER Section A-A’ traverses over 13 miles of the GSA from west to east along Poso Creek, beginning approximately one mile west of the western GSA boundary, following Poso Creek, and extending into the foothills containing the Poso Creek and Kern Front oil fields. Cross Section B-B’ traverses about 18 miles along the eastern side of the GSA, from north to south. Cross Section A-A’ (Figure 3-8) and B-B’ (Figure 3-9) illustrate the lithology and textures that characterize the Principal Aquifer. Lithologies were derived from Drillers’ reports for water supply wells in the Cawelo Water District that had high quality descriptions of the lithology. Cross Section A-A’ includes 20 wells, eight of which are owned Cawelo Water District and have geophysical logs. Cross Section B-B’ includes 24 wells, seven of which are owned by Cawelo Water District and, with the exception of Well 13, have geophysical logs. The water supply wells are completed primarily within the younger alluvium and older alluvium, with some of the deeper wells along the eastern areas reaching to the Kern River Formation. Well depths and screens are relatively similar across the section, with wells at an average depth of 1,254 feet below ground surface (bgs) and ranging from 870 to 1,530 feet bgs. Screen intervals range from a depth of 380 to 1,530 feet bgs. The CWD wells are deeper than other wells on the cross section, extending to approximately 1,100 feet below mean sea level (msl). The deepest well (drillers’ report number 48334 on B-B’) extends to approximately 1,500 feet below mean sea level. The screened interval depths are relatively consistent, except for in the south where wells are shallower, and their screens are shorter. The average well depth is 1,251 feet, almost the same as cross section A-A’, and ranges from 463 to 2,223 feet bgs. Screen intervals range from a depth of 300 to 1,830 feet bgs. Wells are deeper in the northern and central regions of the GSA than in the southern GSA. In some parts of the Kern County Subbasin, the Santa Margarita and Olcese Sandstones are locally significant aquifers; however, in the Cawelo GSA, these units are primarily oil reservoirs. Because of their depth and the presence of hydrocarbons, these units are not considered part of the principal aquifer in the Cawelo GSA. Cross Section A-A’ shows the relationship of the oil producing formations in the Poso Creek and Kern Front Oil Fields relative to the water supply wells in the Cawelo Water District (Figure 3-8). The shallowest oil producing horizon in these fields is the Etchegoin Formation, which is present at an elevation of approximately 1,000 feet below mean sea level (DOC, 1998) in the oil fields. However, because of the westward dip, the Etchegoin Formation dips occurs at depths of 2,000 feet below mean sea level or greater beneath the water supply wells. Along Cross Section B-B’, the oil producing zones are generally below the elevation of the cross section (2,000 feet below mean sea level), so are not shown. The water supply wells in the Cawelo Water District are completed far above the oil producing zones.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 38 TODD GROUNDWATER Table 3-1: Summary of Wells on Cross Sections

Drillers' Report Township/ Depth (feet bgs) Number or Well Range-Section Geophysical Log Number Well Bottom Top of Screen Bottom of Screen Cross Section A-A' 258904 27S/25E-1 1,040 400 1,020 no 50074 27S/26E-16 1,199 593 1,199 no 63291 27S/26E-16 1,200 450 1,200 no e0187945 27S/26E-22 870 510 870 no 22Q1 - Well#4 27S/26E-22 1,248 744 1,248 no 565142 27S/26E-23 1,320 Not Available no 915724 27S/26E-26 1,075 674 1,075 no 26K1 27S/26E-26 1,002 702 1,002 no 116324 27S/26E-25/26 1,236 402 1,236 no 943146 27S/26E-25 1,044 604 1,044 no 32112 27S/26E-25 1,200 450 1,200 no 6L1 27S/26E-6 968 380 968 no Well 10 27S/26E8H 1,500 550 1,500 yes Well 11 27S/26E8D 1,500 500 1,500 yes Well 12 27S/27E30N 1,500 700 1,500 yes Well 14 27S/27E30J2 1,520 1,060 1,520 yes Well 15 27S/27E30F 1,530 1,050 1,530 yes Well 7 27S/26E8Q2 1,200 500 1,200 yes Well 8 27S/26E8N 1,470 510 1,470 yes Well 9 27S/26E8J 1,460 550 1,460 yes Cross Section B-B' 71290 26S/27E-07 1,200 700 900 no /7 26S/27E-18 1,400 450 1,400 no 116277 26S/27E-18 1,500 440 1,500 no 48334 26S/27E-30 2,223 Not Available no Well 13 27S/27E-06 1,500 700 1,500 yes 6Q1 27S/27S-06 1,266 504 1,266 no 116493 27S/27E-18 1,830 530 1,830 no Well 5 27S/27E-19 1,500 400 1,500 yes Well 4 27S/27E-19 1,388 985 1,388 yes Well 15 27S/27E-30 1,530 1,050 1,530 yes Well 14 27S/27E-30 1,520 1,060 1,520 yes Well 12 27S/27E-30 1,500 700 1,500 yes Well 1 28S/27E-06 1,235 550 1,200 yes Well 3 28S/27E-06 1,366 552 1,366 yes 76883 28S/27E-07 1,200 600 1,200 no 18A1 28S/27E-18 1,500 382 1,500 no 118501 28S/27E-18 1,300 480 1,300 no 19C1 28S/27E-19 1,055 Not Available no 19L 28S/27E-19 990 470 990 no 30A 28S/27E-30 745 Not Available no 30L 28S/27E-30 814 480 814 no 480170 28S/27E-31 463 410 440 no 26364 28S/27E-31 500 300 500 no 27770 29S/27E-5 500 300 500 no

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 39 TODD GROUNDWATER 3.1.4.3 Geologic Texture Analysis In the unconsolidated continental deposits, the USGS recognizes three major facies (Lofgren and Klausing, 1973): oxidized alluvial deposits, reduced flood-plain and lacustrine deposits, and lacustrine clays. These facies represent distinct depositional environments and are differentiated by their color and texture and by the state of preservation of plant remains as revealed in well cores or samples. In general, the oxidized alluvial deposits are thickest in the eastern part of the area and interfinger with and overlie the reduced deposits; also, they are characterized by their yellow, red, and brown color and by highly weathered, crumbling feldspar grains. The reduced lacustrine and flood-plain deposits, on the other hand, are recognized by their drab green, blue, and dark-gray color, well-preserved plant remains, and an ever-present dissemination of iron sulfide (Lofgren and Klausing, 1973). These grade into the Kern River Formation at depth, which consists of sandstone and conglomerate with interbeds of poorly sorted lenticular deposits of clay, silt, sand and gravel also derived from the Sierra Nevada (DWR, 2006). It is coarsest in the east, generally south of the Kern River (GEI, 2018b). The Kern River Formation is described (Bartow, 1983) as a nonmarine, semi-consolidated, coarse- grained and pebbly sandstone and conglomerate, containing beds and lenses of siltstone and mudstone; it generally is coarser with decreasing depth and to the east, indicating a source in Sierran granites; however, most coarse-grained units are south of the Kern River.

The cross sections (Figures 3-8 and 3-9) depict the hydrofacies textures to illustrate the geologic heterogeneity of the unconsolidated deposits within the Cawelo GSA. It is not clear whether any of the wells penetrate to the Kern River Formation. Descriptions on the drillers’ reports were used to categorize the lithology into two textures: coarse material, which includes sand and gravel, and fine textures, which includes silt and clay. Where available, the electric logs were used to verify the lithology and unit thickness provided on the drillers’ reports. Textures shown on the cross sections are based on drillers’ reports from the California Department of Water Resources (DWR) and geophysical logs from CWD. Locations of deep formations are estimated based on oil and gas field information available from the California Department of Conservation Division of Oil, Gas, and Geothermal Resources (DOGGR). Ground surface elevations were generated from the National Elevation Dataset developed by the USGS. The texture analysis was conducted for the wells on the cross sections and the textures are shown at the same scale as they were described on the drillers’ reports. It is difficult to correlate coarse and fine material between the wells because of the interbedded and heterogenous nature of the material. Cross Section A-A’ (Figure 3-8) illustrates a relatively even distribution of coarse and fine material, both vertically and laterally along Poso Creek. Cross Section B- B’ (Figure 3-9) shows that there is a higher percentage of fine material than coarse material in the northern GSA. The wells in the central and southern regions of the GSA have a relatively even distribution of coarse and fine material, both vertically and laterally. The textures show more clay layers, including noted blue clay layers, consistent with the reduced flood-plain and lacustrine deposits, and lacustrine clays facies of Lofgren and Klausing (1973). The younger alluvium is sandier and shows consistency with the oxidized alluvial deposits.

3.1.4.4 Aquifer Hydraulic Properties As summarized in the Draft Basin Setting for the Kern County Subbasin (GEI, 2018b), hydraulic property information is available within Kern County Subbasin from pumping tests conducted by the USGS in the 1950s and 1960s (McClelland, 1962) and by engineering consultants in the 2000s (Todd, 2018). These pumping tests were not conducted within Cawelo GSA, two of the USGS pumping tests were conducted

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 40 TODD GROUNDWATER close to Cawelo GSA, within the North Kern Water Storage District approximately 3.5 and 4.0 miles south of Famoso. These pumping tests were conducted in 1958 in well numbers 27S/26E-30F1 and 27S/26E-32G1 (McClelland, 1962). Well 27S/26E-30F1 was pumped for 90 minutes at a flow rate of 1,928 gallons per minute (gpm). The pumping well was 700 feet deep and water levels were measured in the pumping well and two observation wells at depths of 650 and 866 feet. The estimated transmissivity values based on several methods of analysis, ranged from 250,000 to 470,000 gallons per day per foot (gpd/ft). The storage coefficient was estimated to be 0.0001 (McClelland, 1962). Well 27S/26E-32G1 was pumped for 115 minutes at a rate of 1,640 gpm. The pumping well was 780 feet deep and water levels were measured in the pumping well and two observation wells at depths of 640 feet and an unknown depth. The estimated transmissivity was like the first pumping test, ranging from 260,000 to 450,000 gpd/ft. The storage coefficient was estimated to be 0.001, the same as the first test (McClelland, 1962). The analysis conducted for the Draft Basin Setting for the Kern County Subbasin (GEI, 2018b) estimated a range in hydraulic conductivity from 3 to 250 feet per day (ft/day). These values are within the range of hydraulic conductivities used for the CVHM, C2VSIM and Todd (2018) groundwater models (GEI, 2018b).

3.1.5 Oil Fields

The shallow-most top of oil production in an oil field would provide a conservative estimate of the bottom of the Subbasin. In addition, the occurrence of petroleum hydrocarbons in the formation would inherently limit the use of formation water. This formation water would not be connected to the groundwater system and not be considered part of the groundwater basin pursuant to groundwater management. Most of the local oil fields have been exempted from the USEPA definition of protected groundwater (discussed in more detail in Section 3.2.5.3).

The location of a regional geologic cross section line (labeled C-D) that crosses the Kern County Subbasin starting from near the Cawelo GSA is shown on Figure 3-10. This cross section was prepared by DOGGR (CDOC, 1998) to show the subsurface geology beneath the oil fields in the southern San Joaquin Valley. It has been modified to include the average depth of the shallowest oil-producing zone in the oil fields (indicated by the red triangles on Figure 3-10). The cross section provides the stratigraphic relationships of the key geologic formations for the Kern County Subbasin and the underlying older continental and marine sedimentary formations. As indicated on the cross section, the shallowest hydrocarbon zone in most of the oil fields occurs within older marine sedimentary units (purple shading) of the Subbasin. Two exceptions include shallow productive hydrocarbon zones at the Kern River and Elk Hills oil fields on the eastern and western sections of the cross section, respectively. In the Kern River and Elk Hills fields, oil production occurs in the continental and continental/marine deposits of the Kern River Formation and the San Joaquin Formation, respectively.

The Cawelo GSA overlaps three active oil fields: Kern Front, Kern River, and Poso Creek. The locations of oil fields are available for download from the California Division of Oil, Gas, and Geothermal Resources (DOGGR) website; administrative boundaries and productive limits of these oil fields are mapped on Figure 3-11. The producing hydrocarbon zones are the Etchegoin and Chanac for the Kern Front, Poso Creek, and Rosedale Ranch field. The Kern River, Jewett, and Vedder are the hydrocarbon zones for the Kern River field.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 41 TODD GROUNDWATER CWD receives treated produced water for irrigation. Between 2007 and 2015, delivery of treated produced water ranged from approximately 20,000 AFY in 2007 to 37,000 AFY in 2012 (CWD, 2015). The water is tested in conformance with the Central Valley Regional Water Quality Control Board’s (CVRWQCB) waste discharge requirements and then blended with other sources and used for irrigation. Most of the treated produced water is from Chevron USA Inc., which operates in the Kern River field (CRWQCB WDR, 2012), while some is from CRC, which operates in the Kern Front field (CRWQCB WDR, 2006).

3.1.5.1 Regional Hydrostratigraphy A cross section was developed to evaluate that the hydrostratigraphic relationships of the exempt aquifers of the oil field reservoirs and SGMA-managed principal aquifers within the Cawelo GSA. Figure 3-13 shows the location of Cross Section C-C’ which extends southeast to northwest: it starts from the Kern River Oil Field in the southeast, crosses the Kern Front and Poso Creek Oil Fields, extends across the Cawelo Water District and ends near the Famoso recharge basins just across the GSA boundary in the North Kern WSD. The cross section (Figure 3-14) shows the relationship of the oil producing formations in the Poso Creek and Kern Front Oil Fields relative to the water supply wells in the Cawelo Water District. Portions of the cross sections from Figure 3-8 and 3-9 are included on the Cross Section C-C’ to show the relative scale of the groundwater basin water supply pumping to the oil field operations. In the Kern River Oil Field in the southeast, the oil production occurs in the shallow alluvial sediments of the Kern River Formation. The oil reservoir is confined by the Kern Front Fault which forms a hydraulic barrier to oil and water flow (Figure 3-14). It is observed that oil does not occur in the Kern River Formation to the west of the Kern Front Fault, which demonstrates that the Kern Front Fault is an effective hydraulic barrier, and, thereby, the oil field reservoir in the Kern River Oil Field is separate from the SGMA-managed groundwater Kern River Subbasin. In the Kern Front Oil Field, the shallowest oil producing horizon in these fields is the Etchegoin Formation, which is present at an elevation of approximately 1,000 feet below mean sea level (DOC, 1998). However, because of the westward dip, the Etchegoin Formation occurs at depths of 2,000 to 5,000 feet below mean sea level or greater beneath the water supply wells in CWD (Figure 3-14). In the Kern Front Oil Field, the oil producing zones generally occur at elevations between 1,500 to 4,000 feet below mean sea level. The water supply wells in the Cawelo Water District are completed well above the oil producing zones.

3.1.5.2 Oil Fields Aquifer Exemptions Upon recommendation from the State, the USEPA may exempt an aquifer as a potential underground source of drinking water (USDW) if it satisfies 40 CFR §146.4, which states “An aquifer or a portion thereof which meets the criteria for a USDW in §146.3 may be determined under §144.7 of this chapter to be an “exempted aquifer” for Class I-V wells if it meets the criteria in paragraphs (a) through (c) of this section.” In accordance with §146.4, the relevant criteria for the subject exemption for Class II injection (subsurface injection of liquids associated with oil and gas production) include:

• 40 CFR § 146.4 (a) “It does not currently serve as a source of drinking water.” • 40 CFR § 146.4 (b)(1) “It cannot now and will not in the future serve as a source of drinking water because it is mineral, hydrocarbon, or geothermal energy producing, or can be demonstrated by a permit applicant as part of a permit application for a Class II or III operation

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 42 TODD GROUNDWATER to contain minerals or hydrocarbons that considering their quantity and location are expected to be commercially producible.” • 40 CFR § 146.4(c) “The total dissolved solids content of the ground water is more than 3,000 and less than 10,000 mg/L and it is not reasonably expected to supply a public water system.” The primacy aquifer exemptions were existing prior to or identified in 1974 when DOGGR was granted primacy to implement the Class II injection UIC program (UICP MOA, 1982) or they were approved after 1974 and meet one or more of the following criteria defined in 40 CFR § 146.4. The primacy aquifer exemption boundaries are based on the 1973-1974 production limits as hydrocarbon producing reservoirs shown in Volumes I and II of "California Oil and Gas Fields" (the report), published by the California Division of Oil and Gas (dated 1973 and 1974, respectively). The exempt aquifers are those formations described and depicted as the shaded portions on the maps and cross sections of the report. The location and extent of the existing approved aquifer exemptions in the GSP area are shown in Figure 3-11.

Several aquifer exemptions exist within the Cawelo GSA boundary, including the Kern Front, Poso Creek, and Kern River oil fields. The U.S. EPA’s has recently approved some exempt aquifers for oil and gas extraction as part of its Underground Injection Control (UIC) program (CDOC, 2018). As shown on Figure 3-12, the Kern Front oil field aquifer exemption overlaps with parts of the Cawelo GSA. The Fruitvale and Round Mound aquifer exemptions are located to the south and east of the Cawelo GSA, respectively (Figure 3-12). These aquifer exemptions are for Class II wells, which are for the injection of fluids related to oil and gas operations, such as enhanced recovery and disposal of production wastes. The Kern Front aquifer exemption is for waste disposal in the Vedder Formation, at a depth of 3,900 feet (CDOC, 2018). These exempt aquifers are described next.

3.1.5.3 Kern Front Oil Field Aquifer Exemption The primacy aquifer exemption boundary for the Kern Front Oil Field is based on the 1973-1974 production limits as hydrocarbon producing reservoirs shown in Volumes I and II of "California Oil and Gas Fields" are shown on Figure 3-12). Expansion of the Kern Front Oil Field aquifer exemptions were submitted to the USEPA for approval are described below.

The Kern Front Oil Field Vedder Formation aquifer exemption (Figure 3-12) meets Federal Criteria (40 § CFR 146.4) (a) and (c) and was approved by the USEPA on August 30, 2017 (USEPA August 30, 2017). The Kern Front Vedder exempt aquifer is non-hydrocarbon bearing with TDS ranging from 3,500 to 10,700 mg/L and is used for waste disposal injection. The exempt aquifer is bounded to the west by formation waters exceeding 10,000 mg/L TDS and to the east is included in the older aquifer exemption (1983). The top of the exempt aquifer ranges from 3,900 to 5,000 feet bgs. The Freeman-Jewett Silt overlies and confines the Vedder Formation and is up to 900 feet thick in the Kern Front Oil Field. Pressure gradients within the exempt aquifer boundary are mainly controlled by hydrocarbon production activities including injection activities.

The Kern Front Oil Field Upper Chanac Formation aquifer exemption meets (Figure 3-12) Federal Criteria (40 § CFR 146.4) (a) and (b)(1) and was approved by the USEPA on June 21, 2018 (USEPA, June 21, 2018). The Kern Front Upper Chanac Exempt Aquifer contains hydrocarbons with TDS ranging from 320 to 350 mg/L. Cyclic steam and steam flood injection for enhanced oil recovery (EOR) is used in the Kern Front Upper Chanac exempt aquifer along with waste disposal injection. The exempt aquifer is defined by sealing faults, stratigraphic pinch-out, and the oil-water contact within the Upper Chanac Formation. The depth to the top of the Aquifer Exemption ranges from approximately 1,400 to 2,500 feet bgs (-700

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 43 TODD GROUNDWATER to -1,700 feet msl). A pressure sink created by hydrocarbon production from the Upper Chanac Formation also serves to confine fluids.

3.1.5.4 Poso Creek Oil Field Aquifer Exemption The primacy aquifer exemption boundary for the Poso Creek Oil Field is based on the 1973-1974 production limits as hydrocarbon producing reservoirs shown in Volumes I and II of "California Oil and Gas Fields" are shown on Figure 3-12). Expansion of the Poso Creek Oil Field aquifer exemptions were submitted to the USEPA for approval are described below.

Poso Creek Oil Field has two aquifer exemptions, including the Basal Etchegoin and Chanac Formations (McVan Area) and Basal Etchegoin Formation (Premier & Enas Areas) (Figure 3-12), which meet Federal Criteria (40 § CFR 146.4) (a) and (b)(1) and were both approved by the USEPA on May 4, 2018 (USEPA, May 4, 2018). The Poso Creek exempt aquifers contain hydrocarbons with TDS ranging between 260 to 680 mg/L in the Basal Etchegoin and Chanac Formation (McVan Area) exempt aquifer and 480 to 1,300 mg/L in the Basal Etchegoin Formation (Premier & Enas Areas) exempt aquifer. Cyclic steam and steam flood injection is used for EOR in the Poso Creek exempt aquifers.

In the McVan Area, the Chanac Formation and the Basal Etchegoin Member of the exempt aquifer extends for approximately 1,530 acres (1983 and 2018 Aquifer Exemptions). The Macoma Claystone (60 to 100 feet thick) overlies and confines the Basal Etchegoin Member and Chanac Formation while the Lower Chanac Claystone is the underlying confining unit. Lateral confinement occurs by faults at the east, west, and south that form barriers and through pressure gradients to the north that are controlled by hydrocarbon production.

In the Premier & Enas Areas, the Basal Etchegoin Member exempt aquifer is approximately 7,870 acres (1983 and 2018 Aquifer Exemptions). The top of the exempt aquifer in the Basal Etchegoin Member in the Premier & Enas Areas is approximately -1,060 to -2,050 feet msl. In the Premier & Enas Areas, the Macoma Claystone (40 to 170 feet thick) is the upper confining unit. The lower confining unit is an unnamed shale about 15 feet thick. Faults and pressure gradients controlled by hydrocarbon production provide lateral confinement.

3.1.5.5 Kern River Oil Field Aquifer Exemption The primacy aquifer exemption boundary for the Poso Creek Oil Field is based on the 1973-1974 production limits as hydrocarbon producing reservoirs shown in Volumes I and II of "California Oil and Gas Fields" are shown on Figure 3-12). The primacy aquifer exemption boundary for the Kern River Formation in the Kern River Field. There is currently a proposal for an expansion of the exemption area based on Federal Criteria (40 § CFR 146.4) (a) and (b) (1) that is under review by DOGGR and USEPA.

The main body of the Kern River Field occupies approximately 17,900 acres in the southern San Joaquin Valley, approximately 2 miles northeast of Bakersfield, California (Figure 3-12). In the Kern River Field, oil is produced from the Kern River Formation. Commercial production occurs at depths ranging from less than 100 feet below ground surface (bgs) near the eastern extent of the field, where the Kern River Formation outcrops, to more than 1,600 feet bgs at the western extent of the field (Figure 3-14).

There are multiple bounding conditions for the lateral limits of the aquifer exemption area. The west, north, northeast and southwest limits are bounded by faults that represent barriers to flow (Figure 3-14). In the east, the oil-bearing formations outcrop within the Kern River Field administrative boundary, limiting the eastern extent of fluid flow through the proposed exempted aquifer boundary. The southeast and south aquifer exemption boundaries are established by areas containing tar seals. Oil

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 44 TODD GROUNDWATER field operations through fluid extraction activities related to hydrocarbon production have formed a low-pressure zone in the center of the field, creating an inward hydraulic gradient.

3.1.6 Basin Geometry and Basin Bottom

The top and lateral sides of the Kern County Subbasin have been defined by DWR (DWR, 2006 and 2016). As described in DWR’s Bulletin 118, the Subbasin is “bounded on the west, southwest, and east by the bedrock formations of the Coast Range, San Emigdio Mountains, and Sierra Nevada, respectively. It is separated by the White Wolf Subbasin on the southeast by the White Wolf Fault. The northern boundary is generally coincident with the County line.” (DWR, 2016).

The bottom of the Subbasin varies significantly across the subbasin based on changes in basin geometry, structural features at depth, and groundwater quality. Previous Central Valley studies have observed saline groundwater in various areas and depths and have used water quality as the effective bottom of groundwater subbasins.

Another factor affecting the definition of the basin bottom is the presence of oil field reservoirs and the delineation of exempt aquifers by the USEPA. The purpose of the GSP is not to exempt aquifers, nor is it to define the maximum depth or water quality concentration at which groundwater is economically recoverable or treatable now or in the future. However, by applying the criteria of 40 CFR §144.3 and 40 CFR §146.4, active oil and gas aquifers and exempted aquifers are not a part of the groundwater basin for beneficial use. As described above, the following whichever is shallowest, are the lateral and vertical boundaries of the groundwater Subbasin:

• depth to producible minerals or hydrocarbons or primacy productive limits, • depth to exempted aquifers, • depth that makes recovery of water for domestic, commercial, or industrial purposes no longer economically or technologically feasible, or • the depth at which groundwater cannot now or in the future serve as a source of drinking water. The base of the Subbasin beneath the Cawelo GSA is evaluated on available information of water quality changes with depth. In the vicinity of the oil field reservoirs, the shallow-most top of oil production in an oil field or the shallowest exempted interval provides a conservative estimate of the bottom of the Subbasin. The methods used to delineate the bottom of the basin are described below.

3.1.6.1 Base of Freshwater Fresh groundwater is underlain by more saline groundwater in many basins of the Central Valley. The base of this fresh water can be used to define the basin bottom. In 1973, a USGS investigator (Page, 1973) mapped the base of fresh water in the Central Valley using a specific conductance value of 3,000 micromhos per centimeter (µmho/cm), which is equivalent to a TDS range of about 2,000 to 2,880 milligrams per liter (mg/L), or parts per million (ppm), varying with temperature and differences in water chemistry. Page’s (1973) base of fresh water elevation contours are shown on Figure 3-15. The base of fresh water is approximately 1,600 feet below mean sea level (msl) along the western edge of the southern San Joaquin Valley and deepens towards the center of the Valley. Depths exceed 2,400 feet below msl around Shafter and along the western and southern boundaries of the Cawelo GSA. The elevation of the base of fresh water reaches its shallowest point of 800 feet below msl in the

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 45 TODD GROUNDWATER Eastern Extension Area of the Cawelo GSA, and dips to the northeast reaching 1,600 feet below msl in the northeast corner of the GSA. Figure 3-14 shows the relationship of the mapped base of fresh water elevation from Page (1973) on the regional hydrostratigraphic cross section. The base of fresh water is mapped to occur in the deeper portions of the Kern River Formation at an elevation near 2,000 feet below sea level, or about 2,500 feet below ground surface (bgs). Page (1973) did not extend the mapping of the base of freshwater into the oil producing areas in the eastern Cawelo GSA area.

3.1.6.2 Base of Underground Source of Drinking Water (USDW) and Exempt Aquifers The depth of USDW has recently been defined in the southern San Joaquin Valley by a team of researchers from California State University, Bakersfield (Gillespie, et al., 2017). The group used geophysical log analyses to estimate the depth where water salinity increased above the 10,000 mg/L threshold included in the USDW definition. This map, showing the depth to a water salinity of 10,000 mg/L, was designated as the base of the USDW by the investigators; the map is shown as Figure 3-16.

As shown on Figure 3-16, the contours defined by water salinity are very deep beneath the Cawelo GSA and extend below 6,000 feet deep in the southwestern portion of the Plan Area. While it seems highly unlikely that groundwater would be extracted from such depths, there is no basis for assuming that USDW could not extend that deep. Further, depths in the eastern Cawelo GSA are in the range of 3,000 feet to 4,000 feet deep, which are more comparable to depths associated with the base of fresh water (compare Figures 3-15 and 3-16).

Figure 3-14 shows the relationship of the mapped base of the USDW from Gillespie, et al. (2017) on the regional hydrostratigraphic cross section. The base of the USDW is mapped to occur in the deeper portions of the Kern River Formation at an elevation near 2,500 feet below sea level, or about 3,000 feet below ground surface (bgs) in the western portion of the Cawelo GSA. Underneath the CWD, the base of the USDW crosses into the older Etchegoin Formation at an elevation of about 3,000 feet below sea level. Towards the east, the base of the USDW extends stratigraphically downward to below the exempt aquifers of the Poso Creek, Kern Front and Kern River Oil Fields to an elevation of about 5,000 feet below sea level. As set forth in the Safe Drinking Water Act, the USEPA has defined groundwater to be protected as part of the Underground Injection Control (UIC) program (CFR, Title 40, Chapter 1, Subchapter D, Part 144.A.). This definition of protected groundwater, referred to as the Underground Source of Drinking Water (USDW), is reproduced below: Underground source of drinking water (USDW) means an aquifer or its portion: (a) (1) Which supplies any public water system or (2) Which contains a sufficient quantity of ground water to supply a public water system and (i) Current supplies drinking water for human consumption or (ii) Contains fewer than 10,000 mg/L total dissolved solids; and (b) Which is not an exempted aquifer. (40 CFR §144.3).

In general, this definition indicates that any formation containing groundwater with less than 10,000 mg/L outside of an exempted aquifer (including oil-producing zones) would qualify as a USDW if it contains a sufficient quantity of groundwater. Recognizing that this federal law defines protected

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 46 TODD GROUNDWATER groundwater, it seems reasonable to incorporate the USDW concept into the analysis of the bottom of the groundwater basin.

It is recognized that the method used to create the USDW map did not consider whether the salinity mapping resulted in depths below an exempt aquifer and/or the top of an oil producing zone (Gillespie, et al., 2017); this suggests that the USDW may be shallower than mapped in some areas. To correct the map for shallow exempt aquifer zones, information on exempt aquifers was downloaded from the USEPA and DOGGR websites and considered in the analysis with the oil field data.

Aquifer exemptions are approved by USEPA and typically represent formations that produce oil or will receive oil field produced water. A typical method of produced water disposal is to inject it back into the oil zone where it originated or into another isolated subsurface zone. Consistent with the methodology of excluding oil fields and Exempt Aquifers from the groundwater basin, the USDW map requires correction if oil fields or exempt aquifers occur at shallower depths than indicated on Figure 3-16.

3.1.6.3 Basin Bottom Delineation Based on the maps and analysis described above, the bottom of the Subbasin beneath the Cawelo GSA is defined as groundwater outside of a hydrocarbon zone that contains no more than 10,000 mg/L TDS unless that water has been determined to be an exempt aquifer pursuant to the Code of Federal Regulations, Title 40 part 146.4. It is further assumed that the Subbasin would be a continuous unit from the surface down to the basin bottom; no formations below the shallowest oil producing zone or shallowest exempt aquifer would be included.

This approach to modifying the base of fresh water and USDW and defining the bottom of the groundwater Subbasin is illustrated by the conceptual diagram on Figure 3-17. Specifically, the bottom of the groundwater Subbasin beneath the Cawelo GSA will follow the base of the USDW as mapped by Gillespie et al. (2017, Figure 3-16) but will be modified by the top of oil fields and exempt aquifers where shallower than the base of the USDW. In addition, the Base of Fresh Water will also be modified by the top of oil fields and exempt aquifers where shallower that the elevation of fresh water as mapped by Page (1973) (Figure 3-15). As indicated on Figure 3-17, the adjusted base of fresh water will be used to define the usable fresh water storage of the groundwater basin. The adjusted USDW will be used to define the bottom of the Subbasin and allow for an emergency water supply.

As summarized on Table 3-2, the depth to the base of fresh water within the oil fields that underlie Cawelo GSA ranges from 1,600 feet at the Poso Creek field, which overlaps the eastern boundary of the Cawelo GSA, to 2,900 feet at the Rosedale Ranch field administrative area, which overlaps with a small area of the southern boundary (Figure 3-11). The depth to the top of the hydrocarbon zone ranges from 1,900 feet at the Poso Creek field to 4,200 feet at the Rosedale Ranch field. In the hydrocarbon zone, sodium chloride (NaCl) concentrations range from 60 mg/L in the Poso Creek field to 28,400 mg/L in the Rosedale Range field, and total dissolved solids (TDS) ranges from 220 mg/L in the Poso Creek field to 30,000 mg/L in the Rosedale Ranch field (Table 3-2).

Rather than re-contouring the base of fresh water around these shallower exempt aquifers, the contour map is simply adjusted by assigning one elevation to or contouring the surface of each applicable exempt aquifer and ending the contours of the base of fresh water at the exempt aquifer boundary; this methodology is shown on Figure 3-18. As shown on Figure 3-18, the exempt aquifer associated with each of the four oil fields within the Cawelo GSA area are shallower than the fresh water elevations. In the uplands of the eastern Subbasin, Subbasin aquifers are thin and shallow and the base of fresh water

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 47 TODD GROUNDWATER compared to the local shallow oil production is less certain. The Page analysis of the base of fresh water ends at the edge of the Kern River and Kern Front oil fields. In this area, the basin bottom is likely to be limited by the top of the shallow oil production rather than groundwater salinity.

Table 3-2: Oilfields and Adjustments to Subbasin Bottom in the Cawelo GSA Area

A B C D E F G H Adjustments to Base of Fresh Water Adjustments to USDW Average Depth to Average Elevation Elevation of Elevation Bottom of Oil and Gas Depth to Depth to Base of Top of Base of USDW Fields in Base of Exempt Exempt Fresh Exempt Fresh Water Basin Cawelo GSA USDW in Aquifers Aquifers Water in Aquifers for Oil Adjusted Cawelo in Area Cawelo Cawelo GSA Production for Oil GSA (ft) Cawelo GSA (ft, msl) (ft, msl) Production GSA (ft) (ft, msl) (ft) Vedder, -1,100 to -1,100 to 1,400 to 1,400 to Kern Front -1,600 6000 Upper -700 -700 2,500 2,500 Chanac Kern River, 100 to Kern River -1,600 -330 to 1,000 -1,000 to 730 > 6,000 50 to 900 Jewett, 1,600 Vedder Basal Poso Creek 700 to 700 to -800 -420 to 120 -150 < 2,500 Etchegoin, McVan Area 1,300 1,300 Chanac Poso Creek -2,050 to 1,800 to 1,800 to Basal Premier & -1,600 -1,600 5,500 -1,060 2,800 2,800 Etchegoin Enas Area

Table 3-2 also lists the depths to the base of the USDW at each of the productive areas in the Cawelo GSA. A comparison of the depth of the USDW with the depth of exempt aquifers associated with oil field production indicates that all four of the exempt aquifers in the Cawelo GSA area are shallower than the currently mapped depth for the USDW (compare column E to column F). These same exempt aquifers were also shallower than the base of fresh water. Similar to the methodology applied for the base of fresh water, the depth to the USDW map is modified by assigning one depth to the exempt aquifers associated with each oil field in the Cawelo GSA Area and ending the previously-mapped contours at the exempt aquifer boundaries. This adjusted map is shown on Figure 3-18.

Collectively, these two maps are used in the definition of the Subbasin bottom. Figure 3-18 defines the elevation on the bottom of usable fresh groundwater in storage. Figure 3-19 represents the bottom of the groundwater Subbasin beneath the Plan Area and serves as the base of an emergency supply. Due to the shallow oil production zones in the Kern River Oil Field, there is an area, shown on Figure 3-20, where groundwater does not occur above the bottom of the groundwater Subbasin as defined by this approach. In these areas, the first encountered saturated zone is the oil reservoir within the exempt aquifer.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 48 TODD GROUNDWATER 3.2 CURRENT AND HISTORICAL GROUNDWATER CONDITIONS (REG. § 354.16)

3.2.1 Groundwater Occurrence and Flow

The Cawelo GSA is underlain by continental deposits of poorly bedded, loosely consolidated sands, gravels, silts, and clays. The permeable alluvium forms an aquifer system, which is naturally recharged by the Sierra Nevada mountain block. The groundwater basin beneath the GSA is hydraulically continuous with surrounding areas and groundwater flows across the GSA boundary (Cawelo, 2007). Groundwater in the area is generally deep, usually between 300-500 feet below ground surface. Groundwater levels in the alluvial aquifer fluctuates seasonally with local recharge and temporarily in response to drought and wet conditions. Due to the high intensity agriculture in the GSA, groundwater pumping is likely the largest controlling factor on water levels with depth.

3.2.1.1 Groundwater Elevations Water levels have been measured within the Cawelo GSA since the 1930s, but data before the 1970s are sparse. The availability of water level data increased significantly in the 1970s, providing a more complete record of water level trends and fluctuations over the last 50 years. Long-term records of water levels within the GSA are maintained by several agencies, including Kern County Water Agency (KCWA), Famoso, CWD, Department of Water Resources (DWR), and the California State Groundwater Elevation Monitoring (CASGEM) program (also managed by DWR). Water levels are available at over 340 wells within the Cawelo GSA. A hydrograph was generated for each well and 14 representative hydrographs throughout the GSA are shown on Figure 3-21. The hydrographs are identified by their unique state well number and numbered consecutively from 1 to 14 for reference. The hydrographs show historical water level trends between 1970 and 2018. The vertical scale of the hydrographs is standardized to a range of 400 feet, either from -100 to 300 feet msl or from 0 to 400 feet msl, depending on the range of groundwater elevations. The ground surface elevations are above 400 feet at each well and are therefore provided as a note under the well name. Wells that are located on the western side of the GSA generally have a strong relation to climatological trends, such as hydrographs 1, 11, 12, 13, and 14. These hydrographs show water level rise during the wet years from 1978 to 1983, declines during the drought period of the late 1980s into the early 1990s, rise after the wet years in the late 1990s, and declines in the late 2000s during dry conditions. Historical low water levels occurred during the recent severe drought from 2012 to 2016. During this period, groundwater levels declined on the order of 100 to 150 feet. Hydrographs in the northern GSA, such as hydrographs 2, 3 and 4, show that low levels in the late 1970s followed by generally increasing trend through 2011. The recent drought from 2012 through 2016 resulted in groundwater level declines of greater than 100 feet over this period. Hydrographs in the eastern GSA generally have less temporal variability and steadier groundwater level trends than hydrographs in the western GSA. Hydrographs 5, 6, and 7, located near Little and Poso Creeks, show that water levels have been relatively stable and do not reflect wet and dry periods as much as wells in the western GSA, although each show response to the recent drought. The recent drought from 2012 through 2016 resulted in groundwater level declines of 50 to 100 feet over this period. Groundwater is generally deeper in the eastern GSA, about 500 feet below ground surface, than wells in the western GSA. Hydrographs in the southern GSA, such as hydrographs 8, 9 and 10, also show less temporal variability and steadier groundwater level trends than other hydrographs in the GSA. The stability of the groundwater levels in these wells is likely associated with recharge from the nearby Kern River. During

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 49 TODD GROUNDWATER the recent drought from 2012 through 2016, groundwater levels declines were minimal ranging from less than 10 feet to about 50 feet.

3.2.1.2 Groundwater Elevation Maps Groundwater elevation contour maps prepared by KCWA and CWD have been used to examine groundwater flow patterns in the Cawelo GSA. KCWA prepares annual contour maps from water levels measured in the spring, prior to the summer irrigation season, when numerous cones of depression complicate local groundwater flow. Groundwater elevation contour maps from spring 1998, a wet year associated with El Niño variability, spring 2013, a critically dry year, and spring 2017, a wet year after the recent severe drought are shown on Figures 3-22, 3-23, and 3-24. The spring 1998 groundwater elevation contour map (Figure 3-22) shows the effects of surface water recharge from Little Creek and Kern River during a wet year. Groundwater elevations within the Cawelo GSA ranged from <100 feet msl to >200 feet msl. Groundwater elevations were highest along the eastern boundary of the GSA near Little Creek and lowest in the central GSA, south of Poso Creek and in the southern portion of the Eastern Extension Areas of the GSA. A groundwater mound with elevations of >200 feet msl is present in the northeastern GSA, where Little Creek enters the GSA. Groundwater flows radially outwards from the Little Creek mound, to the northwest, west, and southwest. High groundwater elevations in the southern GSA, and to the south of the GSA, are likely a result of mounding from Kern River recharge. Groundwater flows north and northeast from the Kern River mound. The spring 2013 groundwater elevation contour map (Figure 3-23) shows groundwater conditions in a critically dry year. Groundwater elevations are generally lower than they were in spring 1998, ranging from approximately 0 to 180 feet msl within the GSA. Groundwater elevations are highest in the southern portion of the CWD area of the GSA at the Kern River mound and in the Eastern Extension Area of the GSA along the foothills near Poso and Little Creeks. Groundwater elevations are lowest along the central-eastern GSA boundary, approximately one mile south of Poso Creek and in the Eastern Extension Area of the GSA. Groundwater flows to the west and southwest from the foothills in the northern GSA and to the north and northwest from the Kern River mound in the southern GSA. Groundwater flow direction in the Eastern Extension Area of the GSA is generally from southwest to northeast. The spring 2017 groundwater elevation contour map (Figure 3-24) shows that groundwater elevations are lower than they were in 2013, after a multi-year severe drought. This groundwater elevation contour map also shows more localized detail because of its smaller, 10-foot contour interval. Groundwater levels within the GSA were typically between 0 and 200 feet msl with groundwater levels highest in the northeast portion of the GSA and lowest in the western GSA south of Poso Creek and in the southwestern GSA. Like 1998 and 2013, groundwater elevations are high in the southern GSA from the Kern River mound. Groundwater elevation data from Spring 2017 did not cover the Eastern Extension Area of the GSA. Localized cones of depression are evident throughout the GSA, likely due to agricultural pumping. Groundwater elevations in 2017 have not recovered to pre-drought (2012) levels. The change in groundwater storage in Cawelo GSA was estimated based on water budget accounting and the groundwater model. In general groundwater storage declined during below normal water years, and groundwater storage recovered during above normal water years. Additional discussion of the estimation of groundwater storage is provided in Section 4.

3.2.1.3 Well Completion Analysis A well completion analysis was made to evaluate the well completion depth to the range of depth to groundwater levels (DTW) to assess the relative vulnerability of water supply wells to changes in

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 50 TODD GROUNDWATER groundwater levels. The well screen data was taken from available DWR well completion records in the Cawelo GSA. Because of horizontal and vertical variability in groundwater levels across an area, the average well depth was compared to the average and maximum DTW during the period from 2006 to 2018. This focused the assessment on recent conditions including the period of historically low groundwater levels that occurred during the 2012 to 2016 drought. As a screening level assessment, the average and maximum DTW was determined over an entire township. The difference between the average well depth and the average or maximum DTW provides an indication of the available saturated thickness for water production by the well. The greater this difference, the less vulnerable the well is to changes in groundwater levels. The maximum DTW is for any well within the township so it provides a conservative assessment of the well vulnerability. The assessment was done separately for public/domestic supply wells and agricultural supply wells. The results of this assessment are shown on Table 3-3.

Table 3-3: Well Completion Analysis using Available Data for the Cawelo GSA Township/ Number Average Well Average DTW Maximum DTW Difference to Difference to Range of Wells Depth Average DTW Maximum DTW

Units Feet Feet Feet Feet Feet Public and Domestic Supply Wells T26S/R26E 4 798 436 675 363 123 T26S/R27E 4 1,126 577 735 549 391 T27S/R26E 16 780 403 626 378 154 T27S/R27E 16 1,150 549 690 601 460 T28S/R26E 10 614 311 559 304 55 T28S/R27E 18 930 416 900 515 30 Agricultural Water Supply Wells T26S/R26E 31 1,432 436 675 997 757 T26S/R27E 17 1,434 577 735 857 699 T27S/R26E 85 1,173 403 626 770 547 T27S/R27E 15 1,456 549 690 908 766 T28S/R26E 38 924 311 559 614 365 T28S/R27E 39 1,081 416 900 666 181 DTW – Depth to Groundwater in feet below measuring point (at or near ground surface)

For the public and domestic supply wells, the average well depth ranges from 614 to 1,150 feet below groundwater surface (bgs). Wells tend to be deeper in the north and eastern part of the GSA, and shallower in the southeastern part of the GSA. In general, difference to average DTW ranged from about 300 to 600 feet bgs whereas the difference to maximum DTW ranged from 30 to 460 feet bgs. The only major water supply well in the GSA supplies the Lerdo Jail and it is completed to a depth of about 1,400 feet bgs, so it has sufficient capacity. Other public/domestic wells would have low water supply requirements that these conditions should be adequate for maintaining water supplies. In the southernmost part of the GSA, groundwater levels are generally more stable so the range from 30 to 55 ft bgs appears to be adequate. However, further assessment of the conditions of public/domestic wells in the southernmost part of the GSA will be evaluated in the future, For the agricultural supply wells, the average well depths range from 924 to 1,456 ft bgs with the deepest wells located in the northern and eastern part of the GSA, and shallower in the southeastern part of the GSA. With their deeper average well depths, the difference to average DTW ranged from

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 51 TODD GROUNDWATER about 600 to 1,000 feet bgs whereas the difference to maximum DTW ranged from 180 to 760 feet bgs. These conditions indicate that the agricultural wells have sufficient capacity to produce water even during a severe drought.

