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  • In Re Santa Maria Valley Groundwater Litigation (coordinated into Twitchell Dam Cases, JCCP4948) Other Complaint (Not Spec) Unlimited (42)  document preview
  • In Re Santa Maria Valley Groundwater Litigation (coordinated into Twitchell Dam Cases, JCCP4948) Other Complaint (Not Spec) Unlimited (42)  document preview
  • In Re Santa Maria Valley Groundwater Litigation (coordinated into Twitchell Dam Cases, JCCP4948) Other Complaint (Not Spec) Unlimited (42)  document preview
  • In Re Santa Maria Valley Groundwater Litigation (coordinated into Twitchell Dam Cases, JCCP4948) Other Complaint (Not Spec) Unlimited (42)  document preview
  • In Re Santa Maria Valley Groundwater Litigation (coordinated into Twitchell Dam Cases, JCCP4948) Other Complaint (Not Spec) Unlimited (42)  document preview
  • In Re Santa Maria Valley Groundwater Litigation (coordinated into Twitchell Dam Cases, JCCP4948) Other Complaint (Not Spec) Unlimited (42)  document preview
  • In Re Santa Maria Valley Groundwater Litigation (coordinated into Twitchell Dam Cases, JCCP4948) Other Complaint (Not Spec) Unlimited (42)  document preview
  • In Re Santa Maria Valley Groundwater Litigation (coordinated into Twitchell Dam Cases, JCCP4948) Other Complaint (Not Spec) Unlimited (42)  document preview
						
                                

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1997-1-CV-770214 Santa Clara — Civil 2019 Annual Report of Electronically Filed Hydrogeologic Conditions, uftyuperior Court of CA, of Santa Clara, Water Requirements, Sup pte x . 7 Walker PM and Disposition Case #1997-1-CV-770214 Envelope: 4295328 Santa Maria Valley Management Area af ey a — t's ia tu vas — Sar ae he Be Ce = AS Je e -. (a3 a BY ya ed ae, oe rey i Ld nod as iia is oe hi od WZ maf ey POs ) eS exe rats os Aa en April 29, 2020 Prepared by Ay Luhdorff & Scalmanini Consulting Engineers 2019 Annual Report of Hydrogeologic Conditions Water Requirements, Supplies, and Disposition Santa Maria Valley Management Area April 29, 2020 Ay prepared by Luhdorff & Scalmanini Consulting Engineers or om 2£0 7g” ESN i No. 6475 No. see)'3| (4a. ]* 3/3 a. }* 44 Peter Leffler, P.G., C.HG. LEO yy Principal Hydrogeologist OR; C7 Luhdorff and Scalmanini, Consulting Engineers 500 1st Street Woodland, CA 95695 feta Lh 2019 ANNUAL REPORT OF HYDROGEOLOGIC CONDITIONS APRIL 29, 2020 WATER REQUIREMENTS, SUPPLIES, AND DISPOSITION PREAMBLE This report provides an assessment of hydrogeologic conditions and accounting of water used in the Santa Maria Valley Management Area (SMVMA) in 2019 in accordance with provisions of the Stipulation entered in 2008 by the Superior Court of the State of California, County of Santa Clara (the Court). The Stipulation specifies that the Twitchell Management Authority (TMA) administer relevant provisions of the Stipulation regarding the SMVMA,; further, it specifies that the SMVMA Engineer (the Engineer) compile the results of the annual assessment and accounting into a report for submittal to the Court. The guidelines for this report are as approved by the Court, which holds continuing jurisdiction over the Santa Maria Groundwater Basin regarding the disposition of groundwater. The report is compiled from information derived from the monitoring program for the SMVMA. Per the Stipulation, the program collects information, including groundwater level and groundwater quality data, sufficient to assess groundwater conditions. The program also collects information to account for water use in the SMVMA, including the demand, supply, and disposition. Based on the annual assessment of hydrogeologic conditions and accounting of water used in the SMVMA, the Stipulation requires a determination be made by the Engineer as to whether a condition of severe water shortage exists in the SMVMA. The Stipulation delineates four specific criteria that, when all are met in any given year, define a condition of severe water shortage; those four criteria are: . chronic decline in groundwater levels (over period of not less than 5 years); . groundwater levels below lowest recorded levels; . groundwater level decline not caused by drought; and . material increase in groundwater use during the five-year period. Should a condition of severe water shortage exist, the Stipulation directs the Engineer to provide findings and recommendations as part of its annual report to alleviate such a condition or the associated adverse effects. LSCE 2019 ANNUAL REPORT OF HYDROGEOLOGIC CONDITIONS APRIL 29, 2020 WATER REQUIREMENTS, SUPPLIES, AND DISPOSITION Contents 1 INTRODUCTION a eee eeeeeeee a pee ee ee 11. Physical Setting sstenevsonsnsesovonee suearovswvsronsa esnsroesersvoern eastesseneseess Sexsassseusosess Sodsaseveneessns 1.2 Previous Studies... eee peer ee peers esas Seer ee 1.3 SMVMA Monitoring Program pees eet et ene pieeteeeeressd Beeesreerseee Deerereeee sete 1.4, Additional Monitoring and Reporting Programs a eee ee ee 15. Report Organization. 