Groundwater Management Plan 2017-2018 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 ...... 3-7 3.1 Hydrologic Conditions ...... 3-7 3.2 Groundwater Substitution Transfer, Schedule 6, and Additional Local Pumping ...... 3-7 3.2.1 Groundwater Substitution Transfer Pumping In 2008, 2009, 2010, 2013, and 2014 ...... 3-7 3.2.2 2015 Groundwater Pumping – Schedule 6, Deficiency, and Additional Local Pumping . 3-7 3.2.3 2017 Groundwater Pumping – Local Pumping ...... 3-10 3.3 Elevations and Storage ...... 3-11 3.3.1 Comparison of Current and Historical Spring Groundwater Levels ...... 3-17 3.3.2 Groundwater Elevation Contour Maps ...... 3-17 3.4 Groundwater Quality ...... 3-26 3.5 Groundwater Surface Water Interaction ...... 3-29 3.6 Compliance with Monitoring Requirements ...... 3-33 3.7 Comparison to Fall 1991 Groundwater Levels ...... 3-33 3.8 Third Party Groundwater Impacts ...... 3-35

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 ...... 3-9 Figure 4. Key Groundwater Hydrographs in the North Yuba Subbasin ...... 3-13 Figure 5. Key Groundwater Hydrographs in the South Yuba Subbasin ...... 3-14 Figure 6. 2008-2017 Groundwater Hydrographs in North Yuba Subbasin ...... 3-15 Figure 7. 2008-2017 Groundwater Hydrographs in South Yuba Subbasin ...... 3-16 Figure 8. Comparison of 2018 and Historical Spring Groundwater Levels for the South Yuba Subbasin ...... 3-18 Figure 9. Comparison of 2018 and Historical Spring Groundwater Levels for the North Yuba Subbasin ...... 3-19 Figure 10. Spring 2017 Groundwater Elevations in the Yuba Subbasins ...... 3-20 Figure 11. Spring 2018 Groundwater Elevations in the Yuba Subbasins ...... 3-21 Figure 12. Fall 2016 Groundwater Elevations in the Yuba Subbasins ...... 3-22 Figure 13. Fall 2017 Groundwater Elevations in the Yuba Subbasins ...... 3-23 Figure 14. Spring 2017 to Spring 2018 Hydraulic Head Difference Map...... 3-24 Figure 15. Fall 2016 to Fall 2017 Hydraulic Head Difference Map ...... 3-25 Figure 16. Electric Conductivity Trends in Key Wells in Yuba Subbasins ...... 3-28

Yuba Water Agency i August 2018 Groundwater Management Plan 2017-2018 Annual Monitoring and Measurement Report Contents

Figure 22. 2008-2018 Hydrographs for Yuba River and Bear River Areas ...... 3-31 Figure 23. 2008-2018 Hydrographs for Feather River and Honcut Creek Areas ...... 3-32 Figure 24. Fall 2017 Conditions Compared to Fall 1991 Conditions and Long-Term Fall Conditions in the South Yuba Subbasin ...... 3-34

List of Tables Table 1. Groundwater Substitution Transfer Pumping by Member Unit Since 2008 ...... 3-8 Table 2. Groundwater Substitution Transfer Pumping by Pumping Zone Since 2008 ...... 3-8 Table 3. Schedule 6, Deficiency, and Additional Pumping During 2015 ...... 3-10 Table 4. Additional South Yuba Subbasin Local Pumping During 2017...... 3-11 Table 5. Summary of Water Quality Indicators for Yuba Subbasins ...... 3-27

Appendices Appendix A – GMP Implementation Progress

Yuba Water Agency ii August 2018 Groundwater Management Plan 2017-2018 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 Agencies GSC Groundwater Sustainability Committee GSP Groundwater Sustainability Plan GWS Groundwater Substitution Transfer MCL Maximum Contaminant Level NCRO North Central Region Office RD Reclamation District 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

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Yuba Water Agency iv August 2018 Groundwater Management Plan 2017-2018 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 through spring of 2010 and presents updated lists of basin management objectives and groundwater management actions. Locations of the North and South Yuba groundwater subbasins are shown on 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 to document progress in implementing the GMP. The Annual Monitoring and Measurement 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 thirteenth Yuba Water GMP Annual Monitoring and Measurement Report, and covers the period from spring 2017 through spring 20181. The Report summarizes groundwater monitoring results collected by Yuba Water and by the California Department of Water Resources (DWR), including groundwater elevations, groundwater quality, and groundwater-surface water interaction. The Report also documents groundwater management actions during the annual period covered by the Report, and future planned actions.