3.2.1.4 Estimate of Groundwater Storage The change in groundwater storage in Cawelo GSA was estimated based on water budget accounting and the groundwater model. In general groundwater storage declined during below normal water years, and groundwater storage recovered during above normal water years. Additional discussion of the estimation of groundwater storage is provided in Section 4.

3.2.2 Groundwater Quality

The purpose of this section is to describe and assess the historical and current groundwater quality conditions of the Cawelo GSA. This assessment gives an indication of where data are present or lacking and helps define the temporal and geographic extent of groundwater quality concerns, thereby providing a framework for the GSP. In the following sections, the compilation of historical and current data is described, including the sources of data, screening procedures and quality assurance of the data, and characteristics of the resulting data sets. Statistical summaries are presented for select constituents.

3.2.2.1 Regional Groundwater Quality Groundwater quality in the region is variable and depends on the quality of the recharge water, the chemical changes that occur as surface water infiltrates into the aquifer, and chemical changes that occur within the aquifer (Dale et al., 1966). Groundwater in the southern San Joaquin Valley can be divided into three groups based on geography: eastside, westside, and axial trough (Dale et al., 1966). The Cawelo GSA is located in the eastside region. Groundwater quality in these regions can be summarized as follows: • Eastside groundwater quality is generally high quality with low total dissolved solids (TDS). • Westside groundwater quality is generally poor quality with higher TDS, sulfate or chloride concentrations than the east side. • Groundwater quality in the axial trough is a mixture of east side and west side groundwater that is more variable in constituent concentration and chemical character.

3.2.2.2 Vulnerable Areas to Irrigated Agriculture The CWD has prepared a Groundwater Quality Assessment Report (GAR) in 2015 as required by the Waste Discharge Requirements General Order for Growers within the Tulare Lake Basin Area that are Members of a Third‐Party Group, R5‐2013‐0120 (General Order) (CWDC, 2015). The objective of the GAR is to provide a groundwater quality assessment using all available, applicable and relevant data and to determine high and low vulnerability areas where discharges from irrigated agriculture may degrade groundwater quality (CWDC, 2015). The GAR provides a basis for establishing priorities for groundwater quality trend monitoring work plans, evaluation of effective management practices, and groundwater quality management plans in the high vulnerability areas.

- The GAR primarily focused on nitrate (reported as NO3 ) and electrical conductivity (EC). As noted in the GAR, nitrate and EC in groundwater can be derived from natural sources but have also been identified as water quality constituents that may indicate potential impact from irrigated agriculture. The Regional Board has concern for all constituents with potential to degrade groundwater quality but have placed a

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 52 TODD GROUNDWATER priority on nitrate (CWDC, 2015). The publicly available data used in the GAR were obtained from the State Water Resources Control Board’s Groundwater Ambient Monitoring and Assessment Program (GAMA), which includes data from the California Department of Public Health, California Department of Public Health, California Department of Pesticides Regulation, USGS GAMA Priority Basin and GAMA Domestic Wells. The maximum known values of nitrate and EC in the GAR were used to determine high vulnerability areas, which were delineated along existing parcel boundaries in the CWDC. The high vulnerability areas were additionally based on groundwater levels, soil characteristics, irrigation and nutrient practices in the CWD, as well as Community Buffer Parcels, and high vulnerability areas in the Kern River Watershed Coalition Authority (KRWCA) (CWDC, 2015). The high vulnerability areas are generally located in the western areas of the CWD and south of Poso Creek (Figure 54 in CWDC, 2015). In response to the high vulnerability areas designated in the GAR, the CWDC will prepare and submit a Comprehensive Groundwater Quality Management Plan (CGQMP) (CWDC , 2015). The implementation of the CGQMP will focus on irrigation and nutrient management practices through an outreach and education program (CWDC , 2015). Additionally, the Groundwater Quality Trend Monitoring Program (GCTMP) is generating long-term groundwater quality information to evaluate the regional effects on irrigated agriculture. The CWDC has an extensive ongoing groundwater monitoring program that has collected data for approximately 25 years (CWDC , 2015).

3.2.2.3 Famoso Basins Antidegradation Analysis The CWD, Chevron North America (Chevron), and Valley Waste Disposal Company (VWDC) conducted an antidegradation analysis for the Famoso Groundwater Banking Project as part of the Report of Waste Discharge (RWD) (Kennedy Jenks, 2011). Produced water blended with groundwater and surface water in Reservoir B is discharged to the Famoso Basins for percolation or distributed for irrigation. Seven basins with a combined area of 374 acres and storage capacity of 834 acre-feet overlie fluvial sediments that extend 700 feet below the ground surface and have no significant low permeability layers. Depth to groundwater is about 300 to 350 feet. Blended water is discharged to the percolation basins for 120 days when irrigation demand is low (October 1 and March 31, 2019). During irrigation seasons, the blended water is discharged to the CWD irrigation distribution system for agricultural irrigation (Kennedy Jenks, 2011). Three objectives of the Antidegradation Analysis are: • Evaluate the potential of the Banking Project to degrade groundwater by assessing background groundwater quality, establishing water quality objectives, and developing an analysis procedure to assess the potential for groundwater quality degradation. • Determine acceptability of potential groundwater quality degradation resulting from the Famoso Groundwater Banking Project. • Establish that requirements for Best Practicable Treatment or Control are met.

Prior to implementation of the Famoso Groundwater Banking Project, groundwater quality data were collected and analyzed to establish conditions prior to use of the Famoso Basins for discharge of blended water. Groundwater samples were analyzed for arsenic, boron, chloride, electrical conductance (EC), nitrate, and sodium along with other major anions and cations. Comparison of concentrations of water quality constituents in the blended recharge water to baseline values established five constituents with concentration higher in the blended water than the baseline water quality. Baseline groundwater concentrations of the five primary constituents of interest are (Kennedy Jenks, 2011): • Arsenic: 3.4 µg/L • Boron: 0.14 mg/L,

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 53 TODD GROUNDWATER • Chloride: 87.7 mg/L, • Sodium: 55.7 mg/L, and • Salinity as EC: 618 µmho/cm.

Water quality requirements for agricultural beneficial uses define the criteria for discharge of water at the Famoso Basins (WQCP TLB, 2018). The water quality objectives for the following constituents for discharge at the Famoso Basins are (Kennedy Jenks, 2011): • Boron: < 0.75 mg/L, • Chloride: < 175 mg/L, • Sodium: < 175 mg/L, and • Salinity as EC: < 1,000 µmho/cm.

The water quality goal for arsenic is the MCL as established by California’s Title 22 Water Recycling Criteria for municipal water supply (Kennedy Jenks, 2011). • Arsenic: < 10 µg/L

The Water Quality Control Plan for the Tulare Lake Basin for the Poso Creek Subarea establishes discharge limits for EC.

The four water sources for blending the discharge to the Famoso Basins are treated produced water from Chevron, treated produced water from VWDC, surface water via CWD Pump Station B, and groundwater. Blended water is applied at the Famoso Basins at approximately 198 acre-feet per day (65 mgd) and spread over 374 acres for a daily hydraulic load of about 0.5 foot per day. A design water quality representing the average for 120 days of discharge was determined for the blended discharge water, as listed below.

• Arsenic: 120 µg/L • Boron: 1 mg/L, • Chloride: 200 mg/L, • Sodium: 135 mg/L, and • Salinity as EC: 1000 µmho/cm.

Groundwater flow and transport modeling was conducted to assess potential impacts to groundwater from blended water discharge through the Famoso Basins (Kennedy Jenks, 2011). Groundwater is not expected to be degraded by arsenic because arsenic is strongly absorbed during unsaturated transport (Kennedy Jenks, 2011). Groundwater degradation is expected to occur for boron, chloride, sodium, and salinity (EC) but modeling of the initial, worst case scenario showed downgradient groundwater quality to below water quality objectives (Kennedy Jenks, 2011). Additional modeling was performed for the Most Probable Discharge Scenario for a thirty-year period with consideration for treated produced water flows, winter irrigation, changing surface water availability, precipitation, and infiltration through Poso Creek near the Famoso Basins. Concentrations of constituents of interest were between the discharge values and the background groundwater values below the Basins and less than the water quality objectives downgradient of the Basins. Produced water discharge and groundwater banking of surface water is not expected to impair groundwater for agricultural beneficial uses (Kennedy Jenks Addendum, 2011).

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 54 TODD GROUNDWATER 3.2.2.4 Environmental Cleanup Sites The open environmental cleanup sites within the Cawelo GSA are shown on Figure 3-25. The sites were identified in the State Water Resource Control Board’s GeoTracker system and include Leaking Underground Storage Tank (LUST) Cleanup Sites, Cleanup Program Sites regulated by the State Water Resources Control Board, and Department of Toxic Substances Control (DTSC) Cleanup Sites. DTSC Cleanup Site information was obtained from DTSC’s EnviroStor system. There is only one open environmental cleanup site within the Cawelo GSA. This site is located along the western boundary of the GSA between Shafter Airport and Poso Creek and owned by PureGro, an organic home and gardening products company. GeoTracker lists the site as an open verification monitoring site where potential contaminants of concern are pesticides and herbicides in soil. Verification monitoring at the site began in May 2010, and site inspections and sampling are conducted on an annual basis.

3.2.2.5 Local Groundwater Quality The following is a summary of groundwater quality conditions in the Cawelo GSA during historical (water year 1995 to 2014) and present (2015 to present (2019)) periods. All publicly available groundwater quality data for the Cawelo GSA were used in this analysis, including data collected by the CWD and other data downloaded from the GeoTracker-GAMA and GAMA database. The data compiled here includes all well types and all local groundwater quality monitoring programs in the Cawelo GSA, including the CWD’s Famoso Monitoring program. Using these data, a Microsoft Access database was built that includes over 32,000 groundwater quality records collected from 134 wells between the start of water year 1995 (October 1, 2014) to present (2019). The database includes 223 unique water quality constituents. However, only the most relevant water quality constituents for the Cawelo GSA are analyzed here. Prior to analysis, quality assurance/quality control (QA/QC) steps were performed on the data, including the identification and removal of duplicate samples and cross-checking the correct well location.

This analysis emphasizes total dissolved solids (TDS), nitrate (as N), and pesticides because these constituents of concern are the most likely to affect groundwater quality from irrigated agriculture, which is the dominant land use across much of the GSA (P&P, 2015). Nitrate is reported here as - nitrogen (as N); nitrate values reported in the original data sources as nitrate (as NO3 ) were converted to nitrogen (as N) prior to analysis. Arsenic and boron were also analyzed. Well construction and well screen information was available for only 18 of the 134 wells and, as a result, the analysis does not evaluate well-screen depth or aquifer material associated with groundwater quality.

3.2.2.5.1 Total Dissolved Solids Total dissolved solids (TDS) represents the total concentration of anions and cations in water and is a useful indicator of mineralization, salt content, and overall groundwater quality. Table 3-4 documents the range of TDS concentrations in groundwater from wells for water years 1994 to 2019. A total of 1,242 groundwater samples in the Cawelo GSA have TDS analyses. The majority (63 percent) of the samples have TDS concentrations less than 500 mg/L, 29 percent of samples are between 500 and 1,000 mg/L and 8 percent of samples are greater than 1,000 mg/L (Table 3-4). The TDS concentrations in groundwater of the Cawelo GSA generally meet drinking water quality standards and irrigation requirements.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 55 TODD GROUNDWATER As shown in Figure 3-26, concentrations of TDS are generally lowest (less than 500 mg/L) in the northern area of the GSA near Poso Creek and the recharge basins. TDS concentrations are generally higher in the southwest GSA (Figure 3-25). The GAR presents maps of the EC values from wells in the CWD (CWDC, 2015). The maps of median TDS in this GSP (Figure 3-26) and EC in the GAR (Figure 27, CWDC, 2015) both generally show elevated TDS and EC concentrations that exceed the TDS SMCL (1,000 mg/L) along the western half of the Cawelo GSA and relatively lower TDS and EC concentrations less than half of the SMCL along the eastern half of the Cawelo GSA. The spatial patterns of median TDS presented in this GSP are very similar to comparable EC maps in the GAR.

3.2.2.5.2 Nitrate Nitrate is a naturally occurring form of nitrogen that can be produced in relatively low concentrations from the atmosphere or from decomposing organic matter (P&P, 2015). Sources of nitrate in groundwater include excess application of nitrogen fertilizer in irrigated areas, feedlot and dairy drainage, leaching from septic systems, wastewater percolation, industrial wastewater, aerospace activities, and food processing wastes. Elevated nitrate in groundwater in the Tulare Lake Basin has been linked primarily to crop and animal agricultural activities with urban wastewater, septic systems, and other sources identified as significant in localized areas (Viers, et al., 2012). Nitrate (as NO3) has an MCL of 45 mg/L for drinking water. Table 3-4 summarizes the nitrate concentrations in groundwater from wells in the Cawelo GSA during the period water year 1994 to 2019. A total of 1,314 groundwater samples have nitrate analyses with a median concentration of 2.6 mg/L (as N), 73 percent of sample meet drinking water quality standards (Table 3-4). The median value is within the range of nitrate concentrations (2 to 3 mg/L) that have been established by previous studies as representing relative background concentrations from natural processes (Gurdak and Qi, 2012). Figure 3-27 shows the median concentrations of nitrate in groundwater from wells in the Cawelo GSA during the period of water year 1994 to 2019. Nitrate concentrations are illustrated as green circles (less than 5 mg/L), yellow circles (between 5 mg/L and MCL of 10 mg/L), orange circles (between 10 and 15 mg/L), and red circles (greater than 15 mg/L). Wells with median nitrate concentrations below the MCL of 10 mg/L (as N) tend to be located within the northern, eastern, and southern areas of the GSA. The 10 wells with median nitrate concentrations that exceeding the MCL are generally located in the central and western areas of the GSA. The GAR also presents nitrate concentration maps (CWDC, 2015), and the spatial patterns of nitrate concentrations are very similar to those shown on Figure 3-25. The distribution of median nitrate concentrations in Figure 3-27 and in the GAR (Figure 26, CWDC, 2015) both show elevated nitrate concentrations exceeding the MCL along the western half of the Cawelo GSA and relatively lower nitrate concentrations (less than half of the MCL) along the eastern half. Although some relatively minor differences exist between the nitrate maps in this GSP and the high vulnerability areas designated in the GAR, the two analyses result in similar spatial patterns of elevated nitrate in groundwater.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 56 TODD GROUNDWATER Table 3-4: Summary Statistics of Select Groundwater Quality Constituents

Percentage of Samples Concentrations California Number Water Quality MCL1 or of >0.5MCL Constituent <0.5MCL >MCL Min. Median Max. SMCL2 Samples to MCL Constituents of Concern nitrate (as N), mg/L 101 1,314 63% 10% 27% 0 2.6 50 total dissolved solids, mg/L 1,0002 1,242 63% 29% 8% 58 359 2,151 Trace Elements arsenic, µg/L 101 520 77% 15% 8% 0 2.3 27 boron, mg/L 1** 1,078 98% 2% 0% 0 0.07 0.96 Notes: 1MCL: Maximum Contaminant Level 2SMCL: California drinking water Secondary Maximum Contaminant Level <0.5MCL: percentage of samples with concentrations less than one-half the MCL >0.5MCL to MCL: percentage of samples with concentrations between one-half of the MCL to the MCL *Federal Action Level (AL). Sodium does not have an MCL. **California State Notification Level (CA-NL). Boron does not have and MCL min: minimum concentration max: maximum concentration

3.2.2.5.3 Pesticides Pesticides in groundwater can result from the over-application on agricultural lands or from point- source contamination and preferential flow down improperly constructed wells. While pesticides are typically soluble in water, many can be highly sorptive to soils, which can slow their transport to the water table. There is a total of 1,148 pesticide water quality analyses from 25 wells3 (see Figure 3-28) in the Cawelo GSA between water year 1994 and 2019. These involve 77 unique pesticide or pesticide degradates that were analyzed. Of the 1,148 pesticide analyses, the majority (94 percent) have concentrations that are below the detection limit. Only 72 of the 1,148 (6 percent) pesticide analyses were above the detection limit; 18 pesticide analyses were detected below their respective MCL or notification level (NL) and 54 pesticide analyses were detected above their respective MCL or NL. Of the 77 pesticide or pesticide degradates analyzed, only two were detected above the detection limit. These were 1,2-Dibromo-3-chloropropane (DBCP) (MCL = 0.2 μg/L) and 1,2,3-Trichloropropane (1,2,3 TCP) (NL = 0.0005 μg/L). DBCP was more commonly detected than 1,2,3-Trichloropropane (1,2,3 TCP). As illustrated o Figure 3-28, all detections of DBCP and 1,2,3-Trichloropropane (1,2,3 TCP) occurred from the same well. All other 24 wells with pesticide analyses had pesticide concentrations below the detection limit. This suggests an isolated point-source contamination near the well rather than a widespread issue.

3 Several of these are nested monitoring wells shown on Figure 3-26 as single dots.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 57 TODD GROUNDWATER 3.2.2.5.4 Trace Elements Some trace elements, specifically arsenic and boron, have been identified as constituents of concern because of the potential threat to groundwater quality in the Cawelo GSA. The concentrations of arsenic are generally low in groundwater of the Cawelo GSA as compared to the MCL (Table 3-4). A total of 520 groundwater samples have arsenic analyses and only 8 percent of those analyses exceed the California MCL of 10 µg/L (Table 3-4). The wells with median concentrations of arsenic that exceed the MCL are generally located in the northern GSA (Figure 3-29). Arsenic concentrations in the Cawelo GSA may be attributed to the pH-dependent desorption from aquifer sediments, which tends to occur at relatively high pH. Results of statistical analysis indicate a significant (p-value = <0.001, α-level = 0.05) weak and positive correlation (Spearman’s ρ correlation coefficient = 0.207) between pH and arsenic concentrations. The positive correlation between pH and arsenic may help support the pH-dependent desorption mechanism. However, there are too few measurements of dissolved oxygen (only 3 analyses) in the database to evaluate if oxic or anoxic conditions exist. Future groundwater quality monitoring that includes measurements of dissolved oxygen could help explain the source of the arsenic in the groundwater. Boron is a naturally occurring trace element in many minerals and rocks, including igneous rocks such as granite and pegmatite, and some evaporite minerals. Boron is an essential element for plant growth in relatively small concentrations. However, for many crops, boron concentrations greater than 1 to 2 mg/L may be toxic (Ayers and Westcot, 1994). The concentrations of boron are generally low in groundwater of the Cawelo GSA as compared to the NL (Table 3-4). A total of 1,078 groundwater samples have boron analyses and 100 percent of those analyses have concentrations that are less than the California NL of 1.0 mg/L (Table 3-4). The median boron concentrations of groundwater in wells (Figure 3-30) indicate no spatial patterns across the GSA. Of the samples collected, 98 percent of the boron analyses have concentrations below 0.5 mg/L (Table 3-4), and thus the boron concentrations in groundwater of the Cawelo GSA are is well below toxic levels for plants.

3.2.3 Land Subsidence

The overdraft conditions exacerbated by the recent (2012 to 2016) historic drought have resulted in lowered groundwater levels – a condition that can contribute to subsidence of the ground surface. As water levels decline in the subsurface, dewatering and compaction of predominantly fine-grained deposits such as clay and silt can cause the overlying ground surface to subside. This process is illustrated by two conceptual diagrams shown on Figure 3-31. The upper diagram depicts an alluvial groundwater basin with a regional clay layer and numerous smaller discontinuous clay layers. Water level declines associated with pumping causes a decrease in water pressure within the pore space (pore pressure) in the aquifer system (Galloway, et al., 1999). Since the water pressure in the pores helps support the weight of the overlying aquifer, the pore pressure decrease causes more weight of the overlying aquifer to be transferred to the grains within the structure of the sediment layer. The difference between the water pressure in the pores and the weight of the overlying aquifer is termed the effective stress. If the effective stress borne by the sediment grains exceeds the structural strength of the sediment layer, then the aquifer system begins to deform. This deformation consists of re- arrangement and compaction of fine-grained units.as illustrated on the lower diagram of Figure 3-31. Although extraction of groundwater by pumping wells causes a more complex deformation of the aquifer system than discussed herein, the simplistic concept of vertical compaction is often used to illustrate the land subsidence process (Galloway, et al., 1999; LSCE et al., 2014).The tabular nature of the

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 58 TODD GROUNDWATER fine-grained sediments allows for preferred alignment and compaction. As the sediments compact, the ground surface can sink, as illustrated by the 2nd column on the lower diagram of Figure 3-31. Land subsidence due to groundwater withdrawals can be temporary (elastic) or permanent (inelastic). Elastic deformation occurs when sediments compress as pore pressures decrease but expand by an equal amount as pore pressures increase. A decrease in water levels from groundwater pumping causes a small elastic compaction in both coarse- and fine-grained sediments; however, this compaction recovers as the effective stress returns to its initial value. Because elastic deformation is relatively minor and fully recoverable, it is not considered an impact. Inelastic deformation occurs when the magnitude of the greatest pressure that has acted on the clay layer since its deposition, or preconsolidation stress, is exceeded. This occurs when groundwater levels in the aquifer reach a historically low water level. During inelastic deformation, or compaction, the sediment grains rearrange into a tighter configuration as pore pressures are reduced. This causes the volume of the sediment layer to reduce, which causes the land surface to subside. Inelastic deformation is permanent because it does not recover as pore pressures increase. Clay particles are often planar in form and more subject to permanent realignment (and inelastic subsidence). In general, coarse-grained deposits (e.g., sand and gravels) have sufficient intergranular strength and do not undergo inelastic deformation within the range of pore pressure changes encountered from groundwater pumping. The volume of compaction is equal to the volume of groundwater that is expelled from the pore space, resulting in a loss of storage capacity. This loss of storage capacity is permanent but may not be substantial because clay layers do not typically store significant amounts of usable groundwater (LSCE, et al., 2014). Inelastic compaction, however, may decrease the vertical permeability of the clay resulting in minor changes in vertical flow. The following potential impacts can be associated with land subsidence due to groundwater withdrawals (modified from LSCE, et al., 2014): • Damage to infrastructure including foundations, roads, bridges, or pipelines; • Loss of conveyance in canals, streams, or channels; • Diminished effectiveness of levees; • Collapsed or damaged well casings; and • Land fissures. Damage to CVP infrastructure related to historical land subsidence has been documented north of the Kern County Subbasin. In 1976, subsidence along the Tulare-Wasco reach of the Friant-Kern Canal was determined to have interfered with operations (Prokopovitch, 1984). A 17-mile segment of the canal required rehabilitation and raising of three pumping plants. In 1984, post-construction land subsidence along the damaged reach was reported to be more than about five feet. Land subsidence in the San Joaquin Valley has been documented for more than 90 years and recent investigations using satellite imagery indicate continuing problems in some areas. Although the areas with the most documented subsidence are generally north of Kern County Subbasin, both historical and recent subsidence have been documented in various parts of the Cawelo GSA.

3.2.3.1 Land Subsidence 1926 – 1970 The amount of land subsidence estimated by the USGS within the Cawelo GSA from 1926 to 1970 is illustrated on Figure 3-32 (Ireland, et al., 1984). Although data represent the accumulated subsidence over a 44-year period, USGS estimates that about 75 percent of the subsidence occurred in the 1950s and 1960s because of extensive groundwater development (Galloway, et al., 1999). As shown on

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 59 TODD GROUNDWATER Figure 3-32, subsidence of two feet occurred in the northern portions of Cawelo GSA primarily north of Poso Creek. The amount of mapped subsidence decreases to the south to less than one foot in the southern and eastern extension GSA. The southern portions of the Cawelo GSA are located on the coarse-grained sediments of the Kern Fan and are generally considered not to have experienced inelastic subsidence.

3.2.3.2 Land Subsidence 2007 – 2011 and May 2015-December 2016 More recently, the California Water Foundation commissioned a report on subsidence from groundwater use in California that illustrated total subsidence from 2007 to 2011 (LSCE, et al., 2014), as shown in Figure 3-33. This map uses a color ramp to depict subsidence derived from Interferometric Synthetic Aperture Radar (InSAR) data provided by NASA-JPL4. The map also shown regional contours, in feet, of land subsidence from 1926 to 1970 (Ireland, et al., 1984) and discussed above. Based on Figure 3-33, most of the Cawelo GSA has experienced less than one-half foot of land subsidence from 2007 through 2011. Based on InSAR data measured by NASA-JPL from May 2015 to December 2016 (DWR, 2018) and shown on Figure 3-34, land subsidence throughout most of the Cawelo GSA ranged from 1 to 4 inches. Areas in the north-central GSA had measured subsidence between 4 and 8 inches during this time. This is consistent with measured data from May 2015 to September 2016 that was published by NASA-JPL (Farr et al., 2017).

3.2.3.3 Historical Groundwater Lows Evaluation of historical groundwater low levels is key to understanding historical subsidence and assessing the potential for future subsidence associated with groundwater pumping. Geologic factors aside, the amount of subsidence is governed by the lowest groundwater level experienced which typically occurs during periods of maximum groundwater pumping. These periods are generally associated with the late summer months when surface water supplies are lower leading to a greater reliance on groundwater. To assess the change over time, the lowest groundwater level elevation measured in any well was tabulated annually for each township section where data are available. This evaluation found four specific episodes of historical groundwater elevation lows occurring in the Cawelo GSA. These include: • 1952 to 1955 – Prior to 1952 groundwater elevations were generally declining in response to groundwater pumping in the region. After 1955, additional use of imported surface water and improving climatic conditions helped groundwater levels to recover. • 1976 to 1977 – Groundwater levels, especially in the northern Cawelo GSA, reached a period of historical groundwater lows caused by a statewide drought that significantly reduced surface water imports. After 1977, development of managed aquifer recharge operations and improving climatic conditions helped groundwater levels to recover. • 1991 to 1993 – Groundwater levels declined in response to another statewide drought that significantly reduced surface water imports. Due to managed aquifer recharge operations, much of the Cawelo GSA did not experience historical groundwater lows during this period except for a limited area along the western margin of the GSA.

4 National Aeronautics and Space Administration, Jet Propulsion Laboratory in Pasadena, California.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 60 TODD GROUNDWATER • 2014 to 2016 – A protracted five year statewide drought from 2012 to 2016 led to significantly reduced surface water imports and Kern River flows. Much of the Cawelo GSA experienced historical groundwater lows except for the parts of the northern GSA and the far southern GSA margin where levels did not reach 1976 to 1977 levels. Figure 3-35 provides a map showing the distribution of the historic groundwater lows for the Cawelo GSA where there is sufficient history of groundwater level measurements. The lowest groundwater levels are experienced in the summer during the period of maximum groundwater pumping. In the Famoso recharge basin area, monthly groundwater level measurements defined historic groundwater levels lows in the western GSA of below -100 feet msl. Other, more periodically-collected groundwater level measurements confirm these historic low periods Available data for areas south of Poso creek do not show as extensive historic groundwater levels as deep as those demonstrated with monthly measurements . Comparison of the range of historical water level declines to historical subsidence can be used to determine a general rate of potential subsidence. While acknowledging some lag effects, most, if not all, of the potential land subsidence associated with a historical low groundwater level occurs during that same period. Subsequently, additional subsidence would be contingent upon groundwater levels falling below previous historical groundwater level lows. Therefore, SGMA planning for subsidence will be considered with respect to the mapped historical groundwater lows shown on Figure 3-33.

3.2.3.4 Historic Rate of Subsidence Land subsidence in the Cawelo GSA has primarily occurred in the northern portion of the GSA, north of Poso Creek. South of Poso Creek, the sediments typically consist of more coarse-grained deposits that are less susceptible to inelastic deformation.

Maximum land subsidence in the Cawelo GSA over the period from 1926 to 1970 is estimated to be on the order of 2 to 3 feet (Section 3-44), occurring in areas north of Poso Creek. South of Poso Creek, total land subsidence ranges from about 1 to 2 feet near Poso Creek and decreases southward to where there is little to no land subsidence in the southern portions of the Cawelo GSA. Based on data from well T26S/R26E-16P1, groundwater levels over the period declined about 200 to 225 feet in this area. Therefore, the rate of land subsidence is approximately one-percent of the groundwater level decline below the previous historically lowest groundwater level.

From 2007 to 2016, land subsidence was on the order of 0 to 0.5 foot across the Cawelo GSA (Figures 3-33 and 3-34). Areas of the greater land subsidence, potentially up to one-foot were localized suggesting a causal relationship with significant pumping and well interference that led to historic groundwater lows. Subsidence during this period occurred with declines in groundwater levels below previous historic lows about 100 feet. During this time, the rate of land subsidence is approximately one-percent of the groundwater level decline below the previous historically lowest groundwater level in the areas most susceptible to land subsidence. Subsidence in the southern GSA ranged from about 0.25 feet to essentially zero subsidence along the southern GSA margin.

Based on this analysis, the potential maximum rate of land subsidence, in the areas most susceptible to land subsidence, is approximately one-percent of the groundwater level decline below the previous historically lowest groundwater level.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 61 TODD GROUNDWATER 3.2.3.5 Oil Field Land Subsidence Subsidence has been documented due to oil field operations at the Kern Front and Poso Creek oil fields on the order about 1 foot based on a USGS report on the “Historical Surface Deformation near Oildale, California” (Castle et. al., 1983). However, no evidence of subsidence has been documented at the Kern River Oil Field (Castle et. al., 1983). Subsidence associated with producing oil fields is governed by the same general principles as those that control subsidence associated with ground-water withdrawals from a confined aquifer. In the case of the Kern Front and Poso Creek subsidence, this is likely attributed to depressurizing the oil field reservoir due to the removal of subsurface fluids. This de-pressuring would be represented by the decline in natural gas production prior to 1970 compared to current natural gas production rates. Early operations did not reinject water produced from wellfields back into the reservoir as is the current practice. In the case of the Kern Front and Poso Creek Oil Fields, the subsidence would be similar to elastic deformation where the pressure of the reservoir fluids is reduced (Castle et. al., 1983).. However, for the oil field operations, the initial reservoir pressures cannot be re-established making the elastic deformation permanent. The clay layers of the Etchegoin are considered to have experience prior compaction due to tectonic stresses so that they would not be susceptible to further compaction due to reservoir fluid removal. Because the oil reservoirs are in a secondary recovery operational stage, little future reservoir depressurizing is anticipated that would lead to further land subsidence in this area. This is supported by the InSAR data which did not indicate significant additional subsidence in these areas (Figures 3-33 and 3-34). In the Kern River Formation, the oil migrated into the shallow Kern River Formation where it became trapped by overlying siltstones and vitrified oil deposits. The lack of observed subsidence in the Kern River Oil Field is attributed to the lack of compressible clay layers in the Kern River Formation and in the Kern Fan deposits along the Kern River (Castle et. al., 1983). Similar to the observations from groundwater pumping in the Kern Fan area, these deposits are less susceptible to compaction leading to land subsidence.

3.2.4 Interconnected Surface Water and Groundwater Dependent Ecosystems

The SGMA and GSP Regulations define interconnected surface water as surface water that is hydraulically connected at any point by a continuous saturated zone to the underlying aquifer and to overlying surface water that is not completely depleted (California Code of Regulations Title 23). Groundwater Dependent Ecosystems (GDEs) are defined in the GSP Regulations as ecological communities or species that depend on groundwater emerging from aquifers or on groundwater occurring near the ground surface. Thus, GDEs refer to plants, animals, and natural communities that rely on groundwater to sustain all or part of their water needs (TNC, 2018). GDEs occur in areas where groundwater either discharges to the surface (springs, seeps, or wetlands) or the water table is sufficiently shallow to support natural communities. This includes vegetation with rooting depths sufficiently deep to draw a water supply from the underlying water table, referred to as phreatophytes. GDEs can occur along interconnected surface water but can also occur in any area where natural communities are supported by shallow groundwater. However, the presence of riparian vegetation or wetlands does not necessarily indicate that they are GDEs.

3.2.4.1 Mapped Natural Communities To assist GSAs with the task of identifying GDEs in a groundwater basin, DWR created the Natural Communities Commonly Associated with Groundwater dataset (hereafter referred to as the NCCAG or

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 62 TODD GROUNDWATER Natural Communities dataset). This dataset is a compilation of 48 publicly available State and Federal agency datasets that map vegetation, wetlands, springs, and seeps in California. A working group composed of DWR, the California Department of Fish and Wildlife (CDFW), and The Nature Conservancy (TNC) reviewed the compiled dataset and conducted a screening process to exclude vegetation and wetland types less likely to be associated with groundwater and to retain types commonly associated with groundwater, based on criteria described in Klausmeyer et al. (2018). Two habitat classes are included in the Natural Communities dataset: (1) wetland features commonly associated with the surface expression of groundwater under natural, unmodified conditions; and (2) vegetation types commonly associated with the sub-surface presence of groundwater (phreatophytes). The NCCAG mapped areas of vegetation and wetlands are provided as polygons of in GIS shapefiles, which also contain information on vegetation types and species; rooting depths and local habitat are available in separate databases developed by TNC (TNC, 2018). DWR notes that the data included in the Natural Communities dataset do not represent DWR’s determination of a GDE but are a starting point for identifying GDEs. Determination of GDEs within a groundwater basin is the responsibility of the GSAs.

The NCCAG-mapping of the Cawelo GSA indicates 70 polygons of vegetation and 51 additional polygons of wetlands (Figure 3-36). Most of the wetlands and vegetation areas occur along Poso Creek in Assessment Area #1 and the Kern River in Assessment Area #2 (Figure 3-36). The number of polygons and area (acres) by community type (vegetation and wetlands) are summarized in Table 3-5 for the GDE Assessment Areas #1 and #2, as shown there are 456 acres of natural communities in the Cawelo GSA. Assessment Area #1 has 199 acres of NCCAG compared to 257 acres in Assessment Area #2.

Table 3-5: NCCAG-Mapped Natural Communities Polygons and Acres in the Cawelo GSA

Total Natural Vegetation Wetlands Communities Areas Area (number of (number of (number of polygons) polygons) polygons) GDE Assessment Area #1 39 45 84 GDE Assessment Area #2 31 6 37 Total in Cawelo GSA 70 51 121 Total Natural Vegetation Wetlands Communities Areas Area (number of (number of (number of polygons) polygons) polygons) GDE Assessment Area #1 115 84 199 GDE Assessment Area #2 131 126 257 Total in Cawelo GSA 246 210 456

The evaluation of interconnected surface water is focused on Poso Creek and Kern River because most of the natural communities are located along these surface-water bodies (Figure 3-36). In Assessment Area #1, 94 percent of the vegetation and 82percent of the wetlands by area are located adjacent to Poso Creek. In Assessment Area #2, 89 percent of the vegetation and 100 percent of the wetlands by area are located adjacent to the Kern River. The analysis of potential GDEs focuses on depth to water, groundwater conditions, climate variability, and local land use.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 63 TODD GROUNDWATER 3.2.4.1 Poso Creek A patchwork of disconnected riparian habitat occurs along Poso Creek with natural communities of wetlands and vegetation (Figure 3-36). The habitat includes Fremont Cottonwood stands, mule fat shrub, California broomsage, saltbrush, and salt cedar (Klausmeyer et al., 2018). To determine whether interconnected surface water is present within GDE Assessment Area #1, groundwater elevation profiles were developed along Poso Creek (Figure 3-37). As illustrated on Figure 3-37, the profile follows the transect of cross section A to A’ (Figure 3-7), from about one mile west of the western GSA boundary to the foothills east of the GSA. These profiles were created in GIS based on groundwater elevation contour maps from a wet year (1998), critically dry year (2013), and a recent wet year (2017), which followed the historic drought from 2012 to 2016. The groundwater elevation profiles for each year are shown in relation to the ground surface elevation, which is based on the USGS DEM illustrated in Figure 3-1. Figure 3-37 illustrates the substantial vertical separation between Poso Creek and the water table throughout the entire stretch of Poso Creek within the Cawelo GSA in 1998, 2013 and 2017. Groundwater elevations were hundreds of feet below Poso Creek during this time and there was no baseflow into Poso Creek. Therefore, groundwater is not hydraulically connected to Poso Creek within the GSA. The profile along Poso Creek shows that ground surface elevations rise steadily from west to east, from an elevation slightly higher than 400 feet in the western GSA to slightly higher than 500 feet in the eastern GSA (Figure 3-37). Groundwater elevations were highest in 1998, the wettest year in the last 35 (or more) years, and lowest in 2017, after several years of a severe drought. Groundwater elevations in 2013, a critically dry year at the beginning of the severe drought, were between 1998 and 2017. The groundwater surfaces in 1998, 2013 and 2017 range from 250 to more than 500 feet below ground surface (bgs) along Poso Creek (Figure 3-37). In 1998, groundwater elevations are relatively steady at approximately 150 feet msl (approximately 250 feet bgs) in the western GSA and decrease to approximately 100 feet msl (approximately 400 feet bgs) in the eastern GSA. The relatively sharp decrease in groundwater elevations that occurs approximately 5.5 miles into the profile corresponds to the bend in the profile that follows Poso Creek. In 2013, groundwater elevations rise gently towards the central GSA and then drop slightly in the eastern GSA before rising again in the foothills to the east of the GSA. Depth to groundwater in 2013 ranges from approximately 350 feet in the western GSA to more than 400 feet in the eastern GSA. In 2017, groundwater elevations are more variable along the profile, mounding slightly in the western GSA, relatively stable in the central GSA, and then dropping to below sea level in the eastern GSA before rising in the eastern GSA and into the foothills. The profiles also illustrate the difference in groundwater elevations along Poso Creek in response to climate variability. Groundwater elevations are lower in the dry year (2013) and after the recent drought (2017) than in the wet year (1998). Groundwater elevations in 2013 and 2017 differ by approximately 100 feet along Poso Creek throughout most of the GSA. This changes in the eastern GSA, where groundwater elevations in 2017 rise relatively steeply. Approximately one mile east of the GSA in the foothills, groundwater elevations in all three years are similar, which suggests that groundwater elevations in the foothills are less affected by climate variability than within the GSA. There are limitations to the groundwater elevation profiles because they are based on groundwater contours, which are not exact representations of groundwater elevations. Furthermore, the profile follows the general path of Poso Creek, but does not follow the path of all its meanders. Despite these limitations, the profiles demonstrate that Poso Creek is not hydraulically connected at any point by a

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 64 TODD GROUNDWATER continuous saturated zone to the underlying aquifer. The flow in Poso Creek does not depend on groundwater discharge. Figure 3-36 illustrates vegetation and wetlands commonly associated with groundwater from the NCCAG mapping. This map shows that there are wetlands and vegetation along Poso Creek, small patches of vegetation to the north and south of Poso Creek in the eastern GSA, and small areas of wetlands at the Poso-Kern County Airport and in the northern GSA. Depth to groundwater in Spring of 1998 is shown, which represents historic high groundwater levels. Despite 1998 being classified as a wet year having nearly 16 inches of precipitation, groundwater remained hundreds of feet below ground surface. Within the GSA, groundwater is very deep, ranging from 200 to greater than 500 feet below ground surface. Groundwater is deeper with proximity to the eastern foothills and becomes shallower in the western portion of the GSA. Within the eastern extension of the GSA, groundwater is deepest in the northern portion, representing the eastern foothills, and becomes shallower approaching the Kern River to the south of the GSA. As described in Section 3.3.1 and illustrated by the hydrologic profiles on Figure 3-37, groundwater elevations are hundreds of feet below Poso Creek within the GSA and therefore, groundwater is not hydraulically connected to Poso Creek. Based on the groundwater elevation contour maps (Figures 3-22, 3-23 and 3-24) at Poso-Kern County Airport and in the northern GSA, groundwater is well below ground surface and not connected to these localized wetlands.

3.2.4.2 Kern River For the Kern River, previously published data are available to support the analyses of interconnected surface water and GDEs. Surface water flows and losses in the Kern River are monitored to allocate river water diversions by surface water rights holders in the Kern County Subbasin. Data are published in annual hydrographic reports prepared by the City of Bakersfield on behalf of the Kern River Watermaster. The City also actively manages and maintains the river channel throughout the GDE Assessment Area #2 and downstream to prevent flooding and to enhance groundwater recharge. The Kern River is a highly-managed system. Operations and management of the river by the City of Bakersfield, including measurements in the channel along the southern boundary of Assessment Area #2 have demonstrated that the Kern River is a losing stream. Similarly, in a separate Kern County Subbasin GSP, the Kern Groundwater Authority (KGA) GSA has conducted a basin-wide evaluation for the potential of interconnected surface water and concluded that the Kern River is not interconnected with the underlying groundwater where the Kern River passes through the Assessment Area #2.

The City of Bakersfield implements a channel maintenance program, which includes removal of sand, soil, and vegetation within the designated floodway; channel alignment within the designated and secondary floodway; and maintenance and operations of designated river weirs and diversion structures. Riparian vegetation along the Kern River is supported by regulated releases from Isabella Reservoir, as well as surface water and imported water that is intentionally released into the channel for groundwater banking and/or replenishment of groundwater to support local wellfields.

The reach of the Kern River that passes through GDE Assessment Area #2 is consistently a wetter part of the stream compared to many downstream reaches. The result is a biodiverse riparian habitat along the river with natural communities of wetlands and vegetation (Figure 3-36). The habitat includes riparian evergreen and deciduous woodland, Fremont Cottonwood stands, arrowweed, European elder, saltbrush, and California broomsage (Klausmeyer et al., 2018). Despite the fact that this reach of the Kern River is a losing stream with relatively large amounts of recharge, it has natural communities of

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 65 TODD GROUNDWATER riparian vegetation and wetlands. The depth to groundwater adjacent to the river is typically more than 100 feet deep in where the Kern River passes through the Cawelo GSA Area. Given these conditions, the reach of the Kern River that passes through Assessment Area #2, is not an interconnected surface water.

3.2.4.3 Assessment of Surface Water Interconnectedness Consequently, the findings from this analysis of interconnected surface water and GDEs indicate that the vegetation and wetlands along the Poso Creek and Kern River as mapped by DWR (Figure 3-36) are not GDEs because they do not depend on groundwater. Furthermore, these reaches of the Poso Creek and Kern River are not interconnected surface water because they are not hydraulically connected at any point by a continuous saturated zone to the underlying aquifer. The flow in these reaches of Poso Creek and Kern River and associated natural communities of vegetation and wetlands do not depend on groundwater discharge.

3.3 MANAGEMENT AREAS

SGMA provides the option for GSAs to define management areas for portions of basins to facilitate groundwater management and monitoring. A management area is defined in SGMA as an “area within a basin for which the [GSP] may identify different minimum thresholds, measurable objectives, monitoring, or projects and management actions based on differences in water use sector, water source type, geology, aquifer characteristics, or other factors” [CCR Title 23, Division 2, §351(r)]. However, GSAs in the basin must provide descriptions of why those differences are appropriate for the management area, relative to the rest of the basin (DWR, 2017).

At this time, the entire Cawelo GSA is treated as a single management area within the Kern County Subbasin for the purposes of defining sustainability criteria. However, the Cawelo GSA recognizes that a consistent application of methods used to establish minimum thresholds and management objectives for each sustainability indicator can have a similar result of managing areas of the Subbasin without formally creating Management Areas. The GSAs may informally establish zones within their jurisdiction, in which to manage differently.