2 HYDROGEOLOGIC CONDITIONG..... fesseveses sseceossrseres 2.1. Groundwater Conditions eae peers Seer feet) peeeeee penetrates 2.1.1. Geology and Aquifer System ee a 2.1.2. Groundwater Levels 2.1.3. Groundwater Quality. a seeeaeeeeeeseees a ee 13 2.2. Twitchell Reservoir Operations. otsesssseseissse eseeeessesscses pecteeesects) ee sensueuranssess 15 2.2.1. Reservoir Stage and Storage pee es perrererssre| peers eee 15 2.2.2. Reservoir Releases.. 17 2.3. Streams. ee Sees See es ee ee ee 17 2.3.1. Discharge eee See cerreeseneses ee a ee 17 23:2. Surface Water Quality esteeteceeceneseecese eaerieeritsserss fsvrerstssre) ronserssonee i onsteseosetes 20 2.4. Climate. 21 2.4.1. Precipitation ae eas ee eee ee ee 22 2.4.2. Evapotranspiration.... a ne ee a 22 3 WATER REQUIREMENTS AND WATER SUPPLIES. ateseseeeeeee Beeseeeacces| peceeeeees a 24 3.1. Agricultural Water Requirements and Supplies oe pete Boe erecers ees Seeeerees eres a 24 3.1.1. Land Use .... seaverarears earersse feasevavrasevoa deeshsrassoresn caseunssantorers sebnnverernsrsrere 24 3.1.2. Applied Crop Water Requirements pees eee ee oe 25 3.1.3. Total Agricultural Water Requirements. a a a — 27 3.1.4. Agricultural Groundwater Pumping a ee ere pee 27 3.2. Municipal Water Requirements and Supplies saeavevenrt daseversevsesrs setseversoresers earsea 27 3.2.1. Municipal Groundwater Pumping sara doveatorsvratsr sysiesesexevessn sexsessexsssees Setinsvantonevento 28 3.2.2. Imported Water ee ee eee ee ae 29 3.2.3. Total Municipal Water Requirements ee Se a eo 30 LSCE 2019 ANNUAL REPORT OF HYDROGEOLOGIC CONDITIONS APRIL 29, 2020 WaTER REQUIREMENTS, SUPPLIES, AND DISPOSITION 3.3. Total Water Requirements and Supplies. eae ees peer steer pe eee 30 4 WATER DISPOSITION.... Becceeercce| a a Serer peeeeneee pecceeeceee| 32 4.1. Agricultural Return Flows a peer eereee os ee ee ee 32 4.2. Municipal Return Flows pera peered ee 33 4.3. Agricultural Drainage .. 35 44, Intra-Basin Water Transfer... Peres seers es peers peereesreer| peeetees pees 35 5 CONCLUSIONS AND RECOMMENDATIONS sees a a eserseres ee 37 5.1. Conclusions. 37 5.1.1. Hydrogeologic Conditions Pere nces peer) pacers Peeters 37 5.1.2. Water Requirements, Supplies, and Disposition tees ee : seeeeeeseees 33 5.1.3. Stipulation ee ee sere ete ee pee eee 39 5.2. Recommendations 39 6 REFERENCES a seseaeeenen ssesesesensel a pececeeeccesl aeeeeeeee ee 42 LIST OF APPENDICES AppendixA SMVMA Monitoring Program Appendix B Historical Groundwater Quality, Coastal Monitoring Wells Appendix C 2018 Revised Agricultural Crop Information; 2018 and 2019 Land Use Inventory Appendix D Estimated Historical Return Flows, Waste Water Treatment Plants Appendix E Calculation of Landscape Irrigation Return Flows, Annually from 2008 LSCE ii 2019 ANNUAL REPORT OF HYDROGEOLOGIC CONDITIONS APRIL 29, 2020 WATER REQUIREMENTS, SUPPLIES, AND DISPOSITION LIST OF TABLES Table 2.3-1 Selected General Mineral Constituent Concentrations, Santa Maria Valley Streams Table 2.4-1 Precipitation Data, 2019, Santa Maria Airport Table 2.4-2 Reference Evapotranspiration and Precipitation Data, 2019, SMVMA CIMIS Stations Table 3.1-1a Distribution of Irrigated Acreage, 2019 Table 3.1-1b Historical Distribution of Irrigated Acreage Table 3.1-1c Applied Crop Water Requirements and Total Agricultural Water Requirements, 2019 Table 3.2-1a Municipal Groundwater Pumpage, 2019 Table 3.2-1b Municipal State Water Project Water Deliveries, 2019 Table 3.2-1c Historical Municipal Water Requirements and Supplies Table 3.3-1a Total Water Requirements and Supplies, 2019 Table 3.3-1b Recent Historical Total Water Supplies Table 4.1-1 Applied Crop Water Requirements, Total Agricultural Water Requirements and Return Flows, 2019 Table 4.2-1 Treated Municipal Waste Water Discharge, 2019 Table 4.2-2 Estimated Recent Historical Return Flows from WWTPs and Landscape Irrigation Table 5.1-1 Summary of 2019 Total Water Requirements, Water Supplies, and Disposition LIST OF FIGURES Figure 1.1-1 Santa Maria Valley Groundwater Basin and Management Area Figure 2.1-1a Generalized Geologic Map with Cross Section Locations Figure 2.1-1b Longitudinal Geologic Cross Section, A-A’ Figure 2.1-1c Transverse Geologic Cross Section, B-B’ Figure 2.1-2 Historical Groundwater Levels Figure 2.1-3a Contours of Equal Groundwater Elevation, Shallow Zone, Spring 2019 Figure 2.1-3b Contours of Equal Groundwater Elevation, Shallow Zone, Fall 2019 LSCE iii 2019 ANNUAL REPORT OF HYDROGEOLOGIC CONDITIONS APRIL 29, 2020 WATER REQUIREMENTS, SUPPLIES, AND DISPOSITION Figure 2.1-3c Contours of Equal Groundwater Elevation, Deep Zone, Spring 2019 Figure 2.1-3d Contours of Equal Groundwater Elevation, Deep Zone, Fall 2019 Figure 2.1-4a Seasonal Groundwater Level Fluctuations, Northern Santa Maria Valley Figure 2.1-4b Seasonal Groundwater Level Fluctuations, Southern Nipomo Mesa Figure 2.1-5 Historical Groundwater Quality Figure 2.2-1a Historical Stage and Storage, Twitchell Reservoir Figure 2.2-1b Historical Releases, Twitchell Reservoir Figure 2.3-1a Historical Surface Water Discharge, Cuyama River and Twitchell Reservoir Figure 2.3-1b Historical Stream Discharge, Sisquoc River Figure 2.3-1c