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 August 2018 Groundwater Management Plan 2017-2018 Annual Monitoring and Measurement Report Introduction

Figure 1. North and South Yuba Groundwater Subbasins

Yuba Water Agency 1-2 August 2018 Groundwater Management Plan 2017-2018 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 development of a Groundwater Sustainability Plan (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 development of a GSP for the North and South Yuba Subbasins. These activities have included 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 September 2017, January 2018, and March 2018 to educate stakeholders and receive input and direction on GSP development. 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 August 2018 Groundwater Management Plan 2017-2018 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 four of these wells3. Two of the remaining wells that DWR discontinued monitoring have 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 monitoring4. Additionally, Yuba Water assumed monitoring tasks in spring 2018 for a nested well cluster5 at Riverside Meadows Elementary School in Plumas Lake. Installation of data loggers for continuous monitoring is anticipated for this well cluster. Of the wells monitored by Yuba Water for water levels during the period covered by this Report, 11 wells are measured semiannually, 15 wells are measured monthly6, and 19 wells are measured continuously using data loggers7. 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. Figure 2 displays the network of wells monitored by Yuba Water and DWR in Yuba County. 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. As no transfer pumping occurred during the reporting period, such monitoring did not take place.

2 State Well Numbers (SWN) 14N04E20H001M, 14N04E30F001M, 15N04E11K002M, 15N04E25H003M, 17N03E22R001M, 17N04E27F001M, 17N04E33Q001M 3 SWNs 14N04E20H001M, 14N04E30F001M, 17N03E22R001M, 17N04E27F001M 4 Accessibility issues: SWNs 15N04E25H003M, 14N04E30F001M; no wellhead: SWN 15N04E11K002M 5 Three total wells in well cluster (SWNs 13N04E08H002M, 13N04E08H003M, 13N04E08H004M) 6 Count does not include assumed monitoring for four discontinued DWR wells (see footnote 3). 7 Count does not include Plumas Lake well cluster monitoring (see footnote 5).

Yuba Water Agency 2-2 August 2018 Groundwater Management Plan 2017-2018 Annual Monitoring and Measurement Report Groundwater Management Actions

Figure 2. Yuba County Alluvial Basin Groundwater Monitoring Network

Yuba Water Agency 2-3 August 2018 Groundwater Management Plan 2017-2018 Annual Monitoring and Measurement Report Groundwater Management Actions

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 groundwater subbasin and the North Yuba groundwater 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 Hydstra8. 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. 2.3 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 Wheatland Canal 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 uses 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, would cover 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

8 Kisters Pty Ltd, Engineering & Environmental Data Management Software

Yuba Water Agency 2-4 August 2018 Groundwater Management Plan 2017-2018 Annual Monitoring and Measurement Report Groundwater Management Actions 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. 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 the Sustainable Groundwater Management Act (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 GSPs for the North Yuba and South Yuba Subbasins. An award notification for the full requested amount was received from DWR in early 2018. Yuba Water is tracking opportunities for grant opportunities to support SGMA compliance. Yuba Water is exploring potential funding opportunities as part of Technical Support Services (TSS) funding from DWR to aid in GSP development and implementation. It is anticipated DWR will begin distributing funds for its TSS program during summer 2018, although initial funding is likely to be directed towards basins identified as Critically Overdrafted, rather than to other basins such as the North and South Yuba Subbasins. The North and South Yuba Subbasins continue to be operated in a sustainable manner. Evaluation of sustainability indicators defined in California’s SGMA, including groundwater levels, groundwater storage, groundwater quality, land subsidence, and depletions of interconnected surface water, will allow for a 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 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 2018 marks the eighth 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 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 YWCA’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 have 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 development of the Yuba GSPs. Small differences between basin boundaries, county boundaries, and Yuba Water boundaries remain to be resolved, likely through a potential small basin boundary modification in mid-2018.

Yuba Water Agency 2-5 August 2018 Groundwater Management Plan 2017-2018 Annual Monitoring and Measurement Report Groundwater Management Actions

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 plan for GSP development, which must be completed by 2022. • 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 Yuba subbasins. • Continue working with DWR to improve the sharing and exchange of data. • 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.

Yuba Water Agency 2-6 August 2018 Groundwater Management Plan 2017-2018 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 During Water Year 2017 (October 2016 to September 2017), the recorded precipitation in Yuba County9 was 27.07 inches, representing 131 percent of the long-term (1948-2017) average precipitation at that location. Yuba River flow10 at Smartville for the same period was 5.57 million acre-feet, representing about 237 percent of the long-term (1901-2017) average flow at that location. The significant difference in percentage increase in observed flow compared to observed precipitation may be due to higher levels of precipitation in other portions of the Yuba River watershed outside of Yuba County. Recorded precipitation in Yuba County9 during the portion of Water Year 2018 from October 2017 through May 2018 was 16.11 inches, representing 79 percent of the long-term average precipitation during this period. Unimpaired Yuba River flow10 at Smartville during the same period was about 1.78 million acre-feet, representing 87 percent of the long-term average flow during this period. 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, and 2014 and pumping for Schedule 6, deficiency, and additional local pumping during 2015. No pumping for GWS transfers, Schedule 6, or deficiency occurred during 2017, although local pumping did occur in 2017 to replace water not delivered due to construction on the surface water delivery system to the South Yuba Subbasin. In 2010, analysis and planning for future GWS transfer programs was 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 similarity of hydrogeologic conditions and groundwater response. Figure 3 shows the Member Units, pumping zones, and GWS transfer wells for the Yuba subbasins. 3.2.1 Groundwater Substitution Transfer Pumping In 2008, 2009, 2010, 2013, and 2014 Yuba Water Member Units participated in GWS transfers in 2008, 2009, 2010, 2013, and 2014, pumping a total of almost 360,000 acre-feet of groundwater. Table 1 presents GWS pumping volumes by Member Unit and Table 2 presents GWS transfer pumping volumes by pumping zone. No pumping for GWS transfers has taken place since 2014, including 2017.However, as described in the below section, during 2015, extremely dry conditions necessitated Schedule 6 pumping, deficiency pumping, and additional pumping for local water supplies. 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