3.4 DATA AND KNOWLEDGE GAPS

GSP regulations define “data gap” as “a lack of information that significantly affects the understanding of the basin setting or evaluation of the efficacy of GSP implementation and could limit the ability to assess whether a basin is being sustainably managed.” This definition recognizes the importance of identifying the data gaps that specifically relate to sustainable groundwater management and does not necessarily include all missing or incomplete data.

• Well Construction Information • Groundwater levels and water quality data in the eastern portion of the Cawelo GSA • Influence of geologic heterogeneity on groundwater flow

In general, well construction information is unknown for many wells currently monitored, especially for private wells being monitored. Efforts to match known active wells to construction data have been difficult. Well completion reports are a source of general information on pumping depths within the Principal Aquifer but are difficult to match to each active agricultural well. A systematic approach to

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 66 TODD GROUNDWATER better link water level response to well construction throughout the Cawelo GSA would provide useful information.

The undeveloped areas in the eastern portion of the Cawelo GSA has limited data. It would be useful to coordinate with local land owners, such of the oil field operators, to coordinate groundwater monitoring data being conducted in these areas. Groundwater monitoring requirements have increased in recent years, so new data and monitoring locations are anticipated to be available in the future that were not available in the past. Also, KCWA has added private wells to its water level monitoring program when candidate wells could be found. For the GSP, a few of these currently-monitored wells are being incorporated into the monitoring program, but long-term access is uncertain.

A source of uncertainty that may influence the groundwater pumping and recharge operations is the potential influence of geologic heterogeneity on groundwater flow. Although the analysis did not clearly identify any specific trends, these may exist. Ongoing data evaluation during the 20-year implementation period on the performance of the implementation of the GSP Projects and management actions should be conducted to identify potential geologic influences.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 67 TODD GROUNDWATER 4 WATER BUDGET

Surface and groundwater budgets have been developed for the Cawelo GSA Plan Area to quantify historical changes in the amount of groundwater in storage and to identify the amount of sustainable groundwater available for future use. In particular, reductions of groundwater in storage are estimated to assess the potential for undesirable results.

The water budget analysis presented herein allows the response of the physical groundwater system to be correlated to current and historical groundwater use. This analysis also provides the foundation for identifying potential future deficits of groundwater based on future projections of surface water supplies and demands. A primary objective of the groundwater budget analysis is to quantify historical, current, and projected groundwater deficits so that management actions can be identified to mitigate undesirable results attributable to potential groundwater deficits.

4.1 WATER BUDGET APPROACH

The water budget accounts for the components of the Basin’s hydrologic cycle and assesses how the flows change with the purpose of developing a Sustainable Groundwater Management Plan. Sustainability indicators are identified and evaluated through assessment of the water budget leading to selection of sustainability criteria and development of projects and management actions that lead to and maintain long-term sustainable groundwater management for the Cawelo GSA.

The groundwater budgets for the Cawelo GSA quantify inflows and outflows to the groundwater system and illustrate how these flows change over time. Flows into, out of, and through the Cawelo GSA result from movement of water between the atmospheric, land surface, surface water, and groundwater systems (CDWR, 2016). The difference between the flows into and out of the Basin is the change in the volume of water stored in the Basin.

=

Groundwater enters the groundwater𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴 𝐼𝐼𝐼𝐼 −basin𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴 as inflow𝑂𝑂𝑂𝑂𝑂𝑂 (supply).𝐶𝐶ℎ𝑎𝑎 𝑎𝑎𝑎𝑎𝑎𝑎 𝑖𝑖𝑖𝑖 𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆

• Subsurface groundwater flow into the Basin • Percolation from the surface • Managed Aquifer Recharge • Infiltration through streambeds

Groundwater leaves the groundwater basin as outflow (demand).

• Subsurface groundwater flow out of the Basin • Groundwater extraction through wells

These data were also used to support integrated surface water-groundwater modeling of historical, current, and future projected groundwater budgets. The approach to this analysis applies independent methods to compare and corroborate water budget results, as summarized below:

• Checkbook groundwater budgets were prepared to provide a detailed accounting of inflows and outflows for historical and current study periods. These data also support the development

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 68 TODD GROUNDWATER and analysis of projected future water budgets and are used to identify potential future deficits in sustainable groundwater supply. For planning purposes, this analysis does not consider subsurface flows and allows groundwater managers to focus on the inventory of water supplies that they each control and manage. The checkbook water budget approach does not account for subsurface flows into and out of the Cawelo GSA.

• C2VSimFG-Kern model water budgets were developed using the DWR regional C2VSim model, which has been revised with Subbasin-specific water budget data to represent a local Subbasin model. Data from the checkbook method described above was used as input for model revisions and analysis of the Cawelo GSA. This analysis provided estimates of subsurface flows, which had not been included in the Checkbook method. Water budgets were analyzed on both a Subbasin- wide and Plan Area basis for historical and current study periods and over a 50-year planning horizon, which included climate change analyses for 2030 and 2070 climate change conditions, as required by GSP regulations. The Subbasin modeling was supported by all GSAs in the Subbasin for a coordinated and consistent analysis, which incorporated the same data and methodologies.

Types and sources of data used to develop the checkbook water budgets and also to provide input for the C2VSimFG-Kern local model are described in the sections below. The data descriptions are followed by an analysis of changes in groundwater in storage for historical and current Study Periods using the checkbook method and C2VSimFG-Kern model. Finally, future projected water budgets over a 50-year period are summarized including a projected baseline and projected conditions of climate change for 2030 and 2070 scenarios.

4.2 STUDY PERIOD

Various study periods are being employed in the Cawelo GSA depending on the needs of specific analysis and data sources available. However, GSP requirements indicate a need to identify an average hydrologic Study Period for purposes of the groundwater analyses in the basin-wide water budgets. In order to select a consistent study period for both local and subbasin-wide analyses, the Cawelo GSA coordinated with other Kern County Subbasin GSAs on an average hydrologic study period covering WY 1995 through WY 2014. This coordination is consistent with GSP regulation requirements, which generally require all GSAs in a subbasin to use the “same data and methodologies” for development of multiple GSPs (§357.4(a)). In particular, GSP regulations require that the water budgets be coordinated for the entire subbasin (§357.4(b)(3)(B)). It was also acknowledged that the use of this study period does not preclude any of the Cawelo GSA GSP analyses – or analyses done by others – from incorporating data from a different time period when available and necessary for the GSP development. The historical average hydrologic study period of WY 1994 through WY 2014 covers 20 years on a water year basis, from October 1, 1994 through September 30, 2014. The selection of the study period was based on a variety of technical criteria including: • 100 percent of the long-term average streamflow conditions on the Kern River (as indicated by an average annual Kern River Index of 100 percent) • About 104 percent of long-term average precipitation (NOAA Bakersfield Meadows Field Airport Station) • Sufficiently short time period associated with widely-available and higher-quality data

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 69 TODD GROUNDWATER • Inclusion of recent time periods to capture ongoing water management practices and more recent land use patterns • Covers at least 10 years consistent with GSP regulations (§354.18(c)(2)(B)) • Contains 10 years characterized as above normal or wet years based on precipitation; also contains 10 years of below normal or dry years, including 4 critically-dry years • Begins in a time of relatively stable water levels (October 1994) • Overlaps time period with consistently-developed basin-wide contour maps by Kern County Water Agency (KCWA).

More recent water years of WY 2015 and, as applicable, WY 2016 to present are used for current conditions throughout this GSP. The study period was proposed in 2016 when GSPs were first being initiated in the Subbasin; accordingly, WY 2016 data were not yet widely available. In addition, WY 2016 was not available in the Beta version of the C2VSim model, which was the best available data when the model was released by DWR in Spring 2018 and revised with local data. It is recognized that this study period ends in the drought of record at a time when then-current water levels were at or near historic lows (and continued to decline as drought conditions persisted in 2015 and 2016). Ending a study period in drought will almost always result in a decline of groundwater in storage from the beginning of the study period to the end of the study period. However, that decline alone does not necessarily indicate overdraft conditions. Even though the overall period represents average hydrologic conditions, resulting changes in groundwater in storage from the beginning to the end can be either positive or negative depending on the order of the dry and wet years in the period.

4.3 HISTORICAL AND CURRENT WATER BUDGET

The approach to a water budget analysis for this large, multi-faceted area begins with an understanding of the local management operations that either recharge (inflow) or extract (outflow) groundwater. These and other inflows and outflows to the groundwater system were tabulated monthly to create a hydrologic inventory over the 20-year historical Study Period WY 1994 through WY 2014 and the one- year current Study Period WY 2015. Tables providing average annual summaries using the checkbook method are provided in the text with additional data provided in Appendix E.

4.3.1 Imported Water

During the twenty-year historic period, the CWD received almost two thirds on average of imported water from the Kern River and the SWP. Other sources of imported water include the Central Valley Project water and treated produced water, among other sources of water banked in the Cawelo GSA. Annual imported surface water inflows are summarized in Table 4-1. The average annual volume of water imported into the CWD during the current period (69,798 acre-feet) is 15 percent less than the 82,215 acre-feet imported during the twenty-year historic period. WYs 2012-2016 were a period of drought. The current period of WYs 2015-2017 represents three years of drought and one year of recovery from the drought. During WYs 2014 and 2015, imported water deliveries where almost one half of the historical average.

The average annual amount of Kern River water imported to the CWD (Table 4-1) during the twenty- year historic period is 25,508 acre-feet and ranged from 627 acre-feet in WY 2013/2014 and 39,602 acre-feet in WY 1995/1996. Between Water Year 2015 and 2017, the current period, the average

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 70 TODD GROUNDWATER annual volume of imported Kern River water is 9,575 acre-feet which is 37 percent of the historical annual average. North Kern Water Storage District (NKWSD, City of Bakersfield) has an agreement to deliver Kern River water to the Cawelo Water District through the Beardsley and Lerdo Canals to Pump Station B. Water is delivered during the irrigation season at 2,700 acre-feet per month during March and April and 5,400 acre-feet per month from May through August (CWD 2015). Kern River water flows through the Lerdo Canal to Pump Station B and is stored in Reservoir B for distribution to CWD users. Kern River water availability is affected by precipitation and snow melt (Schafer 2007).

Table 4-1 Summary of Imported/Exported Water Deliveries (Acre-Feet per Water Year).

Historical Period Current Period

(1995-2014) (2015-2017) INFLOWS Total Average Total Average Kern River 510,169 25,508 28,724 9,575 State Water Project (SWP) 544,233 27,212 80,042 26,681 Central Valley Project (CVP) 17,716 886 7,626 2,542 Treated-Oilfield Produced Water 481,880 24,094 86,863 28,954 Banking/Exchanges 82,754 4,138 5,939 1,980 Groundwater from outside of GSA 7,544 377 200 67 Total Inflows 1,644,297 82,215 209,394 69,798 OUTFLOWS Total Average Total Average Banking/Exchanges 40,256 2,013 12,338 4,113 Total Outflows 40,256 2,013 12,338 4,113

The average annual volume of State Water Project (SWP) water delivered to the CWD for the twenty- year historic period is 27,212 acre-feet and for the current period is 26,681 acre-feet (Table 4-1). The SWP supply of water has ranged from 8,061 acre-feet in 2009 to 42,484 acre-feet in 1999. During the recent drought in WY 2015 the annual SWP delivery was 6,551 acre-feet, about one quarter of the historic annual average. SWP water is transported from the California Aqueduct through the Cross Valley Canal and Pump Station A to the Beardsley Canal. The original firm entitlement for SWP water is 38,200 acre-feet and a surplus water entitlement (Article 21 water) of 6,800 acre-feet per year (Schafer 2007). The SWP water is allocated through the Kern County Water Agency and regulated by court ordered constraints on pumping from the Sacramento-San Joaquin River Delta (Delta). Restrictions on pumping SWP water from the Delta has reduced the availability of Article 21 water (CWD 2015).

The average annual volume of Central Valley Project water conveyed to CWD for the twenty-year historic period is 886 acre-feet and for the current period is 2,542 acre-feet (Table 4-1). Occasionally, the Bureau of Reclamation will make annual contracts with non-Central Valley Project contractors such as the CWD when waters in the Project are un-storable flood flows (Section 15 water). CWD received these flows during ten years of the twenty-year historic period and two of the current period years. Diversions are made through the Friant-Kern Canal and the Calloway-to-Lerdo Intertie (CWD 2015).

The average annual volume of oilfield produce water supplied to CWD during the twenty-year historic period is 24,094 acre-feet and 28,954 acre-feet during the current period (Table 4-1). Oilfield water sources include Chevron USA Inc (Chevron), Schaefer Oil Company, and Valley Water Disposal Company (currently CRPC). The treated produced water is delivered to the CWD and blended with other water

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 71 TODD GROUNDWATER sources including SWP water prior to distribution to the District’s users or for percolation in the Famoso Basin Groundwater Banking Project. Chevron has a right to deliver up to 29,405 acre-feet annually and has typically averaged 19,000 acre-feet per year (CWD, 2015). The Valley Water Disposal Company (CRPC) has an agreement to deliver 3.22 acre-feet per day (CWD, 2015).

Water entering the CWD for water banking or exchange during the historic period averaged 4,138 acre- feet per year and during the current period averaged 1,980 acre-feet per year (Table 4-1). Agricultural Pumping. During the twenty-year historic period the volume of water entering the CWD for banking or exchange ranged from zero during dry years to 16,242 acre-feet in 2002. CWD has, or has had in the past, agreements with North Kern Water Storage District, Kern-Tulare Water District, Buena Vista Water Storage District, Dudley Ridge Water District, Alameda County Flood Control and Water Conservation District (Zone 7), and other agencies to bank, capture, exchange, and/or purchase water (Schafer 2007). Local water bank supplies are conveyed to the CWD through the Central Valley, Calloway, or Lerdo Canals.

4.3.2 Groundwater Pumping

Groundwater extraction within the Cawelo GSA is summarized in Table 4-2 and is predominantly for agricultural use. Private (unmetered) pumping for agriculture is about 78 percent of groundwater extraction occurring within the Cawelo Groundwater Sustainability Basin. During dry years, CWD pumps banked groundwater to supplement water deliveries for agriculture. Groundwater is also used at Municipal and industrial facilities and domestic sites.

Table 4-2 Summary of Groundwater Pumping (Acre-Feet per Water Year).

Historical Period Current Period

(1995-2014) (2015-2017) Ag Pumping Total Average Total Average District (metered) 157,469 7,873 52,133 17,378 Private (unmetered) 640,083 32,004 114,222 38,074 Total Ag Pumping 797,552 39,878 166,355 55,452 Urban Pumping Total Average Total Average M & I Pumping 20,098 1,005 2,945 982 Domestic Pumping 1,145 57 172 57 Total Urban Pumping 21,243 1,062 3,116 1,039 Total Groundwater Pumping 818,795 40,940 169,472 55,452

4.3.2.1 District Pumping

The CWD owns and operates 18 deep wells that are used to provide irrigation water when the surface water supplies are insufficient. Some private wells within the District also supplement the surface water supplies provided by CWD. Most private wells within the CWD are located on farms. Private well use is measured by the CWD when water is transferred through the District’s distribution system. The CWD wells range from 1,200 to 1,500 feet deep and are typically screened in the lower 500 feet of the well. The CWD wells have a 30-inch diameter borehole. The average pumping lift is 500 feet (CWD, 2015).

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 72 TODD GROUNDWATER The average annual volume pumped groundwater discharged into the CWD distribution system during the twenty-year historic period is 7,873 acre-feet and 17,378 acre-feet for the current period (Table 4-2). Water pumped by the CWD and private wells for distribution ranged from 158 acre-feet in WY 2010/2011 to 24,149 acre-feet during WY 2013/2014 (Appendix E). WY 2010/2011 was a wet year and surface water was available for banking and/or recharge to the groundwater system and for delivery for irrigation. Very little District and private groundwater was added to the CWD deliveries to landowners for irrigation. Water Years 2012—2016 were a period of drought. In WY 2015 during the drought, the district pumped 31,087 acre-feet of groundwater to supplement deliveries for irrigation which is almost 4 times the historical annual average.

4.3.2.2 Private Pumping

Unmetered agricultural pumping was estimated based on crop water requirements allowing for crop demand and irrigation return flow (10 percent of crop demand). Agricultural pumping is determined as the difference between the crop water requirements and available surface water supplies in the form of effective precipitation and water deliveries from CWD. Effective precipitation is the portion of precipitation that is available to satisfy crop water requirements. For the Cawelo GSA, it is the total of the monthly precipitation remaining after 0.5 inches per month for consumptive loss is removed or zero if monthly precipitation is less than the consumptive loss.

A private riparian diversion exists upstream of the CWD Poso Creek diversion. The riparian right limits the diversion to a rate of no more than 25 cfs not to exceed 6,500 acre-feet annually (CWD, 2007). This diversion is an available source of surface water used to meet crop water requirements.

Groundwater extraction through unmetered, private wells for irrigation is summarized in Table 4-2 and Appendix E Private pumping averages 32,004 acre-feet per year during the twenty-year historic period and ranges from 20,917 acre-feet in WY 2012 to 44,288 acre-feet during WY 2014. WYs 2011/2012 through 2013/2014 are the first and third years of a drought with total rainfall of 4.95 inches in WY 2011/2012 and 2.2 inches in WY 2013/2014. During the fourth year of the drought, WY 2015, 57,338 acre-feet of groundwater was extracted through unmetered, private wells. WY 2010/2011 was very wet with 10.32 inches of precipitation resulting in high antecedent soil moisture going into the drought. Lack of rainfall, reduced soil moisture, and decreased surface water supply resulted in increased groundwater usage for irrigation during the drought period.

4.3.2.3 Urban Pumping

Total estimated municipal and industrial pumping within the Cawelo GSA averaged 985 acre-feet per year during the twenty-year historic period and 962 acre-feet per year during the current period. Industrial and municipal pumping sites within Cawelo GSA include the county airport, commercial facilities, commercial agricultural facilities, and feed lots. Small water systems exist at the Lerdo Detention Facility (AECOM, 2010) and North Kern Golf Course (SDWIS, 2019). Small water systems pumped an estimated average of 710 acre-feet per year during the historic period. Domestic pumping averaged 57 acre-feet per year during both the historic and current periods. There are about 53 domestic sites within Cawelo GSA pumping an estimated 0.25 to 5 acre-feet per year each depending on the site water requirements.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 73 TODD GROUNDWATER 4.3.3 Surface Water Flow

Surface water flows into and out of the Cawelo GSA are summarized in Table 4-3. Poso Creek is the main source of surface water inflow and outflow with minor amounts of inflow occurring in small watersheds during a few very wet years. There was no measurable flow out of the Cawelo GSA through small watersheds. Groundwater discharge to rivers and streams is assumed to be zero as the depth to groundwater under Poso Creek and its tributaries ranges from 300 to 400 feet indicating that surface water and groundwater are not hydraulically connected within the Cawelo GSA.

Table 4-3 Summary of Surface Water Flows (Acre-Feet per Water Year).

Historical Period Current Period

(1995-2014) (2015-2017) INFLOWS Total Average Total Average Poso Creek 329,481 16,474 75,267 25,089 Small Watershed 20,698 1,035 0 0 From Groundwater 0 0 0 0 Total Inflows 350,179 17,509 75,267 25,089 OUTFLOWS Poso Creek 217,728 10,886 9,965 9,288 Small Watershed 0 0 0 0 Stormwater Runoff 53,878 2,694 6,420 2,140 Total Outflows 271,606 13,580 16,385 11,428

4.3.3.1 Poso Creek

The upper portion of Poso Creek is precipitation fed and typically only flows during the winter and spring months (November through May). Poso Creek flows are summarized in Table 4-3 and Appendix E. The Trenton Weir gage is located upstream of Highway 65 and operated and monitored by the Cawelo Water District. Operation of the Trenton Weir gage began in 1982 and records the discharge from a 320 square mile basin. The average annual volume of flow for Poso Creek entering the Cawelo GSA is 16,474 acre-feet during the twenty-year historic period with above average annual flow occurring in a just six, wet years. The annual flow ranges from zero in dry years to 110,990 acre-feet in WY 1998. For the WYs 2015 through 2017, the average annual flow entering Cawelo GSA through Poso Creek is 25,089 acre-feet. During the drought, no flow occurred in WY 2015 and little in WY 2016. Water year 2017 was wet and 71,576 acre-feet flowed into the Cawelo GSA.

The average annual volume of flow for Poso Creek at Highway 99 where Poso Creek leaves the GSA is 10,886 acre-feet during the twenty-year historic period with above average annual flows occurring in just five wet years. The State Highway 99 gage is located on Poso Creek at the west boundary of the Cawelo GSA. Measurable flows were recorded at Highway 99 during eight out of twenty years in the historic period. The average annual flows range from zero in dry years to 115,409 acre-feet in WY 1997/1998. During the current period, most of the flow leaving the Cawelo GSA through Poso Creek occurred in WY 2017 (33,784 acre-feet). The drought that spanned the end of the historic period and beginning of the current period left Poso Creek at Highway 99 between 2012 and 2016.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 74 TODD GROUNDWATER 4.3.3.2 Small Watershed

Flows into the Cawelo GSA are through small watersheds are summarized in Table 4-3 and are estimated to be 2,939 acre-feet in WY 1995, 8,431 acre-feet during WY 1998, and 9,329 acre-feet during WY 2011. Little Creek is a small, natural, ephemeral tributary of Poso Creek that enters the Cawelo GSA north of Poso Creek crossing about two miles of irrigated agricultural land then connecting with Poso Creek. Little Creek is generally dry with flows observed only in three of 33 years (CWDC, 2014) like the small watersheds in the Cawelo GSA. Flow into the Cawelo GSA through small water sheds like Little Creek likely occurred in water years 1995, 1998, and 2011 which were exceptionally wet. The small amount of rain that typically falls percolates into the permeable soils without any significant surface runoff occurring. Flow in small watersheds was estimated using an SCS runoff analysis and based on an estimate of the watershed area (24,198 acres) using Google Earth.

4.3.4 Precipitation

The average annual precipitation in the Tulare Lake Basin varies from five to seven inches per year in the Tulare Lake Basin valley floor at Highway 99 up to 40 inches per year in the Greenhorn Mountains. Most precipitation occurs from December through March (CWD 2015).

Precipitation for the Cawelo GSA is summarized in Table 4-4 and was measured at the CWD office and applied to the groundwater areas shown on Figure 3-20. The average annual precipitation in the Cawelo GSA during the twenty-year historic period was 34,590 acre-feet (7.31 inches) and ranged from 15,318 acre-feet (3.07 inches) in WY 2014 to 83,964 acre-feet (18.75 inches) WY 1998. Over the entire Cawelo GSA, the average annual precipitation is 38,876 AFY.

During the water years 2015 through 2017, an average of 33,239 acre-feet per year of precipitation fell. As discuss previously, the twenty-year historic period ended during a drought that began in 2012 and ended in 2016. The water year 2015 (beginning of current period) was the third consecutive critically dry year for the Cawelo GSA. Precipitation in Water year 2017 was above the average for the historic period assisting in recovery from the drought.

Table 4-4 Summary of Precipitation (Acre-Feet per Water Year).

Historical Period Current Period

(1995-2014) (2015-2017) Region Total Average Total Average Irrigated Agricultural Areas 428,782 21,439 61,253 20,418 Other Areas 263,026 13,151 38,463 12,821 Total Precipitation 691,808 34,590 99,716 33,239

4.3.5 Evapotranspiration

The average annual evapotranspiration (ET) for the twenty-year historic period is 115,831 acre-feet as shown in Table 4-5. ET occurs in the form of crop water demand, ET from undeveloped/native land, and ET from municipal, industrial, and domestic land uses. Crop water demand is approximately 91percent of all ET occurring within the Cawelo GSA. Irrigated crops within the Cawelo GSA are predominantly permanent crops. The major irrigated crops included citrus, trees and nuts including almonds and

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 75 TODD GROUNDWATER pistachio, and vineyard with an average annual distribution of 29.9 percent, 35.1 percent, and 32.1 percent during the twenty-year historic period, respectively. Minor irrigated crops included date palms, cherry, alfalfa, potato, grain, carrot, blueberry, melon, and pasture (CWD data; CWD, 2015).

Table 4-5 Summary of Evapotranspiration (Acre-Feet per Water Year).

Historical Period Current Period

(1995-2014) (2015-2017) Component Total Average Total Average Crop ET 2,137,329 106,866 317,339 105,780 M&I/Domestic Use & ET 8,375 419 1,031 344 Native/Undeveloped ET 210,779 10,539 33,854 11,285 Total ET 2,356,483 117,824 352,224 117,408

The average annual crop water demand during the twenty-year historic period was 106,866 acre-feet. WY 2014 was the second critically dry consecutive year during the recent drought and the lowest acreage irrigated during the historic period (31,754 acres) resulting in a lower crop water demand of 97,891 acre-feet per year. The highest crop water demand within the historic period of 112,304 occurred in WY 1997/1998 which was unusually wet and had the largest acreage (36,330 acres) irrigated during the historic period (CWD data). During the current period, the crop water demand averaged 105,780 acre-feet per year.

The estimated average urban ET during the historic period is 419 acre-feet per year and 344 acre-feet during the current period. Urban ET was estimated based on the difference between urban pumping (Section 4.3.2.3) and return flow from urban uses (Section 4.3.6).

The average annual ET from native or undeveloped land is 10,539 acre-feet during the twenty-year historic period and 11,285 acre-feet during the current period. ET is estimated from the difference between the precipitation on native or undeveloped land (Section 4.3.4) and the portion of the precipitation that percolates to the groundwater (Section 4.3.9).

4.3.6 Percolation to Groundwater

Percolation to groundwater due to irrigation water transport and agricultural and urban uses is summarized in Table 4-6. The portion of water applied to irrigate crops that percolates to groundwater, irrigation return flow, is two thirds of the recharge to groundwater that occurs due to agricultural and urban activities within the Cawelo GSA.

Irrigation return flow is the component of effective precipitation plus applied agricultural irrigation water that exceeds crop ET (crop water demand) and percolates to the groundwater. The CWD provides water for irrigation when precipitation is insufficient for crop water requirements. Imported surface water is used to satisfy crop water requirements and pumped groundwater is used when the crop water demand is greater than the imported surface water supply. Excess water (irrigation return flow) percolates through the vadose zone to the groundwater. Local sediment properties control the time of

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 76 TODD GROUNDWATER travel of the water through the vadose zone. There is a time lag between application of water for irrigation and groundwater recharge. No lag time has been incorporated into the water budget. Table 4-6 Summary of Percolation to Groundwater (Acre-Feet per Water Year).

Historical Period Current Period

(1995-2014) (2015-2017) Component Total Average Total Average Irrigation Return Flow 213,733 10,687 31,734 10,578 Conveyance Recharge 98,505 4,925 12,477 4,159 M&I/Domestic Return Flow 6,382 319 926 309 Total Percolation 318,621 15,931 45,137 15,046

4.3.6.1 Irrigation Return Flow Percolation to groundwater is assumed to be 10 percent of the crop ET (CWD, 2015) and is the estimated volume of the irrigation return flow. During the twenty-year historic period, the estimated average annual irrigation return flow is 10,687 acre-feet per year ranging from approximately 9,789 acre-feet in WY 2013/2014 (drought) to 11,230 acre-feet in WY 1997/1998 (very wet water year). During the twenty-year historic period, the total average annual crop water requirement including a 10 percent leaching requirement was about 117,553 acre-feet for an annual average of 3.4 acre-feet per irrigated acre.

4.3.6.2 Conveyance Recharge

The CWD conveyance system annual water losses during the historic period average 4,925 acre-feet per year. Water that escapes from the conveyance system percolates to the underlying groundwater system contributing to groundwater inflow. Losses occur in the Beardsley, Lerdo, and Cross Valley Canals and from the CWD distribution system. The Beardsley, Lerdo, and Cross Valley Canals are unlined, and leakage from the canals infiltrates to the groundwater system. The Cawelo Water District’s distribution system includes six pump stations with associated discharge pipelines, an irrigation distribution system, and five reservoirs (CWD 2015). Monthly canal and distribution system losses are provided by CWD.

The lowest annual loss within the historic period from the conveyance system was 3,046 acre-feet and occurred in WR 2014 which was a critically dry year with lowest delivery of imported water during the historic period. WY 2014 was the third year of the recent drought. The average annual conveyance system water loss for the current period is 4,159 acre-feet which is lower than the historic average and reflects three years of drought followed by one year of recovery and conveyance system improvements. Conveyance system improvements include the Calloway Canal-to-Lerdo Canal Intertie Project, the Cross Valley Canal-to-Calloway Canal Intertie, and Calloway Canal lining (CWD 2015).

The highest annual loss during the historic period was 7,411 acre-feet which occurred in WY 1997, a wet year with large annual volume of imported water deliveries. WYs 2006,2011, and 2017 experienced larger deliveries of imported water and smaller conveyance losses than WY 1997 reflecting the effectiveness of conveyance system improvements.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 77 TODD GROUNDWATER 4.3.6.3 Municipal, Industrial, and Domestic Return Flow

The average annual municipal, industrial, and domestic return flow is 319 acre-feet for the historic period and 309 acre-feet during the current period. Sources of municipal, industrial, and domestic return flows in the Cawelo GSA are municipal and industrial sites, residential sites, the Lerdo Detention Facility, and the North Kern Golf Course. Municipal and industrial return flow is estimated as 60 percent of the water use and were assumed to be constant throughout the historic and current periods. Return flow for rural residences is estimated as 60 percent of rural residential water use and were assumed to be constant throughout the historic and current periods. The return flow for the Lerdo Detention Facility is estimated as 60 percent of the groundwater pumped for the facility minus recycled water delivered for agricultural irrigation. The return flow for the Lerdo Detention Facility was assumed to be constant throughout the historic and current periods. The North Kern Golf Course return flow has two components, urban return flow and irrigation return flow. The urban return flow is estimated as 60 percent of the non-irrigation water use at the North Kern Golf Course. The irrigation return flow is estimated as 10 percent of the water used for irrigation. The implementation of conservation practices and reduction of irrigated acres decreased the amount of return flow throughout the historic and current periods.

4.3.7 Managed Aquifer Recharge

Surplus surface water is sent to CWD’s recharge basins and Poso Creek for groundwater recharge. Surplus waters sources include Poso Creek diversions, treated produced water, Kern River water, State Water Project water, Central Valley Project water, and other water for banking/exchange. WY 2009 was the last year Poso Creek was used for groundwater recharge. Currently, managed aquifer recharge occurs through the East Poso Creek Basin and the Famoso Basins.

Poso Creek has been a source of water for the CWD since 2000. The Permit to divert water is at a rate of about 110 cfs with the total annual volume limited to 30,000 acre-feet between November 1 and June 14 of the following year. The first 135 cfs measured at the Highway 65 gage is allocated to the CWD (CWD 2015). Diversions from Poso Creek are delivered to the Famoso Basins for groundwater banking. The Poso Creek Diversion includes a concrete check structure for diversion to the Famoso Water Banking Project and CWD distribution system. The CWD is permitted to divert up to 110 cfs and 30,000 acre-feet annually, between November 1 and June 14 within the water year. At Highway 65, the CWD can divert up to 135 cfs measured at the Trenton Weir. Eight temporary sand berms are maintained in Poso Creek to provide diversion of 40 cfs for recharge to underground storage with an annual limit of 17,899 acre-feet (CWD, 2007). The Famoso Groundwater Banking Project basins provide percolation ponds for percolation of surplus water for groundwater replenishment or banking. There are seven spreading basins at the Famoso site with a combined area of 374 acres and storage capacity of 834 acre-feet. The depth to groundwater under the Famoso Basins is 300 to 350 feet (K/J, 2011). Based on a long-term infiltration rate of 0.3 feet per day, the recharge capacity of the Famoso basins is approximately 14,000 acre-feet per year (CWD, 2007). East Poso Basin has a storage capacity of 400 acre-feet (Table 4-7).

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 78 TODD GROUNDWATER Table 4-7 Summary of Managed Aquifer Recharge (Acre-Feet per Water Year).

Historical Period Current Period

(1995-2014) (2015-2017) Facility Total Average Total Average Recharge Basins 58,181 2,909 43,107 14,369 Poso Creek 63,940 3,197 0 0 Total MAR 122,120 6,106 43,107 14,369

An annual average of 6,106 acre-feet per year was recharged and banked through East Poso Basin, Famoso Groundwater Banking Project Basins, and Poso Creek during the twenty-year historic period and 14,369 acre-feet during the current period (Table 4-7). During the historic period, the average annual volume of recharge water ranges from zero in WYs 1994 and 1995 to 29,629 acre-feet in WY 2011.

4.3.8 Stream Natural Recharge

The estimated average annual volume of percolation through the Poso Creek streambed during the historic period is 6,106 acre-feet (Table 4-8). Flows measured at the Highway 99 gage are compared with the flows at the Highway 65 gage to estimate infiltration losses to the subsurface. Surface runoff within the Cawelo GSA, private riparian diversions, and diversions by CWD are accounted for when estimating percolation losses. Groundwater is not hydraulically connected to Poso Creek and does not contribute to streamflow. Percolation losses occur every water year when there is flow in Poso Creek. Measurable flow occurred in Poso Creek between the Highway 65 and 99 gages during fourteen years of the twenty-year historic period.

Table 4-8 Summary of Stream Natural Recharge (Acre-Feet per Water Year).

Historical Period Current Period

(1995-2014) (2015-2017) Stream Total Average Total Average Poso Creek 130,645 6,532 40,468 13,489 Small Watershed 10,349 517 0 0 Total Natural Recharge 140,994 7,050 40,468 13,489

WY 1998 was unusually wet and is the only year during the historic period in which measurable surface runoff is shown between the Highway 65 and 99 gages. The difference in flows reflects surface runoff entering Poso Creek between the two gages. During other wet years such as WYs 1995 and 2011, normally dormant ephemeral streams in small watersheds within the Cawelo GSA were actively flowing. Storm water runoff for small watersheds was estimated using the SCS method. These ephemeral streams contributed to percolation through their streambeds. Fifty percent of the flow in these streams was assumed to percolate through the streambed and to groundwater. During the historical period, the average annual volume of streambed percolation in small watershed is 517 acre-feet. No significant percolation is estimated to have occurred during the current period.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 79 TODD GROUNDWATER 4.3.9 Precipitation Percolation

Percolation of winter precipitation over irrigated agricultural land, precipitation over non-irrigated land, and stormwater runoff is summarized in Table 4-9.

Table 4-9 Summary of Precipitation Percolation (Acre-Feet per Water Year).

Historical Period Current Period

(1995-2014) (2015-2017) Source Total Average Total Average Stormwater Recharge 12,678 634 1,514 505 Native/Undeveloped Return Flow 24,581 1,229 2,940 980 Total Natural Recharge 37,259 1,863 4,455 1,485

During wet years, storm water runoff occurs, percolating as it flows across the land surface and where it collects in low lying areas. Storm water runoff was estimated using the SCS method with 30 percent assumed to flow to creeks with the other 70 percent going to consumptive loss, ET, and percolation. Eighty-five percent of the storm runoff that does not reach the creek is assumed to percolate to groundwater. The estimated, average annual volume of percolation of storm water runoff is 634 acre- feet during the twenty-year historic period and 505 acre-feet during the current period.

During the twenty-year historic period, the average annual recharge from precipitation for non-irrigated land is 1,863 acre-feet. In the Cawelo GSA, non-irrigated land includes urban, non-irrigated agricultural land, and agricultural land in the winter. In non-irrigated areas of the Cawelo GSA, percolation of precipitation is estimated as 8 percent of the monthly precipitation less 0.5 inches for consumptive loss or zero when precipitation is less that the consumptive loss.

4.3.10 Historical and Current Water Budget Summary

Surface water inflows and outflows are summarized for the historic and current periods in Table 4-10. Imported water deliveries are the largest inflow of surface water to the Cawelo GSA with an average annual volume of 81,838 during the historic period and declining to 67,731 during the current period. Evapotranspiration is the largest outflow of surface water during the twenty-year historic period for an average of 72 percent of the annual surface water outflow and as high as 86 percent during dry years. Crop water requirements are met by a combination of effective precipitation, surface water provided by CWD, and groundwater pumping in amounts that vary according to availability of effective precipitation and imported surface water.

Agricultural and managed recharge are two beneficial uses for which surface water is diverted to and applied for within the Cawelo GSA. The average annual volume of water applied for irrigation (agricultural beneficial use) during the twenty-year historic period is about 120,000 acre-feet per year. Managed recharge includes losses from canals and the distribution system and water applied to the East Poso and Famoso Basins and water detained in or discharged to Poso Creek for Banking or groundwater replenishment. The average annual volume of water applied for managed recharge during

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 80 TODD GROUNDWATER the twenty-year historic period is about 6,100 acre-feet. Canal and distribution system losses are applied over the current (2012) service area of the CWD (33,071 acres) (CWD, 2015).

Agricultural use is the predominant beneficial use for which groundwater is extracted within the Cawelo GSA as shown in Table 4-10. The average annual volume of groundwater extracted for agriculture during the twenty-year historic period is 39,878acre-feet and ranges from 26,330 acre-feet in WY 2010/2011 to 69,189 acre-feet during WY 2013/2014. Table 4-10 Surface Water Budget Summary (Acre-Feet per Water Year).

Historical Period Current Period

(1995-2014) (2015-2017) INFLOWS Total Average Total Average Imported Water Deliveries 1,636,752 81,838 209,194 69,731 Agricultural Pumping 797,552 39,878 166,355 55,452 Urban Pumping 21,243 1,062 3,116 1,039 Surface Water Inflows 350,179 17,509 75,267 25,089 Precipitation 691,808 34,590 99,716 33,239 Total Inflows 3,497,534 174,877 553,694 184,550 OUTFLOWS Exported Water Deliveries 40,256 2,013 12,338 4,113 Evapotranspiration (ET) 2,356,483 117,824 352,224 117,408 Percolation to Groundwater 318,621 15,931 45,137 15,046 Managed Aquifer Recharge 122,120 6,106 43,107 14,369 Stream Natural Recharge 140,994 7,050 40,468 13,489 Stream Outflow 271,606 13,580 16,385 9,288 Precipitation Percolation 37,259 1,863 4,455 1,485 Total Outflows 3,287,339 164,367 514,114 175,198

Inflows and outflows from the Cawelo GSA groundwater system are influenced primarily by water year type, duration of drought or wet periods and amount of managed aquifer recharge.. Groundwater outflow exceeded groundwater inflow during 14 years of the 20-year historic period. The largest groundwater inflows occurred in WYs 2011 and 2017 (84,394 and 88,052 AFY, respectively) which were both wet years with good surface water availability and very active managed aquifer recharge and water banking occurring. The groundwater inflows during WYs 2011 and 2017 are 61 percent and 68 percent larger than the groundwater inflow during the wettest year of the historic period, WY 1998. Managed aquifer recharge during WYs 2011 and 2017 was over 400 times greater than managed aquifer recharge in WY 1998. Groundwater inflows and outflows for the historic and current periods are summarized in Table 4-11. Irrigation return flow, part of percolation from the surface, is a consistent source of inflow to the Cawelo groundwater basin regardless of the water year type. Crop water requirements are met through precipitation and irrigation regardless of the water year type. Crops grown in the CWD are predominantly permanent crops where the distribution change from year to year is small resulting in return flows that are similar each year. Natural recharge through stream and precipitation percolation, managed aquifer recharge, and groundwater banking are dependent on the amount of precipitation which influences surface water availability for natural or managed recharge. Inflows and outflows from the Cawelo GSA groundwater system are influence by surface water availability which is influenced by the water year type, locally, regionally, and at the sources of

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 81 TODD GROUNDWATER imported water supplies. Surface water inflows and outflows from the Cawelo GSA are illustrated in the Surface Water Balance Chart shown in Figure 4-1. The largest inflow of surface water in most years is imported water which is dependent on the hydrologic conditions at the water sources. The largest most consistent outflow is ET which is dependent on crop distribution, irrigation efficiency, and local hydrologic conditions. Table 4-11 Groundwater Budget Summary (Acre-Feet per Water Year).

Historical Period Current Period

(1995-2014) (2015-2017) INFLOWS Total Average Total Average Percolation from the Surface 318,332 15,917 45,094 15,031 Managed Aquifer Recharge 122,120 6,106 43,107 14,369 Stream Natural Recharge 140,994 7,050 40,468 13,489 Precipitation Percolation 37,259 1,863 4,55 1,485 Total Inflows 618,994 30,950 133,167 44,389 OUTFLOWS Agricultural Pumping 797,552 39,878 166,355 55,452 Urban Pumping 21,243 1,062 3,116 1,039 Groundwater discharge to Streams 0 0 0 0 Total Outflows 818,795 40,940 169,472 56,491 INFLOWS - OUTFLOWS -199,801 -9,990 -33,304 -12,101

During the twenty-year historic period, as shown in Figure 4.2, outflow from the Cawelo groundwater basin exceeded inflow during 14 water years. The average annual change in storage during the historic period was -9,990 acre-feet. Significant positive increase in groundwater storage only occurred in WYs 1998 and 2011 with minor increases in four other water years. WYs 1998 and 2011 were exceptionally wet years. During the historic period, 199,801 acre-feet of groundwater has been removed from storage in the aquifer.

A period of drought began in WY 2012 and continued through the end of the historic period (WY 2014) and the first two years of the current period (WYs 2015 and 2016). Precipitation was as low as 3.07 inches during WY 2014 during the middle of the drought. Imported water supplies were reduced and little to no flow occurred in Poso Creek. Groundwater pumping increased to meet crop water requirements with 202,454 acre-feet removed from storage between 2013 and 2016. WY 2017 was a wet year with 32,735 acre-feet of active managed recharge occurring allowing 71,516 acre-feet of natural and managed recharge water to be returned to storage. The total volume of water removed from storage during the 20-year historic period is estimated to be 199,801 acre-feet (Table 4-11).

4.4 C2VSIMFG-KERN MODEL WATER BUDGET ANALYSIS

The primary goal of the C2VSim-Kern local model is to analyze historical, current, and projected water budgets for the entire Kern County Subbasin. In brief, the water budget data in the DWR regional C2VSim-FG model were revised with local water budget data provided by water and irrigation districts, municipalities, and GSAs in the Subbasin. To facilitate review of the revised input data in the model, the modeling team produced numerous local water budgets for distinct zones within the Subbasin, typically on a District- or GSA-basis, using the Z-Budget tool in the model. Tables providing average annual

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 82 TODD GROUNDWATER summaries using the checkbook method are provided in the text with additional data provided in Appendix F.

4.4.1 Application of the C2VSimFG-Kern Model

In general, input data for the C2VSimFG-Kern Model were revised for the Cawelo GSA based on the historical and current inflows and outflows described above. Although the C2VSimFG-Kern numerical model was based on the inflows and outflows from the checkbook method, the model analysis differs significantly from the checkbook analysis. Some of the more significant differences are summarized below:

• The model estimates urban pumping by populations and per capita water use rather than the metered pumping by well used by the checkbook method. The per capita water use was modified within reasonable and documented ranges to better match metered pumping data, as needed. • The Independent Demand Calculator (IDC) module of the model was used to conduct a soil moisture balance in the unsaturated zone, providing estimates of deep percolation of precipitation and applied water return flows based on current monthly surface water deliveries, soil properties, and antecedent soil moisture conditions. The checkbook method employed simplified assumptions for these estimates, using a percentage of rainfall for deep percolation and an average overall agricultural efficiency of 80 percent to estimate return flows (20 percent of applied water). • The model calculated effective precipitation and agricultural pumping based on METRIC ET crop demand and the estimated mix of crop types by model cell. The checkbook method calculated the METRIC ET for the Plan Area independent of crop type and used an analytical approach for developing monthly estimates of effective precipitation and agricultural pumping.

These differences highlight many of the model features being used to simulate various water budget components. By allowing the model to generate these components independently, the C2VSimFG-Kern model is preserved as a planning and management tool capable of predicting water budget components for future simulations.