Historical Stream Discharge, Santa Maria River at Suey Crossing Figure 2.3-1d Historical Stream Discharge, Santa Maria River at Guadalupe Figure 2.3-1e Historical Stream Discharge, Orcutt Creek near Orcutt Figure 2.3-2a Historical Surface Water Quality, Sisquoc River near Sisquoc Figure 2.3-2b Historical Surface Water Quality, Orcutt Creek near Orcutt Figure 2.4-1 Historical Precipitation and Departure from Mean, Santa Maria Airport Figure 2.4-2 Historical Reference Evapotranspiration, CIMIS Stations Figure 3.1-1a Agricultural Land Use, 2019 Figure 3.1-1b Historical Distribution of Irrigated Acreage, by Crop Category Figure 3.1-1c Historical Agricultural Acreage and Groundwater Pumping Figure 3.2-1a Historical Municipal Groundwater Pumping Figure 3.2-1b Historical State Water Project Deliveries Figure 3.2-1¢ Historical Municipal Water Requirements Figure 3.3-1 Historical Total Water Requirements LSCE iv 2019 ANNUAL REPORT OF HYDROGEOLOGIC CONDITIONS APRIL 29, 2020 WATER REQUIREMENTS, SUPPLIES, AND DISPOSITION LIST OF ACRONYMS AND ABBREVIATIONS af acre-feet afy acre-feet per year af/ac acre-feet/acre AW applied water CASGEM California Statewide Groundwater Elevation Monitoring Program CCAMP Central Coast Ambient Monitoring Program CCRWQCB Central Coast Regional Water Quality Control Board CCWA Central Coast Water Authority cfs cubic feet per second CIMIS California Irrigation Management Information System DU Distribution Uniformity DPR Department of Pesticide Regulation DWR Department of Water Resources ET evapotranspiration ETaw ET of applied water ET. ET of the crop ETo Reference ET Fm Formation GIs Geographic Information System GPD Gallons per day GSWC Golden State Water Company K crop coefficient Laguna CSD Laguna County Sanitation District LSCE Luhdorff & Scalmanini, Consulting Engineers me/L milligrams per liter MOU Memorandum of Understanding msl mean sea level Nipomo CSD Nipomo Community Services District LSCE 2019 ANNUAL REPORT OF HYDROGEOLOGIC CONDITIONS APRIL 29, 2020 WATER REQUIREMENTS, SUPPLIES, AND DISPOSITION NMMA Nipomo Mesa Management Area NMMA-TG Nipomo Mesa Management Area-Technical Group NO3-NO3 nitrate-as-nitrate NOAA National Oceanic and Atmospheric Administration Pe effective precipitation PUR Pesticide Use Report SBCFC&WCD Santa Barbara County Flood Control and Water Conservation District SBCWA Santa Barbara County Water Agency SCWC Southern California Water Company SGMA Sustainable Groundwater Management Program SLODPW San Luis Obispo County Department of Public Works SMVMA Santa Maria Valley Management Area SMVWCD Santa Maria Valley Water Conservation District swe State Water Project SWRCB State Water Resources Control Board TDS Total Dissolved Solids TMA Twitchell Management Authority UCCE University of California Cooperative Extension USDA United States Department of Agriculture USGS United States Geological Survey WIP Waterline Intertie Project WWTP. waste water treatment plant LSCE vi 2019 ANNUAL REPORT OF HYDROGEOLOGIC CONDITIONS APRIL 29, 2020 WATER REQUIREMENTS, SUPPLIES, AND DISPOSITION 4 INTRODUCTION This annual report of conditions in the Santa Maria Valley Management Area, for calendar year 2019, has been prepared to meet the reporting conditions of the June 30, 2005, Stipulation entered by the Superior Court of the State of California, County of Santa Clara, in the Santa Maria Valley Groundwater Basin litigation. The Stipulation divided the overall Santa Maria Valley Groundwater Basin into three management areas, the largest of which overlies the main Santa Maria Valley (the Santa Maria Valley Management Area, or SMVMA) and is the subject of this report. The other two management areas, the Nipomo Mesa Management Area (NMMA) and the Northern Cities Management Area, are addressed in separate annual reports prepared by others. The Stipulation, approved and implemented in 2008, specifies that monitoring shall be sufficient to determine groundwater conditions, land and water uses, sources of water supply, and the disposition of all water supplies in the Basin. Annual Reports for the SMVMA are to summarize the results of the monitoring and include an analysis of the relationship between projected water demand and supply. The Stipulation was preserved in the California Court of Appeal (Sixth Appellate District) Decision of November 21, 2012, and in the Superior Court of the State of California (County of Santa Clara) Final Judgment of April 23, 2014. Thus, the Physical Solution criteria for monitoring and managing groundwater in the basin remain. In accordance with the Stipulation, this report on the SMVMA provides a description of the physical setting and briefly describes previous studies conducted in the groundwater basin, including the long- term monitoring program developed for the SMVMA. As reported herein, the Twitchell Management Authority (TMA) commissioned the preparation ofa monitoring program for the SMVMA in 2008, and its complete implementation is expected to provide the data with which to fully assess future conditions. This report describes hydrogeologic conditions in the management area historically and through 2019, including groundwater conditions, Twitchell Reservoir operations, and hydrologic and climatic conditions. As with all previous annual reports (commencing in 2008), the water requirements and supplies for agricultural and municipal uses are accounted, as are the components of water disposition in the SMVMA. Conclusions drawn regarding water resource conditions are discussed, including any finding of severe water shortage, which is concluded to not be the case through 2019. Finally, recommendations are provided regarding the enhancement of groundwater recharge and expansion of the SMVMA monitoring program. 