Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report

This page left blank intentionally.

Yuba Water Agency December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Contents

Table of Contents 1 Introduction ...... 1-1 2 Groundwater Management Actions ...... 2-1 2.1 GMP Component Category 1: Stakeholder Involvement Plan ...... 2-1 2.2 GMP Component Category 2: Monitoring Program ...... 2-1 2.3 GMP Component Category 3: Groundwater Resource Protection ...... 2-4 2.4 GMP Component Category 4: Groundwater Sustainability ...... 2-4 2.5 Planned Groundwater Management Activities ...... 2-5 3 Groundwater Monitoring and Conditions Assessment ...... 3-1 3.1 Hydrologic Conditions ...... 3-1 3.2 Groundwater Substitution Transfer, Schedule 6, and Additional Local Pumping ...... 3-1 3.2.1 Groundwater Substitution Transfer Pumping In 2008, 2009, 2010, 2013, 2014, and 2018 3-1 3.2.2 2015 Groundwater Pumping – Schedule 6, Deficiency, and Additional Local Pumping ... 3-4 3.3 Elevations and Storage ...... 3-4 3.3.1 Comparison of Current and Historical Spring Groundwater Levels ...... 3-10 3.3.2 Groundwater Elevation Contour Maps ...... 3-10 3.3.1 Groundwater Levels from Transfer Wells ...... 3-10 3.3.2 Groundwater Storage ...... 3-20 3.4 Groundwater Quality ...... 3-21 3.4.1 Electrical Conductivity Measurements from Transfer Wells ...... 3-22 3.5 Groundwater Surface Water Interaction ...... 3-26 3.6 Total Water Use ...... 3-29 3.6.1 Groundwater Use ...... 3-29 3.6.1 Surface Water Use ...... 3-30 3.6.2 Total Water Use ...... 3-30 3.7 Compliance with Monitoring Requirements ...... 3-34 3.8 Comparison to Fall 1991 Groundwater Levels ...... 3-34 3.9 Third-Party Groundwater Impacts ...... 3-36

List of Figures Figure 1. North and South Yuba Groundwater Subbasins ...... 1-2 Figure 2. Yuba County Alluvial Basin Groundwater Monitoring Network ...... 2-3 Figure 3. Yuba County Member Units, Pumping Zone Boundaries, and Groundwater Substitution Transfer Well Locations ...... 3-3 Figure 4. Key Groundwater Hydrographs in the North Yuba Subbasin ...... 3-6 Figure 5. Key Groundwater Hydrographs in the South Yuba Subbasin ...... 3-7 Figure 6. 2008-2019 Groundwater Hydrographs in North Yuba Subbasin ...... 3-8 Figure 7. 2008-2019 Groundwater Hydrographs in South Yuba Subbasin ...... 3-9 Figure 8. Comparison of 2019 and Historical Spring Groundwater Levels for the South Yuba Subbasin ...... 3-11 Figure 9. Comparison of 2019 and Historical Spring Groundwater Levels for the North Yuba Subbasin ...... 3-12 Figure 10. Spring 2018 Groundwater Elevations in the Yuba Subbasins ...... 3-13

Yuba Water Agency i December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Contents

Figure 11. Spring 2019 Groundwater Elevations in the Yuba Subbasins ...... 3-14 Figure 12. Fall 2017 Groundwater Elevations in the Yuba Subbasins ...... 3-15 Figure 13. Fall 2018 Groundwater Elevations in the Yuba Subbasins ...... 3-16 Figure 14. Spring 2018 to Spring 2019 Hydraulic Head Difference Map...... 3-17 Figure 15. Fall 2017 to Fall 2018 Hydraulic Head Difference Map ...... 3-18 Figure 16. Spring 2019 and Spring 2018 Depth-to-Water Measurements in Transfer Pumping Wells by Pumping Zone ...... 3-19 Figure 17: Estimated Groundwater Storage and Change in Storage, North Yuba Subbasin ...... 3-20 Figure 18: Estimated Groundwater Storage and Change in Storage, South Yuba Subbasin ...... 3-21 Figure 19. Electric Conductivity Trends in Key Wells in Yuba Subbasins ...... 3-24 Figure 20. Initial and Final EC Measurements in 2018 Transfer Pumping Wells ...... 3-25 Figure 20. 2008-2018 Hydrographs for Yuba River and Bear River Areas ...... 3-28 Figure 21. 2008-2018 Hydrographs for Feather River and Honcut Creek Areas ...... 3-29 Figure 22. Fall 2018 Conditions Compared to Fall 1991 Conditions and Long-Term Fall Conditions in the South Yuba Subbasin ...... 3-35

List of Tables Table 1. Groundwater Substitution Transfer Pumping by Member Unit Since 2008 ...... 3-2 Table 2. Groundwater Substitution Transfer Pumping by Pumping Zone Since 2008 ...... 3-2 Table 3. Summary of Water Quality Indicators for Yuba Subbasins ...... 3-23 Table 4. North Yuba Subbasin Estimated Groundwater Extraction for Water Year 2018 ...... 3-31 Table 5. South Yuba Subbasin Estimated Groundwater Extraction for Water Year 2018 ...... 3-32 Table 6. North Yuba Subbasin Estimated Surface Water Use for Water Year 2018 ...... 3-33 Table 7. South Yuba Subbasin Estimated Surface Water Use for Water Year 2018 ...... 3-33

Appendices Appendix A – GMP Implementation Progress Appendix B – Groundwater Hydrographs

Yuba Water Agency ii December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Contents

List of Abbreviations and Acronyms µS/cm micro Siemens per centimeter BVID Browns Valley Irrigation District BWD Brophy Water District CID Cordua Irrigation District CASGEM California Statewide Groundwater Elevation Monitoring DCMWC Dry Creek Mutual Water Company DMS Data Management System DWR California Department of Water Resources EC electrical conductivity GAMT groundwater adaptive management tool GIS geographic information system GMP Groundwater Management Plan GSA Groundwater Sustainability Agency GSC Groundwater Sustainability Committee GSP Groundwater Sustainability Plan GWS Groundwater Substitution Transfer HUR Hydrogeologic Understanding Report MCL Maximum Contaminant Level NCRO North Central Region Office RD Reclamation District Report Annual Monitoring and Measurement Report RWD Ramirez Water District SB Senate Bill SGMA Sustainable Groundwater Management Act SWN CASGEM State Water Number SYWD South Yuba Water District TDS total dissolved solids TSS Technical Support Services WWD Wheatland Water District YGM Yuba Groundwater Model Yuba Water Yuba Water Agency YWA Yuba Water Agency

Yuba Water Agency iii December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Contents

This page left blank intentionally.

Yuba Water Agency iv December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Introduction

1 INTRODUCTION Yuba Water Agency (Yuba Water) adopted an updated Groundwater Management Plan (GMP) in December 2010 to build on and formalize the historically successful management of the County’s groundwater resource. Yuba Water initially developed and adopted a GMP in 2005. The updated GMP reflects conditions in the North and South Yuba Groundwater Subbasins (Yuba Subbasins) through spring of 2010 and presents updated lists of basin management objectives and groundwater management actions. Locations of the Yuba Subbasins are shown in Figure 1. The 2010 GMP adopted seven basin management objectives: 1. Maintain groundwater elevations that provide for sustainable use of the groundwater basin. 2. Protect against potential inelastic land surface subsidence. 3. Maintain and improve groundwater quality in the Yuba basin for the benefit of groundwater users. 4. Manage groundwater to protect against adverse impacts to surface water flows. 5. Improve communication and coordination among Yuba groundwater basin stakeholders. 6. Maintain local control of the Yuba groundwater basin. 7. Improve understanding of the Yuba groundwater basin and its stressors. Further, the 2010 GMP identified specific management actions under four main GMP components: 1. Stakeholder involvement. 2. Monitoring program. 3. Groundwater resource protection. 4. Groundwater sustainability. Yuba Water publishes an Annual Monitoring and Measurement Report (Report) to document progress in implementing the GMP. The Report is intended to be an informational document that summarizes groundwater basin conditions and management actions during the annual period covered by the Report. This document is the fourteenth Report and covers the period from spring 2018 through spring 20191. The Report summarizes groundwater monitoring results collected by Yuba Water and by the California Department of Water Resources (DWR), including groundwater elevations, groundwater quality, groundwater-surface water interaction, and subsidence. The Report also documents groundwater management actions during the annual period covered by the Report and future planned actions. This is anticipated to be the final Annual Monitoring and Measurement Report associated with the Groundwater Management Plan. The next Report is anticipated to document progress in implementing the Groundwater Sustainability Plan (GSP) covering the North and South Yuba Subbasins and will include slightly different information to conform with that document and the associated requirements under the Sustainable Groundwater Management Act (SGMA). One such modification is a switch to reporting by water year rather than spring-to-spring, as well as completion of the report in April. This year’s Report is transitional in that it includes several of the newly required items.

1 This reporting period allows for an analysis of groundwater from the typical high-level point in spring through the summer drawdown and subsequent recovery in winter and spring of the following year.