The model water budget areas for the Cawelo GSA are based on boundaries of model cells, which do not precisely align with the Plan Area boundaries (Figure 4-3). Accordingly, the water budgets either include areas outside of the Plan Area or omit some areas within the Plan Area; these small differences in area prevent a direct comparison of some model water budget metrics to similar metrics in the checkbook. Notwithstanding these limitations, the model serves to corroborate the changes of groundwater in storage from the other methods and links aquifer response to historical and current groundwater management activities in the Plan Area.

4.4.2 Model Results for the Cawelo GSA

The results of the groundwater budget from the C2vSimFG-Kern model are presented for the northern and southern portions of the Cawelo GSA in Table 4-12, respectively. Each table provides a summary of the groundwater budget for both historical (WY 1995 – WY 2014) and current (WY 2015) study periods. Results for the historical Study Period are also presented graphically on Figure 4-4 and 4-5.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 83 TODD GROUNDWATER Although model input files are based on detailed checkbook data, the model output is organized a bit differently. Annual inflows (positive numbers) and outflows (negative numbers) are presented in Table 4-12 below and illustrated on Figure 4-4 and 4-5. Inflows associated with the deep percolation of precipitation and applied water (including surface water infiltration and pumping return flows) are combined in the second column of the table. Inflows associated with managed recharge and operational recharge in unlined canals are combined in table column 3. Recharge in the river channel is presented separately in table column 4 because the model calculates this separately based on natural stream flows. Groundwater pumping, presented in table column 5, represents the largest outflow and combines data from all pumpers including municipal, industrial, agricultural, small water systems, and domestic/other private pumping occurring in the Cawelo GSA.

Table 4-12: Historical and Current Groundwater Budget from C2VSimFG-Kern for the Cawelo GSA (1) (2) (3) (4) (5) (6) (7) (8) Water Deep Managed River Groundwater Net Basin Change in Year Percolation Recharge and Channel Pumping Subsurface Inflow Groundwater (precipitation, Canal Recharge Flows in Storage applied water Operational return flows) Recharge Units Acre-ft Acre-ft Acre-ft Acre-ft Acre-ft Acre-ft Acre-ft HISTORICAL STUDY PERIOD WY 1995 - WY 2014 1995 44,655 2,950 21,615 -55,260 -204 0 13,757 1996 39,774 3,634 15,806 -63,277 9,315 0 5,251 1997 48,648 10,542 26,197 -58,342 12,075 0 39,120 1998 60,325 11,296 43,972 -49,395 14,427 0 80,625 1999 39,131 9,172 13,719 -33,718 14,316 0 42,621 2000 33,659 6,747 8,549 -59,204 5,245 0 -5,004 2001 29,858 5,354 4,639 -69,729 -3,990 0 -33,868 2002 28,557 5,442 6,453 -73,513 -9,933 0 -42,994 2003 29,252 6,139 10,757 -67,615 -10,002 0 -31,469 2004 29,045 8,001 5,046 -82,990 -11,954 0 -52,852 2005 38,989 10,492 8,289 -48,835 -5,819 0 3,117 2006 40,939 7,808 8,346 -47,880 3,064 0 12,277 2007 38,549 7,754 3,148 -71,202 -2,373 0 -24,125 2008 33,352 7,260 10,467 -74,319 -8,393 0 -31,632 2009 31,998 7,616 7,728 -62,834 -14,054 0 -29,546 2010 37,381 8,921 15,765 -55,361 -11,278 0 -4,571 2011 65,870 31,156 30,280 -31,549 -16,518 0 79,239 2012 34,713 10,309 5,793 -51,443 -17,107 0 -17,735 2013 29,925 10,748 4,957 -109,211 -26,744 0 -90,325 2014 29,043 3,652 3,308 -113,801 -25,601 0 -103,398 Total 763,663 174,994 254,836 -1,279,479 -105,528 0 -191,514 Average 38,183 8,750 12,742 -63,974 -5,276 0 -9,576 CURRENT STUDY PERIOD WY 2015 2015 32,325 7,047 3,209 -118,797 -22,911 0 -99,127

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 84 TODD GROUNDWATER Subsurface inflows (positive numbers) and outflows (negative numbers) are shown in column 6 of each table and represent the net subsurface flow for each water year. Subsurface flows from the model (unavailable for the checkbook) account for the dynamic conditions around the Cawelo GSA boundary over time. The Cawelo GSA does not border the Kern County Subbasin margin, so there are no inflows from outside of the basin; therefore, this inflow is indicated by the 0s in table column 7.

Finally, table column 8 presents the annual change in groundwater in storage for the Cawelo GSA. The average annual inflows, outflows, and change in groundwater in storage for the historical Study Period are shown at the bottom of each table above the Current Study Period. An annual tabulation of inflows and outflows is presented on Figure 4-4. As indicated in Table 4-12, the average annual change in groundwater in storage is about -9,576 AFY for the Cawelo GSA that is graphically shown on Figure 4-6.

The C2VSimFG-Kern model provides the best available estimates of subsurface groundwater flows into and out of the Cawelo GSA. The model accounts for monthly dynamic conditions governing subsurface inflows and outflows over the entire historical and current study periods. Because these data are not included in the checkbook method, details of the subsurface flows are presented here. For the Cawelo GSA, an average annual net subsurface outflow of -5,276 AFY is estimated by the model (Column 6, Table 4-6). A detailed examination of these subsurface flows on an average annual basis indicates a net inflow of groundwater from areas adjacent to the Cawelo GSA (Table 4-13). The predominance of a net outflow of groundwater is to the north and west. This is historical groundwater elevations north of the Kern River, which are generally flow from east and south towards the north and west. The overall trend shows that groundwater outflows are increasing over the 20-year historical study period, especially from 2009 to 2014. This indicates that changes in groundwater conditions to the north and west are increasing the hydraulic gradient, and hence the groundwater outflows, from the Cawelo GSA.

Table 4-13: Net Subsurface Flows In/Out of Cawelo GSA

Average Annual Net Subsurface Flows Adjacent Agency Areas Flow (AFY) Net Inflow from East 30,876 Undistricted areas to east Net Inflow from South 2,229 Kern River GSA Net Outflow to West -20,262 North Kern WSD Net Outflow to North -13,662 Southern San Joaquin MUD Net Total Subsurface -5,276 Flow:

4.5 CHANGE IN GROUNDWATER STORAGE

The detailed water budget, developed using the checkbook method and the C2VSimFG-Kern model, indicates that, in general, the Cawelo GSA has experienced an average annual decrease in groundwater in storage of about 10,000 AFY on an average annual basis over the 20-year Study Period (Table 4-14). Given the magnitude of the total inflows and outflows average more than 1,400,000 AFY (Tables 4-14), the net change in groundwater storage is less than 1 percent of the total groundwater budget. However, the results show the effects of the recent drought with the 2012 and 2013 change in groundwater storage greater than the 20-year historical study period average. Furthermore, the 2015 change in storage is almost have of the 20-year historical study period average. Collectively, these

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 85 TODD GROUNDWATER results suggest that changing conditions due to recent droughts and availability of imported surface water supplies is contributing to increased groundwater use for water supply within the Kern County Subbasin that is resulting in the recent decreases in groundwater storage.

The water budget analysis using the checkbook method described above incorporated all of the physical recharge (inflows) and pumping (outflows) for the Plan Area to account for all Cawelo GSA groundwater- related activities and to better link aquifer response to ongoing management. This approach did not consider ownership of the water or management activities for and by others within the Cawelo GSA. KGA managers determined that the checkbook method required adjustment for water that had been recharged in the Kern County Subbasin but was contractually obligated to other agencies outside of the Basin. Accordingly, an adjustment was made to the checkbook water budget to account for the out-of- basin obligated water currently stored in the Kern County Subbasin.

Table 4-14: Method Comparison, Change in Groundwater in Storage, Cawelo GSA

Water Budget Change in Groundwater Comments Method in Storage (AFY)1 Tabulates recharge and pumping for the physical Checkbook -10,887 AFY groundwater system beneath the Cawelo GSA (Table 4-11) C2VSimFG-Kern Simulated inflows and outflows including subsurface flows -9,576 AFY Model (Table 4-12) 1Average Annual Change over Historical Study Period (WY 1995 – WY 2014) for the Cawelo GSA

4.5.1 Adjustments for Groundwater Banking and Export Obligations

The out-of-basin banking partners include the Zone 7 Water Agency (located in the Livermore area) and the Dudley Ridge Water District (located in Western Kings County). The total volume of banked water stored in the Cawelo GSA to out-of-basin banking partners was 30,402 acre-feet as of 2014 for an average annual volume of 1,520 AFY over the 20-year historical period. As of 2017, 37,023 acre-feet was obligated to the out-of-basin banking partners. The volume banked from 2014 to 2017 was an additional 6,621 acre-feet or 2,207 AFY. A comparison of the adjusted checkbook to the initial checkbook indicates a greater annual decline in groundwater in storage from -11,951 for the checkbook method and -11,096 AFY for the C2VSimFG-Kern results.

4.5.2 Sustainable Yield

Section 354.18(b)(7) of the GSP Regulations requires that an estimate of the basin’s sustainable yield be provided in the GSP (or in the coordination agreement for basins with multiple GSPs). SGMA defines “Sustainable yield” as the maximum quantity of water, calculated over a base period representative of long-term conditions in the basin and including any temporary surplus, that can be withdrawn annually from a groundwater supply without causing an undesirable result. SGMA does not incorporate sustainable yield estimates directly into sustainable management criteria. Sustainable yield is referenced in SGMA as part of the estimated basinwide water budget and as the outcome of avoiding undesirable results. Basinwide pumping within the sustainable yield estimate is neither a measure of, nor proof of, sustainability. Sustainability under SGMA is only demonstrated by avoiding undesirable results for the six sustainability indicators.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 86 TODD GROUNDWATER To determine the sustainable yield for the Cawelo GSA, the results of the C2VSimFG-Kern model over the historical base period from 1995 to 2014 were used for this estimation of sustainable yield. Using the model results, the sustainable yield was estimated using two methods that would estimate the amount of groundwater pumping that would avoid the undesirable result of a reduction in groundwater storage over the base period. The results

• Sustainable Yield from Groundwater Pumping – The model results produced an average annual groundwater pumping in the Cawelo GSA of 62,483 AFY with a decline in groundwater storage of 10,071 AFY. In addition, 1,520 AFY of out-of-basin groundwater banking obligations were documented remaining in the GSA. Subtracting the groundwater storage decline and out-of- basin groundwater banking obligations from groundwater pumping produced a sustainable yield of approximately 50,892 AFY.

• Sustainable Yield from Groundwater Recharge – The model results produced an average annual groundwater recharge in the Cawelo GSA of 53,157 AFY. The combined groundwater banking obligations along with the subsurface outflow from the GSA total 2,245 AFY. Subtracting these losses from the groundwater recharge produced a sustainable yield of approximately 50,892 AFY.

Sustainable yield estimates are part of SGMA’s required basinwide water budget. Although the SGMA regulations require single value of sustainable yield must be calculated basinwide, it should be noted that the sustainable yield can be changed by implementing recharge projects, variations in climate, or changes in stream flow conditions.

In general, the sustainable yield of a basin is the amount of groundwater that can be withdrawn annually without causing undesirable results. This sustainable yield estimate can be helpful for estimating the projects and programs needed to achieve sustainability.

4.5.3 Native Yield

The native yield is not part of the SGMA regulations. The native yield is comparable to the sustainable yield except that the only recharge that is included in the calculation is the natural, unallocated portion of the groundwater recharge. For the Cawelo GSA, this includes the groundwater recharge derived from precipitation or runoff from unallocated streams. Poso Creek, however, is an allocated stream where specific agencies or parties have rights to specific volumes of flow in the creek.

The C2VSimFG-Kern model results over the historical base period from 1995 to 2014 was again used for the estimation of native yield. The model results were used to determine the amount of precipitation recharge occurs irrigated agricultural areas and the native/urban/undeveloped areas of the GSA. Average precipitation falling in the Cawelo GSA over the historical base period based on C2VSimFG-Kern is 44,787 AFY. The total and average annual volume of precipitation that percolates to groundwater during the 1995 to 2014 base period is listed in Table 4-15. The contribution per acre is estimated by dividing the average annual contribution by the total area in the GSA.

The basinwide contribution is the relative proportion of the runoff along the basin margins from small, unallocated watersheds and inflow from the surrounding basin margin (from areas not defined as DWR groundwater basins) based on the C2VSimFG-Kern results. The Cawelo GSA accounts for about 3.1 percent of the total area of the Kern County Subbasin, so the 3.1 percent of the basin margin inflows

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 87 TODD GROUNDWATER were allotted to Cawelo GSA. The resulting native yield for the Cawelo GSA is 8,867 AFY which is approximately 0.157 acre-feet per acre (Table 4-15).

Although not a SGMA requirement, the native yield is being used in Kern County GSAs for determining a portion of the groundwater allocation within the basin.

Table 4-15: Native Yield estimation for the Cawelo GSA Total Average Contribution

Contribution Annual per acre INFLOWS AFY AFY AF/acre Precipitation Recharge in AG areas 102,973 5,149 0.091 Precipitation Recharge in other areas 43,724 2,186 0.039 Basinwide 30,641 1,532 0.027 Total Inflows 177,338 8,867 0.157

4.6 PROJECTED WATER BUDGETS

Projected water budgets are required to evaluate the performance of proposed management actions with respect to achieving groundwater sustainability. These projected water budgets establish expected baseline conditions to evaluate the impacts of GSA implementation. Projected water budgets were developed for Baseline conditions and expected Early Future and Late Future conditions. These water budgets cover a 50-year planning and implementation horizon.

Three predictive scenarios were developed by extending the “checkbook” version of the historical and current water budget

• Baseline scenario: Repeat historical hydrology with expected future water supply • Early Future scenario: 2030 climatic conditions and expected water supply • Late Future scenario: 2070 climatic conditions and expected water supply

Each scenario represents a different expected future hydrologic condition. These scenario water budgets provide a basis of comparison for evaluating proposed sustainability management actions and projects over the SGMA planning and implementation horizon. Tables providing average annual summaries using the checkbook method are provided in the text with additional data provided in Appendix G.

4.6.1 Baseline Development

The 50-year planning and implementation horizon begins in WY 2021 after GSP submittal and review and extends through WY 2070. This 50-year sequence was developed using actual hydrologic data and water management practices documented in the 20-year historical Study Period WY 1995 – WY 2014, which represents average hydrologic conditions. These years were re-combined/repeated into a 50-year sequence, which also represented average hydrologic conditions in terms of average precipitation and the long-term mean flow on the Kern River. In addition, the intervening years between the last year of

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 88 TODD GROUNDWATER water budget data (Current Condition Study Period of WY 2015) and the beginning of GSP implementation (2021) had to be “bridged” to represent WY 2016 through 2020.

Projected water budgets under Baseline and expected future climatic conditions are required to evaluate the potential effects of climate change with respect to achieving sustainability. The Baseline water budget was modified using DWR climate change data sets for Kern County following procedures outlined in the Guidance Document to develop the Early Future and Late Future scenario models (CDWR, 2018). This approach incorporates GSA requirements and includes the use of:

• A 50-year time-series of historical precipitation, evapotranspiration and stream flow information as the future baseline hydrology conditions; • The most recent land use, METRIC-based evapotranspiration, crop coefficient and urban population growth information as the baseline condition for estimating future water demands; • The most recent water supply projections as the baseline condition for estimating future surface water supply; • DWR Climate Change Guidance and Data Sets (CDWR, 2018) to incorporate estimated climate change conditions for the Kern Subbasin; • Specialized analysis of the Kern River watershed and estimated runoff volumes under climate change conditions; • Specialized analysis of CVP deliveries to Kern County under climate change conditions incorporating implementation of the San Joaquin River Restoration Program; • Specialized analysis of SWP deliveries to Kern County under climate change conditions incorporating implementation of the OCAP Biological Opinion and recent changes in Table A and Article 21 allocations.

Each water budget projection represents the 50-year planning and implementation period WY 2021- 2070. Water years 1995-2014 represent the period for developing predictive scenario hydrology. Detailed demand and supply data are available for this period, and most subbasin water delivery infrastructure was fully developed by the middle of this period. The average Kern River inflow for this period is also very close to the long-term average Kern River inflow. This period is only 20 years long, so a 50-year sequence of historical hydrology was developed by repeating data from this period in the sequence shown in Table 4-16 to match long-term average flows on the Kern River and to assure that the baseline does not end in an extreme drought or wet year.

Table 4-16. Historical hydrology for each simulation period.

Simulation Period Hydrology

WY 2021-2032 WY 2003-2014 WY 2033-2052 WY 1995-2014 WY 2053-2070 WY 1995-2012

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 89 TODD GROUNDWATER Demand data were assembled as follows:

• WY 2013 land use was designated as current land use for all scenarios as drought conditions likely reduced agricultural production in 2014 and 2015. • Monthly urban demands for WY 2013 were projected each year with a 1 percent annual growth. • WY 2013 urban populations were increased by the average rate for Kern County published by the California Department of Finance.

Input data were first developed for the Baseline water budget for WY 2021-2070. Development of this input data generally involved repeating data from the historical water budget in the appropriate sequence. Baseline water budget data files were then modified following DWR guidelines to produce input data for the Early Future and Late Future scenario models. Details on how each data set was modified are provided below.

4.6.2 Imported Water Deliveries

Flows on the Kern River are regulated, so the unimpaired streamflow method was not appropriate. Projected Kern River flows at First Point under 2030 and 2070 central tendency conditions were estimated by GEI for calendar years 1961-2010. This analysis considered the impacts of reduced runoff in each sub-watershed contributing to the Kern River to develop revised streamflow estimates for Kern River at First Point. The WYs 1961-2010 are used to represent projected WYs 2021 to 2070.

The Kern Subbasin is served by both the CVP and the SWP; however, recent changes in CVP and SWP operations and their impacts on future surface water supplies are reflected in surface water diversion rates for the three scenarios. DWR provided projected future deliveries from the CVP and SWP for water years 1922-2003, derived from CalSim-II modeling conducted for WSIP. DWR’s CVP and SWP projections as provided do not fully incorporate these operational changes (Table 4-17).

Table 4.17 Data used to estimate State Water Project deliveries for future scenarios.

Period Baseline 2030 Climate Conditions 2070 Climate Conditions 2030-Level CALSIM, 1995-2003 CALSIM 2030 Projection CALSIM 2070 Projection Increased by 3.03 % Actual, Adjusted for OCAP BO Adjustment, OCAP BO Adjustment, 2004-2007 OCAP BO reduced by 3.03 % reduced by 8.09% 2008-2014 Actual Actual, reduced by 3.03% Actual, reduced by 8.09%

Future SWP deliveries will be affected by operational changes implemented between 2004 and 2008 including the OCAP Biological Opinion, reduced Table A contract amounts and reduced Article 21 deliveries. The SWP projections representing 2030 and 2070 climatic conditions provided by DWR were modified as described in Table 4-17 to incorporate the impacts of SWP operational changes in the three scenarios. 2019 SWP Table A contract amounts were used to allocate these SWP deliveries to individual districts such as CWD.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 90 TODD GROUNDWATER Delivery of CVP water for the Baseline water budget were developed by repeating input flow rates from the historical water budget in the appropriate sequence. Future CVP deliveries will be affected by implementation of the San Joaquin River Restoration Program (SJRRP). CVP for future scenarios were modified from the Baseline using DWR provided factors for 2030 and 2070 central tendency climatic conditions for diversions. For the future scenarios, treated produced water deliveries were held constant for twenty years at 30,838 acre-feet per year which is 28 percent above the historical average rate and 75 percent above the average current rate of delivery. The future reliability of treated produced water is based on projections from local oil field operators. The projected reliability for future treated produced water for the Cawelo GSA is expected to be stable for the next twenty years. After twenty years, the delivery rates for treated produced water decrease by one percent every year from 2041 through 2070 to reflect the aging of the oil fields and reduction in oil and gas production. These deliveries are not impacted by changing climatic conditions. Delivery of other water for banking/exchanges for the Baseline water budget were developed by repeating flow rates from the historical water budget in the appropriate sequence. Banking/exchanges for future scenarios were modified from the Baseline using DWR provided factors for 2030 and 2070 central tendency climatic conditions. The total volume of imported water deliveries, including treated produced water is summarized in Table 4-18.

Table 4-18: Projected Future Surface water Budget Summary for Baseline, 2030 Climate Change and 2070 Climate Change Conditions over 50-year Hydrologic Period (Acre-Feet per Water Year)

2030 Climate 2070 Climate Baseline Conditions Conditions Conditions INFLOWS Total Average Average Imported Water Deliveries 71,574 70,660 68,970 Agricultural Pumping 46,131 49,740 57,492 Urban Pumping 1,118 1,118 1,118 Surface Water Inflows 17,455 16,265 15,063 Precipitation 34,590 34,697 34,375 Total Inflows 170,842 172,480 177,019 OUTFLOWS Exported Water Deliveries 2,013 1,872 1,876 Evaporation (ET) 117,300 120,915 126,433 Percolation from the Surface 14,888 15,573 15,970 Managed Aquifer Recharge 6,506 6,099 8,044 Stream Natural Recharge 7,050 7,100 7,301 Stream Outflow 13,580 13,041 12,791 Precipitation Percolation 1,863 1,038 1,028 Total Outflows 163,199 166,294 174,171 INFLOWS - OUTFLOWS 7,643 6,186 2,847

4.6.3 Precipitation Rates

Precipitation rates for the Baseline water budget were developed by repeating precipitation rates from the historical water budget in the appropriate sequence. DWR provided monthly change factors for

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 91 TODD GROUNDWATER Zone 20 for precipitation under 2030 and 2070 central tendency climatic conditions for calendar years 1915 through 2011. The Baseline scenario precipitation rates were multiplied by the appropriate factors to produce precipitation rates for the Early Future and Late Future scenarios. The total volume of precipitation is summarized in Table 4-18.

4.6.4 Evapotranspiration Rates

Baseline crop ET rates are based on the 2013 distribution of crops with projected ET rates determined by the appropriate hydrologic year and adjusted for projected total irrigated acres for water year. Urban pumping conditions for 2013 which represent recent average climate conditions were projected forward with a 1 percent annual growth rate for Baseline and Early Future and Late Future scenarios.

Municipal and industrial use related ET is projected forward based on 2013 data with one percent annual growth rate. Evapotranspiration rates native and undeveloped land for the baseline water budget were developed by repeating input evapotranspiration rates from the historical water budget in the appropriate sequence. DWR provided monthly change factors for ET values for Subregion 20 in the Kern Subbasin Zone under 2030 and 2070 central tendency climatic conditions for calendar years 1915 through 2011. Baseline scenario ET rates were then multiplied by the appropriate factors to produce time-series ET rates for the Early Future and Late Future scenarios. The total volume of evapotranspiration is summarized in Table 4-18.

4.6.5 Surface Water Inflows and Outflows

Inflow and outflow rates for Poso Creek and inflow rates for small watersheds for the Baseline water budget were developed by repeating input inflow rates from the historical water budget in the appropriate sequence. DWR provided unimpaired streamflow change factor datasets for Central Valley streams. These unimpaired streamflow change factors were used to modify Baseline inflows to produce Early Future and Late Future scenario inflows for Poso Creek. Climate change impacts on flow rates for small watersheds were evaluated by recalculating flow rates using the SCS method for future scenarios based on 2030 and 2070 central tendency climatic conditions rainfall data. The total volume of surface water inflows and outflows is summarized in Table 4-18.

4.6.6 Groundwater Pumping

Agricultural groundwater pumping rates for all scenarios were developed by recalculating the pumping rates based on crop ET, precipitation rates, district pumping, and available surface water deliveries for Baseline and 2030 and 2070 central tendency climatic conditions. Urban pumping conditions for 2013 which represent recent average climate conditions were projected forward with a 1 percent annual growth rate for Baseline and Early Future and Late Future scenarios. The total volume of groundwater pumping is summarized in Table 4-18 and 4-19.

4.6.7 Percolation to Groundwater

Percolation to groundwater results from precipitation and land application of water. Precipitation percolation rates for the Baseline water budget were developed by repeating percolation rates from the historical water budget in the appropriate sequence. DWR provided monthly change factors for Zone 20 for precipitation under 2030 and 2070 central tendency climatic conditions. The Baseline scenario precipitation percolation rates for stormwater recharge and native/undeveloped land were recalculated

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 92 TODD GROUNDWATER based on Baseline precipitation rates. The percolation rates were recalculated using precipitation rates for the Early Future and Late Future scenarios.

Table 4-19: Projected Future Groundwater Budget Summary for Baseline, 2030 Climate Change and 2070 Climate Change Conditions over 50-year Hydrologic Period (Acre-Feet per Water Year)

2030 Climate 2070 Climate Baseline Conditions Conditions Conditions INFLOWS Total Average Average Percolation from the Surface 14,888 15,573 14,888 Managed Aquifer Recharge 6,506 6,099 8,044 Stream Natural Recharge 7,050 7,100 7,050 Precipitation Percolation 1,863 1,692 1,863 Total Inflows 30,306 30,464 33,071 OUTFLOWS Agricultural Pumping 46,131 49,740 46,131 Urban Pumping 1,118 1,118 1,118 Groundwater discharge to Streams 0 0 0 Total Outflows 47,249 50,858 58,610 INFLOWS - OUTFLOWS -16,943 -20,394 -25,539

Land application of water occurs through irrigation, water conveyance, municipal and industrial uses, and urban uses. Irrigation return flow was recalculated for Baseline and Early Future and Late Future crop ET demands. Conveyance recharge was recalculated for Baseline and Early Future and Late Future imported water delivery rates. Municipal, industrial and urban return flows for 2013 which represent recent average climate conditions were projected forward with a 1 percent annual growth rate for Baseline and Early Future and Late Future scenarios. The total volume of percolation to groundwater is summarized in Table 4-18 and 4-19.

4.6.8 Managed Aquifer Recharge

Managed aquifer recharge rates for the Famoso and East Poso Basins for the Baseline water budget were developed by combining the recharge rates from the Famoso and East Poso Basins with the Poso Creek site (no longer in use) from the historical water budget and repeating these combined rates in the appropriate sequence. Managed aquifer recharge rates for future scenarios were modified from the Baseline using DWR provided factors for diversions for 2030 and 2070 central tendency climatic conditions. The total volume of managed aquifer recharge is summarized in Table 4-18 and 4-19.

4.6.9 Stream Recharge

Rates for recharge through the streambeds of Poso Creek and minor streams within the GSA along with the recharge that occurs due to stormwater runoff that occurs with larger precipitation events for the Baseline water budget were developed by repeating recharge rates from the historical water budget in the appropriate sequence. Recharge rates for Poso Creek, minor streams, and storm water runoff were recalculated using the SCS method for future scenarios based on 2030 and 2070 central tendency climatic conditions rainfall data. The total volume of stream recharge to groundwater is summarized in

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 93 TODD GROUNDWATER Table 4-18 and 4-19. Projected future water budgets also assume that no groundwater discharge to surface water will occur as was noted in the historical water budgets.

4.6.10 Projected Water Budget Summary

The projected changes in storage for the baseline and 2030 and 2070 central tendency climatic conditions decline between 2021 and 2070 and are summarized in Figure 4-7 and Table 4-20. The volume of water added to storage during wet years does not offset the reduction in storage that is the general trend. For the baseline projection, a total of 936,358 acre-feet of water is removed from storage over the 50-year period. An additional 19 percent is removed from storage during the 50-year period under 2030 central tendency climatic conditions. Under 2070 central tendency climatic conditions, 46 percent additional water is removed from storage during the projected 50-year period.

The potential deficits projected in Table 4-20 for the 2030 Climate Change conditions occur only 10 years after GSP implementation in 2020 and are within the window for achieving sustainability. Accordingly, those conditions are the focus of the priority GSP projects. It is recognized that the 2070 Climate Change conditions are less certain, given the long-term 50-year implementation and planning horizon. As part of the GSP, future Annual Reports and five-year GSP evaluations will be used to update these potential projected deficits when much more detailed information from the Cawelo GSA water budgets will be available. During those re-evaluations, the GSP will be adapted as needed to maintain sustainable groundwater management.

Comparing the checkbook water budget results in Table 4-19 to the C2VSimFG-Kern water budget results in Table 4-20 show that both methods result in similar estimates of groundwater storage deficits over the implementation and sustainability periods. Accordingly, this deficit is added to the 2030 climate Change conditions deficit of 50,391 AFY in Table 4-12 for a combined potential future water budget deficit of -79,544 AFY. These results are shown graphically on Figure 4-7.

The potential decreases in supply and increases in demand in Table 4-20 are used to develop appropriate projects and management actions that target a more sustainable water budget. Projects and management actions are described in Section 8 of this GSP.

Table 4-20: Future Baseline Groundwater Budget Summary Comparison (Acre-Feet per Water Year).

Implementation Period Sustainability Period

(2021-2040) (2041-2070) Baseline Total Average Total Average Total Inflows 606,124 30,306 919,633 30,654 Total Outflows 944,987 47,249 1,517,128 50,571 INFLOWS - OUTFLOWS -338,863 -16,943 -597,495 -19,916 2030 Total Average Total Average Total Inflows 609,289 30,464 915,408 30,514 Total Outflows 1,017,168 50,858 1,619,364 53,979 INFLOWS - OUTFLOWS -407,879 -20,394 -703,956 -23,465 2070 Total Average Total Average Total Inflows 661,430 33,071 995,906 33,179 Total Outflows 1,172,206 58,610 1,853,945 61,798 INFLOWS - OUTFLOWS -510,776 -25,539 -858,040 -28,601

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 94 TODD GROUNDWATER 4.7 PROJECTED WATER BUDGET RESULTS USING C2VSIMFG-KERN

The projected water budget results using the C2VSimFG-Kern Model were developed in cooperation between the KGA and KRGSA. The KGA managers decided that the C2VSimFG-Kern model results for the projected future water budgets would be presented at the basin scale, but not for each of the local districts and GSAs as was done for the historical water budgets. This was done because of application of some of the assumptions to develop the projected future conditions included some that were more generalized over the basin rather than specifically applied to each district due to the uncertainty in projecting future conditions. The C2VSimFG-Kern model results for the projected future water budgets are included in the KGA Umbrella GSP (GEI, 2019). A more detailed assessment of projected water budgets has been developed for both the Subbasin and the KGA using the C2VSimFG-Kern model.

4.8 DATA AND KNOWLEDGE GAPS FOR THE WATER BUDGET ANALYSIS

As described above, surface water and groundwater components of the water budget analysis represent measured, estimated, and/or inferred amounts of water, each associated with an increasing level of uncertainty. Some uncertainty associated with missing or incomplete historical data cannot be addressed simply due to an absence of information; however, these missing data may not represent significant levels of “uncertainty” or a “data gap” as defined by SGMA. Both of these terms are defined in the regulations as representing significant unknowns that would affect the ability to assess whether a basin is being sustainably managed. For the water budget, the data gap analysis focuses on the larger water budget components that would likely affect the efficacy of GSP implementation or the ability to assess future sustainable management. These include:

• Small water systems and industrial water supply pumping • Agricultural Pumping • Agricultural Return Flows • Stormwater and runoff • Subsurface Groundwater Flows

Although there are only a few active small water systems and industrial facilities within the Cawelo GSA, we do not have consistent groundwater pumping data for these systems. Although some estimates were required to fill incomplete historical data, these estimates are considered reasonable because they are based on other relatively accurate datasets such as population, water demands, and metered data covering similar time intervals. Coordination with the larger small water systems and industrial facilities to collect additional data would reduce this uncertainty and improve tracking of non-agricultural pumping in the GSA.

Private agricultural pumping is inferred based on estimated crop ET, surface water deliveries, and effective precipitation. Although the METRIC ET dataset provides a reasonable estimate for the cumulative agricultural pumping, pumping details are unknown for any specific location. Private agricultural wells are located throughout the Cawelo GSA, but there is no information on which wells are pumping when and how much. Because METRIC ET data are available for the historical study period, estimates are considered sufficient for the historical water budgets. However, future pumping will require either ongoing ET analysis or an alternative method to estimate pumping. This uncertainty in effective precipitation contributes to the uncertainty of how much water needs to be pumped to satisfy the total crop demand.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 95 TODD GROUNDWATER Even if ET and effective precipitation are better known, deep percolation of agricultural return flows associated with agricultural pumping are unknown and are qualitatively based on past analyses and general soil and irrigation assumptions. However, variability in soil and geologic conditions in the Cawelo GSA indicate the potential variability return flow rates across the area.

The development of the groundwater budget indicates the influence of stormwater and runoff on groundwater recharge during above average to wet hydrologic years. Although not a major source of recharge, the analysis of the water budget in Section 4 indicates that it is significant is building up groundwater levels during wet periods. However, this assessment was made using a generalized hydrologic approach that provides a level of uncertainty to the analysis. Additional assessment of the stormwater runoff conditions in the Cawelo GSA will help improve the water budget assessment.

Finally, subsurface flows around the Cawelo GSA perimeter are associated with significant uncertainty. Depending on groundwater recharge, availability of imported surface water to meet agricultural supply, the activities at nearby banking and recovery projects, and other factors, these flows are highly dynamic and change seasonally and with wet/drought cycles. The C2VSimFG-Kern model is the best available tool for analysis of subsurface flows, but this component of the water budget will be more difficult to manage in the future. As GSP implementation projects occur at various times and rates in areas surrounding the Cawelo GSA, the ability to store and capture recharged water will depend on local hydraulic gradients, which are affected by water levels outside of the GSA and the resultant subsurface flows.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 96 TODD GROUNDWATER 5 SUSTAINABILITY GOAL AND UNDESIREABLE RESULTS

This chapter presents the Undesirable Results statements for the Cawelo GSA and presents a set of quantitative thresholds for monitoring points that indicate where Undesirable Results might occur within the Cawelo GSA. These statements and thresholds will shape the monitoring network to detect Undesirable Results during the implementation of this GSP.

Sustainability indicators refers to any of the effects caused by groundwater conditions occurring throughout the basin that, when significant and unreasonable, represent undesirable results, as described in Water Code Section 10721(x). The approach to definition of undesirable results in the Cawelo GSA relies on analysis of the six sustainability indicators as defined by SGMA:

• Chronic lowering of water levels • Reduction of groundwater in storage • Seawater intrusion • Degradation of water quality • Land subsidence that substantially interferes with surface land uses • Depletion of interconnected surface water that adversely impact beneficial use of surface water.

GSP regulations state that if any of these indicators are causing significant and unreasonable effects in the Subbasin, then that indicator is defined as an undesirable result. Each of these indicators is examined with respect to conditions within the Cawelo GSA based primarily on the data and analysis described in Section 2 (Plan Area), Section 3 (Basin Setting) and Section 4 (Water Budgets). Conditions relating to each indicator are used to:

• refine the local Cawelo GSA GSP definition of undesirable results, • determine if an undesirable result is occurring, and • propose an appropriate minimum threshold and measurable objective as targets for elimination and future avoidance of undesirable results.

The GSAs in the Kern County Subbasin have coordinated their approach to sustainable management criteria and have defined consistent undesirable results for the entire Subbasin. These definitions provide a flexible construct that allow each GSA to further define local undesirable results within the Subbasin framework. This GSP re-states the Subbasin definition of each undesirable result and refines each definition to local conditions within the Cawelo GSA.

5.1 SUSTAINABILITY GOAL

The Sustainability Goal of the Cawelo GSA is to manage groundwater sustainably in the Cawelo GSA to:

• support current and future beneficial uses of groundwater including agricultural, industrial, public supply, domestic, and environmental • optimize conjunctive use of surface water, imported water, and groundwater • avoid or eliminate undesirable results throughout the planning horizon.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 97 TODD GROUNDWATER This sustainability goal is based on the information in the Plan Area (Section 2), Basin Setting (Section 3), and Water Budget (Section 4) sections of this GSP. The Sustainability goals are defined as the culmination of conditions in the absence of undesirable results within 20 years of the applicable statutory deadline and are intended to maintain a viable groundwater resource for the beneficial use of the people and the environment of the Cawelo GSA now and into the future.

The Cawelo GSA will achieve this goal through coordinated implementation of projects and management actions to increase groundwater recharge, expand groundwater banking programs, increase access to available surface water and other local water supplies and reduce groundwater demand for a more sustainable future. As described in subsequent sections, a series of projects and management actions are proposed that begin in Year One and are implemented over the 20-year timeline for achieving sustainability. This will allow early monitoring to assess project performance and allow time for project adjustments, as needed. It should be noted that these projects involve continuation and expansion of similar ongoing management actions that already have a proven track record for successful conjunctive management.

5.2 APPROACH TO UNDESIRABLE RESULTS

This section describes the Undesirable Results defined for the Cawelo GSA Area. Pursuant to the GSP Emergency Regulations, Undesirable Results are to be defined consistently throughout the basin (23-CCR § 354.20). As noted in the Sustainability Goal, sustainable management is meant to eliminate and avoid any undesirable results in the Plan Area over the planning and implementation horizon. However, each GSA in the Kern County Basin has unique hydrogeological and land use conditions. Therefore, the basin-wide definitions of Undesirable Results were considered and adjusted as necessary to better reflect Cawelo GSA groundwater conditions. Information is provided below for each effect as it applies to the Basin. For any indicator not present, a justification for not establishing Undesirable Results is provided. This information was developed based on the California Water Code, SGMA regulations, BMPs, and stakeholder input.

5.3 CHRONIC LOWERING OF GROUNDWATER LEVELS

SGMA defines an undesirable result from chronic lowering of water levels as “indicating a significant and unreasonable depletion of supply if continued over the planning and implementation horizon” (§10721(x)(1). The definition considers the duration of water level declines, as well as the cause. Specifically, the definition continues: “Overdraft during a period of drought is not sufficient to establish a chronic lowering of groundwater levels if extractions and groundwater recharge are managed as necessary to ensure that reduction in groundwater levels or storage during a period of drought are offset by increasing groundwater levels or storage during other periods” (§10721(x)(1)).

5.3.1 Description of Undesirable Result

The SGMA definition of undesirable results, re-stated above, also links chronic lowering of water levels to other sustainability indicators such as reduction of groundwater in storage. In fact, a chronic lowering of water levels is fundamental to most of the remaining sustainability indicators. The Undesirable Result for the chronic lowering of groundwater levels is a result that causes significant and unreasonable reduction in the long-term viability of domestic, agricultural, municipal, or environmental uses over the planning and implementation horizon for the Cawelo GSA. During development of the GSP, undesirable results identified by stakeholders included:

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 98 TODD GROUNDWATER • Significant and unreasonable unusable and stranded groundwater extraction infrastructure • Significant and unreasonable reduced groundwater production • Significant and unreasonable increased pumping costs due to greater lift and deeper installation or construction of new wells • Significant and unreasonable number of shallower domestic wells going dry Declining water levels indicate groundwater storage reductions and increase the potential for inelastic land subsidence in susceptible areas. Undesirable results related to these other sustainability indicators are discussed separately in the associated section below. This section focuses on issues with a deepening groundwater supply and the difficulty in accessing that supply, primarily with groundwater wells.

5.3.2 Definition of Undesirable Result

In coordination with other GSAs in the Subbasin, the KGA developed a Subbasin-wide definition of an undesirable result for each sustainability indicator (December 14, 2018). This undesirable result for chronic lowering of water levels in the Subbasin is defined as:

The point at which significant and unreasonable impacts over the planning and implementation horizon, as determined by depth/elevation of water, affect the reasonable and beneficial use of, and access to, groundwater by overlying users.

This is determined when the minimum threshold for groundwater levels are exceeded in at least three (3) adjacent management areas which represent at least 15 percent of the sub-basin or greater than 30 percent of the Sub-Basin (as measured by each Management Area). Minimum thresholds shall be set by each of the management areas through their respective Groundwater Sustainability Plans.

The definition for an undesirable result due to water levels has been tested against conditions in Cawelo GSA determine whether undesirable results are occurring. This analysis, in turn, is used to select an appropriate minimum threshold for the water level sustainability indicator in each MA. Cawelo GSA is selecting appropriate minimum thresholds consistent with the Subbasin definition above.

As noted above, groundwater level declines during a period of drought are not sufficient to establish an undesirable result for chronic lowering of groundwater levels if extractions and groundwater recharge are managed as necessary to ensure that reductions in groundwater levels or storage during a period of drought are offset by increases in groundwater levels or storage during other periods. Furthermore, dewatering of a single shallow well is not considered significant and unreasonable and is not considered an undesirable result. Accordingly, a proportional subset of monitored wells is used to define an undesirable result. Nonetheless, the GSAs are evaluating management actions for domestic wells that may be dewatered due to future declining groundwater levels.

5.3.3 Potential Causes of Chronic Lowering of Groundwater Levels

The potential causes of Undesirable Results due to chronic lowering of groundwater levels in the Cawelo GSA Area include increased pumping and/or reduced recharge. Because the primary use of groundwater from the principal aquifer in the Cawelo GSA Area is for agricultural purposes, increased pumping could occur as a result of the following:

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 99 TODD GROUNDWATER 1. new land is put into agricultural production, 2. water use per acre on existing irrigated land increases, 3. loss of surface water supplies causing an increased reliance on groundwater pumping.

Loss of surface water supplies could occur for example if state- or federally-driven regulatory programs dedicate additional surface water resources to environmental uses in the San Joaquin River or Sacramento-San Joaquin Delta. This could reduce imported surface water availability to the Kern County Subbasin leading to an increased reliance on groundwater pumping for water supply needs.

Increases in municipal and industrial (M&I) water use is not likely significant. M&I use is limited to two small water systems. The largest single water user is the Lerdo County Jail which houses up to 2,300 inmates. The jail has recently expanded, but no further increases are currently planned. Other water users include scattered industrial facilities and private domestic users, their use is relatively small and unlikely to increase substantially.

Reduced recharge could occur because of decreases in managed aquifer recharge due to loss or changes in operations of surface water supplies, increased agricultural irrigation efficiency or decreased precipitation and increased ET as a result of climate change.

5.3.4 Potential Undesirable Results of Chronic Lowering of Groundwater Levels

The Kern County Subbasin is currently considered in a state of critical overdraft per the DWR Bulletin 118 Interim 2016 Update. Chronic lowering of water levels can adversely impact pumping wells and, in some cases, prevent practical or economical access to groundwater supply. With several hundred active water wells estimated in the Cawelo GSA, these impacts can be widespread and represent a significant economic impact on Cawelo GSA groundwater users. . As documented in Section 2.1, Description of the Plan Area, Cawelo GSA is characterized by a low density of wells, most of which are on-farm, reflecting the prevailing agricultural land uses and scarcity of residences and businesses.

Undesirable Results resulting from chronic lowering of groundwater levels could potentially cause de- watering of existing groundwater wells, starting with the shallowest wells, that could potentially cause changes in irrigation practices or local water supply that could adversely affect property values.

If groundwater were to reach levels that cause undesirable results, effects could include de-watering of a subset of the existing groundwater infrastructure, starting with the shallowest wells, which are generally domestic wells. Lowering levels to this degree could necessitate changes in irrigation and cropping practices and could cause adverse impacts agricultural production and to property values that would affect livelihoods and the regional agricultural-based economy.

Additionally, undesirable results could adversely affect current and projected municipal, industrial and domestic uses, which rely on groundwater in the Subbasin, by limiting availability of water supply or increasing the costs for potable water supplies. As water levels decline, well owners face an increase in energy costs due to the extra distance that the well pump must lift the water from the aquifer to the ground surface. Well capacity can also decline and may not produce sufficient water to meet the beneficial use. If water levels decline below the pump intake, the well will no longer produce. In this case, the pump must be lowered to depths sufficient to accommodate pumping water levels, sometimes at considerable cost. For some wells, this modification may not be feasible, and the well may need to be replaced.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 100 TODD GROUNDWATER If water levels continue to decline, the well may become dry and lose its ability to produce groundwater. Dry wells will occur first in the shallowest wells, such as is more common for a domestic well. If the dry well is the sole source of water for the well owner, drilling a deeper replacement well may be the only option for water supply – an option that may not be economically viable for the water user.