1:1, Physical Setting The Santa Maria Valley Management Area (SMVMA) includes approximately 175 square miles of the Santa Maria Valley Groundwater Basin in northern Santa Barbara and southern San Luis Obispo Counties, as shown by the location map of the area (Figure 1.1-1). The SMVMA encompasses the contiguous area of the Santa Maria Valley, Sisquoc plain, and Orcutt upland, and is primarily comprised of agricultural land and areas of native vegetation, as well as the urban areas of Santa Maria, Guadalupe, Orcutt, Sisquoc, and several small developments. Surrounding the SMVMA are the Casmalia and Solomon Hills to the south, the San Rafael Mountains to the southeast, the Sierra Madre Mountains to LSCE 2019 ANNUAL REPORT OF HYDROGEOLOGIC CONDITIONS APRIL 29, 2020 WATER REQUIREMENTS, SUPPLIES, AND DISPOSITION the east and northeast, the Nipomo Mesa to the north, and the Pacific Ocean to the west. The main stream is the Santa Maria River, which generally flanks the northern part of the Santa Maria Valley; other streams include portions of the Cuyama River, Sisquoc River and tributaries, and Orcutt Creek. 1.2. Previous Studies The first overall study of hydrogeologic conditions in the Santa Maria Valley described the general geology, as well as groundwater levels and quality, agricultural water requirements, and groundwater and surface water supplies as of 1930 (Lippincott, J.B., 1931). A subsequent comprehensive study of the geology and hydrology of the Valley also provided estimates of annual groundwater pumpage and return flows for 1929 through 1944 (USGS, Worts, G.F., 1951). A follow up study provided estimates of the change in groundwater storage during periods prior to 1959 (USGS, Miller, G.A., and Evenson, R.E., 1966). Several additional studies have been conducted to describe the hydrogeology and groundwater quality of the Valley (USGS, Hughes, J.L., 1977; California CCRWQCB, 1995) and coastal portion of the basin (California DWR, 1970), as well as overall water resources of the Valley (Toups Corp., 1976; SBCWA, 1994 and 1996). Of note are numerous land use surveys (California DWR, 1959, 1968, 1977, 1985, and 1995) and investigations of crop water use (California DWR, 1933, and 1975: Univ. of California Cooperative Extension, 1994; Hanson, B., and Bendixen, W., 2004) that have been used in the estimation of agricultural water requirements in the Valley. Investigation of the Santa Maria groundwater basin provided an assessment of hydrogeologic conditions, water requirements, and water supplies through 1997 and an evaluation of basin safe yield (LSCE, 2000). 1.3. SMVMA Monitoring Program In accordance with the Stipulation, a monitoring program was initially prepared in 2008 to provide the fundamental data for ongoing annual assessments of groundwater conditions, water requirements, water supplies, and water disposition in the SMVMA (LSCE, 2008). As a basis for designing the monitoring program, historical data on the geology and water resources of the SMVMA were compiled to define aquifer depth zones, specifically a shallow unconfined zone and a deep semi-confined to confined zone, into which a majority of monitored wells were classified based on well depth and completion information. Assessment of the spatial distribution of the wells throughout the SMVMA, as well as their vertical distribution within the aquifer system, provided the basis for designation of two well networks, one each for the shallow and deep aquifer zones. All network wells are to be monitored for groundwater levels, with a subset of those wells to be monitored for groundwater quality. Those wells with inconclusive depth and completion information were originally designated as unclassified wells; in 2009 and 2013, review of groundwater level and quality records allowed classification of some wells into the shallow or deep aquifer zones. Accordingly, the monitoring program was revised in 2009 and 2013 to reflect those minor changes to the well networks. Commencing in 2019, the US Geological Survey (USGS) ceased groundwater level measurements in a network of approximately 55 wells across the SMVMA, at the direction of the contracting agency, the Santa Barbara County Water Agency (SBCWA). Included in this network are about 30 wells useful for LSCE 2019 ANNUAL REPORT OF HYDROGEOLOGIC CONDITIONS APRIL 29, 2020 WATER REQUIREMENTS, SUPPLIES, AND DISPOSITION annual assessment of groundwater