Yuba Water Agency 1-1 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Introduction

Figure 1. North and South Yuba Groundwater Subbasins

Yuba Water Agency 1-2 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Management Actions

2 GROUNDWATER MANAGEMENT ACTIONS During the period covered by this Report, Yuba Water has been working – in coordination with its Member Units and DWR – to implement elements of its updated GMP in order to achieve the basin management objectives. In addition, the agency is continuing to develop the Yuba County Conjunctive Use Program, which is aimed at ensuring sustainable and reliable water supplies within the county and, as available, to meet demands in other areas of the state. Appendix A provides a detailed listing of Yuba Water’s GMP action items and the implementation status of each item. The following four sections summarize each of the major groundwater management activities and accomplishments for the reporting period, grouped by the components of the GMP, as applicable. The final section describes planned groundwater management actions, including the development of a GSP for the North and South Yuba Groundwater Subbasins. 2.1 GMP COMPONENT CATEGORY 1: STAKEHOLDER INVOLVEMENT PLAN Yuba Water actively promoted public and stakeholder involvement in the development of its updated GMP. Although not specifically required by the California Water Code, Yuba Water provided public noticing of its GMP update to maximize stakeholder involvement in the update process. In addition, public meetings were held in August and November of 2010 to provide information about the GMP update process and solicit comments from stakeholders and the general public. Yuba Water is continuing its efforts to inform and involve the public throughout the implementation of the GMP by providing public briefings at selected meetings of Yuba Water’s Board of Directors. Yuba Water has posted groundwater-related documents, including the Annual Monitoring and Measurement Report and Annual Report Fact Sheets, to its website for public viewing. Yuba Water also developed a conjunctive use brochure to educate the general public on the benefits of conjunctive water use and an agency fact sheet describing Yuba Water’s history, water supply and infrastructure, water deliveries, and participation in the Lower Yuba River Accord. In addition, as part of the Lower Yuba River Accord implementation activities, Yuba Water conducts regular meetings with its Member Units to coordinate and proactively manage the groundwater resource and groundwater substitution (GWS) transfers. Recent stakeholder activities have focused on the development of a GSP for the North and South Yuba Subbasins as required under SGMA. These activities have included the formation of a Groundwater Sustainability Committee (GSC), composed of representatives of agencies throughout Yuba County, to provide guidance on the development of the GSP to the three Groundwater Sustainability Agencies (GSA). During this Report’s reporting period, meetings of the GSC were held in May 2018, August 2018, September 2018, October 2018, February 2019, and April 2019 to educate stakeholders and receive input and direction on GSP development. Education included information relevant to GSP development and information on overall groundwater conditions. In addition to the GSC meetings, stakeholder outreach has included individual meetings with stakeholders to discuss the SGMA process and overall groundwater management. 2.2 GMP COMPONENT CATEGORY 2: MONITORING PROGRAM Yuba Water continues to coordinate with DWR-North Central Region Office (NCRO) on collection of groundwater-level and water quality data from the Yuba County monitoring network. These data are used to evaluate the health of the groundwater basin and improve understanding of the basin hydrogeology. Results of these monitoring efforts are summarized in Section 3.

Yuba Water Agency 2-1 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Management Actions

DWR and Yuba Water each monitored groundwater elevations in wells throughout the basin during the period covered by this Report. In spring 2017, DWR discontinued monitoring of seven wells2 in Yuba County, due to either a lack of construction information or excessive oil in the casing. Yuba Water has worked cooperatively with DWR to assume monitoring tasks for five of these wells3. One of the remaining wells that DWR discontinued monitoring has accessibility/permission issues at the well sites that prevent Yuba Water from monitoring; the seventh well has a new wellhead that does not allow for water level monitoring. Additionally, Yuba Water assumed monitoring tasks in spring 2018 for a nested well cluster4 at Riverside Meadows Elementary School in Plumas Lake. Installation of data loggers for continuous monitoring was completed for this well cluster in December 2018. Of the wells monitored by Yuba Water for water levels during the period covered by this Report, 11 wells are measured semiannually, 20 wells are measured monthly, and 22 wells are measured continuously using data loggers. Figure 2 displays the network of wells monitored by Yuba Water and DWR in Yuba County. DWR also maintains historical water quality data for 129 wells in Yuba County, and currently collects data for 9 of the wells on a biennial basis, analyzing for field parameters, metals, major ions, and general chemistry. Note that in 2018, DWR did not collect water quality data from any of these wells, as the department re-assesses its water quality monitoring program. Yuba Water is investigating performing water quality sampling to cover the temporary or permanent cessation of monitoring of these wells by DWR. In addition to the ongoing groundwater monitoring activities, Yuba Water and the Member Units have implemented a monitoring plan for GWS transfers. This plan includes monitoring groundwater levels and water quality in participating transfer wells. Member Units are required to perform increased monitoring activities until groundwater levels recover to pre-pumping levels or until the spring high- water level is reached. Such monitoring took place in 2018 along with the associated transfer pumping. Yuba Water is compliant with Senate Bill (SB) X7 6, passed in 2009, which established the California Statewide Groundwater Elevation Monitoring (CASGEM) Program. Yuba Water submitted all required documentation, including a groundwater-elevation monitoring plan, to DWR and, in December 2011, was formally recognized as the monitoring entity for the South Yuba Subbasin and the North Yuba Subbasin. As the monitoring entity for Yuba County, Yuba Water provides DWR with monitoring well data at least semiannually. This data is accessible to the public at DWR’s CASGEM website. To standardize data collection and centralize data management, Yuba Water has implemented a Data Management System (DMS) using Hydstra5. The DMS centralizes data storage for groundwater elevation data collected by Yuba Water. It also provides automated tools for data collection, reporting, and sharing. The DMS was developed in coordination with DWR, which also uses Hydstra for its Water Data Library database. To compile the various geographic information system (GIS) mapping products developed for the Yuba Water Conjunctive Use Program, a digital library of the major map features was developed. The digital library contains dynamic map layers for effective use and distribution of mapping data.

2 State Well Numbers (SWN) 14N04E20H001M, 14N04E30F001M, 15N04E11K002M, 15N04E25H003M, 17N03E22R001M, 17N04E27F001M, 17N04E33Q001M 3 SWNs 14N04E20H001M, 14N04E30F001M, 17N03E22R001M, 17N04E27F001M, 17N04E33Q001M 4 Three total wells in well cluster (SWNs 13N04E08H002M, 13N04E08H003M, 13N04E08H004M) 5 Kisters Pty Ltd, Engineering & Environmental Data Management Software

Yuba Water Agency 2-2 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Management Actions

Figure 2. Yuba County Alluvial Basin Groundwater Monitoring Network

Yuba Water Agency 2-3 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Management Actions

2.3 GMP COMPONENT CATEGORY 3: GROUNDWATER RESOURCE PROTECTION Yuba Water is continuing its coordination efforts with various local, state, and federal agencies that monitor groundwater quality and are responsible for projects that clean up groundwater contamination. Detailed groundwater resource protection actions by Yuba Water are summarized in Appendix A. 2.4 GMP COMPONENT CATEGORY 4: GROUNDWATER SUSTAINABILITY To increase conjunctive use opportunities and provide more recharge to the groundwater basin, Yuba Water completed construction of the Yuba Wheatland Canal Project and associated pumping stations to deliver surface water supplies to Wheatland Water District (WWD), which had historically been supplied by groundwater. Monitoring wells in WWD indicate that groundwater-level recovery began in 2011 when WWD began receiving regular surface water deliveries. Yuba Water is responsible for making yearly recommendations to the Member Units regarding the volume and distribution of pumping during GWS transfers, based on basin hydrologic conditions. Hydrologic condition assessments are based on analysis of monitoring data and output of management tools, historically the groundwater adaptive management tool (GAMT) and more recently the Yuba Groundwater Model (YGM). To formalize the adaptive management of the Yuba Groundwater Basin, an empirically based GAMT was developed as a planning tool for the Yuba Water Conjunctive Use Program. The GAMT used a regression analysis of available historical spring and fall groundwater elevation data to quantitatively predict basin response to proposed GWS transfer pumping, and basin recovery post-transfer pumping for each Member Unit. This tool helped the agency proactively manage the groundwater basin and avoid long-term impacts from substitution transfer pumping. In July 2012, Yuba Water submitted an application to DWR for a grant under the Local Groundwater Management Assistance Act of 2000 to develop a groundwater model. The groundwater model, called the Yuba Groundwater Model or YGM, covers the Yuba groundwater subbasins and Wyandotte Creek groundwater subbasin to support groundwater management. In summer 2013, DWR notified Yuba Water that its grant application was successful and would be funded at the highest possible level (90 percent of requested grant funds). Work on Phase 1 of the YGM began in late 2014 and continued through successful completion in late 2016. Phase 2 work on the YGM spanned from late 2016 to mid-2018 and included stakeholder outreach, refinements to input datasets, calibration, sensitivity analysis, and documentation. Continued enhancement to the YGM was performed during 2018 and 2019 to incorporate additional detail on water supplies and to investigate the level of confinement of the groundwater system. The YGM has replaced GAMT as the primary technical tool to support GWS transfer pumping planning and is a key technical tool in overall groundwater management, including supporting GSPs required under SGMA. In November 2017, Yuba Water applied for funding under DWR’s Proposition 1 Sustainable Groundwater Planning Grant, Round 2 – GSP Preparation funding program. The purpose of this grant is to aid in the development of a GSP for the North Yuba and South Yuba Subbasins. An award notification for the full requested amount was received from DWR in early 2018. A draft GSP was completed in fall 2019. Yuba Water is tracking opportunities for grant opportunities to support SGMA compliance. Yuba Water submitted applications for funding through DWR’s Technical Support Services (TSS) program to allow for the installation of additional monitoring wells in the North and South Yuba Subbasins. No funding decision had been made by DWR at the time of writing.