5.4 REDUCTION OF GROUNDWATER STORAGE

SGMA defines an undesirable result from reduction of groundwater storage as “indicating a significant and unreasonable depletion of supply if continued over the planning and implementation horizon” (§10721(x)(1)). The definition considers the duration of water level declines, as well as the cause. Specifically, the definition continues: “Overdraft during a period of drought is not sufficient to establish a chronic lowering of groundwater levels if extractions and groundwater recharge are managed as necessary to ensure that reduction in groundwater levels or storage during a period of drought are offset by increasing groundwater levels or storage during other periods” (§10721(x)(1)).

5.4.1 Subbasin Definition of Undesirable Results for Groundwater in Storage

In coordination with other GSAs in the Subbasin, the KGA developed a Subbasin-wide definition of an undesirable result for each sustainability indicator (December 14, 2018). This Subbasin-wide definition of Undesirable Results for the Groundwater Storage sustainability indicator is as follows:

The point at which significant and unreasonable impacts, as determined by the amount of groundwater in the basin, affect the reasonable and beneficial use of, and access to, groundwater by overlying users over an extended drought period. (10-years?)

This is determined when the volume of storage (above the groundwater level minimum thresholds) is depleted to an elevation lower than the groundwater level minimum threshold in at least three (3) adjacent management areas that represent at least 15 percent of the subbasin or greater than 30 percent of the subbasin (as measured by the acreage of each Management Area).

Minimum thresholds shall be set by each of the management areas through their respective Groundwater Sustainability Plans.

The reduction of groundwater storage (§354.28(c)(2)) is required to be defined in terms of the total volume of groundwater that can be withdrawn from the basin without causing conditions that may lead to undesirable results based on the sustainable yield of the basin, calculated based on historical trends, water year type, and projected water use in the basin. Because the undesirable results due to the Reduction of Groundwater Storage is generally correlated to Chronic Lowering of Groundwater Levels, monitoring of groundwater levels is considered an appropriate proxy for monitoring undesirable results due to the reduction of groundwater storage. This GSP adopts changes in groundwater elevation as a proxy for the change in groundwater storage metric as allowed in §354.36(b)(1) of the SGMA regulations. Accordingly, groundwater elevation data at selected Representative Monitoring Sites (RMS, as discussed in Section 6) will be reported annually as a proxy for changes in the amount of groundwater in storage.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 101 TODD GROUNDWATER 5.4.2 Description of Undesirable Result

Undesirable Results due to the Reduction of Groundwater Storage are defined as the amount of stored groundwater in the basin at which the reasonable and beneficial use of groundwater by overlying users is affected by significant and unreasonable impacts. As indicated by the discussion of groundwater levels in Section 3.2 Current and Historical Groundwater Conditions, this would be most likely to occur with extended drought. It also would occur with overdraft. The Undesirable Result for the reduction in groundwater storage is defined as causing significant and unreasonable reduction in the viability of domestic, agricultural, municipal, or environmental uses over the planning and implementation horizon of this GSP.

The change in groundwater storage is the volume of groundwater represented by the overall net difference in groundwater inflows and outflows that is physically manifested by the change in groundwater levels. It is assessed over an extended period of time with representative hydrologic conditions referred to as the base period. Over the base period, the change in groundwater storage will vary in response to hydrologic conditions (including drought) and groundwater management activities including recharge operations and pumping. The Undesirable Result would involve lack of storage to support beneficial uses through prolonged drought.

A chronic reduction of groundwater storage of significant magnitude may represent overdraft conditions. Overdraft is when the net outflows significantly exceed net inflows over the base period resulting in depletion of groundwater storage. The Undesirable Result would be significant and unreasonable loss of groundwater supply for beneficial uses.

5.4.3 Potential Causes of Reduction of Groundwater Storage

The potential causes of Undesirable Results due to Reduction in Groundwater Storage are generally the same as the potential causes listed above for Undesirable Results due to Chronic Lowering of Groundwater Levels (i.e., increased groundwater pumping and reduced recharge).

5.4.4 Potential Undesirable Results from Reduction of Groundwater Storage The primary potential effects of Undesirable Results caused by Reduction of Groundwater Storage on beneficial uses and users of groundwater in the Cawelo GSA Area include reduced groundwater supply reliability. The effect of reduced groundwater reliability would be most significant during periods of reduced surface water supply availability due to, for example, drought, regulatory restrictions, natural disasters, or other causes. If overdraft persists, this would lead to depletion of groundwater supplies (in addition to undesirable results associated with decline in groundwater levels). As with groundwater level declines, loss of reliable storage would necessitate changes in irrigation and cropping practices (for example, more fallowing and shifting from high value perennial crops). These would cause potential adverse impacts to agricultural production and to property values, and adversely affect livelihoods and the regional agricultural-based economy.

5.5 SEAWATER INTRUSION

Seawater intrusion is not an applicable sustainability indicator in the Basin, because seawater intrusion is not present and is not likely to occur due to the distance between the Basin and the Pacific Ocean, bays, deltas, or inlets. Accordingly, seawater intrusion is not occurring, not expected to occur in the future, and is not an applicable sustainability indicator for the Cawelo GSA Plan Area or the Subbasin. As

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 102 TODD GROUNDWATER allowed in the GSP regulations (§354.28(e)), no sustainable management criteria are defined for this indicator and seawater intrusion is not considered further in this GSP.

5.6 LAND SUBSIDENCE

Per Section 354.28(c)(5) of the GSP Emergency Regulations, the criteria used to define Undesirable Results for land subsidence is “the rate and extent of subsidence that substantially interferes with surface land uses and may lead to undesirable results”. Significant and unreasonable rates of land subsidence in the Subbasin are those that lead to a permanent subsidence of land surface elevations that impact critical infrastructure. For clarity, this Sustainable Management Criterion adopts two related concepts:

• Land Subsidence is a gradual settling of the land surface caused by compaction of subsurface materials due to lowering of groundwater elevations from groundwater pumping. Land subsidence in an inelastic process, and the decline in land surface is permanent.

• Land Surface Fluctuation is the periodic or annual measurement of the ground surface elevation. Land surface may rise or fall in any one year. Declining land surface fluctuation may or may not indicate long-term permanent subsidence.

5.6.1 Description of Undesirable Result

Inelastic compaction is initiated when the magnitude of the greatest pressure that has acted on the clay layer since its deposition, or preconsolidation stress, is exceeded. With respect to the effects of groundwater pumping, the preconsolidation stress is exceeded when groundwater levels in the aquifer reach a new historically low water level. The volumetric compaction of the clay layers in the subsurface is transmitted to the land surface where it is manifested as land subsidence.

If groundwater withdrawals continue to cause land subsidence, critical infrastructure could be impacted. Adverse impacts would be more pronounced if subsidence occurred unevenly through the area. The following potential impacts have been associated with land subsidence due to groundwater withdrawals (modified from LSCE, et al., 2014):

• Damage to infrastructure including foundations, roads, bridges, or pipelines • Loss of conveyance in canals, streams, or channels • Diminished effectiveness of levees • Collapsed or damaged well casings • Land fissures. During the compaction process, the water in these pore spaces is forced out of the clay layers as the sediments are forced into a tighter configuration. The volume of compaction is equal to the volume of groundwater that is expelled from the clay layers and can represent a substantial volume of water. However, once the water is expelled and the structure rearranged, this represents a permanent loss of the water storage volume in the clay layers. Although space within the aquifer is reduced by an amount equivalent to subsidence of the land surface, this storage reduction does not substantially decrease usable storage for groundwater. This is because the compressed clay layers do not typically store significant amounts of usable groundwater (LSCE, 2014). However, inelastic compression may decrease the vertical permeability of the clay layer resulting in minor changes in vertical flow.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 103 TODD GROUNDWATER 5.6.2 Subbasin Definition of Land Subsidence

In coordination with other GSAs in the Subbasin, the KGA developed a Subbasin-wide definition of an undesirable result for each sustainability indicator (December 14, 2018). The definition of Undesirable Results for the Land Subsidence Trends sustainability indicator is as follows:

• The point at which significant and unreasonable impacts, as determined by a subsidence rate and extent in the basin, that affects the surface land uses or critical infrastructure.

• This is determined when subsidence results in significant and unreasonable impacts to critical infrastructure as indicated by monitoring points established by a basin wide coordinated GSP subsidence monitoring plan.

5.6.3 Potential Causes of Land Subsidence

The overdraft conditions described above, exacerbated by the recent drought, have resulted in lowered groundwater levels – a condition which can contribute to subsidence of the ground surface. As water levels decline in the subsurface, dewatering and compaction of aquifer materials, predominantly fine- grained materials such as clay, can cause the overlying ground surface to subside.

Land subsidence in the San Joaquin Valley has been documented for more than 60 years and recent investigations using satellite imagery and other local methods indicate continuing problems in some areas. Although the areas with the most documented subsidence are generally north of the Study Area, both historical and recent subsidence have been documented in various parts of Kern County. From 1967 to 1980 a series of key studies on land subsidence in the San Joaquin Valley were published by the U.S. Geological Survey in cooperation with DWR (Ireland, et al., 1984; Lofgren, 1975; Lofgren and Klausing, 1969). Collectively, these studies document areas of historical land subsidence in the Study Area as shown on Figure 3-44.

5.6.4 Potential Undesirable Results of Land Subsidence

The potential undesirable results caused by land subsidence on beneficial uses and users of groundwater and overlying land uses may include damage to above-ground and near-surface infrastructure including gravity-driven water conveyance infrastructure (i.e., canals and pipelines); utility infrastructure (i.e., gas pipelines); and water storage infrastructure, including shallow ponds used for temporary storage of imported water supplies. Potential effects could also include damage to below- ground infrastructure including groundwater well casings.

Undesirable results for land subsidence also include loss of capacity in major water conveyance infrastructure such as the Friant-Kern Canal or California Aqueduct; however, these major water conveyance structures do not cross the Cawelo GSA. Subsidence damage along the Friant-Kern Canal has resulted in loss of capacity and the need for expensive repairs. DWR and others maintains ongoing monitoring stations along the aqueduct to identify potential land subsidence issues. Cawelo GSA managers rely on the regional conveyance system and are interested in the mitigation of any undesirable results that may lead to a loss of capacity in regional water conveyance infrastructure.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 104 TODD GROUNDWATER 5.7 DEGRADED WATER QUALITY

As documented in Section 3.2.2, groundwater in the Cawelo GSA contains both naturally occurring and anthropogenic constituents. Analysis of trends generally indicates that groundwater quality in terms of key constituents like TDS and nitrate has been steady or improving. Only one environmental cleanup site exists, which is under regulatory inspection and monitoring.

Water quality already is regulated through numerous programs by a variety of federal, state, and local agencies. GSAs do not have the mandate or authority to duplicate these programs. Furthermore, GSAs are not required to correct historical problems, naturally-occurring degradation, or degradation caused by others. Nonetheless, to support sustainable groundwater supplies for all beneficial uses, this GSP includes cooperation with regulatory programs that address management and prevention of degraded groundwater quality. In addition, this GSP avoids management actions that would contribute to water quality degradation or spread groundwater contamination through pumping or other means. Therefore, the definition of undesirable results focuses on groundwater quality that could be impacted by management actions.

Section §354.28(c)(2)of the SGMA regulations states that undesirable results from degraded water quality are defined on the basis of the number of supply wells, a volume of water, or a location of an isocontour that exceeds concentrations of constituents determined by the Agency to be of concern for the basin.

5.7.1 Subbasin Definition of Undesirable Results for Degraded Water Quality

In coordination with other GSAs in the Subbasin, the KGA developed a Subbasin-wide definition of an undesirable result for each sustainability indicator (December 14, 2018). The definition of Undesirable Results for the Degraded Water Quality Trends sustainability indicator is as follows:

The point at which significant and unreasonable impacts over the planning and implementation horizon, as caused by water management actions, that affect the reasonable and beneficial use of, and access to, groundwater by overlying users.

This is determined when the minimum threshold for a groundwater quality constituent of concern is exceeded in at least three (3) adjacent management areas that represent at least 15 percent of the subbasin or greater than 30 percent of the designated monitoring points within the basin. Minimum thresholds shall be set by each of the management areas through their respective Groundwater Sustainability Plans.

Undesirable Results due to the Degraded Water Quality is defined as the point at which significant and unreasonable impacts over the planning and implementation horizon, as caused by water management actions, that affect the reasonable and beneficial use of, and access to, groundwater by overlying users. This is determined when the minimum threshold for an individual groundwater quality constituent of concern is exceeded in greater than 30 percent of the designated monitoring points within the basin.

5.7.2 Potential Causes of Degraded Water Quality

Degraded water quality is unique among the six sustainability indicators because it is already the subject of extensive federal, state, and local regulations carried out by numerous entities. Accordingly, for this

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 105 TODD GROUNDWATER GSP, undesirable results for degraded water quality are defined as those impacts that result from SGMA- related management actions such as groundwater extractions, managed aquifer recharge or other SGMA management activities. The two most relevant causes of degraded water quality in the Cawelo GSA are from salts and nitrates. Salts come from imported water, soil leached by irrigation, animal wastes, fertilizers and other soil amendments, municipal and industrial wastewaters, and oil field produced waters. Nitrate comes from nitrogen supplied by inorganic fertilizer, animal manure, and septic systems in residential areas. These salt and nitrate sources can all contributors to increases concentrations of these constituents.

5.7.3 Potential Undesirable Results from Degraded Water Quality

If groundwater quality were degraded to reach levels causing undesirable results, the effect could potentially cause a reduction in usable supply to groundwater users, with domestic wells being most vulnerable as treatment or access to alternate supplies may be unavailable or at a high cost for small users. Water quality degradation could cause potential changes in irrigation practices, crops grown, and adverse effects to property values. Additionally, reaching Undesirable Results for groundwater quality could adversely affect municipal uses, including disadvantaged communities, which could have to install treatment systems.

5.8 DEPLETIONS OF INTERCONNECTED SURFACE WATER

Per Section 354.26(b)(3) of the GSP Emergency Regulations, potential effects of Undesirable Results of Depletion of Interconnected Surface Water may include reduced surface water flows to support downstream or in-stream uses. The Undesirable Result for depletions of interconnected surface water is a result that causes significant and unreasonable reductions in the viability of agriculture or riparian habitat within the Basin over the planning and implementation period. Wildlife or habitat could be damaged or killed if there is a decrease in groundwater contribution to its water supply.

Potential causes of future Undesirable Results for depletions of interconnected surface water are associated with groundwater production, particularly in the shallowest zones, where surface water and groundwater are connected. Increased depletions could result in lowering of groundwater elevations in shallow aquifers near surface water courses, which changes the hydraulic gradient between the water surface elevation in the surface water course and the groundwater elevation, resulting in an increase in depletion.

In coordination with other GSAs in the Subbasin, the KGA developed Subbasin-wide definitions of undesirable results for each sustainability indicator applicable to the Kern County Subbasin. Because the Basin Setting analysis by KGA had not identified interconnected surface water in the Subbasin, no Subbasin-wide definition of undesirable results for this sustainability indicator was developed. Similarly, available data further supports that the depletion of interconnected surface water has not been observed within the Cawelo GSA Area. As described in Section 3.4.3, the depth to groundwater below the streams has historically been well below the level of the streambed in the Cawelo GSA that there is no direct interactions between groundwater and stream flow in the Cawelo GSA, and is limited to percolation of streamflow to groundwater through an intervening unsaturated zone. Other lines of evidence (i.e., depth to groundwater water levels, water quality data, and hydrostratigraphy) further support that the principal aquifer is hydraulically separated from the surface water bodies.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 106 TODD GROUNDWATER 6 MONITORING NETWORK

This chapter describes the monitoring networks that exist and that will be developed in the Cawelo GSA as part of GSP implementation. The description of the monitoring networks is prepared in accordance with the SGMA emergency regulations §354.32 and includes monitoring objectives, monitoring protocols, and data reporting requirements.

The monitoring networks are based on existing monitoring sites and expanded where necessary to both demonstrate sustainability and meet the monitoring objectives. Data gaps exist for every monitoring network, and a discussion is provided of how these data gaps will be addressed during GSP implementation. Addressing data gaps will be conducted to improve the overall ability to demonstrate sustainability and refine the hydrogeologic conceptual model and water budgets.

The monitoring networks and protocols for the Cawelo GSA have been developed in coordination with the Kern Groundwater Authority (KGA) for the Kern County Subbasin (5-022.14). The Kern Coordination Committee of the KGA has prepared a series of white papers that address each of the following seven coordination elements:

a. Groundwater Elevation Data b. Groundwater Extraction Data c. Surface Water Supply d. Total Water Use e. Change in Groundwater Storage f. Water Budget g. Sustainable Yield

The purpose of the white paper series is to advance the dialogue between participating members of the KGA on the development of a coordination agreement required under SGMA and included in the KGA Umbrella GSP (GEI, 2019). Relevant information from these white papers are described in the subsequent sections.

6.1 MONITORING NETWORK OBJECTIVES

A primary objective of the monitoring network is to collect sufficient data to demonstrate seasonal, short-term (1 to 5 years), and long-term (5 to 10 years) trends in groundwater and related surface conditions and yield representative information about groundwater conditions as necessary to evaluate GSP implementation (23 CCR §354.34). The regulations allow the GSP to use existing monitoring sites for the monitoring network. The approach for establishing the monitoring network for the Cawelo GSA is to include existing monitoring programs and incorporate additional monitoring locations that have been made available by cooperating entities. The monitoring network is limited to data and locations that are publicly available and not confidential. Additionally, the monitoring network objectives for the Cawelo GSA will be implemented to achieve the following (23 CCR §354.34):

• Demonstrate progress toward achieving measurable objectives described in this GSP. • Monitor impacts to the beneficial uses or users of groundwater. • Monitor changes in groundwater conditions relative to measurable objectives and minimum thresholds.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 107 TODD GROUNDWATER • Quantify annual changes in water budget components.

These objectives will be achieved using the monitoring networks and protocols described in the following sections.

The monitoring networks described here will maintain data quality to meet the measurable objectives of the Cawelo GSP. As described by DWR (2016), the processes for maintaining quality control and quality assurance are iterative and will be evaluated every five years for effectiveness. The monitoring networks implemented with this GSP include the analytical approaches to obtain acceptable data that can monitor the sustainability indicators against minimum thresholds and interim milestones. Where necessary, revisions can be made every five years.

6.1.1 Monitoring of Sustainability Indicators

Groundwater monitoring is a fundamental component of SGMA. Monitoring networks are developed for each of the five sustainability indicators that are relevant to Cawelo GSA: • Chronic lowering of groundwater levels • Reduction in groundwater storage • Degraded water quality • Land subsidence • Depletions of interconnected surface water

The Cawelo GSA is isolated from the Pacific Ocean and is not threatened by seawater intrusion, therefore this GSP does not provide monitoring for the Seawater Intrusion sustainability indicator. Although the discussions in Section 3 (Basin Setting) indicate that surface waters in Poso Creek and Kern River are not interconnected with the groundwater aquifer, existing surface water monitoring programs will continue to be utilized to maintain an appropriate understanding of surface water conditions that are necessary to quantify annual changes in water budget components and other monitoring objectives.

6.1.2 Monitoring Rationale

The SGMA regulations require monitoring networks be developed to promote the collection of data of sufficient quality, frequency, and distribution to characterize groundwater and related surface water conditions in the basin and to evaluate changing conditions that occur through implementation of the Plan. For these reasons, a standard set of protocols is developed and implemented. The measurable objectives and minimum thresholds monitored by the networks are described in Section 7.1, Sustainable Management Criteria.

The regulations require that if management areas are established, the quantity and density of monitoring sites in those areas shall be sufficient to evaluate conditions of the basin setting and sustainable management criteria specific to that area. At this time, separate management areas have not been defined for the Cawelo GSA.

The monitoring rationale also includes monitoring and data collection protocols that are based on best available scientific methods (DWR, 2016). Regulations (23 CCR §351(h)) define best available science as the use of sufficient and credible information and data, specific to the decision being made and the time frame available for making that decision, that is consistent with scientific and engineering professional standards of practice. Additionally, consistently applied protocols across the Cawelo GSA and other GSAs

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 108 TODD GROUNDWATER within the Kern County Subbasin will likely result in comparable data. The consistency of data collection methods reduces uncertainty in the comparison of data and facilitates more accurate communication within the basins and between basins (DWR, 2016).

SGMA regulations (23 CCR §352.2) state that each GSP shall include monitoring protocols that are adopted by the GSA for data collection and management, as follows:

• Monitoring protocols shall be developed according to best management practices. Best management practices refer to a practice, or combination of practices, that are designed to achieve sustainable groundwater management and have been determined to be technologically and economically effective, practicable, and based on best available science (§351(i)). • The GSA may rely on monitoring protocols included as part of the best management practices developed by DWR or may adopt similar monitoring protocols that will yield comparable data. • Monitoring protocols shall be reviewed at least every five years as part of the periodic evaluation of the Plan and modified as necessary.

The monitoring program protocols for the Cawelo GSA have been evaluated in conjunction with the monitoring networks and identification of data gaps. The monitoring protocols have been developed in consideration with the previously described hydrogeologic conceptual model, water budget, and modeling, and the corresponding data needs to meet the objectives and sustainability goals of the Cawelo GSA (DWR, 2016). It is important to note that the monitoring protocols of the Cawelo GSA have been designed to generate information that promotes efficient and effective groundwater management in accordance with regulation §10727.2 (DWR, 2016).

As suggested by DWR, the monitoring program protocols of the Cawelo GSP generally incorporate and follow the Data Quality Objective (DQO) process (USEPA, 2006) that has been developed for the Kern County Subbasin. The DQO is a robust approach that helps ensure data are collected with a specific purpose, and efforts for monitoring are as efficient as possible to achieve the objectives of the Cawelo GSP and compliance of SGMA regulations. The DQR process was applied to the sustainability criteria requirements using the following steps, as described by DWR (2016):

1. State the problem – Define sustainability indicators and planning considerations of the GSP and sustainability goal. 2. Identify the goal – Describe the quantitative measurable objectives and minimum thresholds for each of the sustainability indicators. 3. Identify the inputs – Describe the data necessary to evaluate the sustainability indictors and other GSP requirements. 4. Define the boundaries of the study – Because the Cawelo GSA is within the San Joaquin Valley – Kern County Subbasin, the coordination plan within the Subbasin was evaluated with specific focus on how the monitoring will be comparable and meet the sustainability goals for the entire Kern County Subbasin. 5. Develop an analytical approach – Determine how the quantitative sustainability indicators will be evaluated. 6. Specify performance or acceptance criteria – Determine what quality of data is needed to achieve the objective and provide some assurance that the analysis is accurate and reliable.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 109 TODD GROUNDWATER 7. Develop a plan for obtaining the data – Once the objectives are known, determine how these data should be collected. Existing data sources should be used to the greatest extent possible. DWR (2016) notes that the DQO is an iterative process and should be evaluated regularly to improve monitoring efficiencies and meet changing planning and project needs. This GSP also includes a data quality control and quality assurance (QA/QC) plan to guide the data collection within the Cawelo GSA.

Following DWR (2016) recommendations, the Cawelo GSP will collect and document the following information for each monitoring site: • Long-term access agreements. The access agreements include year-round site access to allow for increased monitoring frequency. • A unique identifier that includes a general written description of the site location, date established, access instructions and point of contact, type of information to be collected, latitude, longitude, and elevation.

As described above, monitoring protocols should include a description of technical standards, data collection methods, and other procedures or protocols for monitoring sites or other data collection facilities to ensure that the monitoring network utilizes comparable data and methodologies. However, there is no definitive rule for the density of groundwater monitoring points needed in a basin. Table 6-1 that was adopted from the CASGEM Groundwater Elevation Monitoring Guidelines (DWR, 2010) to provide guidance for the density of monitoring wells per hundred square miles. In selecting monitoring well density, it is important to consider how this information will be used for comparison to quantitative thresholds of undesirable results.

Table 6-1. Select Guidelines for Density of Monitoring Wells. Monitoring Well Density Reference (wells per 100 miles2) Heath (1976) 0.2 - 10 Sophocleous (1983) 6.3 Basins pumping more than 10,000 AFY per 100 miles 4.0 Basins pumping between 1,000 and 10,000 AFY per 100 miles 2.0 Basins pumping between 250 and 1,000 AFY per 100 miles 1.0 Basins pumping between 100 and 250 AFY per 100 miles 0.7

6.2 EXISTING MONITORING PROGRAMS

Cawelo Water District (CWD) established a groundwater monitoring program as part of its 2007 Groundwater Management Plan (GWMP), including monitoring of groundwater levels, groundwater quality, imported surface water, Poso Creek gaging, and conjunctive use operations (CWD, 2007). Additional monitoring and data are available from local, state, and federal agencies. The existing groundwater and surface-water resource monitoring programs for the Cawelo GSA are summarized below.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 110 TODD GROUNDWATER 6.2.1 Water Supply Monitoring

Climate. The CWD maintains a rainfall gauge at the district offices that has a rainfall record from 1982 to present. Data from this gauge has been used to support the technical analysis for this GSP. Climate data are also available from the California Irrigation Management Information System (CIMIS) developed by DWR. CIMIS involves a network of over 145 automated weather stations in California; the closest active station to Cawelo is the Station #5 Shafter located at a former USDA Cotton Research facility on Shafter Avenue. The station’s record began June 1, 1982, with a one-year gap in 2012-2013 and currently is active. Sensors at the station measure the following:

• Total solar radiation • Soil temperature • Air temperature/relative humidity • Wind direction • Wind speed • Precipitation CIMIS Station #138, located at Famoso within the Cawelo GSA, is currently inactive but historical data are available from April 9, 1997 to December 29, 2015. Information on CIMIS stations and CIMIS data are available online (CIMIS, 2018). Long-term climate data also are available from the Bakersfield Airport climate station (NOAA, 2018) from 1937 to present.

Surface water flows. Poso Creek is the primary natural channel that enters CWD and exits into other areas that can benefit from its beneficial uses (CWD, 2014). Poso Creek flows are measured at several gages including the USGS gage at Coffee Canyon in the Sierra Nevada watershed east of CWD. Records at this gage span from July 1959 to present. CWD has monitored Poso Creek since 1982 at a gage upstream of State Highway 65 on the east and at State Highway 99 on the west; the latter data are from the Annual Hydrographic Reports for Kern River. Monthly flow data (acre-feet) have been compiled since 1993 by CWD.

Little Creek is a small tributary to Poso Creek that enters the CWD area from the northeast. Little Creek rarely flows; as of 2014, CWD reported detectable flows in only 3 of the previous 33 years. Little Creek is not gaged. Additionally, the Kern River flow within and along the southern boundary of the Cawelo GSA (Figure 2-4). Several stream flow gages are located on the Kern River; the USGS operates several gages upstream of the City of Bakersfield and flow data on the Kern River has been collected since the 1890s.

Imported water deliveries. The Cross Valley Canal and its Extension, operated by Kern County Water Agency (KCWA), is used to convey State Water Project water supply from the California Aqueduct near Tupman to the Beardsley and Lerdo canals, then to CWD's distribution system.

To monitor irrigation water deliveries throughout the distribution system, CWD has installed meters on all pumping plants and canal and pipeline turnouts. CWD staff take meter readings at each turnout every day that a turnout is running and at the end of every month, using propeller meters equipped with totalizers. These are periodically checked for measurement accuracy as part of the CWD maintenance program. When properly calibrated, the meters provide accurate measurements of the flow rate and volume of water delivered at the turnouts. CWD agricultural water measurement practices and protocols are consistent with Water Code requirements and are documented in the CWD Agricultural Water Management Plan (CWD, 2015b).

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 111 TODD GROUNDWATER Regionally, KCWA (the wholesaler for SWP water) regularly accounts for and reports its SWP supplies for Kern County in its Report on Water Conditions. KCWA monitors daily all turnouts from the California Aqueduct and all turnouts along the Cross Valley Canal (KCWA, 2001).

Conjunctive use programs. CWD monitors the amounts of water received from oil extraction operations for irrigation and delivery and monitors the flow into its Famoso and Poso Creek recharge basins.

6.2.2 Groundwater Conditions Monitoring

Wells and groundwater pumping. CWD has operated 18 wells: 3 Famoso wells and Wells 1 through 15. Groundwater pumping for these wells has been tabulated monthly since initiation of pumping for each well and totaled on a monthly basis since 1990. Estimates of pumping from privately-owned wells are not reported to CWD unless the water is pumped into the CWD system for conveyance and delivery. Although infrequent, water pumped from certain private wells is used for CWD purposes through an agreement with the private well owner (CWD, 2015b).

The density of water supply wells in and around Cawelo GSA is based on the DWR Well Completion Report Map Application tool (Figures 2-6a, 2-6b, and 2-6c). As indicated, the density of supply wells is relatively low in Cawelo GSA, ranging from zero to ten wells per section. This reflects the prevailing agricultural land uses and scarcity of residences and businesses, all of which depend on groundwater.

Groundwater levels. CWD commenced a Groundwater Monitoring Program in the fall of 1979 utilizing 55 wells within the District that were selected for monitoring and mapping of groundwater levels on a semi-annual basis. The monitoring program was expanded in 1985 and currently groundwater levels are measured in approximately 250 wells semiannually. The data obtained in the spring (normally February) reflects the "seasonal high" water table as measurements are made prior to significant pumping. The data obtained in the fall (normally October), after a full season of agricultural irrigation pumping, indicates the "seasonal low" water levels.

Beginning in 2009, the DWR developed and has coordinated the California Statewide Groundwater Elevation Monitoring (CASGEM) Program, which has tracked seasonal and long-term groundwater elevation trends in groundwater basins statewide in collaboration with local monitoring entities. CWD is the local CASGEM monitoring entity and registered in the CASGEM database; the program includes regular measurement of seven wells in the Cawelo GSA. CASGEM data are available from CWD and from DWR’s Groundwater Information Center Interactive Map (GICIMA), a database that collects and stores groundwater elevations and depth-to-water measurements. CASGEM data are incorporated into this Cawelo GSP monitoring program. This program is an important monitoring tool for groundwater and to help achieve the goals set out under SGMA.

The CWD is part of the Semitropic Water Storage District (SWSD) Water Banking Project Monitoring Committee. In addition to CWD, the SWSD Water Banking Project Monitoring Committee is made up of SWSD, Southern San Joaquin Municipal Utility District (SSJMUD), Shafter-Wasco Irrigation District (SWID), Rosedale Rio Bravo Water Storage District (RRBWSD), and Buena Vista Water Storage District (BVWSD), with KCWA and DWR working alongside the monitoring committee. Beginning in 1995, the committee submits biennial monitoring reports that include groundwater elevation maps, discussion of groundwater flow trends, groundwater quality, land subsidence, and time series data on hydrographs.

The KCWA published Water Supply Reports (WSR) for select years between 1977 to 2011. These reports contained groundwater elevation maps, estimates of water accounting, and groundwater quality data

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 112 TODD GROUNDWATER for the production zone of the aquifer system and maps of groundwater storage, and maps of the shallow perched water on the distal edges of the Kern Fan. KCWA continues to maintain all data, which is available for use by management areas but are no longer published in annual reports. The KCWA database contains over 10,000 well records (mostly supply wells), with some water levels ranging from the 1970s to present. Some well construction information is available in the database. The WSRs include estimates of effective precipitation, estimated groundwater pumping, irrigated acreage, change in groundwater storage, and percent of normal evaporation.

Land subsidence. Subsidence has been documented in Kern County through a series of key studies by the USGS and DWR. The studies are cited in the CWD GWMP (2007), which recommends continued use of regional subsidence reporting to track subsidence. The subsidence monitoring networks are available as part of the land subsidence investigations covering areas of the Kern Count Subbasin, largely outside the Cawelo GSA. Some of the most accessible data are in the area north of the Kern River portion of the Kern County Subbasin, and include USGS and DWR elevation surveys along the California Aqueduct, borehole extensometer monitoring by Semitropic Water Storage District and the Kern Water Bank Authority, continuous and conventional GPS measurements available from the UNAVOCO5 PBO dataset, leveling surveying by the USGS California Water Science Center, and elevation monitoring along the Friant Kern Canal by the US Bureau of Reclamation (USBR). The USBR monitors two multi-port monitoring wells in NKWSD (and other monitoring points outside of the Cawelo GSA) to track the ongoing potential for subsidence-related problems. Areal datasets include remote sensing studies by NASA Jet Propulsion Laboratory and collaborators using Interferometric Synthetic Aperture Radar (InSAR) and Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR).

The subsidence monitoring data such as the borehole extensometers and GPS datasets are available to incorporate into regular monitoring networks, whereas the areal InSAR and UAVSAR datasets are dependent on future scheduled studies as well as the ability for an entity to post-process the data. According to the USGS, the European Space Agency’s Sentinel satellites collect InSAR data at an approximately weekly rate, and the data are available for download and consumption as necessary. These data are available as long as users continue to post-process and distribute the data.

6.2.3 Water Quality Monitoring

Water quality monitoring and management have a long history in the Cawelo GSA area. Monitoring and management programs are conducted by water agencies and entities at local and regional scales, such as CWD and Oildale Mutual Water Company, and by state and federal programs and regional plans. The existing water quality monitoring programs in the Cawelo GSA include the following.

6.2.3.1 Local GSA Monitoring Irrigated Lands Regulatory Program (ILRP). ILRP of the Regional Water Quality Control Board (RWQCB) regulates waste discharges from irrigated lands. The ILRP was established in 2003 with a focus on protecting surface waters; groundwater regulations were added in 2012. ILRP was implemented to protect water bodies from impairment associated with agricultural runoff, tile drain flows, and storm water runoff from irrigated fields. The ILRP provides requirements for discharging waste from irrigated agriculture to surface water. The ILRP also required completion of an environmental impact report for

5 UNAVOCO is a non-profit university-governed consortium to facilitate geoscience research and education using geodesy.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 113 TODD GROUNDWATER the long-tern ILRP to protect California groundwater and surface waters. The general goals of the long- term ILRP are to provide the highest reasonable quality of state waters and safe and reliable drinking water.

The State of California Central Valley Regional Water Quality Control Board adopted the Waste Discharge Requirements General Order for Growers within the Tulare Lake Basin Area that are Members of a Third-Party Group, Order R5-2013-0120 (General Order) on September 19, 2013 replacing the Ag Waiver Program (General Order R5-2006-0053). Requirements for evaluating and protecting surface water quality are established by the General Order include:

• Surface Water Monitoring Plan (SWMP) with a Quality Assurance and Project Plan (QAPP), • 2019 Pesticide Monitoring Plan, and • Sediment Discharge and Erosion Assessment Report.

Requirements for evaluating and protecting groundwater quality established by the General Order include:

• Groundwater Quality Assessment Report (GAR), • Comprehensive Groundwater Quality Management Plan (CGQMP), • Groundwater Quality Trend Monitoring Program (GQTMP), and • Management Practices Evaluation Program (MPEP).

Elements of the ILRP that overlap with SGMA requirements are the monitoring programs focused on identifying groundwater impairment associated with irrigated agriculture. The ILRP focuses on priority water quality issues, such as pesticides and toxicity, nutrients, and sediments. Throughout the Central Valley, ILRP coalitions are coordinating their efforts as the Central Valley Groundwater Monitoring Collaborative. There are 14 coalitions in the Central Valley region that help growers comply with the general orders; one of these is the Cawelo Water District Coalition (CWDC), which operates programs to monitor (and improve) surface water and groundwater quality associated with agricultural activities (CWD, 2015b). The CWDC is the third-party representing the growers in the CWD for compliance with the General Order and Revising Order R5-2014_0143 (Revising Order). The CWDC was authorized to act as the third-party group representative on April 25, 2014 and assist irrigated agriculture within the CDWC area with ILRP compliance. Management practices include sediment discharge and erosion prevention and irrigation and nitrogen management. The focus of ILRP’s groundwater regulation is to create trends of nitrate and demonstrate that current management practices are protecting groundwater from further degradation. The State Water Resources Control Board’s (SWRCB) objective is to eventually restore nitrate concentrations to levels below the drinking water standard of 10 mg/L (as N). Data that are collected as part of the ILRP are provided to the SWRCB and are available in the GeoTracker and Groundwater Ambient Monitoring and Assessment (GAMA) database for download and use. However, the groundwater trend data is currently limited because initial sampling started in the Fall of 2018. The CWDC will sample wells (<600-ft deep) as part of the ILRP. Annual monitoring will include static water level, temperature, pH, electrical conductivity (EC), dissolved oxygen (DO), and nitrate as N. Once every five years, a limited group of general water quality parameters (anions and cations) will be collected. Nitrate and salinity levels in groundwater can be indicators of potential impacts on groundwater quality due to irrigation.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 114 TODD GROUNDWATER In response to the RWQCB’s General Order, CWDC prepared a GAR (2015), which provided a groundwater quality assessment and documented high vulnerability areas where discharges from irrigated agriculture may have degraded groundwater quality. The focus was primarily on nitrate (NO3) with evaluation of EC in the same area. In general, high vulnerability areas could be grouped in a regional high vulnerability area that spans the western CWDC boundary from near Poso Creek to the south tip of CWDC. Details about the GAR and vulnerable areas is described in Basin Setting of this Cawelo GSP. The CWDC GAR was conditionally approved on April 13, 2016 by the CVRWQCB. Additional data and information are required to be obtained, evaluated, and included in the CWDC conceptual hydrogeologic model. The information contained in the GAR is used for the development of the MPEP, GQTMP, and GQMP (CVRWQCB, 2016). With the recognition of high vulnerability areas and areas with confirmed water quality exceedances, CWDC also prepared a CGQMP (see Section 2.2.1 on Management Plans). While CGQMP implementation is focused on irrigation and nutrient management practices to improve water quality, it also provides a GQTMP to develop long-term groundwater quality information to evaluate regional effects of irrigated agriculture. CWDC has been collecting groundwater quality data for over twenty years as part of requirements for receiving treated produced water for irrigation and groundwater recharge and for monitoring groundwater levels (Orders R5-2012-0058 and R5-2012-0059). The CWDC groundwater monitoring program has been incorporated into the GQTMP to continue collection of water quality data, determine of long-term trends in water quality, and evaluate regional effects of irrigated agriculture on groundwater quality. Key requirements of the GQTMP include the following (CWDC , 2015a; CWDC, 2018): • Establish a monitoring network covering High and Low Vulnerability areas including use of shallow wells and rational for well selection. • Collect and evaluate sufficient data to identify trends and report in the annual Monitoring Report.

The General Order requires, at a minimum, groundwater samples be analyzed for the following water quality parameters. The Annual Monitoring Constituents of Concern include conductivity, pH, dissolved oxygen, temperature, nitrate (as N). The Five-Year Monitoring Constituents of Concern include total dissolved solids, anions (carbonate, bicarbonate, chloride, and sulfate), and cations (boron, calcium, sodium, magnesium, and potassium). The CVRWQCB has identified pesticides and metals to be constituents of concern that may impact groundwater quality through irrigated agricultural practices (CVRWQCB, 2017). The proposed monitoring network will consist of 19 locations for a well density of 1 well per 3.7 square miles. Water samples will be obtained during the summer when wells are providing water for agricultural irrigation. Samples will be collected after two well casing volumes have been pumped (agricultural production wells) or two pump column volumes (domestic wells). Sample collection will follow the best practices and protocols of the water analysis industry. Static water levels will be measured in the spring and fall each year. CWD Famoso Basins Antidegradation Analysis and Monitoring. As described in the Section 3, Basin Setting, there was groundwater and surface water quality monitoring associated with the antidegradation analysis for the Famoso Groundwater Banking Project as part of the Report of Waste Discharge (RWD) (K/J, 2011a and 2011b), which was conducted by CWD, Chevron North America (Chevron), and Valley Waste Disposal Company (VWDC). Treated produced water blended with groundwater and surface water in Reservoir B is discharged to the Famoso Basins for percolation or

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 115 TODD GROUNDWATER distributed for irrigation. Seven basins with a combined area of 374 acres and storage capacity of 834 acre-feet overlie fluvial sediments that extend 700 feet below the ground surface and have no significant low permeability layers. Depth to groundwater is about 300 to 350 feet. Blended water is discharged to the percolation basins for 120 days when irrigation demand is low (October 1 through March 31). During irrigation seasons, the blended water is discharged to the CWD irrigation distribution system for agricultural irrigation (K/J, 2011a and 2011b). Three objectives of the Antidegradation Analysis are: • Evaluate potential of the Banking Project to degrade groundwater by assessing background groundwater quality, establishing water quality objectives, and developing an analysis procedure to assess the potential for groundwater quality degradation. • Determine acceptability of potential groundwater quality degradation resulting from the Famoso Groundwater Banking Project. • Establish that requirements for Best Practicable Treatment or Control is met. Prior to implementation of the Famoso Groundwater Banking Project groundwater quality data was collected and analyzed to establish condition prior to use of the Famoso Basins for discharge of blended water. Groundwater samples were analyzed for arsenic, boron, chloride, EC, nitrate, and sodium along with other major anions and cations. Comparison of concentrations of water quality constituents in the blended recharge water to baseline values established five constituents with concentration higher in the blended water than the baseline water quality. Baseline groundwater concentrations of the five primary constituents of interest are: arsenic: 3.4 µg/L, boron: 0.14 mg/L, chloride: 87.7 mg/L, sodium: 55.7 mg/L, and salinity as EC: 618 µmho/cm (K/J, 2011a and 2011b). Water quality requirements for agricultural beneficial uses of water define criteria for discharge of water at the Famoso Basins (CVRWQCB, 2018). The water quality objectives for the following constituents for discharge at the Famoso Basins are: boron: < 0.75 mg/L, chloride: < 175 mg/L, sodium: < 175 mg/L, and salinity as EC: < 1,000 µmho/cm (K/J, 2011a and 2011b). The water quality goal for arsenic is the MCL as established for by California’s Title 22 Water Recycling Criteria for municipal water supply (K/J, 2011): arsenic: < 10 µg/L (K/J, 2011a and 2011b). The Water Quality Control Plan for the Tulare Lake Basin for the Poso Creek Subarea establishes discharge limits for EC. The four water sources for blending for discharge to the Famoso Basins are (i) treated produced water from Chevron, (ii) treated produced water from VWDC, (iii) surface water via CWD Pump Station B, and (iv) groundwater. Blended water is applied at the Famoso Basins at approximately 198 acre-feet per day (65mgd) and spread over 374 acres for a daily hydraulic load of about 6 inches per day. A design water quality representing the average for 120 days of discharge was determined for the blended discharge water. Groundwater flow and transport modeling was conducted to assess potential impacts to groundwater from blended water discharge through the Famoso Basins. Groundwater is not expected to be degraded by arsenic because arsenic is strongly absorbed during unsaturated transport (K/J, 2011a and 2011b). Groundwater degradation is expected to occur for boron, chloride, sodium, and salinity (EC) but modeling of the initial, worst case scenario shows downgradient groundwater quality to below water quality objectives (K/J, 2011a and 2011b). Additional modeling was performed for the Most Probable Discharge Scenario for a thirty-year period with consideration for treated produced water flows, winter irrigation, changing surface water availability, precipitation, and infiltration through Poso Creek near the Famoso Basins. Concentrations of constituents of interest were between the discharge values and the background groundwater values below the Basins and less than the water quality objectives

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 116 TODD GROUNDWATER downgradient of the Basins. Treated produced water discharge and groundwater banking of surface water is not expected to impair groundwater for agricultural beneficial uses (K/J, 2011b). CWD Water Quality Monitoring. CWD actively monitors imported surface water quality. Most monitoring locations are at District pumping stations where the principal surface water supplies from the SWP and Kern River are imported to CWD. Samples are collected and analyzed at each of Pump Stations “A” and “B” on a monthly basis. In addition, DWR regularly monitors the water quality at several locations along the California Aqueduct. The USBR also conducts routine water quality testing along the Friant‐Kern Canal. Treated oilfield water is sampled monthly at Reservoir B for agricultural suitability (CWD, 2015b). Water quality reports for this source of supply are prepared by the treated oilfield producers and provided to the CVRWQCB to illustrate compliance with regulations and guidelines contained in their respective discharge permits. Other Local Groundwater Quality Monitoring. CWD conducts groundwater monitoring programs to satisfy the requirements of previously existing WDR permits that authorize CWD to receive treated produced waters for the purposes of irrigation and groundwater recharge. Water samples are collected annually from designated wells and analyzed for constituents of concern including nitrate, salinity, and arsenic. This information is compiled and reported to the Regional Board per the requirements of the WDRs (CWDC, 2015). The CWD maintains an extensive water quality monitoring database that reflects distinct programs that monitor water quality for groundwater, surface water, imported water, and treated produced water. Annual sampling is conducted of CWD-owned and some private wells (CWD, 2015b). Groundwater pumped from CWD deep wells is sampled in years of heavy use—typically during years of reduced surface water supplies. Surface Water Quality Monitoring Plan. As described above under the ILRP, CWDC has prepared a Surface Water Monitoring Plan (SWMP) (CWD, 2014) in response to the RWQCB’s General Order No. R5‐ 2013‐0120 (General Order). The purpose of the SWMP is to obtain data and evaluate the impact of irrigated agriculture on surface water quality in the CWDC area and determine if existing or new agricultural management practices comply with surface water receiving limitations defined by the General Order (CWDC, 2014). In the CWDC area, Poso Creek is the only natural channel that enters the CWDC area and extends into other areas that can benefit from its beneficial uses. Approximately seven miles of the Poso Creek channel cross the CWDC area, which is the first area with irrigated agriculture that is traversed by the creek. This irrigated agriculture has potential to impact water quality (CWDC, 2014). Water quality monitoring of this section of Poso Creek provides data to evaluate the impact of agricultural management practices on Poso Creek waters (CWDC, 2014). Little Creek is a small natural channel that is a tributary to Poso Creek and enters the CWDC area from the east and the north side of Poso Creek. It passes through approximately two miles of irrigated agriculture within the CWDC area and joins Poso Creek within a half mile inside the east CWDC boundary. According to CWD, Little Creek rarely has water flows and has had detectable flows in only 3 of the last 33 years. Little Creek is not monitored because of its short run within irrigated farmland, lack of water flow, and immediate confluence with Poso Creek just inside the CWDC eastern boundary. Accordingly, monitoring of Little Creek would provide little or no data that would assist in determination of impacts from irrigated agriculture.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 117 TODD GROUNDWATER Both the Poso Creek at Highway 65 Monitoring Station and the Poso Creek at Highway 99 Monitoring Station are new monitoring locations; these have replaced the previous Poso Creek at Zerker Road Monitoring Station. Poso Creek at Highway 65 Monitoring Station was established to monitor the water flows entering the CWDC area (without having effects from irrigated land), while the Poso Creek at Highway 99 Monitoring Station was established to document any potential impacts from irrigated agriculture within the CWDC area. Both monitoring stations are Core Monitoring Sites with Assessment Monitoring occurring every three years (CWDC, 2014). Sediment toxicity testing is performed twice a year for Poso Creek, which is an intermittent stream. Storm runoff sampling and testing is required for two storm runoff events each year. The sampling of storm runoff flows occurs three days after the flow event begins and there should be no flow for the prior thirty days. For periods of continuous flow in Poso Creek, precipitation will be monitored to determine when a secondary storm runoff event is occurring. Flow is to increase by 50 percent or more to be identified as a storm runoff event and sampling will occur on the third day of the flow event (CWDC, 2014). Sampling occurs when water is present and flowing during a monthly sampling event. Consistent with RWQCB requirements, the surface water monitoring parameters include field measurements, drinking water parameters (such as E. Coli and Total Organic Carbon), general physical parameters, metals, nutrients, pesticides, and water toxicity for designated species. These parameters are provided in the CWD Surface Water Monitoring Plan (CWDC, 2014). The Quality Assurance and Project Plan for sample collection and laboratory analysis is included as part of the SWMP (CWD, 2014). Results and evaluations are submitted through Quarterly and Annual Monitoring Reports and Exceedance Reports (CWDC, 2014). Protocols and procedures for sampling and testing are defined in the Quality Assurance Project Plan (QAPP) under the SWMP. Sample collection includes photo documentation and collection of field conditions at all monitoring events. Documentation of field conditions includes recording the time, weather observations, water and sediment characteristics, and any other observations of interest to the sampling event. Water and sediment sampling and analysis protocols are defined in the QAPP (CWDC, 2014).