conditions in the SMVMA per Stipulation provisions; so those 2019 data were not collected or available for the 2019 assessment. Groundwater level data collected quarterly by the Santa Maria Valley Water Conservation District (SMVWCD, 28 wells in spring, 42 wells in fall) and semi-annually by the TMA under the California Statewide Groundwater Elevation Monitoring Program (CASGEM, an additional 10 wells) were the primary data useful for the 2019 assessment described later in this report. It is important to note that collaboration between the SMVWCD, the TMA, and LSCE in early 2020 resulted in the designation of a subset of 25 USGS wells for water level measurement. In addition, funds were secured for the semi-annual measurement of the well subset commencing in April 2020, with plans to develop longer term financing for their continued monitoring. When these changes to the SMVMA Monitoring Program (monitoring agency and frequency) are implemented successfully, the program will be revised. Related to the cessation of USGS water level monitoring in 2019, groundwater quality sampling conducted by the USGS was reduced in 2019, specifically to only about one-half the typical number of wells in the SMVMA monitoring program. As such, a limited amount of groundwater quality data was available from the USGS, augmented by data from water purveyors’ wells, for the 2019 assessment described later in this report. Additional work will be needed to restore the groundwater quality monitoring program for annual assessment of groundwater conditions. Surface water conditions are to be monitored, specifically Twitchell Reservoir releases, stage, and storage, and stream discharge and quality. Climatic conditions, specifically precipitation and reference evapotranspiration data, are to be monitored although, currently, the single California Irrigation Management Information System (CIMIS) climate station in the SMVMA (“Santa Maria II”) collects only precipitation data. The TMA is collaborating with DWR to locate and implement another CIMIS station in the SMVMA to provide both precipitation and reference evapotranspiration data. Revision of the SMVMA Monitoring Program will include the additional climate station when implemented. In addition to the hydrologic data described above, the monitoring program specifies those data to be compiled to describe agricultural and municipal water requirements and water supplies. These include land use surveys, to serve as a basis for the estimation of agricultural irrigation requirements, and municipal groundwater pumping and imported water records, including any transfers between purveyors. Lastly, the monitoring program for the SMVMA specifies water disposition data be compiled, including treated water discharged at waste water treatment plants (WWTPs) and any water transferred from the SMVMA to the NMMA. As part of this accounting, estimation is to be made of agricultural drainage from the SMVMA and return flows to the aquifer system. For reference, the SMVMA monitoring program is included in Appendix A. LSCE 2019 ANNUAL REPORT OF HYDROGEOLOGIC CONDITIONS APRIL 29, 2020 WATER REQUIREMENTS, SUPPLIES, AND DISPOSITION In order to complete this annual assessment of groundwater conditions, water requirements, water supplies, and water disposition in the SMVMA, the following data for this year were acquired from the identified sources: . groundwater level and/or quality data: the SMVWCD, the TMA, the Technical Group for the adjacent NUMA (NMMA-TG), the City of Santa Maria, the Golden State Water Company, and the City of Guadalupe; the USGS; the California Department of Public Health and the Central Coast Regional Water Quality Control Board (CCRWQCB); and the Laguna County Sanitation District (Laguna CSD). Twitchell Reservoir stage, storage, and release data: the SMVWCD; surface water discharge and/or quality data: the USGS and CCRWQCB; precipitation data: the National Weather Service of the National Oceanic and Atmospheric Administration (NOAA), California DWR, and SMVWCD; reference evapotranspiration and evaporation data: California DWR (CIMIS) and SMVWCD, respectively; agricultural land use data, aerial photography, and satellite imagery: Santa Barbara and San Luis Obispo County Agricultural Commissioner’s Offices; United States Department of Agriculture (USDA); and USGS; municipal groundwater pumping and imported water data: the City of Santa Maria, the City of Guadalupe, and the Golden State Water Company; and treated municipal waste water data: the City of Santa Maria, the City of Guadalupe, the Laguna CSD, and the CCRWQCB. 