9 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. 10 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 3-7 August 2018 Groundwater Management Plan 2017-2018 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment 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.

Table 1. Groundwater Substitution Transfer Pumping by Member Unit Since 2008 Yearly Groundwater Substitution Transfer Member Unit Pumping Volume (acre-feet) 2008 2009 2010 2013 2014 North Yuba Groundwater Subbasin Browns Valley Irrigation District 4,236 4,834 3,057 3,577 2,701 Cordua Irrigation District -- 8,262 -- 8,273 2,320 Hallwood Irrigation Company 11,321 12,015 8,018 10,382 4,983 Ramirez Water District 12,081 10,789 4,552 7,421 5,185 Total North Yuba Subbasin 27,637 35,901 15,628 29,653 15,189 South Yuba Groundwater Subbasin Brophy Water District 11,825 26,958 23,925 19,642 20,122 Dry Creek Mutual Water Company 8,424 7,739 5,740 7,131 6,637 South Yuba Water District 2,103 17,605 13,209 13,531 13,214 Wheatland Water District -- 11,473 9,660 9,474 7,355 Total South Yuba Subbasin 22,351 63,775 52,533 49,778 47,328 Total (North + South) 49,989 99,676 68,161 79,431 62,517 Note: No pumping for groundwater substitution transfers has occurred since 2014, including 2017.

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 North Yuba Groundwater Subbasin 1 16,316 20,662 7,174 16,201 7,815 3 3,128 6,003 1,882 4,001 1,715 4 612 1,244 875 1,359 1,379 5 7,581 7,992 5,696 8,093 4,280 Total North Yuba Subbasin 27,637 35,901 15,628 29,653 15,189 South Yuba Groundwater Subbasin 6 519 813 842 176 - 8 11,306 26,145 23,083 19,466 20,122 9 6,555 20,098 15,347 16,650 15,355 10 0 11,473 9,660 9,474 7,355 11 3,971 5,246 3,602 4,012 4,496 Total South Yuba Subbasin 22,351 63,775 52,533 49,778 47,328 Total (North + South) 49,989 99,676 68,161 79,431 62,517 Note: No pumping for groundwater substitution transfers has occurred since 2014, including 2017.

Yuba Water Agency 3-8 August 2018 Groundwater Management Plan 2017-2018 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 3-9 August 2018 Groundwater Management Plan 2017-2018 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment As shown in Table 3, 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 Water Service Agreements for certain Yuba Water Member Units. When Supplemental Water Supply cannot be provided from the Yuba Project due to shortages in surface water supplies, the Member Units can pump groundwater to meet the deficiency, and Yuba Water compensates the Member Units for pumping power costs. Maximum deficiency pumping is based on the Supplemental Water Supply component of each Member Unit’s Water Service Agreement.

Table 3. Schedule 6, Deficiency, and Additional Pumping During 2015

2015 Pumping Volumes (acre-feet) Additional Member Unit Schedule 6 Deficiency Pumping for Total 2015 Pumping Pumping1 Local Water Pumping Supplies North Yuba Groundwater Subbasin Browns Valley Irrigation District 3,450 -- 6 3,456 Cordua Irrigation District -- -- 476 476 Hallwood Irrigation Company 5,400 -- 313 5,713 Ramirez Water District 3,600 5,874 --2 9,4742 Total North Yuba Subbasin 12,450 5,874 795 19,119 South Yuba Groundwater Subbasin Brophy Water District 6,750 23,940 -- 30,690 Dry Creek Mutual Water Company 2,700 3,061 1,578 7,339 South Yuba Water District 4,500 14,956 -- 19,456 Wheatland Water District 3,600 4,242 --2 7,8422 Total South Yuba Subbasin 17,550 46,199 1,578 65,327 Total ( North + South ) 30,000 52,073 2,373 84,446 Notes: 1 Deficiency pumping is based on the Supplemental Water Supply provisions in the Water Service Agreements for certain Yuba Water Agency Member Units. Water Service Agreements for Browns Valley Irrigation District, Cordua Irrigation District, and Hallwood Irrigation Company do not include Supplemental Water Supply. Accordingly, these Member Units did not participate in deficiency pumping. 2 Ramirez Water District and Wheatland Water District continued pumping for local supplies during early 2016. In addition to 2015 pumping included in Table 1, Ramirez Water District pumped an additional 67 acre-feet from January 2016 through March 2016, and Wheatland Water District pumped an additional 86 acre-feet during January 2016.