6.2.3.2 Regional Water Quality Monitoring Groundwater Ambient Monitoring and Assessment Program. The Groundwater Ambient Monitoring and Assessment (GAMA) Program was created in 2000 by the SWRCB, and it was later expanded by the Groundwater Quality Monitoring Act of 2001 (AB 599). The GAMA Program is based on collaboration among agencies including the SWRCB, RWQCB, DWR, Department of Pesticide Regulation (DPR), USGS and USGS National Water Information System (NWIS), and Lawrence Livermore National Laboratory (LLNL). Local water agencies and well owners also participate in the GAMA Program. The main goals of GAMA are to: (1) improve statewide comprehensive groundwater monitoring, and (2) increase the availability to the general public of groundwater quality and contamination information. There are several GAMA monitoring projects within the Cawelo GSA and larger KGA GSA and include the following projects. The Priority Basin Project provides a comprehensive groundwater quality assessment to help identify and understand the risks to groundwater. The project started assessing public system wells (deep groundwater resources) in 2002 and shifted focus to shallow aquifer assessments in 2012. As part of this project, GAMA personnel have performed baseline and trend assessments and sampled public and domestic water supply wells in the Cawelo GSA and larger KGA GSA. The Domestic Well Project began between 2002 and 2011 and sampled private wells in six California counties, not including Kern County. The Domestic Well Project is currently on hiatus. The

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 118 TODD GROUNDWATER Technical Hydrogeological and Data Support Project includes several divisions and programs at the SWRCB, RWQCB, and other state agencies, and non-governmental organizations. GAMA water quality data, including nitrate, TDS, and arsenic were presented and discussed in the Section 3, Basin Setting of this Cawelo GSP. In the Cawelo GSA, ten contamination sites (all closed) have been identified with water quality data submitted to GAMA. GeoTracker and EnviroStor Databases. The GeoTracker database is overseen by the SWRCB. The GeoTracker database is used by the SWRCB and RWQCB to house data related to sites that impact or have the potential to impact groundwater. Records available from GeoTracker include cleanup sites for Leaking Underground Storage Tank (LUST) sites, Department of Defense sites, and Cleanup Program sites. Other records for various unregulated projects and permitted facilities include Irrigated Lands, Oil and Gas production, operating Permitted Underground Storage Tanks (USTs), and Land Disposal sites. The GeoTracker is a public and secure online portal that can retrieve records and view data sets from multiple SWRCB programs and other agencies through Google maps GIS interface. This database is useful for the public and for helping regulatory agencies to monitor the progress of cases. It also provides a web application tool for secure reporting of lab data, field measurements data, documents, and reports. GeoTracker water quality data, including nitrate, TDS, and arsenic were presented and discussed in Section 3, Basin Setting, of this Cawelo GSP. The California Department of Toxic Substances Control (DTSC) oversees the EnviroStor database. EnviroStor is used to track cleanup, permitting, enforcement, and investigation efforts at hazardous waste facilities and sites with known contamination or sites where further investigation is warranted by the DTSC. Unlike GeoTracker, EnviroStor only houses the records of cases for which the DTSC is the lead regulatory agency, whereas GeoTracker database houses records of cases from many regulatory programs, including the DTSC, Department of Defense, USEPA cleanup sites, and many others. Department of Pesticide Regulation. The Department of Pesticide Regulations (DPR) Groundwater Protection Program evaluates and samples for pesticides to determine if they may contaminate groundwater, identifies areas sensitive to pesticide contamination, and develops mitigation measures to prevent contamination movement. DPR obtains water quality sampling data from other public agencies and from its own sampling program. The data are reported annually along with the actions taken by DPR and the SWRCB to protect groundwater from contamination by agricultural pesticides. In the Cawelo GSA, only legacy pesticides (1,2-Dibromo-3-chloropropane (DBCP) and 1,2,3-Trichloropropane (1,2,3 TCP) are detected in groundwater, as explained in Section 3.2.2,Basin Setting, Groundwater Quality. Central Valley – Salinity Alternatives for Long-term Sustainability. The Central Valley – Salinity Alternatives for Long-Term Sustainability program (CV-SALTS) is a collaborative stakeholder driven and managed program to develop sustainable salinity and nitrate management planning for the Central Valley. The program objective is to facilitate the salt and nitrate implementation strategies recommended in the Salt and Nitrate Management Plan (SNMP) developed in 2017. CV-SALTS is designed to address both legacy and ongoing salt and nitrate accumulation issues in surface and groundwater. The overarching management goals and priorities of the control are: (1) ensure safe drinking water supply, (2) achieve balanced salt and nitrate loading, and (3) implement long-term, managed restoration of impaired water bodies. The program is phased with the primary focus of early actions on nitrate impacts to groundwater drinking water supplies and established implementation activities. The Kern County Subbasin is a Priority 2 basin for nitrate management. As a result, the nitrate control program is scheduled to begin in 2021. CV-SALTS will enact a nitrate control program as part of the SNMP, which requires forming a management zone as a regulatory option to comply with the requirements of the program. The management zones will consist of a defined management area to manage nitrate, ensure safe drinking

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 119 TODD GROUNDWATER water, and meet applicable water quality objectives. Local management plans will be created to implement the long-term goals of the nitrate control program. As programs are implemented, there will be versions of management areas to meet the objectives of their individual programs. While ILRP allows for compliance of their regulatory program through coalitions that cover a broad, non-contiguous area based on similar land use, SGMA and CV-SALTS will require both management areas to be contiguous area’s regardless of land use. The ILRP and CV-SALTS programs involve permittees and local stakeholders working toward water management objectives established by the State. Therefore, collaborative efforts should be made to maximize the resources of each program and provide a more integrated approach to developing local solutions for groundwater management. DWR’s Water Data Library. An additional State-wide source of groundwater quality data is DWR’s Water Data Library (WDL). DWR’s WDL is a repository for groundwater quality data. Samples are collected from a variety of well types including irrigation, stock, domestic, and some public supply wells. WDL has groundwater quality data from 43 wells in the Cawelo GSA; these data have been included in the CWD water quality database.

6.2.3.3 Public Water Supply Monitoring California Drinking Water Information System Database. The SWRCB – Division of Drinking Water (DDW) regulates all public drinking water systems (a system that has 15 or more service connections or regularly serves 25 individuals daily at least 60 days out of the year) to demonstrate compliance with State and Federal drinking water standards through a rigorous monitoring and reporting program. The required monitoring data for each well within the water systems are uploaded to the DDW’s database and subsequently available for the public through the State Drinking Water Information System (SDWIS). In addition to the compliance monitoring data, other information is available, including monitoring frequency, basic facility descriptions, lead and copper sampling, violations and enforcement actions, and consumer confidence reports. All drinking water systems are required to collect samples, known as Title 22 constituents on a given frequency depending on the constituent and regional groundwater vulnerability. The following is a summary of the minimum sampling frequency for public water supply wells in the Cawelo GSA and across California: • General chemistry (anions/cations), metals and organics (Synthetic Organic Chemicals and Volatile Organic Compounds) sampling is required every 3 years. If any organics are detected, sampling frequency must be increased to quarterly. • Nitrate is required annually. If nitrate is >5 mg/L (as N), then sampling is required quarterly. • If arsenic is ≥5 µg/L, sampling should be increased to quarterly but is not always done. • Radiologicals (Gross Alpha and Uranium) are sampled once every 3 (when initial monitoring is ≥ half the MCL), 6 (when initial monitoring is ≤ half the MCL) or 9 (when initial monitoring is non- detect) years depending on historical results. Due to these monitoring requirements, public water systems provide the most abundant source of data because the testing requirements are at frequent intervals, data collection began in 1974, and all sample results are easily available from the SDWIS database. It is important to understand that any water quality characterization using this data is not intended to represent water supplied by purveyors because they may provide wellhead treatment to remove or reduce contaminants.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 120 TODD GROUNDWATER The SDWIS database includes data for active and inactive drinking water sources, for water systems that serve the public, and wells defined as serving 15 or more connections, or more than 25 people per day. No such water systems have been identified within the Cawelo GSA area. Municipal wells for the City of Shafter and Oildale Mutual Water Company (which overlap small areas of the Cawelo GSA) are located outside Cawelo GSA boundaries.

6.2.3.4 Oil & Gas Related Water Quality Monitoring Division of Oil, Gas, and Geothermal Resources. In 2013, Senate Bill 4 (SB-4) requires that the Division of Oil, Gas, and Geothermal Resources (DOGGR) adopt rules and regulations specific to oil and gas wells. SB-4 requires that well owners to participate in notification requirements, water testing and well monitoring. The SWRCB, in consultation with DOGGR, is required to develop groundwater monitoring criteria and implement a groundwater monitoring program. The goal of the groundwater monitoring to assess potential impacts to groundwater due to well stimulation and discharge of treated produced water through such methods as underground injection control (UIC) and treated produced water ponds. As part of SB-4, DOGGR has established model criteria for groundwater monitoring in areas of oil and gas well stimulation (SWRCB, 2015), including the following three components: • Area-specific— groundwater monitoring near stimulation wells by the operator. a. Does not apply to groundwater monitoring programs approved with permits by DOGGR for well stimulation prior to July 2015. b. Groundwater monitoring plans should be structured to characterize baseline water quality and detect potential impacts to protected water. c. Groundwater monitoring is limited to areas of protected water: i. <10,000 mg/L TDS, and ii. Outside an exempt aquifer (Code of Federal Regulations, title 40, part 146.4) • Sampling and testing—requirements for designated contractor. a. DOGGR requires notification of land owners and tenants that have property lines within 1,500 feet of the well or within 500 feet of the horizontal projection of subsurface portions of the well to the surface. b. Land owners and tenants may request water quality testing be performed on water wells or surface water suitable for drinking or irrigation. Data is to be submitted through GeoTracker. • Regional—groundwater monitoring by State Water Board. a. Regional Monitoring Program (RMP) for all waters designated for any beneficial use with drinking water or potential drinking water sources having priority. b. The RMP will focus on well stimulation treatments and fluids produced or introduced in the well including produced water ponds and UIC wells. c. The USGS is the technical lead for implementing the RMP and has summarized the protocols and procedures. Additional details of the groundwater quality monitoring by the SWRCB (2017) . Based on preliminary reports, sample results required by SB-4 will not likely overlap with the data collections for SGMA. However, the infrastructure needs for monitoring wells are likely to have some overlap; shared infrastructure between SGMA and SB-4 monitoring entities should be considered. U.S. Geological Survey. The USGS California Water Science Center (CWSC) provides California water data through data collection, processing, analysis, reporting, and archiving. The USGS archives data in the USGS NWIS database. USGS studies used for the basin setting and to characterize groundwater quality in the Cawelo GSA include:

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 121 TODD GROUNDWATER • Prioritization of Oil and Gas Fields for Regional Groundwater Monitoring (2018). • Preliminary Groundwater Salinity Mapping Near Select Oilfields (2018). • Groundwater Quality Data in 15 GAMA Study Units. • Preliminary Results from Exploratory Sampling in Selected Oil Fields (2014-15).

6.3 GROUNDWATER LEVEL MONITORING NETWORKS

Groundwater levels are a fundamental measure of the status of groundwater conditions within the Cawelo GSA. The following monitoring network and protocols are based on the KGA Coordination Agreement Component white paper for groundwater elevation data and will be implemented during the collection of groundwater level data to ensure that it meets the requirements of the GSP Regulations and the DQOs of the KGA GSA.

6.3.1 Description of Monitoring

Given the significant variations in groundwater elevations throughout the Kern County Subbasin, which are due to variations in hydrologic conditions, no single groundwater elevation surface will be considered a representation of groundwater flow directions in the Cawelo GSA. Many of the monitoring wells in the current monitoring programs are owned by the CWD and present no issue being utilized for monitoring programs. The remaining wells are privately owned, and owners have granted use for the study. Any private wells selected for the Cawelo GSP monitoring program will require additional permission from owners to ensure their long-term use in the program. Generally, the wells are already used for monitoring purposes and there are no foreseeable objections for use of these wells in the Cawelo GSP monitoring program.

6.3.2 Monitoring Protocols

The monitoring protocols that will be implemented during the collection of groundwater level data in the Cawelo GSA will ensure the following considerations, as recommended by DWR (2016): • Groundwater level data are taken from the correct location, well ID, and screen interval depth. • Groundwater level data are accurate and reproducible. • Groundwater level data represent conditions that inform appropriate basin management DQOs for the Kern County Subbasin. • All salient information is recorded to correct, if necessary, and compare data. • Data are handled in a way that ensures data integrity. Additionally, the following data collection protocols for Cawelo GSA groundwater level monitoring will be followed in coordination with the Kern County Subbasin Coordination Agreement Component: • Groundwater level data shall be sufficient to produce seasonal maps of potentiometric surfaces or water table surfaces throughout the basin that clearly identify changes in groundwater flow direction and gradient. • Use the Well Data form provided by the KGA. • Groundwater level data shall be collected from each principal aquifer in the basin. • Static groundwater level measurements will be collected at least two times per year to represent seasonal low and seasonal high groundwater conditions. • Collection of data between the approved time frames only

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 122 TODD GROUNDWATER th th o January 15 to March 30 th th o September 15 to November 15 • A weighted water level meter will be used to measure the depth to groundwater. • Depth to groundwater must be measured relative to an established Reference Point on the well casing. If no mark or reference point is apparent, the person performing the measurement should measure the depth to groundwater from the north side of the top of the well casing • The elevation of the Reference Point of the well must be surveyed to the North American Vertical Datum of 1988. The elevation must be accurate to within 0.1 foot. • Each well’s Reference Point will be cataloged to ensure identical procedures are followed for subsequent measurements. • The data collector should remove the appropriate cap, lid or plug that covers the monitoring access point listening for pressure release. If a release is observed, the measurement should follow a period of time to allow the water level to equilibrate. • Depth to groundwater must be measured to an accuracy of 0.1 foot below the Reference Point. • The water level meter shall be decontaminated after measuring each well. • The data collector shall calculate the groundwater elevation as: o GWE = RPE – DTW o GWE = Groundwater Elevation o RPE = Reference Point Elevation o DTW = Depth to Water • The data collector must ensure that all measurements are consistent units of feet, tenths of feet or hundredths of feet. Measurements and Reference Point Elevations should not be recorded in feet and inches.

The groundwater level monitoring protocols will be reviewed at least every five years as part of the periodic evaluation of the GSP and modified as necessary.

6.4 GROUNDWATER STORAGE MONITORING NETWORKS

The groundwater storage monitoring network for the Cawelo GSA is designed to estimate the change in annual groundwater in storage for the purpose of meeting the definition of the sustainability goal.

6.4.1 Description of Monitoring

Groundwater storage is not a directly measurable condition, and therefore relies heavily on the collection of accurate groundwater levels from the monitoring network (Figure 6-2). The changes in groundwater levels reflect changes in storage and can thus be estimated with assumptions of thickness of units, porosity, and connectivity. These observations will be essential for use in calculating the water budget.

A water budget is a foundational tool used to compile water flows (supplies) and outflows (demands). It is an accounting of the total groundwater and surface water entering and leaving a basin or user-defined area. The difference between flows and outflows is a change in the amount of water stored. Coordination of Water Budget Data to comply with groundwater storage include the following:

• Surface water supply • Total water use

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 123 TODD GROUNDWATER • Water budget • Sustainable yield The change in the annual volume of groundwater storage between seasonal high conditions shall be quantify in the water budget.

6.4.2 Monitoring Protocols

Because the calculations of groundwater storage rely on groundwater level data collected from the monitoring network, the monitoring protocols used for groundwater level data (section 1.3.2) are also appropriate here for the monitoring protocols for groundwater storage. Similarly, the groundwater storage monitoring protocols will be reviewed at least every five years as part of the periodic evaluation of the GSP and modified as necessary.

6.5 GROUNDWATER QUALITY MONITORING NETWORKS

The groundwater quality monitoring network for the Cawelo GSA is designed to demonstrate that the degraded water quality sustainability indicator is being observed for the purpose of meeting the definition of the sustainability goal.

6.5.1 Description of Monitoring

The following requirements for well selection for groundwater quality monitoring have been developed from the KGA Coordination Agreement Component from the analysis of groundwater quality in Section 3, Basin Setting, of this GSP. These requirements are similar to the requirements for the groundwater level monitoring network: • A long-term access agreement that includes year-round site access to allow for increased monitoring frequency. • A unique identifier that includes a general written description of the site location, date established, access instructions and point of contact, type of information to be collected, latitude, longitude and elevation. • Monitoring location should also track all modifications to the site in a modification log. • The use of existing water quality data within the basin should be done to the greatest extent possible. • Monitoring network include monitoring locations where known groundwater contamination plumes are under existing regulatory management.

Based on the analysis of the Basin Setting and the KGA Coordination Agreement Component (Umbrella GSP, GEI, 2019), the planned groundwater quality monitoring network for the Cawelo GSP will include the eight wells in Figure 5-1. These existing wells were selected because they are approved monitoring wells that are part of the ILRP GCTMP for CWDC (CWDC, 2018). The wells are agricultural production wells that have been used for groundwater quality monitoring by the CWD and have known construction information (CWDC, 2018). Additional scientific rational for these eight monitoring wells is their uniform spatial distribution across the Cawelo GSA and their location within both the agricultural and oil drilling land-use activities of the GSA (Figure 5-1). Additionally, the wells in the network are part

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 124 TODD GROUNDWATER of the larger monitoring network of the Kern County Subbasin and thus have comparable spatial density to the other groundwater level monitoring networks of the GSAs within the Kern County Subbasin.

6.5.2 Monitoring Protocols

The following data collection protocols for Cawelo GSA groundwater quality monitoring are consistent with DWR recommendations (DWR, 2016) and were developed under the Kern County Subbasin Coordination Agreement Component. The following monitoring protocols have also been determined based on the analysis of groundwater quality as described in the Section 3, Basin Setting, of this GSP: • Monitor groundwater quality data from each principal aquifer in the basin. • Data should be sufficient for mapping movement of degraded water quality. • Data should be sufficient to assess groundwater quality impacts to beneficial uses and users. • Data should be sufficient to evaluate whether management activities are contributing to water quality degradation. • All analyses should be performed by a laboratory certified under the State Environmental Laboratory Accreditation Program. • Samples will be collected according to the standards listed in the Standard Methods for the Examination of Water and Wastewater, USGS National Field Manual for the Collection of Water Quality Data (Wilde, 2005). • Prior to sampling, the sampler must contact the laboratory to schedule laboratory time, obtain appropriate sampler containers, and clarify any sample holding times or sample preservation requirements. • Each well used for groundwater quality monitoring must have a unique identifier. This identifier must appear on the well housing or the well casing to avoid confusion. • In the case of wells with dedicated pumps, samples should be collected at or near the wellhead. Samples are not to be taken/collected from storage tanks, at the end of long pipe runs or after any water treatment infrastructure. • Samples will be collected only after the appropriate volume of water has been purged from the casing and field parameters have stabilized. • Sampler will clean the sampling port and/or sampling equipment prior to sampling. The sampling port and/or sampling equipment must be free of any contaminants. • Groundwater elevation in the well should be measured following the protocols described in the groundwater level measuring protocols. • To be consistent with the Kern County Subbasin Coordination Agreement, field parameters of pH, electrical conductivity (EC), and temperature should be collected for each sample. Lab pH analysis are typically unachievable due to short hold times. Because 7 of 8 wells in the monitoring network are a part of the CWD’s existing monitoring network for the ILRP, these wells will also include annual monitoring for static water levels, temperature, pH, EC, dissolved oxygen (DO), and nitrate as N as required under ILRP. Once every five years, a limited group of general water quality parameters (anions and cations) will be also collected as part of ILRP. Nitrate and salinity levels in groundwater can be indicators of potential impacts on groundwater quality due to irrigation. The collection of DO data from the groundwater quality monitoring network will satisfy the recommendations made in the groundwater quality analysis of Section 3, Basin Setting, in this GSP. To be consistent with the monitoring network, the groundwater sampling at the new potential monitoring well in the Eastern Extension Area (Figure 5-2) should include the same constituents on the same sampling frequency. This well was not previously in the CWDC monitoring program.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 125 TODD GROUNDWATER • All field instruments should be calibrated daily and evaluated for drift throughout the day. • Sample containers should be labeled prior to sample collection. The sample label must include: o Sample ID (well ID) o Sample date and time o Sample personnel o Sample location o Preservative used o Analytes and analytical method. • Samples shall be collected under laminar flow conditions. This may require reducing pumping rates prior to sample collection. • Samples requiring preservation must be preserved as soon as practically possible. • Samples to be analyzed for metals should be field-filtered prior to preservation. Do not collect an unfiltered sample in a preserved container. • Samples will be chilled and maintained at 4 C to prevent degradation of the sample. • Samples will be shipped under a chain of custody documentation to the appropriate laboratory promptly to avoid violating holding time restrictions. • Custody Seal will be used by the field technician if a third-party transportation service is used. • A Field Sampling Log will be maintained for each sampling event and will include: o Sampler’s identification o Well identification o Climatic conditions o Depth to water prior to purging o Type of purging and sampling device o Purging rate and volume o Relative well yield volume o Field parameter measurements (pH, temperature, EC, DO) o Type and number of samples collected o Date and time collected. The groundwater quality monitoring protocols will be reviewed at least every five years as part of the periodic evaluation of the GSP and modified as necessary.

6.6 LAND SUBSIDENCE MONITORING NETWORKS

Pursuant to SGMA regulations, land subsidence monitoring and protocols must be established to identify the rate and extent of land subsidence, which may be measured by extensometers, surveying, remote sensing technology, or other appropriate methods (DWR, 2016). To the extent possible, the use of existing data should be utilized.

6.6.1 Description of Monitoring

Monitoring and evaluating inelastic land subsidence can use multiple data sources to evaluate the specific conditions and causes (DWR, 2016). Subsidence can be estimated from several methods, including surveying to a known stable benchmark or benchmarks located outside the areas being studied; installing and tracking change in borehole extensometers; obtaining data from continuous GPS (CGPS) locations, static GPS surveys or Real-Time-Kinematic (RTK) surveys; or analyzing InSAR data (DWR, 2016). Currently in the Cawelo GSA, there are no active benchmark surveys, borehole

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 126 TODD GROUNDWATER extensometers, or surveys from CGPS, static GPS, or RTK. However, recent InSAR data is available for the entire Cawelo GSA that was measured by NASA-JPL (DWR, 2018), as shown in Figures 3-26.

Because subsidence is not a significant issue in the Cawelo GSA (Figure 3-26), the planned monitoring network for inelastic land subsidence will use groundwater levels as a proxy for subsidence. These groundwater levels will be measured using the same protocols previously described for the groundwater levels monitoring network. Additionally, Cawelo GSA will participate in the KGA basinwide subsidence monitoring program that will include InSAR and other monitoring networks to-be-determined by KGA GSA. The use of InSAR data for the monitoring is cost-effective and reasonably accurate to estimate subsidence over spatial and temporal scales consistent with groundwater management in the KGA and Cawelo GSAs.

6.6.2 Monitoring Protocols

No standard procedures exist for collecting data from potential subsidence monitoring approaches (DWR, 2016). Prior to development of a specific subsidence monitoring network a screening level analysis will be conducted that include: • Review of the hydrogeologic conceptual model and understanding of grain-size distributions and potential for subsidence to occur • Review of any known regional or correlative geologic conditions where subsidence has been observed. • Review of historic range of groundwater levels in the principal aquifers of the basin. • Review of historic records of infrastructure impacts, including but not limited to damage to pipelines, canals, roadways or bridges or well collapse potentially associated with land surface elevation changes. • Review and evaluation of remote sensing results such as InSAR or other land surface monitoring data. • Review of existing CGPS surveys, as available. The KGA and the Kern County Subbasin GSAs will work together on the land subsidence protocols with a consultant to obtain the required data. The land subsidence monitoring protocols will be reviewed at least every five years as part of the periodic evaluation of the GSP and modified as necessary.

6.7 SURFACE WATER MONITORING NETWORKS

Monitoring surface water is important for the water budget analysis and to evaluate possible stream depletion associated with groundwater extraction (DWR, 2016). Although the discussions in Section 3 indicate that surface waters in Poso Creek and Kern River are not interconnected with the groundwater aquifer, existing surface water monitoring programs, such as the Surface Water Monitoring Plan (SWMP) under the ILRP, will continue to be utilized to maintain an appropriate understanding of surface water conditions. As with other monitoring networks and protocols of the Cawelo GSP, existing monitoring locations and networks are incorporated to the greatest extent possible.

The following monitoring network and protocols are based on the KGA Coordination Agreement Component white paper for surface water supply (Umbrella GSP, GEI, 2019) and will be implemented during the collection of surface water data to ensure that it meets the requirements SGMA and the DQOs of the KGA GSA. This section identifies potential sources of information for documenting surface water supplies. As described in the white paper (Umbrella GSP, GEI, 2019), these are viable methods

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 127 TODD GROUNDWATER that KGA participating member, including Cawelo GSA, have collectively agreed to be used to document surface water supplies. Establishing common and defined methods for determination of surface water supplies is important to establishing a creditable coordination agreement between GSAs within the Kern Subbasin and KGA participating members.

6.7.1 Description of Monitoring

Surface water supplies are currently documented and aggregated by several sources in the Kern County Subbasin. The available sources include the following:

• Kern County Water Agency (KCWA) - KCWA releases annual water supply reports that document water supplies in Kern County. Water supplies documented in the annual water supply reports include State Water Project (SWP), Central Valley Project (CVP), Kern River, minor streams, precipitation, recycled water, and treated produced water sources. KCWA’s annual water supply reports include data at a district or agency level. • Individual District Records - Districts also measure surface water deliveries to verify supplies diverted from the CVP, SWP, and local surface water sources, as well as to document deliveries to individual irrigators within the districts. • Kern River Report - The Kern River Report is also reliable source of surface water supply information. The data sources may be used together to verify or dispute the amounts included in other reports. Discrepancies between reports can be investigated and resolved if necessary.

In addition to the data networks across the Kern County Subbasin, existing monitoring networks from the CWD will provide sufficient spatial and temporal data about surface water in the Cawelo GSA. As described previously, the existing streamflow networks for Poso Creek include the USGS gage east of the Cawelo GSA with a record that spans from 1959 to present and the CWD stream gages upstream of Highway 65 and at Highway 99 with records that span from 1982 to present. Monthly streamflow data (acre-feet) has been compiled by CWD since 1993.

CWD will continue monitoring discharge through its distribution system (pumping plants, canals, and pipeline turnouts) from the Cross Valley Canal and its Extension that conveys SWP water from the California Aqueduct near Tupman to the Beardsley and Lerdo canals. The CWD will continue collecting daily meter readings at each turnout that is running and use totalizers at the end of every month. At the larger Subbasin scale, the KCWA will continue monitoring daily all turnouts from the California Aqueduct and all turnouts along the Cross Valley Canal (KCWA, 2011).

Similarly, CWD will continue monitoring the volume of water received from oil extraction operations for irrigation and the flow into its Famoso and Poso Creek recharge basins. Because of the ample coverage from the existing CWD and KGA monitoring networks for streamflow, imported water, and conjunctive use water, no new surface water monitoring sites will be established as part of the Cawelo GSP.

6.7.2 Monitoring Protocols

• Reporting of Surface Water Data - SGMA requires annual reporting of groundwater elevation data, groundwater extraction, surface water use, total water use, and change in groundwater

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 128 TODD GROUNDWATER storage. Surface water data is reported on a monthly basis and can easily be compiled into an annual report for use in SGMA reporting. • Quality Control and Assurance - Surface water data can be compared for accuracy against values prepared in Agricultural Water Management Plans (AWMP)s. If data from AWMPs is significantly different than the reported surface water data, the AWMP and/or the calculated extraction can be reviewed. Potential changes in irrigation practices and land use may be the cause of the difference and should be investigated. • Imported Water Deliveries - CWD staff periodically checks for measurement accuracy of totalizers as part of the CWD maintenance program. When properly calibrated, the meters provide accurate measurements of the flow rate and volume of water delivered at the turnouts. CWD agricultural water measurement practices and protocols are consistent with Water Code requirements and are documented in the CWD Agricultural Water Management Plan (CWD, 2015b). The surface water monitoring protocols will be reviewed at least every five years as part of the periodic evaluation of the GSP and modified as necessary.

6.8 REPRESENTATIVE REGIONAL MONITORING (REG. § 354.36)

Representative monitoring sites (RMS) are defined in the SGMA regulations as a subset of monitoring sites that are representative of conditions in the basin. The RMS may be designated where site results reflect the general conditions in the area, and where quantitative values for minimum thresholds and interim milestones are defined. The representative monitoring may also include proxies by which on sustainability indicator such as monitoring groundwater elevations may be used in place of other sustainability indicators, for example: • Significant correlation exists between groundwater elevation and the sustainability indicators for which groundwater elevation measurements serve as proxy, and • A reasonable margin of operational flexibility with groundwater elevations will be taken to avoid undesirable results for the other sustainability indicators. Section 3, Basin Setting, of this GSP presents spatial distribution of groundwater quality and groundwater levels for the Cawelo GSA. As a result of this analysis, all of the monitoring sites shown in Figure 6-3 and Table 6-2 are considered RMS in the Cawelo GSA.

6.8.1 Description of Monitoring

Given the significant variations in groundwater elevations throughout the Kern County Subbasin, which are due to variations in hydrologic conditions, no single groundwater elevation surface will be considered a representation of groundwater flow directions in the Cawelo GSA. The following requirements for well selection have been developed from the KGA Coordination Agreement Component (Umbrella GSP, GEI, 2019): • A long-term access agreement that includes year-round site access to allow for increased monitoring frequency.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 129 TODD GROUNDWATER • A unique identifier that includes a general written description of the site location, date established, access instructions and point of contact, type of information to be collected, latitude, longitude and elevation. • Monitoring location should also track all modifications to the site in a modification log • An explanation of why the proposed frequency of collecting data measurements is appropriate for each sustainability indicator will be documented. This will include both short-term and long- term trends in groundwater conditions. • A description of how well monitoring locations covers the primary aquifers in the Cawelo GSA. This will include relevance to estimates of water budget components, surface water features, and groundwater conditions and a map of monitoring locations shown on a map for each aquifer of the Cawelo GSA. Maps should also include relevant information on current hydrogeologic conditions, such as: water level contours, storage change, water quality, land subsidence, interconnected surface water locations, etc.

Table 6-2. Monitoring Well Network in the Cawelo GSA. Historical Minimum Low Monitoring Data Collection Threshold Well ID Well Type Water Level Purpose Frequency (Elevation, (Elevation, feet) feet) agricultural Levels: semi-annual, T26R26-24R Levels & Quality 35 -43 production well Quality: annual agricultural Levels: semi-annual, T27R26-4R Levels & Quality 75 -3 production well Quality: annual agricultural Levels: semi-annual, T27R26-12H Levels & Quality 103 25 production well Quality: annual agricultural Levels: semi-annual, T27R26-33C2 Levels & Quality 20 -64 production well Quality: annual agricultural Levels: semi-annual, T28R26-11M Levels & Quality 3 -81 production well Quality: annual agricultural Levels: semi-annual, T28R27-6C Levels & Quality -1 -85 production well Quality: annual agricultural Levels: semi-annual, T28R27-28L Levels & Quality 110 26 production well Quality: annual Levels: semi-annual, T29R28-05M01 TBD Levels & Quality Quality: annual

Based on the analysis of the Basin Setting, existing CWD monitoring for groundwater levels, and the KGA Coordination Agreement Component (Umbrella GSP, GEI, 2019), the planned monitoring network for the Cawelo GSP will include the eight wells in Figure 6-3 and Table 6-2. These existing wells were selected because they are approved monitoring wells that are part of the ILRP GCTMP for CWDC (CWDC, 2018). The wells are agricultural production wells that have been used for groundwater quality monitoring by the CWD and have known construction information (CWDC, 2018), and are part CWD’s existing regular measurement program in their role as a local CASGEM monitoring entity. Additional scientific rational for these eight monitoring wells is their uniform spatial distribution across the Cawelo

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 130 TODD GROUNDWATER GSA and their location within both the agricultural and oil drilling land-use activities of the GSA (Figure 6-3). The degree of monitoring with these eight sites is consistent with the level of groundwater use and the need for various levels of monitoring density and frequency, as outlined in Table 6-2. Additionally, the wells in the network are part of the larger monitoring network of the Kern County Subbasin and thus have comparable spatial density to the other groundwater level monitoring networks of the GSAs within the Kern County Subbasin. The monitoring well network coverage (Figure 6-3) is based on several factors. These include spatial patterns in crops, recharge, and domestic well locations, monitoring well information, and other factors, as described below. Within Cawelo GSA there are four primary crops that account for over 97 percent of the crops grown in the CWDC area; almonds, citrus, pistachios and vineyards (CWDC, 2018). There are general concentrations of each of the four different crops that can be associated to a region of GSA, but each of these crops has some distribution throughout the area. The eight monitoring wells were selected to provide representative monitoring in these areas of the four primary crops. In general, recharge in the GSA is a result of irrigation water percolating past the root zone of crops, groundwater recharge basins, and delivery system reservoirs. The potential impacts of recharge due to crop irrigation are addressed by taking into consideration the monitoring well locations in relation to the crop variations (CWDC, 2018). The land use in the Cawelo GSA is primarily agriculture. However, there are isolated dwellings and facilities that potentially have domestic groundwater wells. The south end area of the GSA that is primarily industrial land use is serviced by a water company. Based on a search of the GAMA database, there are six domestic or public use wells in the GSA (CWDC, 2018). These wells are of particular interest to the Regional Board because they provide drinking water and typically lift water from the shallower regions of the aquifer. The well information (Table 6-3) is essential to providing an effective groundwater monitoring program. It is important to know well construction information and at what elevation the well is drawing water from within the aquifer. Factors such as well perforation locations, pump settings and well location are key data to determine what zone the water quality data is obtained from. The majority of the monitoring wells have known perforation depths and water levels are routinely measured at these wells as part of the ILRP GQTMP (Table 6-1). Additional information on any remaining data gaps will need to be acquired as part of GSP implementation. Many of the monitoring wells are owned by the CWD and present no issue being utilized for monitoring programs. The remaining well are privately owned and owners have granted use for existing monitoring programs. Any private wells selected for the Cawelo GSP monitoring program will require additional permission from owners to ensure their long-term use in the program. Generally, the wells are already used for monitoring purposes and there are no foreseeable objections for use of these wells in the Cawelo GSP monitoring program.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 131 TODD GROUNDWATER Table 6-3. Construction Information for Monitoring Well Network. Casing Total Perforation Well Construction Well ID Latitude Longitude Size Depth Depth (feet) Completion Year (inches) (feet) Report T26R26-24R 35.64694 -119.11746 2006 16 1780 725-1780 Yes T27R26-4R 35.60230 -119.16900 1960 14 1200 510-1200 Yes T27R26-12H 35.59541 -119.11595 1954 14 1220 500 No T27R26-33C2 35.54391 -119.17809 C.U. C.U. C.U. C.U. C.U. T28R26-11M 35.50440 -119.15020 2000 16 1065 822-1065 Yes T28R27-6C 35.527437 -119.10998 1990 18 1215 560-1215 C.U. T28R27-28L 35.60230 -119.16913 1976 16-14 1000 544 Yes T29R28-05M01 C.U. C.U. C.U. C.U. C.U. C.U. C.U. C.U. – Currently unavailable

6.9 ASSESSMENT AND IMPROVEMENT OF MONITORING NETWORK (REG. § 354.38)

The monitoring networks have been reviewed and evaluated herein the Cawelo GSP. Each five-year assessment will also review and evaluate the monitoring networks, including a determination of uncertainty and whether there are data gaps that could affect the ability of the GSP to achieve the sustainability goal for the Cawelo GSA.

6.9.1 Data Gaps

According to SGMA regulations, an analysis of data gaps within the existing monitoring networks will be performed and documented. Documentation will be provided regarding what qualifies as a data gap and what merely needs additional detail with respect to sampling frequency or additional field testing. The following sections describe data gaps for groundwater elevation and storage, groundwater quality, and land subsidence.

6.9.1.1 Groundwater Elevation and Storage Based on information in Section 3, Basin Setting, existing CWD monitoring for groundwater levels, and the KGA Coordination Agreement Component (Umbrella GSP, GEI, 2019), the planned monitoring network for the Cawelo GSP will include the eight wells in Figure 6-3 and Table 6-2. Seven of the wells are existing monitoring wells that have been used by the CWD to monitor water levels and to meet groundwater quality monitoring requirements by the ILRP GCTMP. These seven wells have a suitable spatial distribution across the agricultural land use in the CWD portion of the Cawelo GSA. However, there is a spatial gap in the Eastern Extension Area of the Cawelo GSA that is located in the oil and gas operations in the Eastern Extension Area. An existing well in that area will be added to the monitoring network (Figure 6-3).

6.9.1.2 Groundwater Quality The same data gap in the Eastern Extension of the Cawelo GSA for groundwater elevations and storage also exists for groundwater quality monitoring. The existing well in that area added to the monitoring program can also be used for groundwater quality to complete the spatial coverage of the Cawelo GSA.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 132 TODD GROUNDWATER 6.9.1.3 Land Subsidence The Cawelo GSA does not currently have a monitoring network for land subsidence. The lack of such a monitoring network is because subsidence is not a significant issue in the Cawelo GSA (Section 3.2.3).

6.9.2 Assessment of Network Improvements

According to SGMA regulations, the GSP should include an assessment of what future activities are needed to improve the monitoring networks. Improvements to each monitoring network plan should be broken out by each sustainability indicator, where relevant. The following sections describe an assessment of network improvement for groundwater elevation and storage, groundwater quality, and land subsidence.

6.9.2.1 Groundwater Elevation and Storage Based on an assessment of the spatial coverage of the monitoring network for groundwater elevation and storage, an additional monitoring well located in the Eastern Extension Area of the Cawelo GSA would improve the overall monitoring network. This well has been added to the monitoring network (Figure 6-3).

Groundwater elevations and hydraulic gradients in the Cawelo GSA are reported according to a range of time between Spring and Fall. DWR’s Monitoring Protocol BMP (DWR, 2016) recommends that groundwater elevation and sampling measurements be conducted during the 1 to 2-week period during the middle of Spring and middle of Autumn. Consequently, the timing of groundwater elevation measurements will be adjusted to occur during these 1 to 2-week periods.

6.9.2.2 Groundwater Quality Based on the assessment of spatial coverage of the monitoring network for groundwater quality, an additional monitoring well located in the Eastern Extension Area of the Cawelo GSA would improve the overall monitoring network. This well has been added (Figure 6-3)

6.9.2.3 Land Subsidence Future activities could improve the data gaps in terms of land subsidence monitoring. Inelastic land subsidence is not currently monitored in the Cawelo GSA. Therefore, the monitoring network for inelastic land subsidence will use groundwater levels as a proxy for subsidence. The groundwater levels will be measured using the same protocols previously described for the groundwater levels monitoring network. Each five-year review will evaluate the suitability of using groundwater levels as a proxy for subsidence.

6.9.3 Plan to fill data gaps

According to SGMA regulations, a plan will be developed and documented to address critical data gaps for the Agency area for all relevant sustainability indicators. This plan will be compliant with the overall Subbasin Coordination Agreement and may be implemented post submittal of the GSP. The following sections describe the plans to fill data gaps for groundwater elevation and storage, groundwater quality, and land subsidence.