1.4. Additional Monitoring and Reporting Programs In 2014, the TMA was designated by the California DWR as the Monitoring Entity for the SMVMA under DWR’s CASGEM Program. Compliance with the CASGEM Program requirements, which include at least semi-annual monitoring and reporting of groundwater levels in a subset of shallow and deep wells already within the SMVMA Monitoring Program, is fulfilled by the TMA. Additionally, in 2016, groundwater resource planning and data reporting requirements under the California DWR Sustainable Groundwater Management Program (SGMA) commenced. Since the SMVMA is part of an adjudicated basin, DWR considers it already managed by the Court and, thus, SGMA groundwater resource planning requirements do not apply. The remaining SGMA requirements for reporting water resources data such as groundwater levels, groundwater pumping, and imported water amounts, are fulfilled by LSCE in its capacity as Management Area Engineer under the Stipulation. 1.5. Report Organization To comply with items to be reported as delineated in the Stipulation, this annual report is organized into five chapters: . this Introduction; LSCE 2019 ANNUAL REPORT OF HYDROGEOLOGIC CONDITIONS APRIL 29, 2020 WATER REQUIREMENTS, SUPPLIES, AND DISPOSITION discussion of Hydrogeologic Conditions, including groundwater, Twitchell Reservoir, surface streams, and climate; description and quantification of Water Requirements and Water Supplies for the two overall categories of agricultural and municipal land and water use in the SMVMA; description and quantification of Water Disposition in the SMVMA; and summary Conclusions and Recommendations related to findings regarding water resource conditions in the SMVMA, for this year as well as historically, and recommended actions pertaining to enhanced groundwater recharge, intra-basin water transfer (SMVMA to NMMA), and expansion of the SMVMA monitoring program. LSCE 2019 ANNUAL REPORT OF HYDROGEOLOGIC CONDITIONS APRIL 29, 2020 WATER REQUIREMENTS, SUPPLIES, AND DISPOSITION 2 HYDROGEOLOGIC CONDITIONS Current and historical hydrogeologic conditions in the SMVMA, including groundwater conditions, Twitchell Reservoir operations, and stream and climate conditions, are described in the following sections of this Chapter. 2.1, Groundwater Conditions To provide a framework for discussion of groundwater conditions, the geology of the SMVMA, including geologic structure and the nature and extent of geologic formations comprising the aquifer system, is described in the following section. Current groundwater levels are then described in relation to historical trends in groundwater levels and flow directions in the SMVMA, as well as in context of Stipulation protocol for defining conditions of severe water shortage. Current and historical groundwater quality conditions are also discussed, including general groundwater quality characteristics as well as groundwater quality degradation, specifically due to elevated nitrate concentrations. Ze. Geology and Aquifer System The SMVMA is underlain by unconsolidated alluvial deposits that comprise the aquifer system, primarily gravel, sand, silt and clay that cumulatively range in thickness from about 200 to 2,800 feet (ft). The alluvial deposits fill a natural trough, which is composed of older folded and consolidated sedimentary and metamorphic rocks with their deepest portions beneath the Orcutt area. The consolidated rocks also flank the Valley and comprise the surrounding hills and mountains; typically, the consolidated rocks do not yield significant amounts of groundwater to wells. The geologic formations comprising the alluvial deposits and the geologic structure within the study area are illustrated in a generalized geologic map (Figure 2.1-1a) and two geologic cross sections (Figures 2.1-1b and 2.1-1c). The alluvial deposits are composed of the Careaga Sand and Paso Robles Formation (Fm.) at depth, and the Orcutt Fm., Quaternary Alluvium, and river channel, dune sand, and terrace deposits at the surface (USGS, Worts, G.F., 1951). The Careaga Sand, which ranges in thickness from about 650 ft to a feather edge, is identified as being the lowermost fresh water-bearing formation in the basin (DWR, 1970), resting on the above-mentioned consolidated rocks (specifically, the Tertiary-aged Foxen Mudstone, Sisquoc Fm., and Monterey Shale and the Jurassic/Cretaceous-aged Franciscan Fm., descriptions of which may be found in USGS, Worts, G.F., 1951). Overlying the Careaga Sand is the Paso Robles Fm., which comprises the greatest thickness of the alluvial deposits (from about 2,000 ft to a feather edge); the thickest portion of this formation is located beneath the Orcutt area. Both the Careaga Sand and Paso Robles Fm. underlie the great majority of the SMVMA (see Figures 2.1-1b and 2.1-1c). The Careaga Sand is mainly composed of white to yellowish-brown, loosely consolidated, massive, fossiliferous, medium- to fine-grained sand with some silt and is reported to be predominantly of marine origin (USGS, Worts, G.F., 1951). The Paso Robles Fm. is highly variable in color and texture, generally composed of yellow, blue, brown, grey, or white lenticular beds of: boulders and coarse to fine gravel and clay, medium to fine sand and clay, gravel and sand, silt, and clay (USGS, Worts, G.F., 1951). This formation is reported to be primarily fluvial (stream-laid) in origin and there is no areal correlation LSCE 2019 ANNUAL REPORT OF HYDROGEOLOGIC CONDITIONS APRIL 29, 2020 WATER REQUIREMENTS, SUPPLIES, AND DISPOSITION possible between the