Elise Watson Tyler D. Johnson Danielle I. Dupuy 20230124 Vector Digital Data Set (Polygon) https://doi.org/10.5066/P931PZRC The California Groundwater Ambient Monitoring and Assessment Program (GAMA) is a statewide assessment of groundwater quality designed to help better understand and identify risks to groundwater resources. GAMA is implemented by the California State Water Resources Control Board. The U.S. Geological Survey (USGS) is the technical lead for the Priority Basin Project (PBP), one of the components of the GAMA Program. Starting in 2012, GAMA began an assessment of water resources in domestic-supply (shallow) aquifers in California. These aquifers provide water for domestic and small community-supply wells, which are often drilled to shallower depths in the groundwater system than public-supply wells. Domestic-supply aquifers are of interest because shallow groundwater may respond more quickly and be more susceptible to contamination from human activities at the land surface, than the deeper aquifers (USGS, 2018). To prioritize domestic-supply aquifers, California was divided into 938 groundwater units consisting of California Department of Water Resources (DWR) groundwater basins and highland areas outside of the basins defined by California Groundwater Units (Johnson and Belitz, 2014) or Hydrologic Units (HUC8) from the Watershed Boundary Dataset (USGS and USDA, 2013). The groundwater units were prioritized for sampling based on the number and density of households relying on domestic wells, water-use, and well-location information compiled from well-completion reports submitted to the DWR. The groundwater units were grouped into study units designed to facilitate comparison of groundwater quality between the shallow aquifer systems and the deep aquifer systems assessed by GAMA from 2004 to 2012 (Bennett, 2018). The study units (and study areas when applicable) were divided into equal area polygons (cells) so that all cells within a given study unit (or study area) have an equal area. These grid cells can be found in the GAMA_PBP_SAA_GridCells shapefile included in this Data Release. Version Notes: This Data Release supersedes the data release published in 2020 (version 1). This data release was updated to include study units sampled since the initial publication. Also, report references for all version 1 study units have been updated to reflect the most recent publications for each study unit. In addition, study unit names were updated to be listed as the full name instead of the study unit abbreviations used in version 1. Minor revisions were also made to the metadata text. The version 1 data release may be obtained by contacting the dataset Point of Contact. This digital data set was created as part of the study design for a statewide, comprehensive groundwater monitoring and assessment program (Belitz and others, 2003; Belitz and others, 2015; California State Water Resources Control Board, 2003). The purpose of this publication is to collect and assemble all of the study unit boundaries into a single GIS dataset. At the time of this publication, a total of 16 study units have been sampled, ranging from 1964 to 9843 square kilometers in size. Additional study units sampled as part of the GAMA program will be added to this data set when sampling for new study units is completed. See the Cross Reference section for related publications. For more information on sampling design, see the individual Study Unit reports (listed in the Entity and Attribute Information section). 2012 2022 ground condition Planned As needed -124.4445 -113.7503 42.0432 32.4890 ISO 19115 Topic Category inlandWaters environment USGS Thesaurus water-quality Groundwater drinking water None GAMA Priority Basin Project shallow aquifer domestic wells domestic-supply aquifer USGS Metadata Identifier USGS:637d5d0dd34ed907bf745e3a Common geographic areas California United States None Although this data set has been used by the U.S. Geological Survey, U.S. Department of the Interior, no warranty expressed or implied is made by the U.S. Geological Survey as to the accuracy of the data and related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the U.S. Geological Survey in the use of this data, software, or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Elise Watson U.S. Geological Survey, SOUTHWEST REGION Physical Scientist mailing address

4165 Spruance Road

San Diego CA 92101-0821 US 619-225-6426 619-225-6436 ewatson@usgs.gov US Geological Survey California Water Science Center Groundwater Ambient Monitoring and Assessment Program Esri ArcGIS 10.5 (Build 6491) Service Pack N/A (Build N/A) Kenneth Belitz Neil M. Dubrovsky Karen Burow Bryant C. Jurgens Tyler D. Johnson 2003 publication n/a US Geological Survey http://pubs.usgs.gov/wri/wri034166/ https://doi.org/10.3133/wri034166 Kenneth Belitz Miranda S. Fram Tyler D. Johnson 20150709 publication Environmental Science & Technology vol. 49, issue 14 n/a American Chemical Society (ACS) ppg. 8330-8338 https://doi.org/10.1021/acs.est.5b00265 George L. Bennett V 2018 publication n/a US Geological Survey https://doi.org/10.3133/sir20175051 California State Water Resources Control Board 200303 publication https://www.waterboards.ca.gov/publications_forms/publications/legislative/docs/2003/ab599.pdf Tyler D. Johnson Kenneth Belitz 2014 publication n/a US Geological Survey https://doi.org/10.3133/ds796 U.S. Geological Survey U.S. Department of Agriculture, Natural Resources Conservation Service 2013 4th publication https://pubs.usgs.gov/tm/11/a3/pdf/tm11-a3_4ed.pdf U.S. Geological Survey 201809 publication https://pubs.usgs.gov/fs/2012/3136/ No formal attribute accuracy tests were conducted. No formal logical consistency tests were conducted. Data set is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details. A