Yuba Water Agency 2-4 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Management Actions

The North and South Yuba Subbasins continue to be operated in a sustainable manner. Evaluation of sustainability indicators defined in SGMA, including groundwater levels, groundwater storage, groundwater quality, land subsidence, and depletions of interconnected surface water, will allow for quantitative analysis of sustainability through technical analysis and stakeholder input. The analysis is expected to indicate that the basin is operating without any significant and unreasonable negative impacts. The South Yuba Subbasin has recovered from historical overdraft conditions, and the North Yuba Subbasin has shown generally stable groundwater levels throughout the historical record. Users in both subbasins have ready access to the groundwater resource due to stable and relatively high groundwater levels. Additional information on the current status of SGMA implementation is included in Section 2.5. 2.5 PLANNED GROUNDWATER MANAGEMENT ACTIVITIES 2019 marks the ninth year since the last update to Yuba Water’s GMP, and Yuba Water had planned to update the GMP every five years. However, SGMA was enacted in 2015 and has changed the regulatory requirements for groundwater planning, including prohibiting development or renewal of GMPs within medium and high priority basins, such as the North and South Yuba Subbasins. SGMA empowers local agencies to form GSAs, and the GSAs are charged with developing a GSP for DWR-designated groundwater basins and subbasins. Yuba Water, along with other Sacramento Valley water agencies, actively participated in the development of the legislation which formed SGMA. In August 2015, Yuba Water’s Board of Directors passed a resolution electing to become the GSA for areas within Yuba Water’s boundaries. No additional GSAs were formed in the South Yuba Subbasin within 90 days of YWA’s notice being posted by DWR. Therefore, Yuba Water is the exclusive GSA for that subbasin. Both Cordua Irrigation District and the City of Marysville filed to become GSAs for their service areas in the North Yuba Subbasin. Yuba Water, Cordua Irrigation District, and the City of Marysville elected to become GSAs prior to the effective date of Senate Bill 13, thus these entities remain GSAs for the North Yuba Subbasin regardless of overlap with other GSAs. The GSC, composed of representatives of agencies throughout Yuba County, was formed to guide the development of the Yuba GSP. Yuba Water submitted a basin boundary modification during 2018 to resolve small differences between basin, county, and district boundaries. The modification was approved in early 2019. Yuba Water followed up with a modification to the GSA boundary to align with the new subbasin boundary. The information presented in this annual report reflects these new boundaries. Yuba Water will continue to implement the management activities identified in the 2010 GMP while a GSP is developed. Planned groundwater management activities for the coming year include the following: • Continue implementation of SGMA. Specifically, Yuba Water plans to continue working with the GSC to develop the GSP, which must be completed by 2022 and is planned for completion in 2020. • Continue to implement the elements of the 2010 GMP to achieve its basin management objectives. • Continue to coordinate with DWR on ongoing monitoring activities in the North and South Yuba Subbasins, including coordination on water quality monitoring. • Continue working with DWR to improve the sharing and exchange of data.

Yuba Water Agency 2-5 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Management Actions

• Continue to maintain an up-to-date inventory of GWS transfer pumping wells. • Continue to make yearly recommendations to Member Units about GWS transfer pumping volumes and distributions. • Continue refinement and use of the Yuba Groundwater Model, a groundwater flow model of the North and South Yuba Subbasins and the Wyandotte Creek Subbasin. • Explore the need for additional groundwater monitoring facilities and associated grant funding opportunities. • Coordinate with Yuba County and water purveyors on well standards to be protective of public health and to support reliable water supplies.

Yuba Water Agency 2-6 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment 3 GROUNDWATER MONITORING AND CONDITIONS ASSESSMENT This section discusses hydrologic conditions, groundwater elevation trends, groundwater quality, and groundwater-surface water interaction in the North and South Yuba Groundwater Subbasins. 3.1 HYDROLOGIC CONDITIONS Hydrologic conditions are presented for the portion of Water Year 2019 covered in this Report. Since May 2019 had significant precipitation, it was included in the analysis below. Water Year 2018 is not discussed since the previous annual report covered through spring 2018 and there was no significant precipitation between spring 2018 and the beginning of Water Year 2019. During the portion of Water Year 2019 (October 2018 to May 2019), the recorded precipitation in Yuba County6 was 28.97 inches, representing 140 percent of the long-term (1948-2019) average precipitation at that location. Yuba River flow7 at Smartville for the same period was 2.61 million acre-feet, representing about 110 percent of the long-term (1901-2019) average flow at that location. 3.2 GROUNDWATER SUBSTITUTION TRANSFER, SCHEDULE 6, AND ADDITIONAL LOCAL PUMPING This section describes pumping in the North and South Yuba Subbasins with respect to GWS transfers in 2008, 2009, 2010, 2013, 2014, and 2018 and pumping for Schedule 6, deficiency, and additional local pumping during 2015. In 2010, analysis and planning for future GWS transfer programs were shifted from what had previously been a Member Unit boundary-based process to a hydrogeologic pumping zone-based process. Pumping zones were assigned to areas of the groundwater basin based on the similarity of hydrogeologic conditions and groundwater response. Figure 3 shows the Member Units, pumping zones, and GWS transfer wells for the North and South Yuba Subbasins. 3.2.1 Groundwater Substitution Transfer Pumping In 2008, 2009, 2010, 2013, 2014, and 2018 Yuba Water Member Units participated in GWS transfers in 2008, 2009, 2010, 2013, 2014, and 2018, pumping a total of over 388,000 acre-feet of groundwater. Table 1 presents GWS pumping volumes by Member Unit and Table 2 presents GWS transfer pumping volumes by pumping zone. As described in the below section, during 2015, extremely dry conditions necessitated Schedule 6 pumping, deficiency pumping, and additional pumping for local water supplies.

6 Precipitation before November 2007 at Marysville was obtained from Western Regional Climate Center available on-line at: http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?ca5385; precipitation data from November 2007 and on was obtained from the National Climatic Data Center for the MARYSVILLE YUBA CO AIRPORT station. 7 Unimpaired Yuba River Flow at Smartville was obtained from the California Data Exchange Center (CDEC) http://cdec.water.ca.gov/misc/monthly_fnf.html.

Yuba Water Agency 3-1 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment Table 1. Groundwater Substitution Transfer Pumping by Member Unit Since 2008

Yearly* Groundwater Substitution Transfer Pumping Volume (acre-feet) Member Unit 2008 2009 2010 2013 2014 2018 North Yuba Groundwater Subbasin Browns Valley Irrigation District 4,236 4,834 3,057 3,577 2,701 1,631 Cordua Irrigation District -- 8,262 -- 8,273 2,320 9,170 Hallwood Irrigation Company 11,321 12,015 8,018 10,382 4,983 4,405 Ramirez Water District 12,081 10,789 4,552 7,421 5,185 2,445 Total North Yuba Subbasin 27,637 35,901 15,628 29,653 15,189 17,651 South Yuba Groundwater Subbasin Brophy Water District 11,825 26,958 23,925 19,642 20,122 4,879 Dry Creek Mutual Water Company 8,424 7,739 5,740 7,131 6,637 1,493 South Yuba Water District 2,103 17,605 13,209 13,531 13,214 2,929 Wheatland Water District -- 11,473 9,660 9,474 7,355 1,489 Total South Yuba Subbasin 22,351 63,775 52,533 49,778 47,328 10,790 Total (North + South) 49,989 99,676 68,161 79,431 62,517 28,441 ** Values are annualized for the full water transfer season, which may extend beyond the end of the indicated water year. Monthly data are provided in Tables 6 and 7.

Table 2. Groundwater Substitution Transfer Pumping by Pumping Zone Since 2008 Yearly* Groundwater Substitution Transfer Pumping Zone Pumping Volume (acre-feet) 2008 2009 2010 2013 2014 2018 North Yuba Groundwater Subbasin 1 16,316 20,662 7,174 16,201 7,815 7,561 3 3,128 6,003 1,882 4,001 1,715 5,031 4 612 1,244 875 1,359 1,379 2,022 5 7,581 7,992 5,696 8,093 4,280 3,037 Total North Yuba Subbasin 27,637 35,901 15,628 29,653 15,189 17,651 South Yuba Groundwater Subbasin 6 519 813 842 176 - 236 8 11,306 26,145 23,083 19,466 20,122 4,643 9 6,555 20,098 15,347 16,650 15,355 3,084 10 0 11,473 9,660 9,474 7,355 1,489 11 3,971 5,246 3,602 4,012 4,496 1,338 Total South Yuba Subbasin 22,351 63,775 52,533 49,778 47,328 10,790 Total (North + South) 49,989 99,676 68,161 79,431 62,517 28,441

** Values are annualized for the full water transfer season, which may extend beyond the end of the indicated water year. Monthly data are provided in Tables 6 and 7.

Yuba Water Agency 3-2 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Figure 3. Yuba County Member Units, Pumping Zone Boundaries, and Groundwater Substitution Transfer Well Locations

Yuba Water Agency 3-3 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment 3.2.2 2015 Groundwater Pumping – Schedule 6, Deficiency, and Additional Local Pumping During 2015, hydrologic conditions were extremely dry and monitoring data indicated that groundwater levels were below normal in some portions of the basin. In addition, due to the recent drought and extended dry hydrologic conditions: 1. Forecasted Yuba River flows and storage at New Bullards Bar Reservoir triggered a Schedule 6 pumping program, as required under Yuba Water’s State Water Resources Control Board water rights permit. During Schedule 6 years, 30,000 acre-feet of stored surface water is released to support environmental flows for fisheries. The Lower Yuba River Accord Member Units are compelled to pump 30,000 acre-feet of groundwater for their supply to offset the additional release of stored water. 2. Forecasted Yuba River flows and storage at New Bullards Bar Reservoir led Yuba Water to notify the Member Units that there would be a shortage in their Yuba Project water supplies during 2015. Due to this deficiency, it was anticipated that the Member Units would need to pump additional groundwater for local water supplies. Pumping during 2015 included Schedule 6 pumping, deficiency pumping, and additional pumping for local water supplies. Deficiency pumping is based on the Supplemental Water Supply provisions in the expired Water Service Agreements for certain Yuba Water Member Units (new Water Supply Agreements effective in 2017 do not contain Supplemental Water Supply provisions but honor the deficiency pumping provisions of the previous agreements). When what would have been Supplemental Water Supply under the previous agreements cannot be provided from the Yuba Project due to shortages in surface water supplies, the Member Units that had Supplemental Water Supply provisions can pump groundwater to meet the deficiency, and Yuba Water compensates them for pumping power costs. Maximum deficiency pumping is based on the Supplemental Water Supply component of each Member Unit’s expired Water Service Agreement. In 2015, Schedule 6 pumping was 30,000 AF, deficiency pumping was approximately 52,100 AF, and additional pumping for local supplies was approximately 2,400 AFY. Additional details on 2015 pumping are contained in previous annual reports. 3.3 ELEVATIONS AND STORAGE This section describes elevation and storage conditions in the North and South Yuba Groundwater Subbasins with respect to pumping for GWS transfers, Schedule 6, deficiency, and additional local water supplies described above, as well as recovery during non-pumping years and the effect of hydrologic conditions. As described below, overall, the North and South Yuba Groundwater Subbasins are in historically healthy conditions that are ideal for supporting future GWS transfers. Groundwater elevations for a representative groundwater level monitoring network are included in Appendix B. Hydrographs8,9 from key wells showing historical trends of groundwater elevations in the North and South Yuba Subbasins are presented in Figures 4 and 5, respectively. Hydrographs from wells along the Feather River (in the North and South Yuba Subbasins) show that groundwater levels have been generally stable in these areas over the period of observations. Figure 4 shows that groundwater elevations in central parts of the North Yuba Subbasin (Ramirez Water District [RWD], Cordua Irrigation District [CID]) have been stable throughout the period of record, with some increases in groundwater levels starting in the 1970s, which coincides with the extension of surface water deliveries

8 Groundwater hydrographs were prepared using data from DWR’s California Statewide Groundwater Elevation Monitoring (CASGEM) website, available online at: http://www.casgem.water.ca.gov/. 9 Except where noted, groundwater elevations in hydrographs were converted to the North American Vertical Datum of 1988 (NAVD88), consistent with CASGEM groundwater data reporting.