individual beds, with the exception of a coarse basal gravel of minor thickness in the Santa Maria Valley oil field, generally in the southeast part of the SMVMA. Above the Paso Robles Fm. and comprising the Orcutt Upland is the Orcutt Fm., which is typically about 160 to 200 ft thick; in the remainder of the SMVMA, the Paso Robles Fm. is overlain by the Quaternary Alluvium, which comprises the majority of the Valley floor and is typically about 100 to 200 ft thick. Further north in the adjacent NMMA, the Paso Robles Fm. is overlain by the Older Dune Sand, which comprises the Nipomo Mesa and ranges in thickness from approximately 400 ft to a feather edge. Along the northeast edge of the Sisquoc plain, the Paso Robles Fm. is overlain by terrace deposits approximately 60 ft thick. The Orcutt Fm. is composed of conformable upper and lower units (“members”), both reported to be mainly of fluvial origin that become finer toward the coast. The upper member generally consists of reddish-brown, loosely compacted, massive, medium-grained clean sand with some lenses of clay, and the lower member is primarily grey to white, loosely compacted, coarse-grained gravel and sand (USGS, Worts, G.F., 1951). The Quaternary Alluvium is also composed of upper and lower members that are reported to be mainly fluvial in origin. The composition of the upper member becomes progressively finer toward the coast, with boulders, gravel, and sand in the Sisquoc plain area; sand with gravel in the eastern/central Valley area; sand with silt from the City of Santa Maria to a point approximately halfway to Guadalupe; and clay and silt with minor lenses of sand and gravel from that area westward. The lower member is primarily coarse-grained boulders, gravel and sand with minor lenses of clay near the coast. The Older Dune Sand is composed of loosely- to slightly compacted, massive, coarse- to fine-grained, well- rounded, cross-bedded quartz sand that is locally stained dark reddish-brown (California DWR, 1999). The terrace deposits, in general, are similar in composition to the coarse-grained parts of the Quaternary Alluvium. The alluvial deposits comprising the aquifer system lack peat (organic) layers and include thin, discontinuous clay lenses, without thick sections of clay at greater depths. Thus, the potential is remote for deep land subsidence to occur as the deposits dewater during periods of declining groundwater levels. There are no known reports of, nor the potential for, land subsidence in the SMVMA, as noted in a recent technical report on the occurrence of subsidence through California (California DWR, 2014). Two geologic cross sections illustrate several points about the geologic structure and variable aquifer thickness throughout the SMVMA. Longitudinal geologic cross section A-A’ (see Figure 2.1-1b) begins in the area near the mouth of the Santa Maria River, traverses the Orcutt Upland, and terminates in the Sisquoc plain area near Round Corral, immediately southeast of the SMVMA. It shows the relative thicknesses of the various geologic formations and their general “thinning” from the central valley area toward the Sisquoc plain. This cross section also shows the Quaternary Alluvium and Orcutt Fm., essentially adjacent to each other and comprising the uppermost aquifer in the SMVMA, divided into the above-described upper and lower members. LSCE 2019 ANNUAL REPORT OF HYDROGEOLOGIC CONDITIONS APRIL 29, 2020 WATER REQUIREMENTS, SUPPLIES, AND DISPOSITION Transverse geologic cross section B-B’ (see Figure 2.1-1c) begins in the Casmalia Hills, traverses the western portion of the Valley (near the City of Guadalupe) and the southern Nipomo Mesa, and terminates at Black Lake Canyon. It shows the prominent asymmetrical syncline (folding of the consolidated rocks and Paso Robles Fm.) within the SMVMA and adjacent NMMA, with the deepest portion of Paso Robles Fm. toward the southern edge of the SMVMA, gradually becoming thinner and more shallow toward the north where it extends beneath the NMMA. This cross section also shows that both the upper and lower members of the Quaternary Alluvium extend north to the Santa Maria River, but only the upper member extends beyond the River to the southern edge of the Nipomo Mesa, and neither member extends northward beneath the Mesa. Several faults have been reported to be located in the SMVMA and adjacent portion of the NUMA. The Santa Maria and Bradley Canyon faults, located in the Valley in the area between the City of Santa Maria and Fugler Point (at the confluence of the Cuyama and Sisquoc Rivers to form the Santa Maria River), are concealed and they are reported to be northwest-trending, high-angle faults, that vertically offset the consolidated rocks, Careaga Sand, and Paso Robles Fm., but not the overlying Quaternary Alluvium or Orcutt Fm. (USGS, Worts, G.F., 1951). The Oceano and Santa Maria River faults are ofa similar nature (the latter fault also has a significant strike-slip component of movement), but they are primarily located in the southern Nipomo Mesa. The maximum vertical offset on