FORTY-THIRD ANNUAL ENGINEERING AND SURVEY REPORT ON WATER SUPPLY CONDITIONS OF THE SANTA YNEZ RIVER WATER CONSERVATION DISTRICT 2020-2021 April 21, 2021 Northern California Southern California Arizona Colorado Oregon FORTY-THIRD ANNUAL ENGINEERING AND SURVEY REPORT ON WATER SUPPLY CONDITIONS OF THE SANTA YNEZ RIVER WATER CONSERVATION DISTRICT 2020-2021 April 21, 2021 CARLSBAD, COVINA, AND SAN RAFAEL, CALIFORNIA APACHE JUNCTION, ARIZONA CENTENNIAL, COLORADO MEDFORD, OREGON INTENTIONALLY LEFT BLANK 1126-13 April 21, 2021 San Rafael Board of Directors Santa Ynez River Water Conservation District P.O. Box 719 Santa Ynez, California 93460 Re: Forty-Third Annual Engineering Survey and Report on Water Supply Conditions of the Santa Ynez River Water Conservation District, 2020-2021 Dear Board Members: Transmitted herewith is our Engineering Survey and Report on Water Supply Conditions of the Santa Ynez River Water Conservation District for 2020-2021. This, the Forty-Third Annual Report, presents the required and pertinent information for the Board of Directors to make necessary determinations for levying groundwater charges upon the production of groundwater from water-producing facilities (water wells) within the District. As such, it provides information on the status of the groundwater and surface water supplies, as well as the annual production of groundwater from within the District. Sincerely, Oliver S. Page OSP:rrk Enclosures INTENTIONALLY LEFT BLANK TABLES OF CONTENTS Page Number 1.0 Executive Summary 1 1.1. Historical Background 1 1.2. Description of the District 2 1.3. Report Summary 3 1.4. Findings 9 1.5. Sources of Information 10 2.0 GroundWater Charges 11 2.1. Revenues 12 2.2. Groundwater Production 12 2.3. Well Registration 16 2.4. Major Producers 16 3.0 Precipitation 25 4.0 Surface Water Conditions 29 4.1. Basin Surface Water Use 29 4.2. State Water Project Water Use 32 4.3. River System Flow Conditions 33 4.4. Water Rights Releases 33 4.5. State Water Code Requirements 40 5.0 Groundwater Conditions 41 5.1. Sources of Groundwater 41 5.2. Groundwater Level Changes 42 5.3. Storage Changes 49 5.4. Change in Storage Trends 57 5.5. Safe Yield 57 5.6. Historical Pumpage 57 5.7. Overdraft 57 5.8. Groundwater Quality 64 APPENDICES A Summary of Provisions in the California Water Code Pertaining to the Implementation of a Groundwater Charge B Historical Groundwater Charge Rates C Additional Streamflow Records, Santa Ynez River Basin D Water Rights Releases E General Description of the Hydrogeology of the Sources of Groundwater within the District F Water-Level Hydrographs of Selected Wells G Well Inventory i LIST OF TABLES Page Number Table 1a Annual Reported Groundwater Production Within the District, All District Zones .................................................................................................. 18 Table 1b Annual Reported Groundwater Production Within the District Agricultutal Water ................................................................................................ 19 Table 1c Annual Reported Groundwater Production Within the District Other Water ........................................................................................................... 20 Table 1d Annual Reported Groundwater Production Within the District Special Irrigation Water ........................................................................................ 21 Table 2 Monthly Precipitation and Departure From Normal at Bradbury Dam and Lompoc January 2020 through March 2021 ......................................................... 26 Table 3 Summary of Cachuma Project Operations 1953 Through 2020 ........................... 30 Table 4 Flow of the Santa Ynez River at the Lompoc Narrows ........................................ 34 Table 5 Flow of Salsipuedes Creek Near Lompoc ............................................................ 37 Table 6 Historical Water Rights Releases.......................................................................... 39 Table 7 Water-Level Changes Lompoc Plain Subarea 2020 to 2021 ................................ 45 Table 8 Water-Level Changes Lompoc Upland and Lompoc Terrace Subareas 2020 to 2021 ......................................................................................................... 46 Table 9 Water-Level Changes Santa Rita and Buellton Upland Subareas 2020 to 2021 ......................................................................................................... 46 Table 10 Water-Level Changes Santa Ynez Upland Subarea 2020 to 2021 ....................... 48 Table 11 Estimated Annual Change of Groundwater in Storage in the Santa Ynez River Alluvium for the Past Ten Years and Current Year (2020-21) ............................. 