3.2.3 2017 Groundwater Pumping – Local Pumping During 2017, hydrologic conditions were extremely wet, with an abundance of surface water available for use. However, the same extreme wet conditions damaged critical surface water delivery infrastructure to the South Yuba Subbasin. Construction to repair the damage limited surface water deliveries to the South Yuba Subbasin; Member Units utilized groundwater to offset these reduced deliveries. This voluntary pumping is not monitored through existing programs other that the monitoring performed individually by the Member Units. Table 4 summarizes estimates of this additional pumping in 2017.

Yuba Water Agency 3-10 August 2018 Groundwater Management Plan 2017-2018 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment Table 4. Additional South Yuba Subbasin Local Pumping During 2017

Total 2017 Additional Local Pumping Member Unit (acre-feet) Brophy Water District1 8,000 Dry Creek Mutual Water Company1 2,500 South Yuba Water District1 3,201 Wheatland Water District2 -- Total3 13,701 – 16,000 Notes: 1 Estimate provided by Member Unit staff. 2 Pumping volume not available or provided. 3 Absent data from Wheatland Water District, total local pumping is estimated based on historical pumping as follows: • Brophy Water District historically pumps 50% of the South Yuba Subbasin total (16,000 acre-feet; estimate upper bound). • South Yuba Water District historically pumps 25% of the South Yuba Subbasin total (12,804 acre-feet; estimate lower bound). o As local pumping volumes provided by the three Member Units (13,701 acre-feet) exceeded this estimated lower bound, this value was used as the lower bound. 3.3 ELEVATIONS AND STORAGE This section describes 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. In addition to pumping, groundwater levels during this period were affected by hydrologic conditions, including the recent extended drought and very wet 2017. As described below, overall, the Yuba groundwater subbasins are in historically healthy conditions that are ideal for supporting future GWS transfers. Hydrographs11,12 from key wells showing historical trends of groundwater elevations in the North and South Yuba subbasins are presented on 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], and Browns Valley Irrigation District [BVID]) improved starting in the 1970s, which coincides with the extension of surface water deliveries 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, and 2015) 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 2018 at selected monitoring wells in the North and South Yuba Subbasins, respectively. Water levels at wells in the North

11 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/. 12 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 3-11 August 2018 Groundwater Management Plan 2017-2018 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment Yuba Subbasin Member Unit areas (including wells YCWA-06, PMW-02B, 16NO4E08A001M, 16N04E17R002M, and PMW-16 shown on Figure 6) either remained approximately stable or decreased slightly during late summer/early fall 2017 in response to drier summer conditions and pumping for local water supplies. From fall 2017 through spring 2018, water levels in the majority of these wells steadily recovered to higher than spring 2017 levels. As shown on Figure 6, Well PMW-16 recovered to spring 2016 levels, but did not recover its spring 2017 levels. 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. Spring 2018 groundwater elevations at YCWA-03 are not as high as in spring 2017, but are above the average spring level of approximately 60 feet. As shown on Figure 7, groundwater levels at monitoring wells in the South Yuba Subbasin Member Unit areas either remained approximately steady or declined during summer/early fall 2017, then increased from fall 2017 through spring 2018. In WWD and DCMWC (PMW-25, PMW-27, PMW-07C and YCWA-13), groundwater levels declined during summer 2017 then increased from fall 2017 to spring 2018. In spring 2018, the groundwater levels in these wells recovered to the groundwater levels observed in spring 2017, which were the highest levels since spring 2013. Declines during summer 2017 are likely due to dry conditions and pumping for local water supplies, such as pumping for the City of Wheatland where municipal water use is supplied by groundwater. 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 generally remained approximately steady during summer 2016, then increased steadily through spring 2018 to above spring 2017 levels.

Yuba Water Agency 3-12 August 2018 Groundwater Management Plan 2017-2018 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Figure 4. Key Groundwater Hydrographs in the North Yuba Subbasin

Yuba Water Agency 3-13 August 2018 Groundwater Management Plan 2017-2018 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Figure 5. Key Groundwater Hydrographs in the South Yuba Subbasin

Yuba Water Agency 3-14 August 2018 Groundwater Management Plan 2017-2018 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Figure 6. 2008-2017 Groundwater Hydrographs in North Yuba Subbasin

Yuba Water Agency 3-15 August 2018 Groundwater Management Plan 2017-2018 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Figure 7. 2008-2017 Groundwater Hydrographs in South Yuba Subbasin