the Oceano fault is reported to be in the range of 300 to 400 ft within the Careaga Sand and Paso Robles Fm.; on the other faults, the vertical offset is reported to be much less, within the range of 80 to 150 ft (USGS, Worts, G.F., 1951; California DWR, 1999). However, these faults do not appear to affect groundwater flow within the SMVMA, based on the review of historical groundwater level contour maps (USGS, Worts, G.F., 1951; LSCE, 2000). There is no known structural (e.g., faulting) or lithologic isolation of the alluvial deposits from the Pacific Ocean, i.e., the Quaternary Alluvium, Orcutt Fm., Careaga Sand, and Paso Robles Fm. aquifers continue beneath the Ocean. Thus, there is geologic continuity that permits groundwater discharge from the SMVMA to the Ocean, and the potential exists for salt water to intrude into the coastal (landward) portions of the aquifers if hydrologic conditions within them were to change. The aquifer system in the SMVMA is comprised of the Carega Sand, Paso Robles Fm., the Orcutt Fm., and the Quaternary Alluvium (USGS, Worts, G.F., 1951). The upper member of the Quaternary Alluvium is consistently finer-grained than the lower member throughout the Valley. Further, the upper member becomes finer grained toward the Ocean such that it confines groundwater in the lower member from the approximate area of the City of Santa Maria's waste water treatment plant westward (approximately eight miles inland from the coast). The result of this has been some artesian conditions in the western valley area (historically, flowing artesian wells were reported until the early 1940s in the westernmost portion of the Valley) (USGS, Worts, G.F., 1951). More recently, many water supply wells belonging to local farmers in the western valley area, specifically in the Oso Flaco area, and monitoring wells located at the coast began flowing again in response to rising confined groundwater levels, such as during the winter of 1999. LSCE 2019 ANNUAL REPORT OF HYDROGEOLOGIC CONDITIONS APRIL 29, 2020 WATER REQUIREMENTS, SUPPLIES, AND DISPOSITION Analysis of the geology, groundwater levels, and groundwater quality indicates that the aquifer system varies across the area and with depth, and this variation was the basis for the shallow and deep aquifer zone designations of the SMVMA monitoring program (LSCE, 2008). In the central and major portion of the SMVMA, there is a shallow unconfined zone comprised of the Quaternary Alluvium, Orcutt Fm., and uppermost Paso Robles Fm., and a deep semi-confined to confined zone comprised of the remaining Paso Robles Fm. and Careaga Sand. In the eastern portion of the SMVMA where these formations are much thinner and comprised of coarser materials, particularly in the Sisquoc Valley, the aquifer system is essentially uniform without distinct aquifer depth zones. In the coastal area where the surficial deposits (upper members of Quaternary Alluvium and Orcutt Fm.) are extremely fine-grained, the underlying formations (lower members of Quaternary Alluvium and Orcutt Fm., Paso Robles Fm., and Careaga Sand) comprise a deep confined aquifer zone. 2.1.2. Groundwater Levels Groundwater levels within the SMVMA have fluctuated greatly since the 1920's, when historical water level measurements began, with marked seasonal and long-term trends, as shown by a collection of representative groundwater level hydrographs from various areas throughout the SMVMA (Figure 2.1- 2). The areas are designated on Figure 2.1-2 for illustrative purposes only, and include the so-called Coastal, Oso Flaco, Central Agricultural, Municipal Wellfield, Twitchell Recharge, and Sisquoc Valley areas. The historical groundwater level hydrographs illustrate that widespread decline in groundwater levels, from historical high to historical low levels, occurred between 1945 and the late 1960's. The declines ranged from approximately 20 to 40 ft near the coast, to 70 ft near Orcutt, to as much as 100 feet further inland (in the area just east of downtown Santa Maria). Those declines were observed in both the shallow and deep aquifer zones and are interpreted today to have been the combined result of progressively increasing agricultural (and to a lesser degree, municipal) demand and long-term drier than normal climatic conditions during that period. Since the late 1960’s, the basin has experienced a general long-term stability as groundwater levels in both aquifer zones have fluctuated between historical-low and near historical-high levels over alternating five- to 15-year periods. Groundwater levels throughout the SMVMA have shown this trend, but with different ranges of fluctuation (see Figure 2.1-2); and groundwater levels have repeatedly recovered to near or above previous historical-high levels, most recently in 2002. Shallow groundwater levels in the Sisquoc Valley fluctuated somewhat differently in that they did not fully recover to historical high levels by 2002. In the primary areas of recharge along the Santa Maria River, groundwater level fluctuations are greater in the shallow aquifer zone than the deep