50 Table 12 Estimated Annual Change of Groundwater in Storage in the Lompoc Plain Subarea for the Past Ten Years and Current Year (2020-21) ............................... 51 Table 13 Estimated Annual Change of Groundwater in Storage in the Lompoc Upland and Lompoc Terrace Subareas for the Past Ten Years and Current Year (2020-21)............................................................................................................... 53 Table 14 Estimated Annual Change of Groundwater in Storage in the Santa Rita Upland Subarea For the Past Ten Years and Current Year (2020-21) .............................. 54 Table 15 Estimated Annual Change of Groundwater in Storage in the Eastern Portion of the Buellton Upland Subarea For the Past Ten Years and Current Year (2020-21)............................................................................................................... 55 Table 16 Estimated Annual Change of Groundwater in Storage in the District Portion of the Santa Ynez Upland Subarea For the Past Ten Years and Current Year (2020-21)............................................................................................................... 56 Table 17 Summary of Change in Quantity of Groundwater in Storage Within the District................................................................................................................... 58 ii Page Number Table 18 Estimated Average Safe Yield of Principal Sources of Groundwater Within the District ............................................................................................................. 61 Table 19 Estimated Average Annual Historical Reported Groundwater Pumpage from the Principal Sources of Groundwater Within the District .......................... 62 Table 20 Average Annual Overdraft of Principal Sources of Groundwater Within the District................................................................................................................... 63 Table 21 Estimated Accumulated Overdraft of Principal Sources of Groundwater Within the District................................................................................................. 65 LIST OF FIGURES 1 Santa Ynez River Water Conservation District 5 2 Groundwater Charge Zones, Santa Ynez River Water Conservation District 13 3 Annual Groundwater Production Within the District, 5-Year Moving Average 23 4 Annual Precipitation and Cumulative Departure from Mean for Lompoc, Santa Barbara, Bradbury Dam, and Gibraltar Dam 27 5 Monthly Surface Flow, Santa Ynez River Near Lompoc 35 6 Major Groundwater Sources, Santa Ynez River Basin 43 7 Accumulated Dewatered Storage 59 8 Graphs Showing Total Dissolved Solids, Chloride and Sodium Concentrations in Groundwater from Selected Wells Located in the Lompoc Plain Subarea 67 LIST OF TERMS Accumulated Overdraft ..........The amount of water necessary to be replaced in the intake areas of the groundwater basins within the District or any zone or zones thereof to prevent the landward movement of salt water into the fresh groundwater body, or to prevent subsidence of the land within the District or any zone or zones thereof, as determined by the board from time to time. Defined in Water Code Section 75505. See also Dewatered Storage Acre-Foot ...............................Volume of water to flood one acre to a depth of one foot (325,851 gallons). Ad Valorem property tax .......Property tax assessed according to value of property. AF, AC-FT .............................Acre-Foot. iii Agricultural water ..................Produced water first used on lands in the production of plant crops or livestock for market. Defined in Water Code Section 75508. Alluvium ................................Sediments deposited through stream or river action. In Santa Ynez these sediments are generally much younger, less consolidated, with greater hydraulic conductivity, than the surrounding marine and non-marine sediments. ANA .......................................Above Narrows Account. Water rights release from Bradbury Dam (Lake Cachuma) made to replenish the groundwater basin upstream of the Lompoc Narrows area. Annual Overdraft ...................The amount, determined by the board, by which the production of water from groundwater supplies within the District or any zone or zones thereof during the water year exceeds the natural replenishment of such groundwater supplies in such water year. Defined in Water Code Section 75506. BNA .......................................Below Narrows Account. Water rights release from Bradbury Dam (Lake Cachuma) made to replenish the groundwater basin downstream of the Lompoc Narrows area, i.e. for the Lompoc Plain subarea. Board .....................................Refers to the five Directors of the Santa Ynez River Water