Yuba Water Agency 3-16 August 2018 Groundwater Management Plan 2017-2018 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 2018 groundwater levels with the range of historical spring levels for monitoring wells in each pumping zone in the North Yuba Subbasin and South Yuba Basin, respectively. Each graph shows spring 2018 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 2018 groundwater levels are historically high for a number of wells, especially those within pumping zone 10. Historical lows occurred during 2015 for 20 of the 54 wells, although many of these wells do not have data records extending back to the 1970s and 1980s when groundwater levels were lower in many portions of the basin. 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 2017 and spring 2018, respectively. Figures 12 and 13 present contour maps of groundwater elevations for fall 2016 and fall 2017, 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 2017 to spring 2018. The map indicates that groundwater elevations throughout much of the North and South Yuba Subbasins have remained steady from 2017 to 2018, while other areas have seen slight increases in groundwater elevation during this time period. This slight amount of recovery is likely due to a combination of fairly average conditions during the portion of Water Year 2018 into spring 2017 and no GWS transfer pumping during 2017. Figure 15 present a hydraulic head difference map for fall 2016 to fall 2017. The map indicates that groundwater elevations throughout much of the North and South Yuba Subbasins have generally increased from fall 2016 to fall 2017, while other areas remained fairly steady. This increase is likely to due to wet conditions through winter and spring of 2016 and lack of GWS transfer pumping in 2017.

Yuba Water Agency 3-17 August 2018 Groundwater Management Plan 2017-2018 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Figure 8. Comparison of 2018 and Historical Spring Groundwater Levels for the South Yuba Subbasin

Yuba Water Agency 3-18 August 2018 Groundwater Management Plan 2017-2018 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Figure 9. Comparison of 2018 and Historical Spring Groundwater Levels for the North Yuba Subbasin

Yuba Water Agency 3-19 August 2018 Groundwater Management Plan 2017-2018 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Figure 10. Spring 2017 Groundwater Elevations in the Yuba Subbasins

Yuba Water Agency 3-20 August 2018 Groundwater Management Plan 2017-2018 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Figure 11. Spring 2018 Groundwater Elevations in the Yuba Subbasins

Yuba Water Agency 3-21 August 2018 Groundwater Management Plan 2017-2018 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Figure 12. Fall 2016 Groundwater Elevations in the Yuba Subbasins

Yuba Water Agency 3-22 August 2018 Groundwater Management Plan 2017-2018 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Figure 13. Fall 2017 Groundwater Elevations in the Yuba Subbasins

Yuba Water Agency 3-23 August 2018 Groundwater Management Plan 2017-2018 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Figure 14. Spring 2017 to Spring 2018 Hydraulic Head Difference Map

Yuba Water Agency 3-24 August 2018 Groundwater Management Plan 2017-2018 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Figure 15. Fall 2016 to Fall 2017 Hydraulic Head Difference Map

Yuba Water Agency 3-25 August 2018 Groundwater Management Plan 2017-2018 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment 3.4 GROUNDWATER QUALITY DWR’s NCRO regularly collects water quality samples from nine wells (four in the North and five in the South Yuba subbasins). Sampling is staggered so that four to five wells are sampled each year; in 2017, samples were collected from five wells – three wells in the North Yuba Subbasin and two wells in the South Yuba Subbasin. 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 5 summarizes the latest available water quality data at the five wells sampled in 2017, and compares each indicator with its respective historical range of measurements. As shown in Table 5, 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 Secondary MCL for total dissolved solids 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 MCL limit for total dissolved solids of 1,000 milligrams per liter. Figure 16 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 16 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 county.

Yuba Water Agency 3-26 August 2018 Groundwater Management Plan 2017-2018 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment Table 5. 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 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 3-27 August 2018 Groundwater Management Plan 2017-2018 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Figure 16. Electric Conductivity Trends in Key Wells in Yuba Subbasins

Yuba Water Agency 3-28 August 2018 Groundwater Management Plan 2017-2018 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 Horcut Creek. Figure 22 displays a hydrograph of stage on the Yuba River near Marysville13 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. These 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. Water elevations were higher throughout 2016-2017 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 is unknown and is 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. 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 22 also displays a hydrograph of stage at the Bear River gage at Pleasant Grove Road13 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. Water elevations were higher throughout the year from the shallowest to deepest wells, showing a downward vertical gradient. Figure 23 displays a hydrograph of stage on the Feather River at Boyd’s Landing13 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 below the river stage, which shows the impact of Oroville Dam upstream through controlled releases. 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. However, the river stage over summer periods shows a small increase even as groundwater elevations decrease during the pumping season. The intermediate 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. No consistent gradient is evident when

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

Yuba Water Agency 3-29 August 2018 Groundwater Management Plan 2017-2018 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment comparing the intermediate or deepest wells with the shallowest well. This gradient changes seasonally, usually downwards during summer and upwards during winter. Figure 23 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. Data from the nearby groundwater wells is only available through May 2017; stage data for North Honcut Creek has only been measured since November 2016. Due to the small amount of overlapping data available to compare groundwater elevations at this location, river stage data was not included in the plot. Similar to the other locations discussed above, the deeper wells exhibit significant drawdowns during pumping periods. Based on limited data, it does not appear to have a significant impact on river stage. Water elevations were higher throughout the year from the shallowest to deepest wells, showing a downward vertical gradient.