Yuba Water Agency 3-4 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment to RWD. Figure 5 shows that groundwater elevations in the central parts of the South Yuba Subbasin (Brophy Water District [BWD], Dry Creek Mutual Water Company [DCMWC], South Yuba Water District [SYWD], and WWD) have largely recovered from historical overdraft. Hydrographs for these areas show increasing groundwater elevation trends starting in the 1980s, which coincides with the extension of surface water deliveries to much of the South Yuba Subbasin. The hydrograph from Pumping Zone 10 shows additional recovery beginning in 2011 when WWD began receiving surface water deliveries. Hydrographs in the central parts of the North and South Yuba subbasins also show the effect of GWS transfers and other pumping programs (during 1991, 1994, 2001, 2002, 2008, 2009, 2010, 2013, 2014, 2015, and 2018) in the form of reduction in groundwater levels followed by recovery to pre- transfer levels. Figures 6 and 7 show groundwater elevation hydrographs for 2008 through spring 2019 at selected monitoring wells in the North and South Yuba Subbasins, respectively. Water levels at wells in the North Yuba Subbasin Member Unit areas (including wells YCWA-06, PMW-02B, YCWA-03, 16NO4E08A001M, 16N04E17R002M, and PMW-16) generally showed declines in the summer of 2018 due to pumping for GWS transfers in addition to typical patterns of groundwater use and recharge. Where declines were seen in the summer, groundwater levels generally recovered to at or near spring 2018 levels by spring 2019. Well YCWA-03, located in the western portion of the North Yuba Subbasin, is in Reclamation District 10, which is supplied entirely by groundwater. The hydrograph for YCWA-03 demonstrates the yearly cycle of drawdown and recovery due to agricultural pumping in this area; summer drawdowns are not noticeably different in years with GWS transfers compared to those without GWS transfers. Spring 2019 groundwater elevations at YCWA-03 are as high as in spring 2017 and are above the average spring level of approximately 60 feet. As shown in Figure 7, groundwater levels at monitoring wells in the South Yuba Subbasin Member Unit areas showed typical summer declines followed by winter recovery, with no notable impact of the relatively small volume of GWS transfer pumping occurring within the South Yuba Subbasin. Groundwater levels typically recovered to Spring 2018 levels in Spring 2019, following 2018 GWS pumping. In the interior portions of the South Yuba Subbasin where recovery and drawdown are relatively slow (e.g., at PMW-21 and PMW-05), water levels have steadily increased since 2016. Wells in the southeastern portion of the basin continue to show increasing groundwater levels associated with the delivery of surface water to WWD.

Yuba Water Agency 3-5 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Figure 4. Key Groundwater Hydrographs in the North Yuba Subbasin

Yuba Water Agency 3-6 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Figure 5. Key Groundwater Hydrographs in the South Yuba Subbasin

Yuba Water Agency 3-7 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Figure 6. 2008-2019 Groundwater Hydrographs in North Yuba Subbasin

Yuba Water Agency 3-8 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Figure 7. 2008-2019 Groundwater Hydrographs in South Yuba Subbasin

Yuba Water Agency 3-9 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment 3.3.1 Comparison of Current and Historical Spring Groundwater Levels Figures 8 and 9 compare spring 2019 groundwater levels with the range of historical spring levels for monitoring wells in each pumping zone in the North Yuba Subbasin and South Yuba Subbasin, respectively. Each graph shows spring 2019 levels in a pumping zone as dark blue circles compared to the range of historical levels at each well, which are represented as black vertical lines. Figures 8 and 9 show that nearly every well’s groundwater level is at the upper end of its recorded historical range. Spring 2019 groundwater levels are historically high for a number of wells, especially those within South Yuba Subbasin. Pumping zone 6 (shown in Figure 8) and pumping zone 7 (shown in Figure 9) are both outside of the Member Unit boundaries. Groundwater levels in these zones have been relatively stable over time, which is likely due to their close proximity to the Yuba and Feather Rivers. 3.3.2 Groundwater Elevation Contour Maps Figures 10 and 11 present contour maps of groundwater elevations for spring 2018 and spring 2019, respectively. Figures 12 and 13 present contour maps of groundwater elevations for fall 2017 and fall 2018, respectively. Groundwater generally flows from the Sierra Nevada foothills on the east side of the basin towards the Feather River on the west. Figure 14 presents a hydraulic head difference map for spring 2018 to spring 2019. The map indicates that groundwater elevations throughout much of the North and South Yuba Subbasins have remained steady from 2018 to 2019, while other areas have seen increases in groundwater elevation during this time period. This slight amount of recovery is likely due to a combination of fairly wet conditions during the portion of Water Year 2019 covered in this report. Even with GWS transfer pumping during 2018, groundwater levels largely recovered or remained the same throughout the basin. Areas with insufficient data were removed from the map. Figure 15 presents a hydraulic head difference map for fall 2017 to fall 2018. The map indicates that groundwater elevations throughout much of the South Yuba Subbasin have generally remained the same or increased from fall 2017 to fall 2018. This increase occurred despite the GWS transfer pumping in 2018 and mimics the behavior seen in historical hydrographs in South Yuba Subbasin. In North Yuba Subbasin, groundwater elevations have either remained the same or decreased slightly. This is likely due to the effects of GWS transfer pumping in 2018, as a relatively greater volume of pumping occurred in the North Yuba Subbasin compared to the South Yuba Subbasin. 3.3.1 Groundwater Levels from Transfer Wells In addition to measuring flow rates, Member Units measured depth-to-groundwater before the start of the GWS transfer pumping program and monthly for approximately five months after pumping stopped at all accessible transfer wells. Figure 16 shows depth-to-groundwater measurements in spring 2018 (April 2018) compared to spring 2019 (April 2019) for all transfer wells in each pumping zone where measurements were available. The charts are formatted so that wells in which the depth to water was the same in spring 2018 as in spring 2019 (i.e., full recovery of the aquifer to pre-transfer levels) fall on the complete recovery line; the dashed line representing 5 feet of drawdown is also presented for comparison. Figure 16 shows that water levels in a majority of the transfer wells have recovered to at least within 5 feet of their pre-transfer levels except for several wells in Pumping Zone 1, where spring 2019 levels in many of the wells are five to ten feet below spring 2018.

Yuba Water Agency 3-10 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Figure 8. Comparison of 2019 and Historical Spring Groundwater Levels for the South Yuba Subbasin

Yuba Water Agency 3-11 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Figure 9. Comparison of 2019 and Historical Spring Groundwater Levels for the North Yuba Subbasin

Yuba Water Agency 3-12 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Figure 10. Spring 2018 Groundwater Elevations in the Yuba Subbasins

Yuba Water Agency 3-13 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Figure 11. Spring 2019 Groundwater Elevations in the Yuba Subbasins

Yuba Water Agency 3-14 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Figure 12. Fall 2017 Groundwater Elevations in the Yuba Subbasins

Yuba Water Agency 3-15 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Figure 13. Fall 2018 Groundwater Elevations in the Yuba Subbasins

Yuba Water Agency 3-16 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Note: Information not shown for areas with insufficient data Figure 14. Spring 2018 to Spring 2019 Hydraulic Head Difference Map

Yuba Water Agency 3-17 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Figure 15. Fall 2017 to Fall 2018 Hydraulic Head Difference Map

Yuba Water Agency 3-18 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Figure 16. Spring 2019 and Spring 2018 Depth-to-Water Measurements in Transfer Pumping Wells by Pumping Zone

Yuba Water Agency 3-19 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment 3.3.2 Groundwater Storage Change in storage is estimated using the YGM, with data prior to the YGM based on information in the Hydrogeologic Understanding Report (HUR) (YWA, 2008), which analyzed groundwater elevations combined with properties of subsurface materials to estimate storage change. Figure 17 and Figure 18 show the change in storage for the North Yuba Subbasin and South Yuba Subbasin, respectively. Both figures include annual total storage volumes and cumulative change in storage since water year 1961. In water year 2018, the North Yuba Subbasin saw a decline of groundwater in storage of 21,800 AF and the South Yuba Subbasin saw a decline in groundwater in storage of 4,100 AF.

Figure 17: Estimated Groundwater Storage and Change in Storage, North Yuba Subbasin

Yuba Water Agency 3-20 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Figure 18: Estimated Groundwater Storage and Change in Storage, South Yuba Subbasin

3.4 GROUNDWATER QUALITY DWR’s NCRO historically regularly collected water quality samples from nine wells (four in the North and five in the South Yuba subbasins). Sampling was staggered so that four to five wells are sampled each year; for instance, in 2017, samples were collected from five wells – three wells in the North Yuba Subbasin and two wells in the South Yuba Subbasin. In 2018 and 2019, DWR did not collect water quality data from any of the wells as it is currently re-assessing the water quality monitoring program. Water quality indicators reported are arsenic, nitrate, sodium, and total dissolved solids (TDS). Arsenic, nitrate, and TDS are important drinking water quality indicators, and sodium and TDS are important agricultural water quality indicators. Table 3 summarizes the latest available water quality data at the five wells last sampled in 2017 and compares each indicator with its respective historical range of measurements. As shown in Table 3, the majority of the 2017 water quality samples fell within historical ranges. However, one sodium measurement in the North Subbasin was an outlier from its historical range; additionally, one nitrate measurement in the South Subbasin was slightly higher than historical measurements. The primary Maximum Contaminant Level (MCL) for dissolved nitrate was slightly exceeded in one well in the North Subbasin, but nitrate levels at all sampled wells were within historical ranges. Arsenic levels in both subbasins generally did not exceed the primary MCL, though one well in the North Subbasin was slightly higher. The recommended Secondary MCL (SMCL) for total dissolved solids (500 milligrams per liter) was exceeded at two out of five sampled wells (both in the North Subbasin), though all samples were within historical ranges as well as under the upper range SMCL limit for total dissolved solids of 1,000 milligrams per liter.