6.9.3.1 Groundwater Elevation and Storage To fill the data gap in the groundwater elevation and storage monitoring network, an additional well has been identified in the Eastern Extension Area that will be added to the monitoring network (Figure 6-3). This new well will be sampled following the same protocol as the other seven wells in the monitoring

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 133 TODD GROUNDWATER network. Additionally, to minimize the effects of a temporal data gap in the future, it will be necessary to coordinate the collection of groundwater elevation data such that it occurs within a two-week window during the key reporting periods of mid-March and mid-October.

6.9.3.2 Groundwater Quality To fill the data gap in the groundwater quality monitoring network, an additional well has been identified in the Eastern Extension Area that will be added to the monitoring network (Figure 6-3). This new well will be sampled following the same protocol as the other seven wells in the monitoring network.

6.9.3.3 Land Subsidence The current gap in monitoring for inelastic land subsidence will be addressed using groundwater levels as a proxy for subsidence. These groundwater levels will be measured using the same protocols previously described for the groundwater levels monitoring network. Additionally, Cawelo GSA will participate in the KGA basinwide subsidence monitoring program that will include InSAR and other monitoring networks to-be-determined by KGA GSA. The use of InSAR data for the monitoring is cost- effective and reasonably accurate to estimate subsidence over spatial and temporal scales consistent with groundwater management in the KGA and Cawelo GSAs.

6.10 REPORTING MONITORING DATA TO THE DEPARTMENT (REG. § 354.40)

The monitoring data will be stored in the Data Management System (DMS) that will be developed pursuant to regulations §352.6. A copy of the monitoring data will be included in the Annual Report and submitted electronically on forms provided by the DWR.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 134 TODD GROUNDWATER 7 MINIMUM THRESHOLDS, MEASURABLE OBJECTIVES AND INTERIM MILESTONES

This chapter presents the Undesirable Results statements for the Cawelo GSA and presents a set of quantitative thresholds for monitoring points that indicate where Undesirable Results might occur within the Cawelo GSA, and to shape the monitoring network to detect Undesirable Results during the implementation of this GSP.

7.1 SUSTAINABLE MANAGEMENT CRITERIA

Sustainability indicators refers to any of the effects caused by groundwater conditions occurring throughout the basin that, when significant and unreasonable, cause undesirable results, as described in Water Code Section 10721(x).Undesirable results are the significant and unreasonable occurrence of conditions that adversely affect groundwater use, as described in Water Code Section 10721(x). These include the following:

• Lowering groundwater levels • Reduction of groundwater storage • Seawater intrusion • Degraded water quality • Land subsidence • Depletion of interconnected surface water

SGMA defines sustainable groundwater management as the management and use of groundwater in a manner that can be maintained during the planning and implementation horizon without causing undesirable results. SGMA requires the application of sustainable management criteria that define minimum thresholds, measurable objectives, and interim milestones to all representative monitoring sites identified in the GSP. These sustainable management criteria will help the Cawelo GSA and other groundwater users evaluate develop measurable, quantitative values for each SGMA sustainability indicators that will help identify progress towards achieving sustainability over the 20-year GSP implementation period. The GSP Emergency Regulations define the sustainability indicators as follows:

• Minimum Thresholds (MT) – MTs are a numeric value for each sustainability indicator, which are used to define when undesirable results occur if minimum thresholds are exceeded in a percentage of sites in the monitoring network (23-CCR §351(s)). • Measurable Objectives (MO) – MOs are specific, quantifiable goals for maintaining or improving specified groundwater conditions that are included in the adopted GSP to achieve the Basin’s sustainability goal (23-CCR §351(q)). • Interim Milestones (IM) – IMs are target values set of increments of five years representing measurable conditions set by an Agency as part of a Plan to help the Basin reach sustainability by 2040 (23-CCR §351(q)). • Margin of Operational Flexibility – A reasonable margin between the minimum threshold and measurable objective that will accommodate droughts, climate change, conjunctive use operations, or other groundwater management activities commensurate with levels of uncertainty. (23-CCR §354.30(c)).

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 135 TODD GROUNDWATER Both the MOs and MTs are developed for each sustainability indicators and evaluated through the monitoring network that provides representative sites to evaluate groundwater conditions across the GSA. These sites will also have IMs calculated for 2025, 2030, and 2035 to help guide the Cawelo GSA toward its 2040 sustainability goals.

Measurable objectives establish quantitative targets above the minimum threshold. The range between the measurable objective and the minimum threshold is known as the margin of operational flexibility that allows for an operational range that can accommodate active management during the implementation of the sustainability plan. The operational flexibility is intended to accommodate droughts, climate change, conjunctive use operations, or other groundwater management activities. Figure 7-1 illustrates the conceptual relationship between the Sustainable Management Criteria with respect to the operational flexibility.

Figure 7-2 shows locations of monitoring wells identified as representative for the GSP monitoring network. All wells meeting the representative well criteria outlined in this GSP are included in the Basin’s monitoring network, although participation in the SGMA monitoring program is dependent upon agreements between the Cawelo GSA and the well owners.

Direct monitoring of groundwater at representative monitoring sites will be supplemented by ongoing tracking of checkbook water budget components (see Section 4.2 Water Budget Approach) to better understand measured data within the context of conjunctive management. To ensure that the entire Subbasin will be operated within its sustainable yield by 2040, the Cawelo GSA will do its part through active monitoring and adaptive management to better match the groundwater response to specific management actions.

The GSP Emergency Regulations specify how GSAs must establish criteria for each applicable Sustainability Indicator. The following subsections describe the process of establishing MOs, MTs, and IMs for each of the sustainability indicators as needed. They also discuss the results of this process.

7.2 CHRONIC LOWERING OF GROUNDWATER LEVELS

The Undesirable Result for the chronic lowering of groundwater levels is a result that causes significant and unreasonable reduction in the long-term viability of domestic, agricultural, municipal, or environmental uses over the planning and implementation horizon of this GSP.

7.2.1 Groundwater Level Trends

As described in Section 3.2.1, water level declines within the Cawelo GSA have occurred primarily during drought cycles, which are also associated with low flows in the Kern River and Poso Creek, less precipitation, and decreases in imported water supplies. This decrease in surface water supply is typically coupled with an increase in groundwater pumping. Collectively, these changes result in decreases in recharge from banking activities, surface water conveyance, and surface water infiltration associated with irrigation and other outdoor water use. In addition, these drought periods are typically associated with increased recovery pumping at groundwater banking projects, which can result in significant local declines. Hydrographs on Figure 3-19 also demonstrate the ability for water levels in the Cawelo GSA to recover following drought conditions (e.g., the water level rise in the late 1990s following drought in the early 1990s). Although the hydrographs in Figure 3-19 end in the drought of record (2015-2016), water levels have since risen in response to the recent wet conditions of 2017 and 2019.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 136 TODD GROUNDWATER Figure 7-3 presents a summary of the average change in groundwater levels measured at 406 wells in the Cawelo GSA. The year-to-year change in groundwater levels was calculated for each well using the spring groundwater level measurement. The calculated change in groundwater levels was then averaged for all wells in five different areas of the Cawelo GSA. The graph shows that for the North, East, West and South areas of the Cawelo GSA, the groundwater levels varied with a 60 foot range from 1981 through 2012. During this time, the groundwater level trends are considered to be reasonably stable. The low groundwater levels during the 2008 to 2012 period were comparable to the low groundwater levels during the droughts of the late-1970s to early 1980s and late 1980s to early 1990s. Groundwater levels were able to recover following these low groundwater level periods. The recovery was due in large part to the availability of greater surface water to supply irrigated agriculture and thereby reduce the need for groundwater pumping.

During the period from 2012 to 2016, an extended drought across California greatly reduced the availability of surface water supplies, including locally available surface water supplies from the Kern River. In response, groundwater pumping in the Cawelo GSA was sustained at high levels over this period. The 60-foot decline in the average groundwater levels from 2012to 2016 was due, in large part, to this significant change in the water supply. Groundwater levels have recovered on the order of 20 feet since 2016, which is comparable to the rate following previous droughts.

Groundwater levels show a general declining trend over the ten year period from 2007 to 2016. This period was characterized by prolonged drought during which 8 of 10 years experienced below average rainfall for the Cawelo GSA with a rainfall deficit over this time exceeding 12 inches (equivalent to 1.7 years of average precipitation). Over this period, groundwater levels across much of the Cawelo GSA declined by about 80 feet (Figure 7-3).

In the absence of reported well problems, it is presumed that undesirable results for the chronic lowering of water levels did not and are not occurring in the Cawelo GSA. This is supported by the well completion analysis in Section 3.2.1.3 (Table 3-4) that showed that lowest groundwater levels during the 2012 to 2016 drought remained above the average well depth for public, domestic and agricultural wells. Moreover, there is no indication that additional lowering of local water levels —commensurate with recent drought declines— would trigger undesirable results. Although matching well construction data to any particular private agricultural well is difficult, DWR well completion reports indicate that most wells in the southern Plan Area appear to be sufficiently deep to accommodate the historic lows of 2015-2016; in addition, well depths have been increasing over time. Groundwater supply wells are typically completed several hundred to a thousand feet below the earlier depth to groundwater. Therefore, wells in the Cawelo GSA were able to remain operational during this time.

During the period from 2012 to 2016, the water contract with the City of Bakersfield was not renewed and it has not been re-established. This has had a significant impact of surface water supplies for the Cawelo GSA. As a result, groundwater pumping in the Cawelo GSA has remained high over this period. Since the water supply contract with the City of Bakersfield has not been renewed, the near-term availability of surface water supplies for the Cawelo GSA are limited. Therefore, the minimum thresholds and measurable objectives will be based on the conditions experienced during the past ten years.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 137 TODD GROUNDWATER 7.2.2 Minimum Thresholds

The minimum thresholds for the chronic lowering of groundwater levels are selected to represent water levels that are just above conditions that could generate significant and unreasonable undesirable results in the Kern County Subbasin, to the extent possible given available information. Future data may allow for refinement of these thresholds.

Given that groundwater levels declined about 80 feet during the period was an extended period of drought from 2007 through 2016, the minimum threshold is set about 80 feet below the low groundwater level that was experienced during this period. This MT is selected to provide operational flexibility in the event that another similar extended drought period was to occur during the implementation period for the GSP. Minimum thresholds are defined for the eight representative monitoring locations (Figure 7-2) selected for the Cawelo GSA and are presented on Table 7-1.

Table 7-1: Groundwater Level Minimum Thresholds, Measurable Objectives, Recent Groundwater Elevations, and Interim Milestones for Representative Wells Well ID Minimum Measurable 2012 – 2016 Interim Interim Interim Threshold Objective Lowest Milestone Milestone Milestone Elevation Elevation Groundwater 2025 2030 2035 Elevation

Units Acre-ft Acre-ft Acre-ft Acre-ft Acre-ft Acre-ft T26SR26E-24R -43 35 35 -23 -3 17 T27SR26E-04R -24 60 60 -4 16 36 T27SR26E-12H 25 103 103 45 65 85 T27SR26E-33C2 -64 20 20 -44 -24 -4 T28SR26E-11M -81 3 3 -61 -41 -21 T28SR27E-06C -85 -1 -1 -65 -45 -25 T28SR27E-28L 26 110 110 46 66 86 T29SR28E-05M01 -58 11 11 -38 -18 8

Because local water levels may fall lower than this MT, the definition of undesirable result for water levels is further modified to incorporate future drought conditions and allow operational flexibility for implementing the GSP during the implementation horizon. As noted in the GSP regulations, SGMA defines an undesirable result from chronic lowering of water levels as:

“indicating a significant and unreasonable depletion of supply if continued over the planning and implementation horizon” (§10721(x)(1).

The definition considers the duration of water level declines, as well as the cause. Specifically, the definition state that:

Overdraft during a period of drought is not sufficient to establish a chronic lowering of groundwater levels if extractions and groundwater recharge are managed as necessary to ensure that reduction in groundwater levels or storage during a period of drought are offset by increasing groundwater levels or storage during other periods” (§10721(x)(1)).

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 138 TODD GROUNDWATER A groundwater elevation falling below a MT at a single representative well is not considered an undesirable result as defined by this GSP. Therefore, evaluation of the chronic lowering of groundwater levels is evaluated based on data collected during a similar period of time over a period of years. The general practice is to assess groundwater levels collected during the spring to evaluate the recovery of groundwater levels following the previous pumping season. This also removes the uncertainty associated with the potential for well interference effects affecting the interpretation of chronic lowering of groundwater levels. Therefore, the undesirable result will be triggered when 30 percent or more of the monitoring wells in the Cawelo GSA fall below the MT during three successive spring measurements.

7.2.3 Measurable Objectives and Interim Milestones

Measurable objectives are quantitative targets that establish a point above the minimum threshold that allow for a range of active management of the basin in order to achieve the sustainability goal for the basin. Under the current surface water supply, the measurable objective has been set at the low groundwater level that was measured at the representative monitoring well, or nearby monitoring well if appropriate, during the 2007 to 2016 period. The measurable objectives are defined for the eight representative monitoring locations selected for the Cawelo GSA following this approach and are presented on Table 7-1.

Interim milestones were set by sequentially adding one-quarter of the range between the MT and MO every five years relative to the MT. The IMs are presented in Table 7-1. As noted above, periods of extended drought have the most significant effect on groundwater levels. Because the occurrence of droughts is not predictable, the timing of a drought may affect the apparent performance relative to an IM. Therefore, the compliance with the IMs will be evaluated with respect to climatic and water supply conditions.

7.3 REDUCTION OF GROUNDWATER STORAGE

The reduction of groundwater storage (§354.28(c)(2)) is required to be defined in terms of the total volume of groundwater that can be withdrawn from the basin without causing conditions that may lead to undesirable results based on the sustainable yield of the basin, calculated based on historical trends, water year type, and projected water use in the basin. Undesirable Results due to the Reduction of Groundwater Storage are defined as the amount of stored groundwater in the basin at which the reasonable and beneficial use of groundwater by overlying users is affected by significant and unreasonable impacts.

7.3.1 Groundwater Storage Trends

With respect to the water budget, the change in groundwater storage represents the net difference between total inflows and outflows. This change is physically represented by the change in groundwater levels and represents the volume of water that contributes to the total inflows and outflows that is derived from the aquifer. Therefore, the change in groundwater storage is intrinsically linked to the change in groundwater levels.

During the period from 2012 to 2016, an extended drought impacted California that greatly reduced the availability of surface water supplies. As discussed in Section 3.2.1 and 7.2, the change in groundwater levels in the Cawelo GSA varied within a 60-foot range during the period from 1981 through 2012, but

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 139 TODD GROUNDWATER then experienced a significant decrease of an additional 60 feet from 2012 to 2016 before recovering about 20 feet from 2017 to 2018 (Figure 7-3).

The correlation between the change in groundwater levels and the change in groundwater storage over the historical study period from 1995 to 2014 is illustrated in Figure 7-4. The groundwater level trends tend to mimic the annual change in groundwater storage over this period. Groundwater levels tend to increase during periods of positive change in groundwater storage and decrease during periods of negative change in groundwater storage. From 1995 to 2012, the cumulative change in groundwater storage was near zero, and the cumulative average change in groundwater levels over the entire Cawelo GSA was also near zero. The recent drought resulted in a significant change in storage in 2013 and 2014, and this is reflected in the large decrease in groundwater levels.

7.3.2 Minimum Thresholds

SGMA regulations define the MT for reduction of groundwater storage as

“…the total volume of groundwater that can be withdrawn from the basin without causing conditions that may lead to undesirable results.”

In accordance with the SGMA regulation cited above, the minimum threshold metric is a volume of pumping per year, or an annual pumping rate. Conceptually, the total volume of groundwater that can be pumped annually without leading to undesirable results is equal to the estimated sustainable yield of the Subbasin. As discussed in Chapter 4, the future estimated long-term sustainable yield for the Cawelo GSA over the 20-year Study Period from 1995 to 2014 is 50,892 AFY. However, the estimated sustainable yield may change in the future as additional data become available, new recharge projects are added, or other local groundwater conditions change.

Groundwater pumping is highly variable from year to year based on the availability of surface water supplies. The CWD also banks available surface water supplies in the aquifer during wet years so that it is pumped from recovery wells during dry years to supplement the local water supply. Although the banking recovery pumping is recovering water stored in the aquifer, it adds to the pumping in dry years. Over the 20-year Study Period from 1995 to 2014, groundwater pumping in the Cawelo GSA varied between 24,000 to 90,000 AFY, with an average annual pumping rate of 56,000 AFY. Due to this high variability in pumping, groundwater levels are considered a more appropriate measure of the change in groundwater storage for defining the MT and MO for the Cawelo GSA.

Because of this close relationship between groundwater levels and groundwater levels, the change in groundwater storage will be monitored by proxy the same methodology and thresholds as groundwater levels, as permitted by Title 23 of the California Code of Regulations in Section 354.26 (d), Chapter 1.5.2.5. Minimum thresholds are defined for the eight representative monitoring locations selected for the Cawelo GSA following this approach and are presented on Table 7-1.

Because local water levels may fall lower than this MT, the definition of undesirable result for the reduction of groundwater storage uses the same operational flexibility as used for chronic lowering of groundwater levels for implementing the GSP during the implementation horizon.

Similar to the chronic lowering of groundwater levels, the evaluation of reduction is groundwater storage requires data collected during a similar period of time over a period of years. The general practice is to assess groundwater levels collected during the spring to evaluate the recovery of

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 140 TODD GROUNDWATER groundwater levels following the previous pumping season to remove the uncertainty associated with the potential for well interference effects. Therefore, the undesirable result will be triggered when 30 percent or more of the monitoring wells in the Cawelo GSA fall below the MT during three successive spring measurements.

7.3.3 Measurable Objectives and Interim Milestones

Measurable objectives for the reduction of groundwater storage are defined to coincide with the quantitative targets establish for the chronic lowering of groundwater levels. Under the current surface water supply, the measurable objective has been set at the low groundwater level that was measured at the representative monitoring well, or nearby monitoring well if appropriate, during the 2007 to 2016 period. The measurable objectives are defined for the eight representative monitoring locations selected for the Cawelo GSA following this approach and are presented on Table 7-1.

Interim milestones also coincide with the quantitative targets establish for the chronic lowering of groundwater levels. The IMs are set by sequentially adding one-quarter of the range between the MT and MO every five years relative to the MT. The IMs are presented in Table 7-1. As noted above, periods of extended drought have the most significant effect on groundwater levels. Since the occurrence of droughts is not predictable, the timing of a drought may affect the adherence to an IM. Therefore, the compliance with the IMs will be evaluated with respect to climatic and water supply conditions.

7.4 LAND SUBSIDENCE

The Undesirable Result for land subsidence is a result that causes significant and unreasonable reduction in the viability of the use of infrastructure over the planning and implementation horizon of this GSP. Detrimental impacts of land subsidence include groundwater storage reductions and potential damage to infrastructure, such as large pipelines, roads, bridges and canals.

7.4.1 Land Subsidence Assessment

Land subsidence can occur when groundwater levels are lowered by pumping causing the water pressure in the sediment pore spaces to decrease causing more of the weight of the overlying aquifer to be transferred to the sediment grains. If the effective stress borne by the sediment grains exceeds the structural strength of the sediment layer, then the aquifer system begins to deform. Aquifer-system deformation can be temporary (elastic) or permanent (inelastic).

Elastic deformation occurs when sediments compress as pore pressures decrease but expands by an equal amount as pore pressures increase. However, elastic deformation is fully recoverable when return to their initial levels. During inelastic deformation, or compaction, the sediment grains rearrange into a tighter configuration that reduces the pore space and thereby effectively decreasing the volume of the subsurface sediment layer. Inelastic deformation does not recover as pore pressures increase, thus this compaction is permanent. Fine-grained sediments, primarily clays, are the most highly compressible sediments and, therefore, are most susceptible inelastic compaction. Generally, coarse-grained deposits (e.g. sand and gravels) generally have sufficient intergranular strength to not undergo inelastic deformation under the range of pore pressure changes encountered as a result of groundwater pumping.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 141 TODD GROUNDWATER Land subsidence in the Cawelo GSA has primarily occurred in localized area in the northern portion of the GSA, north of Poso Creek. South of Poso Creek, the sediments typically consist of more coarse- grained deposits that do not undergo inelastic deformation. Maximum land subsidence in the Cawelo GSA over the period from 1926 to 2015 is estimated to be on the order of 2 to 3 feet (Section 3.44), occurring in the areas north of Poso Creek. South of Poso Creek, total land subsidence ranges from about 1 to 2 feet near Poso Creek and decreases southward to where there is little to no land subsidence in the southern portions of the Cawelo GSA. Based on the analysis in Section 3.2.4, the rate of land subsidence is approximately one-percent of the groundwater level decline below the previous historically lowest groundwater level.

7.4.2 Minimum Thresholds

The undesirable result related to land subsidence is defined in SGMA as:

Significant and unreasonable land subsidence that substantially interferes with surface land uses. [CWC §10721(x)(5)]

Therefore, the undesirable results with respect to land subsidence is the point that land subsidence interferes with the operation of critical infrastructure. The identified critical infrastructure in the Cawelo GSA includes water conveyance facilities including the Beardsley/Lerdo Canals, the CWD surface water distribution system, bridges and overpasses on Highways 65 and 99, and the Meadows Field Airport. However, much of this critical infrastructure is located in the southern Cawelo GSA where little to no land subsidence has occurred or is anticipated to occur. The primary infrastructure in the northern Cawelo GSA includes the CWD surface water distribution system and the bridges and overpasses on Highways 65 and 99.

Land subsidence does not occur uniformly but is typically initiated when groundwater levels reach historic low levels that compaction of fine-grained sediments begins to occur. Since inelastic subsidence is permanent, groundwater level variations above the historically lowest groundwater levels does not initiate further subsidence.

Based on past history, the 2 to 3 feet of land subsidence that has occurred historically has not caused damage or otherwise interfered with the operation of critical infrastructure in the Cawelo GSA. Based on this past experience and knowledge of the critical infrastructure in this area, there is some remaining capacity for land subsidence to occur without damage to critical infrastructure. As a conservative assumption, an additional 1 foot of land subsidence is considered reasonable in avoiding damage to critical infrastructure. Additional evaluation of land subsidence will be conducted, and these thresholds may be revised during the five-year GSP update.

Because land subsidence is closely linked to groundwater levels, the MTs for land subsidence are set at 80 feet below the lowest historical low groundwater level for the immediate area surrounding the representative monitoring point. These groundwater levels are based on the analysis presented in Section 3.2.1 and shown on Figure 3-19. Using the historical rate of subsidence, the potential additional subsidence would be on the order of 0.8 feet, which is considered to be within the capacity for the critical infrastructure to endure without damage or operation interference. The land subsidence MTs are listed in Table 7-2. Since land subsidence can lead to localized undesirable results, the exceedance of the land subsidence MT at a single representative well will be considered an undesirable result as defined by this GSP.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 142 TODD GROUNDWATER Table 7-2: Groundwater Level Minimum Thresholds, Measurable Objectives, Recent Groundwater Elevations, and Interim Milestones for Land Subsidence at Representative Wells

Well ID Minimum Measurable Historically Interim Interim Interim Threshold Objective Lowest Milestone Milestone Milestone Elevation Elevation Groundwater 2025 2030 2035 Elevation

Units Acre-ft Acre-ft Acre-ft Acre-ft Acre-ft Acre-ft T26SR26E-24R -134 -54 -54 -114 -94 -74 T27SR26E-04R -175 -95 -95 -155 -135 -115 T27SR26E-12H 17 97 97 37 57 77 T27SR26E-33C2 -79 1 1 -59 -39 -19 T28SR26E-11M -80 0 0 -60 -40 -20 T28SR27E-06C -100 -20 -20 -80 -60 -40 T28SR27E-28L -144 -64 -64 -124 -104 -84 T29SR28E-05M01 -139 -59 -59 -119 -99 -79

7.4.3 Measurable Objectives and Interim Milestones

The MOs and IMs for land subsidence is set for zero additional lowering of ground surface elevations due to groundwater pumping induced land subsidence within the Cawelo GSA. Therefore, the MO for land subsidence is set at the lowest historical low groundwater level for the immediate area surrounding the representative monitoring point. The land subsidence MOs and IMs are listed in Table 7-2.

7.4.4 Coordination with Kern County Subbasin GSAs

Because of its regional nature, monitoring for land subsidence in the Kern County Subbasin will be a more coordinated action that is addressed in the Umbrella GSP (GEI, 2019). Subsidence monitoring is needed to understand the causes of subsidence, the potential risk of damaging critical infrastructure, and how to set minimum thresholds to avoid significant impacts to critical infrastructure in the Subbasin.

Regional coordination of land subsidence monitoring is key to the design of the network in the Subbasin because regional groundwater extraction is a main driver for regional-scale subsidence, along with subsurface geologic conditions. In addition, subsidence associated with oil and gas activities may also occur in the subbasin. However, any subsidence potentially associated with oil and gas activities is regulated by DOGGR under the California Public Resources Code, and is therefore separate from SGMA requirements, thus, coordination may be needed where there is potential for impacts to critical infrastructure.

The current regional subsidence monitoring network includes regional subsidence screening by InSAR, and monitoring points at existing CGPS stations as described in the Umbrella GSP (GEI, 2019). In addition, local extensometers for SWSD and benchmark monuments of NKWSD are included in the network. Data from leveling surveys of the California Aqueduct and Friant-Kern Canal (FKC) are also valuable points that have some historical data, but which have not been formally incorporated into the local Subbasin network. Details of these datasets for the Aqueduct and FKC are provided below.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 143 TODD GROUNDWATER 7.5 SEAWATER INTRUSION

Due to the geographic location of the Basin, seawater intrusion is not a concern, and thus is not required to establish sustainable management criteria for undesirable results for seawater intrusion, as supported by Title 23 of the California Code of Regulations in Section 354.26 (d), Chapter 1.5.2.5.

7.6 DEGRADED WATER QUALITY

The undesirable result for degraded water quality is the result of SGMA-related groundwater management activities that causes significant and unreasonable reduction in the long-term viability of domestic, agricultural, municipal, or environmental uses over the planning and implementation horizon of this GSP.

7.6.1 Water Quality Assessment

In Section 3.2.2, a thorough assessment of water quality is provided that demonstrates that the overall water quality in the Cawelo GSA is generally good, but there are locally impacted or vulnerable areas that are susceptible to water quality issues resulting from surface activities that are currently being regulated by the State The Anti-degradation program is being operated under State regulators to monitor for potential water quality impacts from the use treated produced water. The Cawelo GSA participants in these programs are maintaining compliance with these programs.

The objective the existing water quality regulatory programs is to provide a groundwater quality assessment using all available, applicable and relevant data and to determine high vulnerability areas where discharges from irrigated agriculture may degrade groundwater quality (Section 3.2.3). The high vulnerability areas in the GAR (Cawelo Water District Coalition, 2015) overlap with nearly all of the wells identified in this GSP with elevated nitrate concentrations above the MCL. The high vulnerability areas are generally located in the western areas of the CWD and south of Poso Creek (Figure 3-26).

Salinity (measured as total dissolved solids [TDS]), arsenic, and nitrates have all been identified as potentially being of concern for water quality in the Basin as described in Section 3.2.2 as follows:

• A total of 1,242 groundwater samples in the Cawelo GSA have TDS analyses with a median concentration of 359 mg/l. The maximum TDS concentrations in groundwater throughout most of the Cawelo GSA is below 1,500 mg/L. TDS concentrations are generally lowest (less than 500 mg/L) in the northern area of the GSA near Poso Creek and near the recharge basins. TDS concentrations are generally higher in the southwestern portion of the GSA.

• Arsenic is a naturally occurring trace element in rocks, soils, and groundwater. A total of 520 groundwater samples have arsenic analyses with a median concentration of 2.3 µg/l. Higher arsenic concentrations in the Cawelo GSA may be attributed to the pH-dependent desorption from aquifer sediments, which tends to occur at relatively high pH.

• Nitrate originates from natural and anthropogenic sources. The primary anthropogenic source in the Cawelo GSA is from excess application of nitrogen fertilizers. A total of 1,314 groundwater samples in the Cawelo GSA have nitrate analyses and a median concentration of 2.6 mg/L (as N) and generally meet drinking water quality standards. The spatial patterns are influenced by the

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 144 TODD GROUNDWATER general land-use pattern and higher concentrations are typically related to the irrigated agricultural areas in the western areas of the GSA.

TDS is being monitored by the GSA for several reasons, and TDS has been identified as one of the constituents of concerns in the GSP development processes, and TDS has had several exceedance measurements near domestic and public supply wells. Although high TDS concentrations are naturally occurring within the Basin, it is believed that management of groundwater levels may help improve TDS concentration levels towards levels reflective of the natural condition.

7.6.2 Minimum Thresholds

Degraded water quality is unique among the six sustainability indicators because it is already the subject of extensive federal, state, and local regulations carried out by numerous entities and SGMA does not directly address the role of GSAs relative to these other entities (Moran & Belin, 2019). The SGMA regulations specify the following:

“minimum thresholds for degraded water quality shall be the degradation of water quality, including the migration of contaminant plumes that impair water supplies or other indicator of water quality as determined by the Agency that may lead to undesirable results.”

SGMA does not specify water quality constituents that must have minimum thresholds. Establishing minimum thresholds for constituents that cannot be managed by increasing or decreasing pumping was deemed inappropriate by the GSAs. Groundwater management is the mechanism available to GSAs to implement SGMA. Other water quality concerns are being addressed through various water quality programs (e.g., ILRP) and agencies (e.g., RWQCB, USEPA) that have the authority and responsibility to address them. The GSAs will abide by any future local restrictions that may be implemented by the agencies or coalitions managing these programs.

The Cawelo GSA has decided to address TDS as the indicator for degraded water quality within the GSA by setting MTs, MOs, and IMs. The major water quality issue being addressed by sustainable groundwater management is the potential migration of higher salinity water into the freshwater principal aquifers. Salts that contribute to TDS typically come from imported water, soil leached by irrigation, animal wastes, fertilizers and other soil amendments, municipal and industrial wastewaters, and oil field produced waters. Due to this natural condition, additional data will be collected during GSP implementation to increase the Cawelo GSA’s understanding of TDS sources in the Basin. It should be noted however, that TDS levels in groundwater do not detrimentally impact the agricultural economy of the Basin. Much of the crops grown in the GSA are not significantly affected by the kinds of salts in the Basin.

TDS does not have a primary maximum contaminant level (MCL) but does have both a California Division of Drinking Water and U.S. Environmental Protection Agency. Secondary standard of 500 milligrams per liter (mg/L), and a short-term standard of 1,500 mg/L. To provide for an acceptable margin of operational flexibility, the MT for TDS levels in the GSA have been set to the temporary MCL of 1,500 mg/L for each representative well.

Evaluation of degraded water quality is the result of SGMA-related groundwater management activities is evaluated based on data collected over a period of time to demonstrate a long-term trend. A concentration exceeding a MT at a single representative well is not considered an undesirable result as

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 145 TODD GROUNDWATER defined by this GSP. Therefore, the undesirable result will be triggered when 30 percent or more of the monitoring wells in the Cawelo GSA have TDS concentrations rising above the MT for two continuous years.

7.6.3 Measurable Objectives and Interim Milestones

In the case of degraded water quality, specifically for salts, there is a natural tendency for salt concentrations to increase over time due to agricultural and urban uses of water, which add salts either directly or through evapotranspiration. As previously noted, increases are not due to a causal nexus with SGMA activities and would not constitute an undesirable result under this GSP. Continued monitoring data will be analyzed for trends, and future increasing trends will be analyzed for evidence of the sources of the trends, such as upward migration of the body of relatively higher salinity water due to over-pumping or due to continued agricultural and urban uses. If caused by upward migration, GSAs will respond accordingly due to the causal nexus with groundwater pumping. If caused by continued urban and agricultural use, the trends will be noted and coordinated with other programs, such as ILRP.

The measurable objective is a TDS concentration of 1,000 mg/L, which aligns with the Secondary MCL for TDS. The margin of operational flexibility is 500 mg/L TDS, the difference between the measurable objective of 1,000 mg/L and the minimum threshold of 1,500 mg/L.

GSP regulations require GSAs to avoid undesirable results by 2040, which means they must meet or exceed the MTs. The Cawelo GSA also recognizes that reaching an MO is a priority, but meeting or exceeding the MT is required by SGMA. For this reason, the IMs for 2025, 2030, and 2035 have been set as the same value as the MT.

7.6.4 Coordination with Existing Water Quality Monitoring Programs

While the GSP does not set thresholds for the types of constituents described above, conditions in the basin are summarized in Section # and will be summarized in future GSP updates. The GSAs will conduct the following ongoing water quality coordination activities:

• Periodic review of data submitted to the Department of Pesticide Regulation (DPR), Division of Drinking Water (DDW), Department of Toxic Substances Control (EnviroStor), and GeoTracker as part of the Groundwater Ambient Monitoring and Assessment (GAMA) database.

• Regular participation with existing monitoring programs, such as ILRP and Famoso Anti- Degradation monitoring.

• Annual review of annual monitoring reports prepared by other programs (such as ILRP and Famoso Anti-Degradation monitoring)

• GSA will coordinate with the Regional Water Quality Control Board and Kern County Division of Environmental Health to discuss constituent trends and concerns in the Cawelo GSA in relation to groundwater pumping.

The purpose of these reviews will be to monitor and summarize the status of constituent concentrations throughout the Subbasin with respect to typical indicators such as applicable MCLs or SMCLs. The Kern Subbasin GSP Annual Report and 5-Year Update will include a summary of the coordination and

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 146 TODD GROUNDWATER associated analyses of conditions. The GSP 5-year updates may include evaluation of whether additional minimum thresholds are needed.

7.7 DEPLETIONS OF INTERCONNECTED SURFACE WATER

The undesirable result for depletions of interconnected surface water is a result that causes significant and unreasonable reductions in the viability of agriculture or riparian habitat in the Basin over the planning and implementation horizon of this GSP.SGMA regulations define the MT for interconnected surface water as

“…the rate or volume of surface water depletions caused by groundwater use that has adverse impacts on the beneficial uses of the surface water and may lead to undesirable results.”

In Section 3.4.3, the groundwater levels beneath the Kern River and Poso Creek within the Cawelo GSA are fully detached from the surface water system. Figure 3-49 shows that the depth to groundwater below Poso Creek is several hundred feet below the streambed elevations. Similarly, available data further supports that the depletion of interconnected surface water has not been observed within the Cawelo GSA Area. Therefore, surface water percolates through the streambed to recharge groundwater; however, recent groundwater conditions preclude any possibility for groundwater outflow from the Primary Aquifer into Poso Creek.

In coordination with other GSAs in the Subbasin, the KGA developed Subbasin-wide definitions of undesirable results for each sustainability indicator applicable to the Kern County Subbasin. The depth to groundwater below the streams has historically been well below the level of the streambed in the Subbasin that there are no direct interactions between groundwater and stream flow in the Subbasin and is limited to percolation of streamflow to groundwater through an intervening unsaturated zone. Other lines of evidence (i.e., depth to groundwater water levels, water quality data, and hydrostratigraphy) further support that the principal aquifer is hydraulically separated from the surface water bodies. Because the Basin Setting analysis by KGA had not identified interconnected surface water in the Subbasin, no Subbasin-wide definition of undesirable results for this sustainability indicator was developed.

Due to the groundwater conditions in the Cawelo GSA and the KGA assessment (GEI, 2019), depletions of interconnected surface water are not present and are unlikely to occur in the Cawelo GSA, and thus the GSP is not required to establish sustainable management criteria for undesirable results for depletions of interconnected surface, as supported by Title 23 of the California Code of Regulations in Section 354.26 (d), Chapter 1.5.2.5.

7.8 COORDINATION WITH KERN COUNTY SUBBASIN GSAS

The Cawelo GSA will continue to coordinate their SGMA management actions with neighboring GSAs and water districts. In brief, these activities will include the following.

7.8.1 Coordination with Neighboring Management Areas

The Cawelo GSA shares management area boundaries with several other KGA Member agencies which are the Kern-Tulare Water District, Eastside Water Management Area, North Kern Water Storage

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 147 TODD GROUNDWATER District, and Southern San Joaquin Municipal Utility District. Additionally, Cawelo GSA shares a common boundary with the Kern River GSA. Figure 7-5 shows the location of all of the KGA Member areas and the other GSAs in the vicinity of the Cawelo GSA.

Each management area is responsible for determining their corresponding Measurable Objectives and Minimum Thresholds that are specific to their determinations for potential Undesirable Results. Due to the diverse characteristics of the various areas within the Kern County Subbasin, including agency operations, underlying geotechnical properties, and groundwater demand type, it is not unreasonable that different management areas would initially set Measurable Objectives and Minimum Thresholds that are appropriate for their area but could potentially impact neighboring Measurable Objectives and Minimum Thresholds. Cawelo GSA will coordinate with neighboring agencies to monitor groundwater levels and groundwater quality, openly share groundwater data, and to determine if ongoing operations and plan implementations are adversely impacting neighboring groundwater sustainability goals. As part of the continued coordination, Cawelo GSA will collaborate with neighbor agencies to reduce data gaps, plan implementation schedules, and continuously evaluate the appropriateness of set Measurable Objectives and Minimum Thresholds.

7.8.2 Water Supply Accounting

The Cawelo GSA, in coordination with the KGA, is developing policies for water allocation within CWD and to the lands outside of CWD but within the Cawelo GSA. The Cawelo GSA will implement those policies regarding the allocation of its operational groundwater supplies that are calculated as part of the sustainable yield. CWD operation water, surface and groundwater, will be allocated to CWD landowners. For areas outside of the CWD, the balance of the sustainable yield is the available natural groundwater resources (Native Yield). Model information indicates that natural groundwater sources in the Cawelo GSA area are on the order of 0.15 acre-feet per acre. Coordinated estimated Native Yield within the KGA is a range of 0.15 to 0.30 acre-feet per acre.

This water supply allocation is currently being developed by Cawelo GSA, in coordination with the KGA, and will the KGA Umbrella GSP (GEI, 2019) when available.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 148 TODD GROUNDWATER 8 PROJECTS, MANAGEMENT ACTIONS AND ADAPTIVE MANAGEMENT

This chapter includes the Projects, Management Actions and Adaptive Management information that satisfies Sections 354.42 and 354.44 of the Sustainable Groundwater Management Act (SGMA) regulations. These projects and their benefits will help achieve sustainable management goals in the Cawelo GSA within the Kern County Subbasin.

8.1 OVERVIEW OF PROJECTS AND MANAGEMENT ACTIONS

8.1.1 Sustainability Target

The Cawelo GSA has developed a number of potential project and management actions to help address overdraft and move the Basin toward sustainability. Table 8-1 lists these proposed activities, along with their current status, benefits, potential timing, and anticipated costs. A summary of the proposed Projects and Management Actions is listed in Table 8-1.

8.1.2 Overdraft Mitigation

The proposed projects and management actions would support maintenance of groundwater levels above minimum thresholds through increased recharge or through reductions in pumping. Overdraft is caused when pumping exceeds recharge and inflows in the Basin over a long period of time. Improving the water balance in the Basin will help to mitigate overdraft.

During drought, groundwater becomes more important due to limited precipitation. Projects that support groundwater levels through increased recharge help to protect groundwater resources for use during future drought, as well as help protect the Basin from the impacts of drought on groundwater storage. Projects that reduce pumping will help manage the Basin for drought preparedness by reducing demands on the Basin both before and during drought, supporting groundwater levels in non-drought years, and decreasing the impacts of drought on users, reducing the need to increase pumping when precipitation levels are low

8.2 PROJECTS

The term Cawelo GSA is generally used throughout this section for simplicity even though some of these projects were initiated or will be operated by the CWD.

8.2.1 Project #1: New Water Supply Purchases

The Cawelo GSA would implement programs that will acquire long-term new water purchase contracts and/or establish a water purchase fund if contracts are difficult to secure because of high demand and competition and resulting high costs. The main goal would be to secure long-term new water contracts but compliance with SGMA will impact future water management practices and could make the availability of new long-term contracts scarce. If long-term contracts can’t be secured then a new water fund would be established to build funding reserves for water purchases. These purchases could occur during favorable times such as hydrologically wet years when water will be more readily available at lower costs. While the Cawelo GSA would likely not need this water in wet years, these types of purchases could be in the form of banked water that the Cawelo GSA could request at a future date.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 149 TODD GROUNDWATER Table 8-1. Proposed SGMA Projects and Management Actions for the Cawelo GSA. Average Est. Range of Implementation Est. Project or Management Project Annual Annual Annual Timeline Capital Action Type Benefit O&M Benefit Cost at 2040 Cost Programs AFY AFY Million $ Million $ Direct and New Water Supply 5,000 to Begin program $2.0 to P1 In-lieu 5,800 Purchases 23,000 in 2020 $13.8 Recharge Increase Recharge Direct 500 to Target 2030 $4.9 to P2 and Banking 400 Recharge 1,500 implementation $12.6 Capacity New Cawelo GSA Direct Begin program P3 500 100 $0.1 Banking Partners Recharge in 2020 Water Treatment In-lieu 7,500 to Begin program $4.5 to P4 15,000 Facilities Recharge 20,000 in 2020 $18.0 Friant Pipeline Direct 1,500 to Construction in Funding P5 500 Project Recharge 2,500 2019 approved Poso Creek Flood In-lieu Target 2030 P6 150 30 $3.9 Water Capture Recharge implementation Surface Water In-lieu Target 2030 P7 500 500 $40.0 Storage Recharge implementation Out of Cawelo GSA In-lieu 500 to Begin program $0.35 to P8 1,250 Banking Recharge 4,000 in 2020 $0.7 Management Actions AFY AFY Million $ Million $ Voluntary Land Demand 2020 to 2040 $4.9 to MA 1 2,000 2,000 Conversion Reduction implementation $12.6 Crop Conversion and Demand 2020 to 2040 MA 2 >2000 3,800 Unknown Irrigation Efficiency Reduction implementation Demand 2020 to 2040 MA 3 Land Acquisition 2,500 2,400 $20.0 Reduction implementation TOTALS 31,780

Alternatively, the funds could be used to make annual water purchases and the revenue for the fund would be consistent from year to year regardless of the hydrological conditions. Therefore, during wet or average hydrologic years the water would cost less, and reserves would be built up for more costly water purchases during the drier years. It is estimated that an additional 5,000 AFY to 23,000 AFY of water could be imported into the Cawelo GSA area through new long-term contracts or establishing a new water purchase fund or both.

8.2.1.1 Public Notice and Outreach Process Public notice would not be required for new water supply purchases or establishment of a fund to purchase water in the future except for discussion and approval of the contract and use of funds by the Cawelo GSA Board that would occur at regular Board meeting. The Cawelo GSA website would include descriptions of projects that are moving forward and a summary of their status. Outreach would be conducted as part of the study to determine long-term contract or annual water purchases possibilities.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 150 TODD GROUNDWATER 8.2.1.2 Permitting and Regulatory Process No permits or regulatory approvals would be needed for new water supply purchases or establishment of a fund to purchase water.

8.2.1.3 Benefits Securing new long-term contracts or establishing a water purchase fund or both could result in an additional 5,000 AFY to 23,000 AFY of water that could be imported into the Cawelo GSA area. This additional water would increase the amount of water in the basin and decrease overdraft.

8.2.1.4 Source and Reliability of Water The source and reliability of the future water source contract cannot be determined at this time since the contracts or purchases have not occurred yet. The terms of the contract would likely indicate if the amount would be guaranteed each year or provide a reduction schedule for years when that water supply source is limited. Groundwater and banked/stored water would likely be more reliable on an annual basis than surface water or imported water (SWP or CVP).

8.2.1.5 Legal Authority Required The Cawelo GSA has the authority to enter into water supply contracts or set up a fund to purchase water.