Yuba Water Agency 3-30 August 2018 Groundwater Management Plan 2017-2018 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Figure 22. 2008-2018 Hydrographs for Yuba River and Bear River Areas

Yuba Water Agency 3-31 August 2018 Groundwater Management Plan 2017-2018 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Figure 23. 2008-2018 Hydrographs for Feather River and Honcut Creek Areas

Yuba Water Agency 3-32 August 2018 Groundwater Management Plan 2017-2018 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment 3.6 COMPLIANCE WITH MONITORING REQUIREMENTS The 2008, 2009, 2010, 2013, and 2014 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 2017 non- pumping year, Member Units in the North Yuba Subbasin collected depth-to-water measurements at a total of 45 wells on a monthly basis from spring 2017 to spring 2018. In the South Yuba Subbasin, Member Units collected spring and fall depth-to-water measurements at a total of 169 wells, and monthly depth-to-water measurements at a total of 40 wells from spring 2017 to spring 2018. • 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. 3.7 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 red horizontal lines on Figure 24, represent the groundwater levels from a subset of wells in that Zone with current groundwater level measurements. As shown in Figure 24, fall 2017 groundwater levels in the South Yuba Subbasin Zones were above fall 1991 levels at these wells. The fall 2017 groundwater levels in the South Yuba Subbasin were generally in the upper range of long-term fall conditions.

Yuba Water Agency 3-33 August 2018 Groundwater Management Plan 2017-2018 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment

Figure 24. Fall 2017 Conditions Compared to Fall 1991 Conditions and Long-Term Fall Conditions in the South Yuba Subbasin

Yuba Water Agency 3-34 August 2018 Groundwater Management Plan 2017-2018 Annual Monitoring and Measurement Report Groundwater Monitoring and Conditions Assessment 3.8 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 due to low groundwater levels during summer 2016. Yuba Water and the Member Units have agreed to enhance monitoring in the RD 10 area, which for 2017 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.

Yuba Water Agency 3-35 August 2018 Groundwater Management Plan 2017-2018 Annual Monitoring and Measurement Report Appendix A – GMP Implementation Progress

APPENDIX A – GMP IMPLEMENTATION PROGRESS

Yuba Water Agency August 2018 Groundwater Management Plan 2017-2018 Annual Monitoring and Measurement Report Appendix A – GMP Implementation Progress

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Yuba Water Agency August 2018

201 7 Groundwater Management Plan Yuba Water Agency Water Yuba - Table A. Summary of Implementation Progress of GMP Action Items (Updated for 2017 – 2018) 201 8

Annual Measurementand Monitoring Report Component Category 1: Stakeholder Involvement Plan Status Comments Involving the Public The 2017-2018 Annual Monitoring and

1. Publish an Annual Groundwater Monitoring Report summarizing groundwater conditions Measurement Report has been prepared and will in the Yuba groundwater basin relative to historical trends, and describing ongoing Recurring be presented in a public meeting. The associated groundwater management activities. Also, annually publish a groundwater fact sheet Annually fact sheet summarizing the findings of the 2017- summarizing the findings of the Annual Groundwater Management Report. 2018 Annual Monitoring and Measurement Report

has also been prepared. 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 conjunctive use.

A Involving other Agencies within and Adjacent to Yuba Water Agency Area - 1 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. Appendix A 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 Progress Implementation GMP 9. Continue to develop working relationships with local, state, and federal regulatory Ongoing agencies.

August 2018 August

201 7 Groundwater Management Plan Yuba Water Agency Water Yuba Table A. Summary of Implementation Progress of GMP Action Items (Updated for 2017 – 2018) (contd.) - 201 8 Component Category 2: Monitoring Program Status Comments

Pursuing Partnership Opportunities Annual Measurementand Monitoring Report 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 – 10. Yuba Water will continue to track and pursue grant GSP Preparation funding program. An award notification for the full requested opportunities to fund groundwater management activities Ongoing amount was received from DWR in early 2018. and local water infrastructure projects Yuba Water is tracking opportunities for grant opportunities to support SGMA compliance. Yuba Water intends to seek Technical Support Services (TSS) funding from DWR to aid in GSP development and implementation. It is anticipated DWR will begin distributing funds for its TSS program during summer 2018 although initial funding is likely to be directed towards basins identified as Critically Overdrafted, rather than to other basins such as the North and South Yuba Subbasins.