Yuba Water Agency 3-21 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment Figure 19 shows the trend of electric conductivity (EC) in representative wells in the North and South Yuba subbasins. EC is highly dependent on the concentration of dissolved constituents in water and is a good indicator of total dissolved solids. Figure 19 shows that over the last 46 years, EC values have been generally stable in the North Yuba Subbasin and in the northern portion of the South Yuba Subbasin. In the interior of the South Yuba Subbasin, where wells are furthest from large recharge sources (e.g., the Yuba and Bear rivers), EC has generally increased. At well 14N04E-, EC was generally around 200 micro Siemens per centimeter (µS/cm) through the mid-1980s but has increased to a maximum of 659 µS/cm in 2017. However, in well 14N05E-, located in WWD, the four most recent samples have exhibited a trend of decreasing EC since 2006, declining from 2183 µS/cm in 2008 to 1908 µS/cm in 2016. The cause of the dramatic increase and decline in EC at 14N05E- is not well understood but is not consistent with other data points in the Yuba Subbasins. 3.4.1 Electrical Conductivity Measurements from Transfer Wells Member Units participating in groundwater substitution transfers collected EC measurements from selected GWS transfer wells at the start of the pumping season, mid-way through the pumping season, and at the end of pumping. Figure 20 shows the first and last EC measurements collected from pumping wells during the 2018 GWS transfer by pumping zone. Wells that plot along the 1:1 line represent locations where EC did not change during the 2018 GWS transfer. Wells plotting above the line represent locations where EC decreased during the transfer, while wells plotting below the line represent an increase in EC. For the 2018 GWS transfer program, many pumping zones (Zones 5, 6, 8, 9, 10, and 11) did not have any wells with EC data collected at both the starting and ending points of the pumping season. This is in part due to the short duration of the transfer pumping in many areas. For those wells with data, the majority of the wells either did not have a significant change or decreased in EC during the 2018 GWS transfer. Select wells had an increase in EC during the pumping season, with increases ranging from 100 to 1350 microSiemens per centimeter (μS/cm). The increase of 1350 μS/cm appears to be an outlier based on the other results and may be the result of a measurement error or transcription error (see Figure 20).

Yuba Water Agency 3-22 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment Table 3. Summary of Water Quality Indicators for Yuba Subbasins

Water Quality Range (Minimum – Maximum) Water (mg/L) Yuba Quality Constituent 1965 to 2016 2017 Subbasin Limit Survey of Water Survey of Water (mg/L) Quality Monitoring Quality Monitoring Wells Wells(1)

North ND – 0.013* ND – 0.012* Arsenic(2) 0.010 (3) South ND – 0.002 ND – 0.002

North ND – 56.3* 6 – 46* Nitrate 45 (3) South ND – 77.6* 8.2 – 31.2

North 5 – 23 6 – 178 Sodium - 5 – 36 South 13 – 26 {11 – 115} North 90 – 551** 141 – 537** Total Dissolved 500- (4) 97 – 445 Solids South 1,500 224 – 420 {128 – 1654*} Notes: 1 No water quality samples from deep wells were reported in 2017 data. DWR is reevaluating its monitoring program and took no water quality samples in 2018 or 2019. 2 Arsenic data only collected since 2011 3 Primary Drinking Water Maximum Contaminant Level (MCL) 4 Recommended Secondary Drinking Water MCL is 500 mg/L, the Upper Secondary Drinking Water MCL is 1000 mg/L, and the Short Term Secondary Drinking Water MCL for TDS is 1500 mg/L. Key: * = Water quality that exceeds the MCL * = Water quality that exceeds the SMCL {} = Water quality samples from deep wells (depth greater than 200 feet) mg/L = milligrams per liter ND = No detect (concentration of constituent in the sample is below detection limit)

Yuba Water Agency 3-23 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Figure 19. Electric Conductivity Trends in Key Wells in Yuba Subbasins

Yuba Water Agency 3-24 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Note: Only pumping zones with starting and ending EC measurements shown Figure 20. Initial and Final EC Measurements in 2018 Transfer Pumping Wells

Yuba Water Agency 3-25 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment 3.5 GROUNDWATER SURFACE WATER INTERACTION The 2010 GMP includes a BMO to protect against adverse impacts to surface water flows. SGMA also considers the impact of groundwater management actions on groundwater-surface water interactions. Yuba Water tracks information on surface water stage and groundwater levels at nested wells installed by DWR adjacent to gages on the Bear River, Feather River, Yuba River, and Honcut Creek. Figure 20 displays a hydrograph of stage on the Yuba River near Marysville10 and hydrographs of groundwater head from a cluster of five vertically distributed groundwater monitoring wells near the Yuba River. Groundwater elevations in the two shallowest wells (YR-2 and YR-1A) are typically within 2 feet of the reported stage on the Yuba River. The deeper wells, YR-1B, YR-1C, and YR-1D, show the strongest response to pumping during the summer months, with groundwater elevations approximately 10 to 30 feet lower than river stage. The difference in seasonal groundwater elevation between the two shallowest wells and the three deepest wells suggest the presence of an aquitard at depths between YR- 1A (screened 70-80 ft bgs) and YR-1B (screened 25-260 ft bgs). The three deeper wells show similar groundwater elevations, except in the summers of 2011 and 2012, where the deepest well, YR-1D, showed less of a decline in groundwater elevation compared to the intermediate wells, YR-1B and YR-1C. Except during portions of the winter, water elevations were higher throughout 2018-2019 in the shallowest wells compared to the intermediate and deepest wells, i.e., the direction of the vertical hydraulic gradient was downward. A downward hydraulic gradient indicates the potential for downward vertical flow of water; however, the magnitude of this flow cannot be determined solely through groundwater elevations as it is also dependent on hydraulic properties of the aquifer material. An exception to this downward gradient exists at the deepest two wells, where an upward vertical gradient exists between YR-1D and YR-1C, most notably in the winter. It should be noted that there are no GWS transfer pumping wells within approximately 8,000 feet of the Yuba River in this area. Figure 20 also displays a hydrograph of stage at the Bear River gage at Pleasant Grove Road10 and hydrographs of groundwater head from a multi-level piezometer screened in four discrete depth intervals near the Bear River. River stage and groundwater elevation in the shallowest monitoring well (BR-1A) are similar for the period shown, but groundwater elevations were lower than river stage in the deeper monitoring wells (BR-1B, BR-1C, and BR-1D), particularly during the summer months when nearby pumping wells were operating. The deeper wells exhibit drawdowns during pumping periods because the deeper portions of the aquifer are more strongly confined and because agricultural pumping occurs in the deeper parts of the aquifer. The difference in seasonal groundwater elevation between the two shallowest wells and the two deepest wells suggest the presence of an aquitard at depths between BR- 1A (screened 28-48 ft bgs) and BR-1C (screened 215-244 ft bgs), with BR-1B (screened 78-97 ft bgs) showing characteristics of both the shallower and deeper wells. Water elevations were higher throughout the year from the shallowest to deepest wells, showing a downward vertical gradient. Figure 21 displays a hydrograph of stage on the Feather River at Boyd’s Landing10 and hydrographs of groundwater piezometric head from a multi-level piezometer screened in four discrete depth intervals near the Feather River. The groundwater elevations for all four wells are typically below the river stage. The deepest two wells (Feather River MW-1C and Feather River MW-1D) show a seasonal cycle. Groundwater elevations dip down during summer and recover during winter. In the middle well (Feather River MW-1B), groundwater elevations drawdown from pumping is evident during the summer months. Potential impacts on river stage are not apparent. In the shallowest well (Feather River MW-1A), groundwater elevations typically follow the same seasonal cycle as in the deeper wells. The intermediate

10 River stage was obtained from California Data Exchange Center (CDEC) available online at: http://cdec.water.ca.gov/queryTools.html.

Yuba Water Agency 3-26 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment well (Feather River MW-1C) is extremely responsive to pumping. Therefore, water elevations are often higher in the deepest wells than in this intermediate well, i.e., the direction of the vertical hydraulic gradient is upwards between these depths. The degree of response to pumping within groundwater levels at MW-1C compared to those at other wells suggests the presence of aquitards that isolates, to some degree, the impacts of pumping in this depth range. No consistent gradient is evident when comparing the intermediate or deepest wells with the shallowest well. This gradient changes seasonally, usually downwards during summer and upwards during winter. Figure 21 also displays a hydrograph of stages of groundwater head from a shallow well with an adjacent multi-level piezometer screened in three discrete depth intervals near North Honcut Creek. Note that stage data for North Honcut Creek has only been monitored since November 2016. Similar to the other locations discussed above, the deeper wells exhibit significant drawdowns during pumping periods. The difference in seasonal groundwater elevation between the shallowest well and the two deepest wells suggest the presence of an aquitard at depths between HC-2A (screened 48-68 ft bgs) and HC-2B (screened 172-202 ft bgs). Based on limited data, groundwater elevations do not appear to have a significant impact on river stage. Note that summer stage conditions on Honcut Creek are significantly driven by upstream agricultural operations. Water elevations were higher throughout the year from the shallowest well to the three deepest wells, showing a downward vertical gradient across the suggested aquitard.