8.2.1.6 Costs and Funding It is estimated that $2,000,000 to $13,800,000 would be needed annually to purchase water. Direct contracts can be established with Cawelo GSA landowners to fund these water purchases. The estimated landowner costs would be on the order of $400 to $600 per acre foot of water. Funding could also come from levying assessments on a per acre basis. This would require landowner voting approval per California Proposition 218 and be an estimated $45 to $307 assessment per acre. The Cawelo GSA would also consider other funding mechanisms.

8.2.1.7 CEQA/NEPA Considerations New water supply purchases or establishment of a fund to purchase water in the future would not trigger a California Environmental Quality Act (CEQA) or National Environmental Policy Act (NEPA) actions because they do not qualify projects under these programs.

8.2.2 Project #2: Increase Groundwater Recharge and Banking Capacity

The Cawelo GSA will implement projects or programs to increase recharge capacity to capture and recharge additional wet year high flow waters to store for future use. The Cawelo GSA has limited groundwater recharge facilities and has not been able to capture and recharge all available water under wet hydrological conditions. This project would entail building additional Cawelo GSA-owned recharge facilities and/or improve the distribution system to increase the capacity to capture more water, especially during wet hydrologic events. Some facilities could be strategically located to capture storm runoff that may otherwise leave the Cawelo GSA area. It is estimated that approximately 200 to 570 acres of new recharge and banking facilities could be developed.

Additionally, the Cawelo GSA will consider implementing a program to incentivize landowners to use their land for recharge (see Management Action #1: Voluntary Land Use Conversion in Section 9.3.1 below). This could provide an opportunity for landowners to bank their privately-owned water for future recovery and possibly allow the Cawelo GSA access to their lands for additional recharge. This program would not only increase recharge capacities during wet years but could also reduce water demand by

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 151 TODD GROUNDWATER replacing crops with recharge facilities. The privately-owned water could be purchased under Project #1, New Water Supply Purchases, described above.

Landowner incentives could be in the form of reduced costs of water purchases, first priority for available water, or other incentives that may be developed over the life of the program.

8.2.2.1 Public Notice and Outreach Process Public notice and outreach are not anticipated during development of the feasibility study, beyond potential outreach to landowners whose property is identified as potential sites for these facilities. Public notice and outreach would be conducted during implementation of a recharge facility construction project. Outreach would also occur to inform landowners of their options to create facilities on their own land. The level of outreach may be dependent upon public perception of each project and some of this outreach would occur as part of the CEQA process.

8.2.2.2 Permitting and Regulatory Process Development of a feasibility study would not require any permits or regulatory approvals beyond approval of the Cawelo GSA for the funding the analysis. Development of the recharge facilities would require construction permits and a CEQA analysis. Additional permits may be required to complete construction and initiate operation of the recharge facilities. The Cawelo GSA would need to secure easements and/or purchase land for the facilities.

8.2.2.3 Benefits There are significant regions within the Cawelo GSA with soil properties that could achieve percolation rates of up to 0.5 AF per day. Assuming an average percolation rate of 0.35 AF/day and approximately 200 to 570 acres of potential new recharge and banking land, about an average of 500 AFY to 1,500 AFY of new water could be recharged for future recovery.

It is not clear what magnitude landowner-owned recharge facilities would have on importing additional waters into the Cawelo GSA area. It could be anywhere between an average of 50 AFY to 500 AFY.

8.2.2.4 Source and Reliability of Water The source and reliability of the water for recharge is dependent upon purchases of new water as identified in Project #1 above. The water could be in the form of exchanges, SWP or CVP water, or other surface water sources.

8.2.2.5 Legal Authority Required The Cawelo GSA has the legal authority to conduct a feasibility study for construction of new recharge facilities. Construction of additional Cawelo GSA-owned recharge facilities would require acquisition of targeted land for spreading facilities and development of conveyance facilities if needed.

8.2.2.6 Costs and Funding It would cost the Cawelo GSA about $4 million to $11.4 million to acquire 200 to 750 acres of land and an additional $0.9 million to $1.2 million for construction of the percolation basins resulting in total costs in the range of $4.9 million to $12.6 million. Assuming an average percolation rate of 0.35 AF/day an estimated 500 AFY to 1,500 AFY of new water could be spread. Development of a Cawelo GSA-owned recharge and banking facility would be a capital project and would require the Cawelo GSA to secure bonding to fund the design and construction. The estimated annual debt service would be $320,000 to $820,000 or approximately $550/AF to $640/AF of additional water.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 152 TODD GROUNDWATER The costs of constructing recharge facilities on landowner land would likely be paid for by the landowner. If the facilities would be shared with the Cawelo GSA, the Cawelo GSA could potentially share the costs of water transportation, facility construction and annual maintenance.

8.2.2.7 CEQA/NEPA Considerations Development of a feasibility study would not trigger CEQA or NEPA. Construction of new recharge facilities could require a CEQA analysis.

8.2.3 Project #3: New Cawelo GSA Banking Partners

The Cawelo Water District benefits from a banking program partnership with the Zone 7 Water Agency. Located in the Livermore-Amador Valley, which is outside of the Kern County Subbasin. The District stores water for Zone 7 and keeps half of the water that it stores. For example, for every 2 AF feet of water delivered to District recharge facilities, the District is obligated to only return 1 AF.

The currently banking program with Zone 7 could be modified to increase the amount of water stored for Zone 7 and/or a new banking programs and partners could be considered to fund the construction of new facilities and/or to improve existing facilities. It is estimated this could increase the annual average water supply up to 500 AFY.

8.2.3.1 Public Notice and Outreach Process The expansion of the Zone 7 agreement or contracting with additional banking partners would not need public notice and outreach other than what is discussed and approved at Cawelo GSA Board meetings. Public notice and outreach would be conducted during implementation of a recharge facility construction project. The Cawelo GSA website would include descriptions of projects that are moving forward and a summary of their status.

8.2.3.2 Permitting and Regulatory Process No permits or regulatory approvals would be needed to expand the contract with Zone 7 or enter a banking contract with another banking partner. Similar to Project #2, recharge facility construction would require construction permits and a CEQA analysis. Additional permits may be needed to complete construction and initiate operation of any new recharge facilities. The Cawelo GSA would need to secure easements and/or purchase land for the facilities.

8.2.3.3 Benefits The expansion of the existing banking contract with Zone 7 and/or the development of additional banking partners would be a beneficial way the Cawelo GSA could increase its groundwater supply by the portion of water each partner agrees to essentially leave in the Cawelo GSA area. Zone 7 has agreed to leave 50 percent of all that is spread. It is estimated that this program would generate about 500 AFY.

8.2.3.4 Source and Reliability of Water The source and reliability of the water for banking is dependent upon the parties that the Cawelo GSA enters into banking agreements with. The water would likely be SWP or CVP water and would be dependent upon the availability of such water.

8.2.3.5 Legal Authority Required The Cawelo GSA has the authority to enter into banking contracts and has the legal authority to conduct a feasibility study for construction of new recharge facilities. Construction of additional recharge

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 153 TODD GROUNDWATER facilities would require acquisition of targeted land for spreading facilities and development of conveyance facilities, if needed.

8.2.3.6 Costs and Funding There are minimal capital costs associated with potentially increasing the use of existing recharge and banking facilities. Developing additional facilities would occur as part of Project #2. It is estimated this could increase the average water supply up to 500 AFY at a cost of $200/AF for a total of $100,000 per year.

8.2.3.7 CEQA/NEPA Considerations Entry into banking agreements would not trigger CEQA or NEPA. Construction of new recharge facilities could require a CEQA analysis.

8.2.4 Project #4: Water Treatment Facilities

The Cawelo GSA is currently evaluating projects to install water treatment facilities that will allow the Cawelo GSA to acquire treated produced water and treat it to a level that is safe for crop irrigation. Treated produced water would be considered a new water source to the basin. There is a substantial volume of treated produced water , available in the vicinity of the Cawelo GSA. The salinity of treated produced water can range and may require some level of blending with fresh water before it can be used on crops. Reverse osmosis or distillation could be needed to remove enough salts to make the treated produced water usable for irrigation.

Near the Cawelo GSA, approximately 20,000 AFY of treated produced water is injected into exempt groundwater aquifers well below the base of fresh water. The Cawelo GSA is evaluating potential projects to treat anywhere from 7,500 AFY to 20,000 AFY of treated produced water.

8.2.4.1 Public Notice and Outreach Process Public outreach would be conducted during development of a feasibility study for the treatment plant to educate the landowners on the safety of using this reclaimed water for irrigation. Public notice and outreach would also be conducted for construction of the treatment plant. The Cawelo GSA website would include descriptions of projects that are moving forward and a summary of their status.

8.2.4.2 Permitting and Regulatory Process Development of a feasibility study would not require any permits or regulatory approvals beyond approval of the Cawelo GSA for the funding the analysis. Development of the treatment plant would require construction permits and a CEQA analysis. Additional permits may be required to complete construction and initiate operation of the treatment plant. The Cawelo GSA would need to secure a location for the treatment plant.

8.2.4.3 Benefits The treated produced water would be a new source of about 7,500 AFY to 20,000 AFY of water for irrigation.

8.2.4.4 Source and Reliability of Water The source of water would be the water that is the byproduct of oil production. It is reliable provided the oilfield is actively producing oil. The feasibility study would include an analysis of the lifespan of the oilfield and the potential for continued supply of treated produced water to the Cawelo GSA. It would

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 154 TODD GROUNDWATER also include an analysis of the quality of the treated produced water and the processes needed to treat it to acceptable irrigation water quality.

8.2.4.5 Legal Authority Required The Cawelo GSA has the legal authority to conduct a feasibility study for construction of treated produced water treatment plant and to construct the facility if determined to be feasible.

8.2.4.6 Costs and Funding With currently technology, the approximate cost to treat this water to roughly fresh water quality is $600/AF to $900/AF, including capital and operational costs. The cost to treat 7,500 AFY to 20,000 AFY of OPW would range from about $4.5 million to $18.0 million per year. A significant portion of the cost estimate is the capital cost that is averaged over a 30-year period and includes an estimated annual debt service. Funding would be achieved by levying new assessments on a per acre basis which would require landowner voting approval per California Proposition 218. The potential new assessment could range from $100 to $400 per acre. The Cawelo GSA would also consider other funding mechanisms and look into the possibility of federal or state grant funding.

8.2.4.7 CEQA/NEPA Considerations Construction of a treated produced water treatment plant would require a CEQA analysis.

8.2.5 Project #5: Friant Pipeline Project

The Cawelo GSA is currently developing the Friant Pipeline Project that would increase water importation capacity into the Cawelo GSA area. Currently, the amount of imported water that the Cawelo GSA can import into the area is limited by conveyance capacity, not by irrigation demand or recharge basin capacities.

The Friant Pipeline Project would increase the total capacity by 100 cubic feet per second (cfs) and connect Cawelo’s Famoso Recharge Basins directly to the Friant-Kern Canal. The increased capacity would allow greater access to high flow water and support banking programs with Friant Contractors. The Friant Pipeline Project would result in an additional 1,500 AFY to 2,500 AFY of water brought into the Cawelo GSA area on an average annual basis.

The initial design focused on the delivery of water from the Cawelo GSA into the Friant-Kern Canal taking advantage of the ground surface elevations and gravity flow. This would allow the return of recovered stored groundwater via the Friant-Kern Canal. The initial design also included provisions to add a pump station to pump water from the Friant-Kern Canal uphill to the Cawelo GSA distribution system at a rate of 50 cfs. Recently, it has been decided to upgrade the design to pump 100 cfs to the Cawelo GSA.

8.2.5.1 Public Notice and Outreach Process This is an active, approved project that the Cawelo Water District has discussed at its public Board meetings. No additional public notice or outreach is planned beyond discussions at future CWD and Cawelo GSA Board meetings. The Cawelo GSA website will have a description and status of this active project.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 155 TODD GROUNDWATER 8.2.5.2 Permitting and Regulatory Process Construction of the Friant Pipeline and associated pumping facilities requires construction permits and a CEQA analysis. Many of these have been obtained since the Friant Pipeline Project is currently underway.

8.2.5.3 Benefits The Friant Pipeline Project would increase the total capacity into the Cawelo GSA by 100 cfs and increase access to CVP high flow waters and allow for banking programs with Friant Contractors. It would result in an additional 1,500 AFY to 2,500 AFY of water brought into the Cawelo GSA area on an average annual basis.

8.2.5.4 Source and Reliability of Water The source of water would be water available through the Friant-Kern Canal. It is assumed that Cawelo GSA will be able to purchase, exchange or otherwise access available water on the FKC primarily during wet and above average hydrology years. During normal and below normal years, minor amounts may be available for limited times. No water is assumed to be available during dry and critically dry hydrology years.

8.2.5.5 Legal Authority Required The Cawelo GSA through the CWD has the legal authority to construct the Friant Pipeline Project.

8.2.5.6 Costs and Funding Funding for this project has been approved and construction will begin this year.

8.2.5.7 CEQA/NEPA Considerations Construction of the Friant Pipeline Project would require a CEQA analysis. CEQA and NEPA have been completed.

8.2.6 Project #6: Poso Creek Flood Water Capture

The CWD has appropriative rights to divert water from Poso Creek, an ephemeral stream, when there are flows into the Cawelo GSA area. Additionally, there are downstream districts that also have subsequent appropriative rights and certain adjacent landowners that exercise their riparian rights. CWD also has additional diversion rights to divert supplementary water when high flows occur. The Poso Creek Flood Water Capture Project would consist of the construction of additional facilities to take advantage of those additional rights and divert supplementary water from the creek during times of high flow. In addition to making more water available to the Cawelo GSA, this capture of additional high flows could reduce potential downstream flooding impacts. Participation from downstream right holders would be needed due to potential water right impacts. The estimated net water gain is up to 150 AFY on average.

8.2.6.1 Public Notice and Outreach Process Public notice and outreach are not anticipated during development of the feasibility study, beyond outreach to downstream water rights holders. Public notice and outreach would be conducted during implementation of construction of additional facilities to divert supplementary water from the creek during times of high flow. The Cawelo GSA website would include descriptions of projects that are moving forward and a summary of their status.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 156 TODD GROUNDWATER 8.2.6.2 Permitting and Regulatory Process Development of a feasibility study would not require any permits or regulatory approvals beyond approval of the Cawelo GSA for the funding the analysis and potential approval from downstream water rights holders. Development of the additional facilities to divert supplementary water during times of high flows would require construction permits and a CEQA analysis.

8.2.6.3 Benefits The Poso Creek Flood Water Capture Project would provide up to 150 AFY on average of additional water and could reduce potential downstream flooding impacts.

8.2.6.4 Source and Reliability of Water The source of this water is Poso Creek during times of high flows. It is estimated that these flows would be available 4 years out of 20 years when looking at historical flows between the 1995 to 2014 time period. During this time period a maximum of 150 AFY, a minimum of zero, and a total of 325 AFY.

8.2.6.5 Legal Authority Required The Cawelo GSA has the authority to construct additional diversion facilities.

8.2.6.6 Costs and Funding The estimated cost of these new facilities is $3.9 million which would require the Cawelo GSA to seek additional bonding to fund the project. The estimated annual debt service would be $255,000 and the estimated net water gain is up to 150 AFY on average. The average per acre cost would be $1,700/acre. A new flood diversion facility on Poso Creek is a costly investment when evaluating on a cost per acre basis as compared to other potential water management projects. In order to implement this project, significant grant funding would be required.

8.2.6.7 CEQA/NEPA Considerations Development of a feasibility study would not trigger CEQA or NEPA. Construction of new recharge facilities could require a CEQA analysis.

8.2.7 Project #7: Surface Water Storage

The Cawelo GSA has several existing reservoirs with a combined storage capacity of 800 AF. This project would consist of constructing a new 5,000 AF reservoir within the Cawelo GSA boundary. This would provide additional storage capacity to bring more water into the Cawelo GSA area during wet years. It is estimated that this new reservoir would provide approximately 500 AFY on average. This program would likely only be implemented conjunctively with other water management programs.

8.2.7.1 Public Notice and Outreach Process Public notice and outreach are not anticipated during development of the feasibility study. Public notice and outreach would be conducted during implementation of a surface water storage facility project. The level of outreach may be dependent upon public perception of the project and some of this outreach would occur as part of the CEQA process. The Cawelo GSA website would include descriptions of projects that are moving forward and a summary of their status.

8.2.7.2 Permitting and Regulatory Process Development of a feasibility study would not require any permits or regulatory approvals beyond approval of the Cawelo GSA for the funding the analysis. Development of the reservoir and associated facilities would require construction permits and a CEQA analysis. Additional permits may be required to

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 157 TODD GROUNDWATER complete construction and initiate operation of the reservoir. The Cawelo GSA may need to secure easements and/or purchase land for the facilities.

8.2.7.3 Benefits A new reservoir would provide approximately 500 AFY on average.

8.2.7.4 Source and Reliability of Water The source and reliability of the water for surface storage is dependent upon the additional contracts for water that the Cawelo GSA enters into. The water would likely be SWP or CVP water and would be dependent upon the availability of such water.

8.2.7.5 Legal Authority Required The Cawelo GSA has the authority to construct a new reservoir and associated facilities provided all necessary regulatory permits are obtained. .

8.2.7.6 Costs and Funding The estimated cost to design and construct a 5,000 AF reservoir is $40 million. A project of this magnitude would require special funding considerations, significant state or federal grant assistance, and potential project partners in order to implement and reduce the estimated cost per acre foot benefit to the Cawelo GSA. With special state and/or federal programs, such as a WIFIA Program, with a reduced interest rates and flexible repayment schedules, the estimated annual debt service would be $1.6 million or $3,200/AF.

8.2.7.7 CEQA/NEPA Considerations Development of a feasibility study would not trigger CEQA or NEPA. Construction of a new reservoir could require a CEQA analysis.

8.2.8 Project #8: Out of Cawelo GSA Banking The Cawelo GSA will evaluate groundwater banking projects that are outside the Cawelo GSA but within the Kern County Subbasin and also groundwater banking projects outside of the Kern County Subbasin. Potential banking projects outside of the Cawelo GSA are likely to have multiple participants and therefore offer a limited share of project benefits. It is estimated the Cawelo GSA can realize an average annual benefit of 500 AFY to 1,000 AFY by participating other banking programs.

8.2.8.1 Public Notice and Outreach Process Public notice would not be required for banking outside the Cawelo GSA area other than for discussion and approval of the contracts by the Cawelo GSA Board that would occur at regular Board meetings. The Cawelo GSA website would include descriptions of projects that are moving forward and a summary of their status.

8.2.8.2 Permitting and Regulatory Process No permits or regulatory approvals would be needed for out of Cawelo GSA area banking.

8.2.8.3 Benefits Project #8 could yield an average annual benefit of 500 AFY to 1,000 AFY through out of Cawelo GSA banking programs.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 158 TODD GROUNDWATER 8.2.8.4 Source and Reliability of Water The water for out of Cawelo GSA banking would likely be SWP or CVP water and would be dependent upon the availability of such water.

8.2.8.5 Legal Authority Required The Cawelo GSA has the authority to enter into contracts for outside Cawelo GSA banking.

8.2.8.6 Costs and Funding Participation costs are estimated to be similar to in-Cawelo GSA banking costs with added operational, extraction and transportation costs. The projected cost to participate in these banking programs is $700/AF or an average of $350,000 to $700,000 annually.

8.2.8.7 CEQA/NEPA Considerations Out of Cawelo GSA area banking would not require a CEQA or NEPA analysis.

8.3 MANAGEMENT ACTIONS

8.3.1 Management Action #1: Voluntary Land Use Conversion

The Cawelo GSA will develop a program to incentivize landowners to reduce their total crop demand by converting farmed land to groundwater recharge areas. This would reduce demands and the increased recharge capability could increase supplies. It could also reduce the potential of currently fallow land being used for future crops. This Management Action could be implemented conjunctively with Project #2: Increase GW Recharge and Banking Capacity (Section 9.2.2 above).

These converted farmland to groundwater recharge areas could be shared with the Cawelo GSA for joint recharge operations. It is estimated that about 700 acres of agriculture could be voluntarily converted and would consequently decrease demands by approximately 2,000 AFY. Ultimately, the removal of agricultural production is a business decision by the landowners or operators which will, in part, be influenced by future groundwater sustainability and compliance with SGMA regulations. Potentially, landowners and operators may elect to retire far more additional land to sustain a certain level of agricultural production.

8.3.1.1 Public Notice and Outreach Process Public notice would not be required for voluntary land use conversion other than for discussion and approval of the contracts and use of funds by the Cawelo GSA Board that would occur at regular Board meetings. The Cawelo GSA website would include descriptions of projects that are moving forward and a summary of their status. Outreach would be conducted as part of the study to identify and contact potential landowners for land use conversion.

8.3.1.2 Permitting and Regulatory Process No permits or regulatory approvals would be needed for the voluntary land use conversion program. The permitting and regulatory approvals for conversion of land to recharge facilities would be part of the Program #2: Increase Groundwater Recharge and Banking Capacity.

8.3.1.3 Benefits The conversion of about 700 acres of agriculture could decrease demands by approximately 2,000 AFY.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 159 TODD GROUNDWATER 8.3.1.4 Source and Reliability of Water There is no source of water for this management action only a water savings through land conversion.

8.3.1.5 Legal Authority Required No legal authority is needed for landowners to take their fields out of production. Legal authority to convert those fields to recharge areas is included in Project #2.

8.3.1.6 Costs and Funding The incentives for landowners to convert cropland to recharge areas would be in the form of shared water banking credits for the water that they recharged. There would be no capital investment on behalf of the Cawelo GSA. Costs associated with water purchase or transportation is included in Project #2: Increase GW Recharge and Banking Capacity (Section 9.2.2 above).

8.3.1.7 CEQA/NEPA Considerations Voluntary land use conversion would not require a CEQA or NEPA analysis.

8.3.2 Management Action #2: Crop Conversion and Irrigation Efficiency Program

The Cawelo GSA will evaluate potential programs to incentivize growers to convert from relatively high water demands crops to crops that require less water and to improve the efficiency of irrigation practices. The Cawelo GSA will partner with Federal, State and local organizations such as the California Department of Food and Agriculture, U.S. Department of Agriculture, and Natural Resources Conservation Service to provide landowners information and access to conservation programs. The programs would educate the landowners on the potential economic savings from conversion to lower water demand crops and increased irrigation efficiencies and incentivize them to seek improved economically viable agricultural operations.

8.3.2.1 Public Notice and Outreach Process Public notice would not be required for crop conversion or irrigation efficiency programs other than for discussion and approval of the contracts and use of funds by the Cawelo GSA Board that would occur at regular Board meetings. The Cawelo GSA website would include descriptions of projects that are moving forward and a summary of their status. Outreach would be conducted as part of the study to identify potential agency partners and to disseminate their information to landowners for crop conversion and irrigation efficiency.

8.3.2.2 Permitting and Regulatory Process No permits or regulatory approvals would be needed for crop conversion and irrigation efficiency education programs.

8.3.2.3 Benefits This management action could result in improved irrigation efficiencies of about 2.5 percent which equates to a demand reduction of about 2,000 AFY. The reduction of high water demand crops to lower water demand crops could result in about 1,500 AFY of water savings.

8.3.2.4 Source and Reliability of Water There is no source of water for this management action only a water savings through crop conversion and improving irrigation efficiencies.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 160 TODD GROUNDWATER 8.3.2.5 Legal Authority Required No legal authority is needed to set up educational programs for landowners to change crops to a lower water use one or to increase irrigation efficiencies.

8.3.2.6 Costs and Funding The estimated costs to implement such programs are unknown. There are cost-share grants available that require a capital contribution or allow in-kind services.

8.3.2.7 CEQA/NEPA Considerations Crop conversion and irrigation efficiency programs would not require a CEQA or NEPA analysis.

8.3.3 Management Action #3: Land Acquisition

The Cawelo GSA will evaluate and potentially implement a program to acquire land that is actively farmed to reduce irrigated acreages within the Cawelo GSA. This would directly eliminate demands and free up the associated water supplies to meet other demands.

This could be a very long-term program seeking to acquire appropriate land when available or to reduce the financial burden. Another method for potential conservation programs will be developed that could place certain easements on land that would minimize potential future increased water demands. These programs could also be implemented by contracts or other types of agreements.

This will be a long-term program seeking to acquire appropriate land when it becomes available and to average the financial burden over many years. The probable funding method would be to seek bonds to generate funds to purchase the lands. The approximate value of demand intensive land is $25K/acre with an average of 3.0 AF/acre demand. By purchasing about 800 acres, the Cawelo GSA can remove 2,500 AF of annual demand. The estimated total cost to acquire 800 acres is $20 million which is an annual debt service of $1.3 million per year for 30 years or $520/AF..

If a voluntary approach is taken then participation would need to be incentivized which could include the redistribution of the water allocation supply (surface and groundwater) to those participating. A voluntary program would need to be implemented early to build the necessary funding to acquire land, assuming it is necessary for sustainability by 2040.

8.3.3.1 Public Notice and Outreach Process Public notice would not be required for land acquisition other than for discussion and approval of the contracts and use of funds by the Cawelo GSA Board that would occur at regular Board meetings. The Cawelo GSA website would include descriptions of projects that are moving forward and a summary of their status. Outreach would be conducted as part of the study to identify potential landowners for land acquisition and to inform them of the benefits of land acquisition.

8.3.3.2 Permitting and Regulatory Process No permits or regulatory approvals would be needed for land acquisition by the Cawelo GSA.

8.3.3.3 Benefits By purchasing about 800 acres, the Cawelo GSA can remove 2,500 AF of annual demand.

8.3.3.4 Source and Reliability of Water There is no source of water for this management action only a water savings through land acquisition.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 161 TODD GROUNDWATER 8.3.3.5 Legal Authority Required No legal authority is needed for the Cawelo GSA to purchase lands to take them out of production.

8.3.3.6 Costs and Funding Land acquisition can be costly and there are various options that Cawelo GSA could implement to generate the funding for this program. The probable funding method would be to sell bonds. The approximate value of water-demand intensive land is $25,000/acre. By purchasing about 800 acres and assuming that the land used an average of 3.0 AF/acre, about 2,500 AFY of water would be saved. The estimated total cost to acquire 800 acres is $20 million which is an annual debt service of $1.3 million per year for 30 years or $520/AF.

8.3.3.7 CEQA/NEPA Considerations Land acquisition would not require a CEQA or NEPA analysis.

8.4 SUSTAINABILITY ASSESSMENT

To assess the potential effectiveness of the proposed projects and management actions for the Cawelo GSA in achieving groundwater sustainability after the 20-year implementation period (2021-2040), the implementation of the projected benefits of the proposed projects and management actions have been in incorporated into the projected future baseline for current, 2030 climate change and 2070 climate change conditions

8.4.1 Projected Implementation of Proposed Projects

The proposed projects and management actions for the Cawelo GSA are planned to be implemented over the 20-year implementation period from 2021 to 2040. Some projects are anticipated to begin immediately in 2021 whereas others will be phased in over this period with project initiation dates ranging from 2021 to 2035 as described in Section 9.3. The planned implementation is as follows:

• During the first five years (2021 to 2025) the proposed groundwater benefit is 8,170 AFY which is about 25 percent of the proposed projects and management actions.

• During the second five year period (2026 to 2030) the proposed groundwater benefit is 16,160 AFY which is about 50 percent of the proposed projects and management actions.

• During the third five year period (2031 to 2035) the proposed groundwater benefit is 23,435 AFY which is about 75 percent of the proposed projects and management actions.

• During the fourth year period (2021 to 2026) the proposed groundwater benefit is 24,810 AFY which is about 80 percent of the proposed projects and management actions.

At the end of the implementation, the complete program of proposed projects and management actions is planned to be implemented. The proposed groundwater benefit is 31,788 AFY. Table 8-2 provides a summary of the projected quantitative benefit of each project towards groundwater sustainability in five year increments over the 20-year implementation period. Tables providing average annual summaries using the checkbook method are provided in the text with additional data provided in Appendix H.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 162 TODD GROUNDWATER Table 8-2. Projected Benefit of Proposed Projects and Management Actions over Implementation and Planning Period. 2021-2025 2026-2030 2031-2035 2036-2040 2041-2070 Proposed Project or Projected Projected Projected Projected Projected Management Action Benefits Benefits Benefits Benefits Benefits Programs AFY AFY AFY AFY AFY New Water Supply P1 22,500 29,500 38,000 33,000 175,000 Purchases Increase Recharge and P2 0 0 3,000 1,500 11,500 Banking Capacity New Cawelo GSA P3 350 600 700 500 3,100 Banking Partners Water Treatment P4 15,000 40,000 50,000 50,000 450,000 Facilities P5 Friant Pipeline Project 0 0 175 150 825 Poso Creek Flood P6 0 0 2,400 4,800 14,400 Water Capture P7 Surface Water Storage 0 0 0 5,000 41,000 Increased Imported P8 3,000 1,500 4,500 1,500 15,000 Water Capacity MA 1 Voluntary Conversion 0 2,400 4,800 7,200 57,600 Crop Conversion and MA 2 0 4,400 8,800 13,200 115,600 Irrigation Efficiency MA 3 Land Acquisition 0 2,400 4,800 7,200 69,600

TOTAL PERIOD BENEFIT 40,850 80,800 117,175 124,050 953,625 AVERAGE ANNUAL PERIOD 8,170 16,160 23,435 24,810 31,788 BENEFIT

8.4.2 Projected Future Water Budgets with Projects

The proposed SGMA projects and management actions were added to the checkbook method projected future water budgets to assess the viability of these actions to achieve sustainability within the Cawelo GSA. The checkbook method evaluates the operational water budget without groundwater flow inflow and outflow. The projected changes in storage for the baseline and 2030 and 2070 climatic climate conditions with projects are summarized in Figures 8-2 and 8-3, and Table 8-3.

In general, the change in net inflows and outflows improves significantly compared to the water budgets without the SGMA projects (Table 4-20). For the baseline and 2030 and 2070 climatic climate conditions there is a net positive inflow in all three cases during the 2041 to 2070 sustainability period when all the proposed SGMA projects are implemented in the analysis. Comparing the net inflow and outflow for the various scenarios both with and without projects is summarized as follows: • Under Baseline Conditions, the average annual net inflow/outflow changes from -16,943 AFY without projects to a +1,317 AFY during the 2021 to 2040 Implementation Period, and from -19,916 AFY without projects to a +11,891 AFY during the 2041 to 2070 Sustainability Period.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 163 TODD GROUNDWATER Figure 8-1 provides a time series comparison of the net inflow/outflow change for Baseline Conditions both with and without projects. • Under 2030 Climate Conditions, the average annual net inflow/outflow changes from -20,394 AFY without projects to a -2,135 AFY during the 2021 to 2040 Implementation Period, and from -23,465 AFY without projects to a +8,342 AFY during the 2041 to 2070 Sustainability Period. Figure 8-2 provides a time series comparison of the net inflow/outflow change for 2030 Climate Conditions both with and without projects. • Under 2070 Climate Conditions, the average annual net inflow/outflow changes from -25,539 AFY without projects to a -7,280 AFY during the 2021 to 2040 Implementation Period, and from -28,601 AFY without projects to a +3,206 AFY during the 2041 to 2070 Sustainability Period. Figure 8-3 provides a time series comparison of the net inflow/outflow change for 2070 Climate Conditions both with and without projects. • The potential deficits projected in Table 4-20 for the 2030 Climate Change conditions occur only during the initial 20 years of the GSP implementation period and are within the window for achieving sustainability. Accordingly, those conditions are the focus of the priority GSP projects. It is recognized that the 2070 Climate Change conditions are less certain, given the long-term 50-year implementation and planning horizon. As part of the GSP, future Annual Reports and five-year GSP evaluations will be used to update these potential projected deficits when much more detailed information from the Cawelo GSA water budgets will be available. During those re-evaluations, the GSP will be adapted as needed to maintain sustainable groundwater management.

Table 8-3: Future Baseline Groundwater Budget Summary Comparison (Acre-Feet per Water Year).

Implementation Period Sustainability Period

(2021-2040) (2041-2070) Baseline with Projects Total Average Total Average Total Inflows 734,008 36,700 1,173,243 39,108 Total Outflows 707,663 35,383 816,513 27,217 INFLOWS - OUTFLOWS 26,345 1,317 356,730 11,891 2030 Climate with Projects Total Average Total Average Total Inflows 727,351 36,368 1,161,020 38,701 Total Outflows 770,055 38,503 910,751 30,358 INFLOWS - OUTFLOWS -42,704 -2,135 250,269 8,342 2070 Climate with Projects Total Average Total Average Total Inflows 769,151 38,458 1,224,963 40,832 Total Outflows 914,752 45,738 1,12,778 37,626 INFLOWS - OUTFLOWS -145,601 -7,280 96,185 3,206

8.5 PROJECTED WATER BUDGET RESULTS USING C2VSIMFG-KERN

The projected water budget results using the C2VSimFG-Kern Model were developed in cooperation between the KGA and KRGSA. The KGA managers decided that the C2VSimFG-Kern model results for the projected future water budgets would be presented at the basin scale, but not for each of the local

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 164 TODD GROUNDWATER districts and GSAs as was done for the historical water budgets. This was done because of application of some of the assumptions to develop the projected future conditions included some that were more generalized over the basin rather than specifically applied to each district due to the uncertainty in projecting future conditions. The C2VSimFG-Kern model results for the projected future water budgets are included in the KGA Umbrella GSP (GEI, 2019). GSA for the Kern County Subbasin. A more detailed assessment of projected water budgets has been developed for both the Subbasin and the KGA using the C2VSimFG-Kern model. The C2VSimFG-Kern model provides a means to assess the performance of the groundwater levels in meeting the MT and MO for each of the proposed monitoring locations. The simulated groundwater levels comparing the Baseline and 2030 Climate Conditions, both with and without SGMA projects, are shown on Figures 8-4 through 8-10 for the proposed monitoring well locations for the Cawelo GSA. In general, the simulation results indicate that implementing the proposed SGMA projects meet the proposed MT and MO for all of the locations with projects; however, that it not so for conditions without projects. Similarly, the simulated groundwater levels comparing the Baseline and 2070 Climate Conditions, both with and without SGMA projects, are shown on Figures 8-11 through 8-17 for the proposed monitoring well locations for the Cawelo GSA. The simulation results indicate that implementing the proposed SGMA projects meet the proposed MT and MO at most but not all of the locations with projects, and for does not meet the proposed MT and MO at most locations for conditions without projects. It should be noted that the C2VSimFG-Kern model has identified the locations along the northeastern margin of the Kern County Subbasin have a higher level of uncertainty due to the hydrologic conceptual model in C2VSimFG-Kern in this location does not accurately represent the stratigraphic relationships. This is issue is most prominent for the simulated groundwater level trend for T27S/R26E-12H (RMW- 167) and T26S/R26E-24R (RMW-170), show a general declining trend, as shown on Figures 8-4, 8-7, 8-11 and 8-14 respectively, that is not considered an accurate representation of groundwater levels in this area. Further work will be performed to improve the analysis of the projected future groundwater levels in future work.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 165 TODD GROUNDWATER 9 PLAN IMPLEMENTATION

The GSP implementation period begins in 2020 and continues until 2040, when the Cawelo GSA anticipates meeting its sustainability goal. During this period, the proposed SGMA projects and management actions are scheduled to begin in 2020 and continue through 2040. Cawelo GSA will conduct ongoing evaluation of the operation of the SGMA projects and management actions in meeting the interim milestones, measurable objectives and minimum thresholds defined in the GSP in meeting the long-term sustainability goal. The results of these evaluations will be documented in the Five-year periodic GSP updates.

9.1 SCHEDULE FOR IMPLEMENTATION

Implementation of the proposed SGMA projects and management actions is planned to begin during the first five years of the 20-year GSP implementation period as indicated on Figure 9-1. SGMA Projects and management actions that will continue to be implemented over the 20-year GSP implementation period as shown on Figure 9-1.

9.2 ANNUAL REPORTING

The Subbasin is currently working on a coordinated effort to develop an approach for the First Annual Report due April 1, 2020. For this effort, GSA managers intend to provide Annual Report information to one party for development of one coordinated Annual Report for the Subbasin. Report will include Subbasin-wide contour maps, and compiled information on GSP implementation activities. Subbasin managers are currently considering options for developing a consistent change in groundwater in storage for the entire Subbasin.

For the Cawelo GSA, annual reports will improve over time as management actions are implemented. The detailed checkbook water budget will be updated and streamlined to facilitate effective annual reporting in the future.

9.3 PERIODIC EVALUATIONS

The GSP and monitoring protocols will be evaluated every five years as part of the five-year GSP periodic update. As indicated above, implementation of the initial SGMA projects and management actions will begin during the first five years. Depending on the complexity of the project or action, implementation will continue into future five-year periods and will be tracked and updated in subsequent five-year periodic evaluations. An evaluation of groundwater conditions and an updated water budget will be used to evaluate then-current progress toward meeting MOs and MTs throughout the Cawelo GSA Plan Area.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 166 TODD GROUNDWATER 10 REFERENCES AND TECHNICAL STUDIES

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Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 169 TODD GROUNDWATER Hem, J.D., 1985, Study and Interpretation of the Chemical Characteristics of Natural Water, Third Ed., USGS Water Supply Paper 2254. http://water.usgs.gov/owq/FieldManual/compiled/NFM_complete.pdf Ireland, R.L., Poland, J.F., and Riley, F.S., 1984, Land Subsidence in the San Joaquin Valley, California as of 1980, Studies of Land Subsidence, USGS Professional Paper 437-I, prepared in cooperation with the California Department of Water Resources. Izbicki, J.A., Stamos, C.L., Metzger, L.F., Halford, K.J., Kulp, T.R., and Bennett, G.L., 2008, Source, Distribution, and Management of Arsenic in Water from Wells, Eastern San Joaquin Ground-Water Subbasin, California, USGS Open-File Report 2008–1272. http://pubs.usgs.gov/of/2008/1272/. Jurgens, B.C., Burow, K.R., Dalgish, B.A., and Shelton, J.L., 2008, Hydrogeology, Water Chemistry, and Factors Affecting the Transport of Contaminants in the Zone of Contribution to a Public-Supply Well in Modesto, Eastern San Joaquin Valley, California, USGS Scientific Investigations Report 2008– 5156. http://pubs.usgs.gov/sir/2008/5156/. Kennedy Jenks Consultants (K/J), 2011a, Cawelo Water District Famoso Basins Antidegradation Analysis, Submitted to California Regional Water Quality Control Board for Cawelo Water District, Chevron North America and Valley Waste Disposal Company, June 30. Kennedy Jenks Consultants (K/J), 2011b, Cawelo Water District Famoso Basins Antidegradation Analysis—Addendum, Submitted to California Regional Water Quality Control Board for Cawelo Water District, Chevron North America, and Valley Waste Disposal Company, October. Kern County Environmental Health Services Division (EHS), 2010, Standards and Rules and Regulations for Land Development: Sewage Disposal, Water Supply, and Preservation of Environmental Health, October 2010, accessed June 15, 2017. https://kernpublichealth.com/wp- content/uploads/2016/03/Standards-and-Rules-and-Regulations-for-Land-Development.pdf. Kern County Planning Department, 2009, Kern County General Plan, September. https://www.kerncounty.com/planning/pdfs/kcgp/KCGP.pdf. Kern County Water Agency (KCWA), 2001, Initial Water Management Plan, Final, Adopted October 25. Kern County Water Agency (KCWA), 2009, Water Supply Report 2009. Kern County, 2019, Development Standards, Department of Engineering, Surveying, and Permit Services, accessed on February 22. http://esps.kerndsa.com/engineering/development- standards#intro. Kern Groundwater Authority (KGA), 2018, Kern Groundwater Authority GSP Approach Presentation, February 5. http://www.kerngwa.com/assets/feb2018coordcomm.pdf. Luhdorff & Scalmanini Consulting Engineers (LSCE), James Borchers, and Michael Carpenter, 2014, Report of Findings: Land Subsidence from Groundwater Use in California, April. McClelland, E.J., 1962, Aquifer-Test Compilation for the San Joaquin Valley, California, USGS Open-File Data Report. McMahon, P.B., Kulongoski, J.T., Wright, M.T., Land, M.T., Landon, M.K., Cozzarelli, I.M., Vengosh, A., and Aiken, G.R., 2017, Preliminary Results from Exploratory Sampling of Wells for the California Oil, Gas, and Groundwater Program, 2014-15, USGS Open-File Report 2016-1100, prepared in cooperation with the California State Water Resources Control Board. Metzger, L.F., and Landon, M.K., 2018, Preliminary Groundwater Salinity Mapping Near Selected Oil Fields Using Historical Water-Sample Data, Central and Southern California, USGS Scientific Investigations Report 2018–5082. https://doi.org/10.3133/sir20185082.

Groundwater Sustainability Plan REVIEW DRAFT Cawelo GSA 170 TODD GROUNDWATER National Oceanic and Atmospheric Administration (NOAA), 2018, National Climatic Data Center (NCDC), Bakersfield Monthly Precipitation, 1889-2010 and 2011-2017. Page, R.W., 1973, Base of Fresh Ground Water (Approximately 3,000 Micromhos in the San Joaquin Valley, California, USGS Hydrologic Investigations Atlas HA-489. Page, R.W., 1986, Geology of the Fresh Ground-Water Basin of the Central Valley, California, with Texture Maps and Sections, Regional Aquifer System Analysis, USGS Professional Paper 1401-C. Poso Creek Regional Water Management Group (Poso Creek RWMG), 2014, 2014 Poso Creek Integrated Regional Water Management (IRWM) Plan Update, June. Prokopovitch, Nikola P., 1984, Predictions of Future Subsidence along Friant-Kern Canal in California, in Bulletin of the Association of Engineering Geologists, May. Provost & Pritchard Consulting Group, 2015, Groundwater Quality Assessment Report, prepared for the Kern River Watershed Coalition Authority, February. Provost & Pritchard Consulting Group, 2016, Kern Storm Water Resource Plan, prepared for Kern County, December. R. L. Schafer & Associates (Schafer), 2007, Cawelo Water District Summary Report 1965-2006, July. Rutqvist, J., Rinaldi, A.P., Cappa, F., and Moridis, G.J., 2013, Modeling of Fault Reactivation and Induced Seismicity During Hydraulic Fracturing of Shale-Gas Reservoirs, Journal of Petroleum Science and Engineering Journal, 107. Safe Drinking Water Information System (SDWIS), 2019, California Drinking Water Watch, Water System Details, accessed May 1. Shafter, City of, 2005, Draft General Plan, April. Shafter, City of, 2016, 2015 Urban Water Management Plan, June. Sierra Scientific Services, 2013, The Geology and Groundwater Hydrology of the Buena Vista Water Storage District, Buttonwillow, CA, Including Descriptions of Relevant Facilities and Operations, May 20. Sophocleous, M., 1983, Groundwater Observation Network Design for the Kansas Groundwater Management Districts, U.S.A., Journal of Hydrology, 61(4): 347-389, DOI: 10.1016/0022- 1694(83)90002-1. State Water Resources Control Board (SWRCB), 2015, Model Criteria for Groundwater Monitoring in Areas of Oil and Gas Well Stimulation, adopted July 7. State Water Resources Control Board (SWRCB), 2017, Underground Injection Control in Oil and Gas Production Areas. https://www.waterboards.ca.gov/water_issues/programs/groundwater/sb4/oil_field_produced/do cs/uic_fact_sheet_08142017.pdf. State Water Resources Control Board (SWRCB), 2019a, Water Quality in Areas of Oil and Gas Production – Regional Groundwater Monitoring, accessed on February 22. https://www.waterboards.ca.gov/water_issues/programs/groundwater/sb4/regional_monitoring/. State Water Resources Control Board (SWRCB), 2019b, Surface Water Ambient Monitoring Program (SWAMP), accessed on March 4. http://www.waterboards.ca.gov/water_issues/programs/swamp/tools.shtml#qa,. Stetson Engineers, Inc., 2017, Final Draft City of Bakersfield 2015 Urban Water Management Plan, June.

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