Groundwater Storage and Elevation To enhance monitoring in the RD 10 area, Yuba Water coordinated with the Member A

- Units and RD 10 to identify production wells that could be used for water-level 2 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 incrementally expand the network. Yuba Water installed six additional monitoring 12. Coordinate with Member Units, DWR, and other basin wells in 2011-2012. Additionally, in 2010 Yuba Water took over monthly monitoring groundwater extractors to ensure that the selected wells are Ongoing responsibilities for 15 groundwater monitoring wells that had previously been under Appendix A maintained as part of a long-term monitoring network. the responsibility of DWR. In 2017 and 2018, Yuba Water took over monthly monitoring activities for 9 additional wells. 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 Progress Implementation GMP Conjunctive Use Pilot Project funded by Proposition 13. protocols are used among agencies, and confirm that data sharing and archiving procedures are implemented. 14. Provide training for the Member Units and other basin groundwater extractors on implementation of data collection Ongoing protocols, as required or if requested. 15. Consider ways to fill gaps in the monitoring well network

August 2018 August Yuba Water installed six additional monitoring wells in 2011-2012. Additional by identifying additional existing suitable wells or identifying Ongoing production wells in RD 10 were identified for groundwater level monitoring. opportunities for constructing new monitoring wells.

201 7 Groundwater Management Plan Yuba Water Agency Water Yuba Table A. Summary of Implementation Progress of GMP Action Items (Updated for 2017 – 2018) (contd.) - 201 8 Component Category 2: Monitoring Program Status Comments

16. Seek outside funding and identify potential candidate wells for well characterization Annual Measurementand Monitoring Report Yuba Water will explore potential 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 installation of a multilevel piezometer near the Yuba Yuba Water will explore potential 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 creation of the Semiannually

potentiometric surfaces when they are provided. 19. Identify opportunities and potential outside funding sources for monitoring Yuba Water will explore potential 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 21. Coordinate with Member Units, DWR, and other basin groundwater extractors (e.g., DWR expanded the set of wells monitored for water Beale AFB, municipalities) to identify an appropriate group of wells for monitoring both Ongoing quality with 15 new wells surveyed in 2006. 2017 A -

3 during transfer and non-transfer years. sampling results are shared in this report. 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. 23. Coordinate with Member Units, DWR, other basin groundwater extractors, and other local, state, and federal agencies to identify where wells may exist in areas with sparse groundwater quality data. Identify opportunities for collecting and analyzing water quality Ongoing samples from those wells. If wells are sampled through other programs, coordinate with

the appropriate agency for sharing data. Appendix A Inelastic Subsidence DWR plans to repeat the level survey in 2018, after 24. Perform repeat level surveys on subsidence monitoring benchmarks at least every 5 Every 5 Years budgetary limitations resulted in the cancellation of

years or on an agreed schedule with DWR. the 2013 survey. –

Progress Implementation GMP One Time with 25. Identify locations especially vulnerable to damage from subsidence (e.g., levees, Periodic canals, 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. 26. Evaluate the need for other future groundwater surface water interaction studies. Ongoing The groundwater model will be useful as one line of August 2018 August evidence in the evaluation of these interactions. 27. Evaluate the need and cost effectiveness of installing additional monitoring stations Yuba Water will explore potential funding under Ongoing adjacent to surface water bodies. DWR’s Technical Support Services for this item.

201 7 Groundwater Management Plan Yuba Water Agency Water Yuba Table A. Summary of Implementation Progress of GMP Action Items (Updated for 2017 – 2018) (contd.) - 201 8 Component Category 2: Monitoring Program Status Comments

28. Coordinate with DWR on the development of uniform data collection protocols and data Yuba Water shares data with DWR via the Annual Measurementand Monitoring Report Complete sharing and archiving procedures. CASGEM web interface. Yuba Water pursued a different project for 2012 AB303 Local Groundwater Assistance Grant funding (which was awarded to Yuba 29. Seek outside funding to characterize production wells near the Bear River to improve Water), but will continue to track other funding One Time understanding of the groundwater-surface water interaction. opportunities. Yuba Water will explore potential funding

under DWR’s Technical Support Services for this item. Yuba Water pursued a different project for 2012 AB303 Local Groundwater Assistance Grant funding (which was awarded to Yuba 30. Seek outside funding to perform aquifer testing at selected Bear River wells to improve Water), but will continue to track other funding One Time understanding of aquifer parameters in this area. opportunities. Yuba Water will explore potential funding

under DWR’s Technical Support Services for this item.

A Yuba Water pursued a different project for - 4 2012 AB303 Local Groundwater Assistance

Grant funding (which was awarded to Yuba 31. Seek outside funding to perform aquifer testing near the Yuba Goldfields while monitoring Water), but will continue to track other funding response in new multilevel piezometer. Correlate groundwater elevations with pond elevations in One Time opportunities. Yuba Goldfields. Yuba Water will explore potential funding under DWR’s Technical Support Services for this item. 32. Exchange groundwater information with companies operating in the Yuba Goldfields to better Ongoing

understand recharge characteristics in this portion of the basin. Appendix A Data Management System Inventory of available data was included and 33. Continue to coordinate with Member Units and other water purveyors to determine types of Ongoing compiled as part of the Hydrogeologic data and data formats available.