Yuba Water Agency 3-27 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Figure 20. 2008-2018 Hydrographs for Yuba River and Bear River Areas

Yuba Water Agency 3-28 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Figure 21. 2008-2018 Hydrographs for Feather River and Honcut Creek Areas

3.6 TOTAL WATER USE 3.6.1 Groundwater Use Groundwater extraction data are available only from a limited number of metered wells within the North and South Yuba Subbasins, with the remainder of extraction information estimated. Metered data are available from municipal water purveyors (California Water Service Company, Olivehurst

Yuba Water Agency 3-29 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment Public Utilities District, and Linda County Water District) and from groundwater substitution transfer wells. Agricultural, rural domestic, and most other groundwater production in the basin is not metered. Metered data were obtained from the individual purveyors or the State Water Resources Control Board’s Water Conservation Portal and other extractions were estimated using the YGM, which bases water use on crop type, hydrologic data (precipitation and evapotranspiration), irrigation efficiency, and population information.

Groundwater use during water year 2018 (October 2017-September 2018) is estimated as 59,620 AF for the North Yuba Subbasin (Table 4) and 88,480 AF for the South Yuba Subbasin (Table 5). These values include groundwater substitution transfers of 16,590 for the North Yuba Subbasin and 10,790 AFY for the South Yuba Subbasin. Note that the transfer volumes do not include 1,060 AF of transfers that occurred after the end of the water year in October 2018 within the North Yuba Subbasin.

3.6.1 Surface Water Use Surface water use by user is estimated using the YGM and is the amount of surface water delivered to meet agricultural demand. This includes the surface water consumptively used by the crop and the surface water that percolates to the groundwater system as part of the irrigation process. These surface water values differ from diverted amounts in that they do not include conveyance losses and return flows. Surface water use during water year 2018 (October 2017-September 2018) is estimated as 121,530 AF for the North Yuba Subbasin (Table 6) and 110,410 AF for the South Yuba Subbasin (Table 7). The majority of surface water is used between April and September.

3.6.2 Total Water Use Total water use is the sum of the groundwater use and surface water use. Total water use during water year 2018 (October 2017-September 2018) is estimated as 181,000 AF for the North Yuba Subbasin and 199,000 AF for the South Yuba Subbasin. In both the North and South Yuba Subbasins, surface water is the majority of total water use.

Yuba Water Agency 3-30 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Table 4. North Yuba Subbasin Estimated Groundwater Extraction for Water Year 2018 User Groundwater Extraction (AF) 2017 2018 Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sept Oct* Total* Urban: Cal Water – Marysville** 170 110 110 100 100 100 110 160 200 240 230 200 * 1,830 Agriculture *** 3,880 20 20 0 1,190 0 2,620 6,640 8,660 7,680 6,350 3,740 * 40,800 Agriculture – Groundwater Substitution Transfers **** 0 0 0 0 0 0 0 0 3,060 7,940 4,640 950 1,060* 16,590 Rural Residential *** 30 20 20 20 20 20 30 40 50 60 50 40 * 400 Total 4,080 150 150 120 1,310 120 2,760 6,840 11,970 15,920 11,270 4,930 * 59,620 * October 2018 is in water year 2019 but is included in this table for completeness for the groundwater substitution transfer program, which ran from May 2018 – October 2018 in the North Yuba Subbasin. Values presented for October 2018 are not included in the totals. ** Data retrieved from State Water Resources Control Board Water Conservation Portal. *** Data estimated using the YGM **** Data based on metered data reported by the Member Units

Yuba Water Agency 3-31 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment Table 5. South Yuba Subbasin Estimated Groundwater Extraction for Water Year 2018 User Groundwater Extraction (AF) 2017 2018 Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sept Total Urban Users Beale AFB ** 70 50 40 40 40 50 50 80 100 110 110 90 830 Olivehurst PUD* 340 180 160 150 150 160 200 360 470 530 470 400 3,570 Linda County Water District* 320 200 200 170 170 180 210 340 410 470 430 380 3,480 Wheatland *** 70 40 30 30 30 30 40 90 120 120 110 100 640 Subtotal, Urban 800 470 430 390 390 420 500 870 1,100 1,230 1,120 970 8,690 Agricultural Users Agriculture ** 9,660 60 130 0 4,890 0 3,330 9,320 16,210 10,010 9,190 4,490 67,290 Agriculture – Groundwater Substitution Transfers, Member Units *** 0 0 0 0 0 0 0 540 820 5,980 3,130 310 10,790 Subtotal, Agricultural 9,660 60 130 0 4,890 0 3,330 9,860 17,030 15,990 12,320 4,800 78,080 Rural Residential ** 140 100 90 90 80 100 110 160 200 240 220 180 1,710 Total 10,600 630 650 480 5,360 520 3,940 10,890 18,330 17,460 13,660 5,950 88,480 * Data retrieved from State Water Resources Control Board Water Conservation Portal. ** Data estimated using the YGM *** Data based on metered data reported by City of Wheatland and the Member Units

Yuba Water Agency 3-32 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment Table 6. North Yuba Subbasin Estimated Surface Water Use for Water Year 2018 User Surface Water Use (AF) 2017 2018 Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sept Total Browns Valley ID* 2,420 560 1,110 0 120 140 740 3,520 3,500 4,450 4,220 980 21,760 Cordua ID 6,410 1,740 2,470 0 50 40 1,230 8,990 10,260 6,570 4,750 1,040 43,550 Hallwood IC 4,650 1,150 1,440 0 320 350 680 6,690 7,290 5,100 5,710 990 34,370 Ramirez WD 3,370 1,030 1,630 0 10 10 860 4,170 2,860 4,200 3,060 650 21,850 Total 16,850 4,480 6,650 0 500 540 3,510 23,370 23,910 20,320 17,740 3,660 121,530 * Note: Browns Valley ID includes only the portion of the district within the North Yuba Subbasin

Table 7. South Yuba Subbasin Estimated Surface Water Use for Water Year 2018 User Surface Water Use (AF) 2017 2018 Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sept Total Brophy WD 3,310 1,610 1,840 0 370 450 900 10,680 9,110 9,180 7,940 1,300 46,690 Dry Creek MWC 830 120 220 0 320 520 650 2,290 1,730 2,360 1,810 940 11,790 Plumas MWC 300 30 60 110 20 240 460 1,170 1,570 1,590 1,110 990 7,650 South Yuba WD 3,960 540 920 0 340 470 880 6,770 4,750 5,530 4,280 1,330 29,770 Wheatland WD 1,570 320 460 0 170 300 390 2,670 2,500 2,910 2,320 900 14,510 Total 9,970 2,620 3,500 110 1,220 1,980 3,280 23,580 19,660 21,570 17,460 5,460 110,410

Yuba Water Agency 3-33 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

3.7 COMPLIANCE WITH MONITORING REQUIREMENTS The 2008, 2009, 2010, 2013, 2014, and 2018 GWS transfers and the 2015 Schedule 6 pumping program were conducted in compliance with the monitoring requirements set forth in the long-term Water Purchase Agreement. There were no GWS transfers in 2016 or 2017. Specific monitoring requirements are discussed below: • Monitoring of Water Levels from Transfer Wells – Depth to groundwater was measured in each accessible transfer well before the start of pumping. Depth-to-groundwater was also measured monthly upon completion of pumping for a period of time sufficient to document recovery or stabilization of water levels in the aquifer. Additionally, although not required, Member Units continued to collect depth-to-water measurements during the non-GWS transfer/non-Schedule 6 pumping years of 2011, 2012, 2016, and 2017. During the 2018 pumping year, Member Units in the North Yuba Subbasin consistently collected depth-to-water measurements at a total of 74 wells from spring 2018 to spring 2019. In the South Yuba Subbasin, Member Units collected depth-to-water measurements at a total of 56 wells. • Water Levels from Monitoring Wells – As described in Section 2, Yuba Water and DWR have monitoring wells throughout the North and South Yuba Subbasins that are monitored at least monthly. Many of the wells were equipped with water-level data loggers, which provided continuous (15-minute to 2-hour recording intervals) measurements of groundwater levels. • Electrical Conductivity Readings – The Member Units measured EC in water samples collected from suitable transfer wells according to the following schedule: as soon as practicable after pumping was initiated, two months after the initial EC measurements, and at the termination of pumping. • Drawdown Analysis – The monitoring requirements state that a drawdown analysis will be conducted at selected groundwater monitoring wells in close proximity to the transfer pumping wells. DWR has offered to assist Yuba Water in identifying wells suitable for the analysis. 3.8 COMPARISON TO FALL 1991 GROUNDWATER LEVELS The South Yuba Subbasin is generally managed to fall 1991 groundwater levels as set forth in language from the Yuba Accord Water Purchase Agreements and the Conjunctive Use Agreements between the Member Units of the Lower Yuba River Accord and Yuba Water. Fall 1991 levels, shown as green horizontal lines in Figure 22, represent the groundwater levels from a subset of wells with recent groundwater level measurements. As shown in Figure 22, fall 2018 groundwater levels in the South Yuba Subbasin Zones were above fall 1991 levels at these wells with data available. The fall 2018 groundwater levels in the South Yuba Subbasin were generally in the upper range of long-term fall conditions.

Yuba Water Agency 3-34 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Figure 22. Fall 2018 Conditions Compared to Fall 1991 Conditions and Long-Term Fall Conditions in the South Yuba Subbasin

Yuba Water Agency 3-35 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment 3.9 THIRD-PARTY GROUNDWATER IMPACTS Yuba Water and the Member Units received no reports of groundwater wells in the Reclamation District (RD) 10 area that had trouble meeting pumping demand during summer 2018 or 2019 due to low groundwater levels. Yuba Water and the Member Units have agreed to enhance monitoring in the RD 10 area, which for 2018 included monthly monitoring of dedicated groundwater monitoring wells. The Member Units also installed pressure transducers and data loggers in four of the RD 10 production wells in early 2013 to record hourly groundwater levels. Yuba Water and the Member Units will collaborate to resolve any future impacts due to GWS transfer pumping. While no reports were received in the RD 10 area, there were nine reported issues of trouble meeting pumping demand due to low groundwater levels, all in the southern portions of the North Yuba Subbasin. These wells were generally located in an area approximately bounded by Highway 20, Loma Rica Rd, Kibbe Rd, and Spring Valley Rd. One well was located off Hallwood Blvd near the Yuba River. While the cause of the issues at these locations could not be determined, the issues were resolved by the Member Units.

Yuba Water Agency 3-36 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Appendix A – GMP Implementation Progress

APPENDIX A – GMP IMPLEMENTATION PROGRESS

Yuba Water Agency December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Appendix A – GMP Implementation Progress

This page left blank intentionally.

Yuba Water Agency December 2019

201 GroundwaterManagement Plan

Yuba Yuba WaterAgency

8 -

Table A. Summary of Implementation Progress of GMP Action Items (Updated for 2018 – 2019) 201 9 9 Component Category 1: Stakeholder Involvement Plan Status Comments Annual Measurementand MonitoringReport Involving the Public The 2018-2019 Annual Monitoring and Measurement Report has been prepared and will 1. Publish an Annual Groundwater Monitoring Report summarizing groundwater conditions be posted on Yuba Water’s website. The in the Yuba groundwater basin relative to historical trends, and describing ongoing Recurring associated fact sheet summarizing the findings of groundwater management activities. Also, annually publish a groundwater fact sheet Annually the 2018-2019 Annual Monitoring and summarizing the findings of the Annual Groundwater Management Report. Measurement Report has also been prepared and will be posted online. 2. Hold annual public/stakeholder meetings to provide updates on groundwater Recurring

management activities and groundwater conditions in the basin. Annually Yuba Water currently posts notices of public One Time with meetings related to groundwater activities on the 3. Develop an enhanced internet presence for Yuba Water groundwater activities. Periodic Yuba Water website. Yuba Water also provides Updates groundwater monitoring data to DWR to post on

the CASGEM website

4. Develop a conjunctive use brochure for the general public highlighting the benefits of Complete

A conjunctive use. -

1 Involving other Agencies within and Adjacent to Yuba Water Agency Area

5. Yuba Water will Invite each of the agencies listed in Table 3-2 of the 2010 GMP to an Recurring annual groundwater briefing to present and discuss the Annual Groundwater Monitoring Annually Report. 6. Yuba Water will encourage sharing of groundwater level, quality, and pumping data Ongoing among these agencies. 7. Yuba Water will attend meetings for groundwater management planning activities in Butte, Sutter, and Placer counties and share relevant information with Yuba County Ongoing interests. AppendixA Formation of Advisory Committee for GMP Development 8. Yuba Water will meet with the Water Advisory Committee (WAC) annually to present Recurring

and discuss findings from the Annual Groundwater Monitoring Report. Annually

–

Develop Relationships with State and Federal Agencies GMP ImplementationProgress 9. Continue to develop working relationships with local, state, and federal regulatory Ongoing agencies.

December2019

201 GroundwaterManagement Plan

Yuba Yuba WaterAgency Table A. Summary of Implementation Progress of GMP Action Items (Updated for 2018 – 2019) (contd.)

8 -

Component Category 2: Monitoring Program Status Comments 201 9 9

Pursuing Partnership Opportunities Annual Measurementand MonitoringReport In 2016, Yuba Water successfully completed a Local Groundwater Assistance grant, utilized to develop a groundwater model of the North Yuba, South Yuba, and

Wyandotte groundwater subbasins.

To support the development of a GSP, Yuba Water applied for funding in late 2017 under DWR’s Proposition 1 Sustainable Groundwater Planning Grant, Round 2 – GSP Preparation funding program. An award notification for the full requested

amount was received from DWR in early 2018. 10. Yuba Water will continue to track and pursue grant

opportunities to fund groundwater management activities Ongoing Yuba Water is tracking opportunities for grant opportunities to support SGMA and local water infrastructure projects compliance. Yuba Water has applied for Technical Support Services (TSS) funding from DWR to aid in the installation of additional monitoring wells in the North and South Yuba Subbasins. It is anticipated that a decision will be made in the fall of 2019.

Additionally, Yuba Water is also tracking the 2019 Proposition 68 SGM Grant

Program, which is expected to be released in fall of 2019 and is expected to provide

A opportunities for additional funding for GSP development. -

2 Groundwater Storage and Elevation

To enhance monitoring in the RD 10 area, Yuba Water coordinated with the Member Units and RD 10 to identify production wells that could be used for water-level 11. Coordinate with Member Units, DWR, and other basin measurements. Measurements have been recorded from selected wells since 2010. groundwater extractors (e.g., Beale AFB, municipalities, Ongoing etc.) to identify an appropriate group of wells for monitoring Yuba Water regularly coordinates with Beale AFB to share groundwater level data. to better understand groundwater level fluctuations. Additionally, Yuba Water shared pumping data with Beale AFB in 2014 for selected wells in close proximity to the base.

Yuba Water has identified its monitoring network needs and is working to AppendixA incrementally expand the network. Yuba Water installed six additional monitoring wells in 2011-2012. Additionally, in 2010 Yuba Water took over monthly monitoring responsibilities for 15 groundwater monitoring wells that had previously been under

12. Coordinate with Member Units, DWR, and other basin the responsibility of DWR. In 2017 and 2018, Yuba Water took over monthly

–

groundwater extractors to ensure that the selected wells are Ongoing monitoring activities for 9 additional wells. GMP ImplementationProgress maintained as part of a long-term monitoring network. In 2019, Yuba Water began an investigation into the potential to assume water quality monitoring activities from DWR, as DWR assesses their water quality monitoring efforts. This investigation included coordination with DWR on their assessment process.

December2019 13. Coordinate with Member Units, DWR, and other basin groundwater extractors to ensure that needed water-level Measurement and monitoring protocols have been developed as part of the data are collected, verify that uniform data collection Ongoing Conjunctive Use Pilot Project funded by Proposition 13. protocols are used among agencies and confirm that data

sharing and archiving procedures are implemented.

201 GroundwaterManagement Plan

Yuba Yuba WaterAgency Table A. Summary of Implementation Progress of GMP Action Items (Updated for 2018 – 2019) (contd.)

8 -

Component Category 2: Monitoring Program Status Comments 201 9 9

14. Provide training for the Member Units and other basin groundwater extractors on Annual Measurementand MonitoringReport Ongoing implementation of data collection protocols, as required or if requested. Yuba Water installed six additional monitoring wells

in 2011-2012. Additional production wells in RD 10 were identified for groundwater level monitoring. 15. Consider ways to fill gaps in the monitoring well network by identifying additional Ongoing existing suitable wells or identifying opportunities for constructing new monitoring wells. Additionally, Yuba Water has applied for Technical Support Services funding to install additional monitoring wells in both the North Yuba and South Yuba Subbasins. 16. Seek outside funding and identify potential candidate wells for well characterization In 2019, Yuba Water applied for funding under survey(s) to determine extraction intervals and total well depth for improved One Time DWR’s Technical Support Services for this item. understanding of vertical gradients. 17. Seek outside funding for the installation of a multilevel piezometer near the Yuba In 2019, Yuba Water applied for funding under One Time Goldfields area to improve understanding of recharge in that portion of the basin. DWR’s Technical Support Services for this item.

Groundwater levels from Beale Air Force Base are Recurring 18. Semiannually obtain groundwater elevation measurements from Beale AFB. requested yearly and are used in the creation of the Semiannually

A potentiometric surfaces when they are provided.

- 3

19. Identify opportunities and potential outside funding sources for monitoring In 2019, Yuba Water applied for funding under Ongoing groundwater levels near current or proposed future municipal pumping locations. DWR’s Technical Support Services for this item. Yuba Water has been established as the CASGEM 20. Track the requirements for the upcoming CASGEM Program and provide the monitoring entity for Yuba County. Yuba Water Complete required information to DWR. provides monitoring data to DWR at least semiannually. Groundwater Quality DWR expanded the set of wells monitored for water quality with 15 new wells surveyed in 2006. 2017 AppendixA 21. Coordinate with Member Units, DWR, and other basin groundwater extractors (e.g., sampling results are shared in this report. With Beale AFB, municipalities) to identify an appropriate group of wells for monitoring both Ongoing DWR’s temporary cessation of water quality

during transfer and non-transfer years. monitoring in 2018/2019, Yuba Water has begun

exploring assuming water quality monitoring of the –

same wells or a different set of wells. GMP ImplementationProgress 22. Coordinate with Member Units, DWR, and other basin groundwater extractors to Measurement and monitoring protocols for Yuba ensure that needed water quality data are collected, verify that uniform data collection Ongoing Water monitoring program have been documented protocols are used among the agencies and confirm that data sharing and archiving in the Annual Measurement and Monitoring Report. procedures are implemented.

December2019 Yuba Water is investigating water quality monitoring 23. Coordinate with Member Units, DWR, other basin groundwater extractors, and other activities, associated with DWR’s potential local, state, and federal agencies to identify where wells may exist in areas with sparse cessation of their water quality monitoring. The groundwater quality data. Identify opportunities for collecting and analyzing water quality Ongoing investigation includes whether Yuba Water should samples from those wells. If wells are sampled through other programs, coordinate with assume water quality activities along with details of the appropriate agency for sharing data.

the locations and frequency of sampling.

201 GroundwaterManagement Plan

Yuba Yuba WaterAgency Table A. Summary of Implementation Progress of GMP Action Items (Updated for 2018 – 2019) (contd.)

8 -

Component Category 2: Monitoring Program Status Comments 201 9 9

Inelastic Subsidence Annual Measurementand MonitoringReport DWR completed the level survey in 2017. 24. Perform repeat level surveys on subsidence monitoring benchmarks at least every 5 years or Every 5 Future surveys are recommended on a 3-5- on an agreed schedule with DWR. Years

year interval. One Time 25. Identify locations especially vulnerable to damage from subsidence (e.g., levees, canals, with Periodic pipelines) and ensure that monitoring network is adequate in those areas. Updates

Groundwater and Surface Water Interaction

Yuba Water is coordinating with DWR on this issue. The groundwater model will be useful 26. Evaluate the need for other future groundwater surface water interaction studies. Ongoing as one line of evidence in the evaluation of these interactions. Yuba Water has submitted for assistance 27. Evaluate the need and cost effectiveness of installing additional monitoring stations adjacent Ongoing under DWR’s Technical Support Services for to surface water bodies. this item. 28. Coordinate with DWR on the development of uniform data collection protocols and data Yuba Water shares data with DWR via the Complete sharing and archiving procedures. CASGEM web interface.