Understanding report. –

Yuba Water acquired and installed a data Progress Implementation GMP 34. Develop data management methods on an as-needed basis for data determined critical to Ongoing management system based on Hydstra. The 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.

August 2018 August Yuba Water began posting data to CASGEM 36. Develop data reporting format consistent with CASGEM requirements Complete in early 2012.

201 7 Groundwater Management Plan Yuba Water Agency Water Yuba Table A. Summary of Implementation Progress of GMP Action Items (Updated for 2017 – 2018) (contd.) - 201 8 Component Category 3: Groundwater Resource Protection Status Comments

Well Construction, Abandonment and Destruction Policies Annual Measurementand Monitoring Report 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 Wellhead Protection Measures

39. Request that municipalities provide vulnerability summaries from the DWSAP to the 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 Yuba County’s recharge areas. parameters in California groundwater was released in late 2014. The report is not known A

- to be finalized and no further action 5 recommended at this time. Recharge will be evaluated during further use of the groundwater model, including for 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, which is currently in draft form. Recharge will also be evaluated

during development of groundwater budgets as Appendix A part of GSP development. 42. Work with Yuba County to publicize the need to protect prominent groundwater Yuba County General Plan contains maps of Ongoing recharge areas, especially in the developing portions of the South Yuba Subbasin. areas with high anticipated recharge rates.

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Control of Migration and Remediation of Contaminated Groundwater Progress Implementation GMP 43. Coordinate with Member Units, DWR, other basin groundwater extractors, and other local, State, and federal agencies to pursue actions that result in containment and Ongoing remediation of water quality problems within the subbasins. 44. Request data annually from Beale AFB, RWQCB, and Yuba County DPH regarding Recurring Annually groundwater contaminant plumes in Yuba County.

August 2018 August Fuel Storage Tanks 45. Provide Yuba Water members units with all information obtained from RWQCB on Documented in the 2008 Hydrogeologic the extent of the contaminant plumes and LUST sites to develop groundwater extraction Complete Understanding report. patterns and site future production or monitoring wells.

201 7 Groundwater Management Plan Yuba Water Agency Water Yuba Table A. Summary of Implementation Progress of GMP Action Items (Updated for 2017 – 2018) (contd.) - 201 8 Component Category 3: Groundwater Resource Protection Status Comments

Control of Saline Water Intrusion Annual Measurementand Monitoring Report 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. 47. Request EC and other water quality data from M&I groundwater users in Yuba Recurring Annually County. No update. Contingent on future funding 48. Seek outside funding to collect TDS concentrations in transfer wells sampled by

opportunities. DWR in 2002. Correlate TDS with depth and distance from recharge areas and One Time Yuba Water will explore potential funding under describe observed trends. DWR’s Technical Support Services for this item. 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 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. A

- Increase Understanding of Groundwater Stressors in Yuba Basin 6 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. Appendix A An award notification for the full requested amount was received from DWR in early 2018. 51. Pursue outside funding to assist in improving available tools and models to One Time support groundwater management.

Yuba Water is tracking opportunities for grant –

opportunities to support SGMA compliance. Yuba Progress Implementation GMP Water is exploring potential funding opportunities as part of Technical Support Services (TSS) funding from DWR to aid in GSP development and implementation. It is anticipated DWR will begin distributing funds for its TSS program during summer 2018 although initial funding is likely to be

August 2018 August directed towards basins identified as Critically Overdrafted, rather than to other basins such as the North and South Yuba Subbasins.

201 7 Groundwater Management Plan Yuba Water Agency Water Yuba Table A. Summary of Implementation Progress of GMP Action Items (Updated for 2017 – 2018) (contd.) - 201 8 Component Category 4: Groundwater Sustainability Status Comments

Analysis of climate change will be possible after Annual Measurementand Monitoring Report 52. Analyze potential effects of climate change on recharge of the Yuba County sufficient tools have been developed as part of the One Time groundwater basin. Groundwater Management and IRWM program (e.g., the groundwater model referenced elsewhere) Recharge at the Goldfields has initially been evaluated during development of the groundwater 53. Develop and implement a plan to characterize recharge of the groundwater model. Documentation of this is ongoing. Future One Time basin from the Yuba Goldfields. efforts to collect additional field data may be

recommended to improve characterization of this area in the model. 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 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 characterization of water usage in its General Plan Completed planning perspective. Update. A

- Key: LUST = Leaky Underground Storage Tank 7

AFB = Air Force Base M&I = municipal and industrial DCMWC = Dry Creek Mutual Water Company OES = Office of Emergency Services DWR = California Department of Water Resources RWQCB = Regional Water Quality Control Board DWSAP = Drinking Water Source Assessment and Protection Program SWRCB = State Water Resources Control Board GAMA = Groundwater Ambient Monitoring & Assessment Program WWD = Wheatland Water District GMP = Groundwater Management Plan YWA = Yuba Water Agency

Appendix A

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Progress Implementation GMP August 2018 August

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Annual Measurementand Monitoring Report

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Appendix A

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Progress Implementation GMP August 2018 August