A Yuba Water pursued a different project for -

4 2012 AB303 Local Groundwater Assistance 29. Seek outside funding to characterize production wells near the Bear River to improve Grant funding (which was awarded to Yuba One Time understanding of the groundwater-surface water interaction. Water) but will continue to track other funding opportunities.

Yuba Water pursued a different project for 2012 AB303 Local Groundwater Assistance 30. Seek outside funding to perform aquifer testing at selected Bear River wells to improve Grant funding (which was awarded to Yuba One Time understanding of aquifer parameters in this area. Water) but will continue to track other funding opportunities. AppendixA

Yuba Water pursued a different project for 2012 AB303 Local Groundwater Assistance

31. Seek outside funding to perform aquifer testing near the Yuba Goldfields while monitoring

Grant funding (which was awarded to Yuba –

response in new multilevel piezometer. Correlate groundwater elevations with pond elevations in One Time Water) but will continue to track other funding GMP ImplementationProgress Yuba Goldfields. opportunities.

32. Exchange groundwater information with companies operating in the Yuba Goldfields to better Ongoing

understand recharge characteristics in this portion of the basin. December2019

201 GroundwaterManagement Plan

Yuba Yuba WaterAgency Table A. Summary of Implementation Progress of GMP Action Items (Updated for 2018 – 2019) (contd.)

8 -

Component Category 3: Groundwater Resource Protection Status Comments 201 9 9

Data Management System Annual Measurementand MonitoringReport Inventory of available data was included and 33. Continue to coordinate with Member Units and other water purveyors to determine Ongoing compiled as part of the Hydrogeologic types of data and data formats available.

Understanding report. Yuba Water acquired and installed a data 34. Develop data management methods on an as-needed basis for data determined Ongoing management system based on Hydstra. The critical to the management of water resources in Yuba County. system is updated as needed. Yuba Water has been established as DWR’s 35. Improve the exchange and sharing of data with DWR. Ongoing CASGEM monitoring entity for the Yuba groundwater subbasins. Yuba Water began posting data to CASGEM 36. Develop data reporting format consistent with CASGEM requirements Complete in early 2012. Well Construction, Abandonment and Destruction Policies 37. Schedule a meeting with the County Division of Environmental Services, Member Units, and interested M&I water purveyors to facilitate the exchange of information on Recurring Annually existing County well ordinances, and discuss possible new ordinances, such as a

minimum depth for new wells.

38. Assist Yuba County with development of well-permitting requirements One Time

A -

5 Wellhead Protection Measures

39. Request that municipalities provide vulnerability summaries from the DWSAP to One Time Yuba Water to be used for guiding management decisions in the basin. Protection of Recharge Areas A draft GAMA Special Studies Report, titled Geostatistical analysis of groundwater age and other noble gas derived parameters in 40. Track the results of ongoing GAMA Special Studies Projects related to groundwater California, describing an analysis of recharge characterization, and determine if these findings warrant further investigation of Ongoing groundwater age and other noble gas derived AppendixA Yuba County’s recharge areas. parameters in California groundwater was released in late 2014. The report is not known

to be finalized and no further action

recommended at this time. –

Recharge will be evaluated during further use GMP ImplementationProgress of the groundwater model, including for the development of groundwater budgets as part 41. Seek grant funding to quantify the components of recharge to the North and South of GSP development. Components of recharge Yuba Subbasins. Compare analytical results to soil and surface geology maps to One Time are presented in the documentation of the

develop a map of areas that are contributing significant recharge to the basin Yuba Groundwater Model. Recharge will also December2019 be evaluated during the development of groundwater budgets as part of GSP

development.

201 GroundwaterManagement Plan

Yuba Yuba WaterAgency Table A. Summary of Implementation Progress of GMP Action Items (Updated for 2018 – 2019) (contd.)

8

- 201

Component Category 3: Groundwater Resource Protection Status Comments 9 9

42. Work with Yuba County to publicize the need to protect prominent groundwater Yuba County General Plan contains maps of areas Annual Measurementand MonitoringReport Ongoing recharge areas, especially in the developing portions of the South Yuba Subbasin. with high anticipated recharge rates.

Control of Migration and Remediation of Contaminated Groundwater

43. Coordinate with Member Units, DWR, other basin groundwater extractors, and other local, state, and federal agencies to pursue actions that result in containment Ongoing and remediation of water quality problems within the subbasins. 44. Request data annually from Beale AFB, RWQCB, and Yuba County DPH Recurring Annually regarding groundwater contaminant plumes in Yuba County. Fuel Storage Tanks 45. Provide Yuba Water members units with all information obtained from RWQCB Documented in the 2008 Hydrogeologic on the extent of the contaminant plumes and LUST sites to develop groundwater Complete Understanding report. extraction patterns and site future production or monitoring wells. Control of Saline Water Intrusion At this time, there is insufficient data to produce 46. Periodically develop contour maps of basin-wide salinity. Recurring Annually basin-wide salinity contour maps. However, this data

is available in tabular form.

A -

6 47. Request EC and other water quality data from M&I groundwater users in Yuba Recurring Annually County. 48. Seek outside funding to collect TDS concentrations in transfer wells sampled by DWR in 2002. Correlate TDS with depth and distance from recharge areas and One Time Contingent on future funding opportunities. describe observed trends. Salinity trends obtained from DWR for both the North 49. Publish information obtained from DWR and other sources on salinity trends in Recurring Annually and South Subbasins are included in this report annual basin report. within Section 2.3 Groundwater Quality.

Component Category 4: Groundwater Sustainability Status Comments AppendixA Sustainable Management of the Groundwater Basin 50. Make yearly recommendations to Yuba Accord Member Units regarding the Recurring Annually

volume and distribution of pumping for groundwater substitution transfers.

–

GMP ImplementationProgress

December2019

201 GroundwaterManagement Plan

Yuba Yuba WaterAgency Table A. Summary of Implementation Progress of GMP Action Items (Updated for 2018 – 2019) (contd.)

8 -

Component Category 4: Groundwater Sustainability Status Comments 201 9 9

Increase Understanding of Groundwater Stressors in Yuba Basin Annual Measurementand MonitoringReport In 2016, Yuba Water successfully completed a Local Groundwater Assistance grant, utilized to develop a

groundwater model of the North Yuba, South Yuba, and Wyandotte groundwater subbasins.

In late 2017, to support the development of a GSP, Yuba Water applied for funding under DWR’s Proposition 1 Sustainable Groundwater Planning Grant, Round 2 – GSP Preparation funding program. An award notification for the full requested amount 51. Pursue outside funding to assist in improving available tools and models to One Time was received from DWR in early 2018. support groundwater management.

Yuba Water is tracking opportunities for grant opportunities to support SGMA compliance and groundwater management. Yuba Water has

submitted an application for support under DWR’s Technical Support Services (TSS) for installation of

A additional monitoring wells. Additional funding

- 7

opportunities are expected in the summer of 2019 through DWR’s Proposition 68-funded Sustainable Groundwater Management Grant Program, Round 3. Analysis of climate change will be possible after sufficient tools have been developed as part of the 52. Analyze potential effects of climate change on recharge of the Yuba County One Time Groundwater Management and IRWM program (e.g., groundwater basin. the groundwater model referenced elsewhere) and will be considered as part of the GSP.

Recharge at the Goldfields has initially been AppendixA evaluated during the development of the 53. Develop and implement a plan to characterize recharge of the groundwater groundwater model. Documentation of this is One Time basin from the Yuba Goldfields. ongoing. Future efforts to collect additional field data

may be recommended to improve the

characterization of this area in the model. –

GMP ImplementationProgress Evaluation of Future Land Use Changes and Impacts to Groundwater Resources 54. Work with Yuba County to develop county policies regarding conversion of Completed agricultural lands, supplied by surface water, to M&I usage, supplied by Yuba Water actively participated in the public groundwater. process for Yuba County’s General Plan Update. As part of this process, Yuba Water provided 55. Work with Yuba County to characterize current and projected groundwater Completed

December2019 assistance, comments, and data on projections of usage in Yuba County outside the Member Unit areas. future land-use patterns from a water resources 56. Work with Yuba County on the characterization of water usage in its General Completed planning perspective. Plan Update.

201 GroundwaterManagement Plan

Yuba Yuba WaterAgency Key: LUST = Leaky Underground Storage Tank

AFB = Air Force Base M&I = municipal and industrial 8 - DCMWC = Dry Creek Mutual Water Company OES = Office of Emergency Services 201

DWR = California Department of Water Resources RWQCB = Regional Water Quality Control Board 9

DWSAP = Drinking Water Source Assessment and Protection Program SGMA = Sustainable Groundwater Management Act Annual Measurementand MonitoringReport GAMA = Groundwater Ambient Monitoring & Assessment Program SWRCB = State Water Resources Control Board GMP = Groundwater Management Plan TSS = Technical Support Services GSP = Groundwater Sustainability Plan WWD = Wheatland Water District

IRWM = Integrated Regional Water Management YWA = Yuba Water Agency

A

-

8

AppendixA

–

GMP ImplementationProgress

December2019

Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

APPENDIX B – GROUNDWATER HYDROGRAPHS

Yuba Water Agency B-1 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Yuba Water Agency B-2 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Yuba Water Agency B-3 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Yuba Water Agency B-4 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Yuba Water Agency B-5 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Yuba Water Agency B-6 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Yuba Water Agency B-7 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Yuba Water Agency B-8 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Yuba Water Agency B-9 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Yuba Water Agency B-10 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Yuba Water Agency B-11 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Yuba Water Agency B-12 December 2019 Groundwater Management Plan 2018-2019 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Yuba Water Agency B-13 December 2019