formal accuracy assessment of the horizontal positional information in the data set has not been conducted. A formal accuracy assessment of the vertical positional information in the data set has either not been conducted, or is not applicable. California Department of Water Resources 2003 publication 246 p. https://cawaterlibrary.net/wp-content/uploads/2003/10/Bulletin_118_Update_2003.pdf Digital and/or Hardcopy 2003 publication date CDWR 2003 The groundwater basins were used in the design of the study units. California Department of Water Resources 2016 vector digital data 45 p. https://water.ca.gov/Programs/Groundwater-Management/Bulletin-118 Digital and/or Hardcopy 2016 publication date CDWR 2016 The groundwater basins were used in the design of the study units. California Department of Water Resources 2018 vector digital data This dataset was downloaded from https://sgma.water.ca.gov/webgis/?appid=SGMADataViewer#boundaries. https://gis.water.ca.gov/arcgis/rest/services/Geoscientific/i08_B118_CA_GroundwaterBasins/FeatureServer Digital and/or Hardcopy 2018 publication date CDWR 2018 The groundwater basins were used in the design of the study units. Tyler D. Johnson Kenneth Belitz 2003 vector digital data n/a US Geological Survey https://doi.org/10.3133/ofr03470 Digital and/or Hardcopy 2003 publication date Johnson and Belitz 2003 The Province boundaries were used in the design of the study units. Tyler D. Johnson Kenneth Belitz 2014 vector digital data n/a US Geological Survey https://doi.org/10.3133/ds796 Digital and/or Hardcopy 2014 publication date Johnson and Belitz 2014 The groundwater units were used in the design of the study units. Stamos, C.L., Martin, P., Nishikawa, T., and Cox, B.F 2001 publication n/a US Geological Survey https://doi.org/10.3133/wri014002 Digital and/or Hardcopy 2001 publication date Stamos and others 2001 The model extent was used for the design of the Mojave Shallow study unit. U.S. Geological Survey, U.S. Department of Agriculture, and Natural Resources Conservation Service, 2013 4 vector digital data https://pubs.usgs.gov/tm/11/a3/pdf/tm11-a3_4ed.pdf Digital and/or Hardcopy 2013 publication date WBD The groundwater basins were used in the design of the Yuba and Bear Watersheds Shallow and the North and South American, Cosumnes, and Mokelumne River Watersheds Shallow study units. S1: The Alexander, Kenwood, Napa-Sonoma, Petaluma, Santa Rosa, Sonoma Valley, and Wilson Grove Formation Highlands groundwater basin polygons were extracted from the CDWR 2003 source dataset. In addition, the Highlands groundwater units (Johnson and Belitz, 2014) associated with these groundwater basins were included to define the North San Francisco Bay Basins and adjacent highlands Domestic-supply Aquifer study unit. 2012 S2: Several groundwater basin polygons were extracted from CDWR 2003 as well as highlands groundwater units outside of the Salinas and Paso Robles Valleys (Johnson and Belitz, 2014) to define the Monterey Bay and Salinas Valley Basins and adjacent highlands Domestic-supply Aquifer study unit. These include the Santa Cruz, Purisima Formation Highlands, Felton Area, Scotts Valley, Soquel Valley, West Santa Cruz Terrace, Pajaro Valley, 180/400 Foot Aquifer, Seaside Area, Corral de Tierra Area, Langley Area, Eastside Aquifer, Forebay Aquifer, Upper Valley Aquifer, and the Quaternary alluvium part of the Paso Robles Area basin. The highlands area was trimmed to exclude a western portion for which there was little well driller’s log information. A 3 kilometer buffer of the Salinas and Paso Robles alluvial area was generated and any watersheds (WBD) outside of the alluvial buffer were excluded from the final study unit boundary. 2012 S3: The Madera, Chowchilla, and Kings groundwater sub basins were extracted from the CDWR 2003 groundwater basin source dataset to define the Madera, Chowchilla, and Kings Basins Domestic-supply Aquifer study unit. 2013 S4: Five selected groundwater unit polygons were extracted from CDWR 2003 to define the Kaweah, Tule, and Tulare Lake Basins and adjacent highlands Domestic-supply Aquifer study unit. These groundwater units include the Tule, Tulare, and Kaweah groundwater basins and the highlands areas for the Kaweah and Tule basins. The Highlands area was extracted from Johnson and Belitz, 2014. 2014 S5: The Upper Bear and Upper Yuba watershed polygons were extracted from the WBD source dataset to define the Yuba and Bear River Watersheds Domestic-supply Aquifer study unit. The two watersheds were clipped to the Sierra Nevada Province from the CA hydrogeologic provinces dataset (Johnson and Belitz, 2003). 2015 S6: The watershed polygons of North American, South American, Cosumnes, and the Mokelumne were extracted from the WBD source dataset to define the Mokelumne, Cosumnes, and American River Watersheds Domestic-supply Aquifer study unit. The watersheds were clipped to the Sierra Nevada Province from the CA hydrogeologic provinces dataset (Johnson and Belitz, 2003). 2016 S7: The North American, South American, and Cosumnes groundwater unit polygons were extracted from CDWR 2016 to define the Cosumnes and American Basins Domestic-supply Aquifer study unit. The groundwater units are all located in the Central Valley hydrogeologic province defined by Johnson and Belitz, 2003. 2017 S8: The groundwater basin boundaries for the Upper Mojave River, Middle Mojave, Lower Mojave River, El Mirage, and Harper Valley were extracted from the CDWR 2003 source dataset to define the Western Mojave Desert Basins Domestic-supply Aquifer study unit. The Harper Valley groundwater basin was clipped to the extent of a regional groundwater flow model (Stamos and others, 2001) designed to model groundwater recharged from the Mojave River. 2017 S9: Groundwater unit polygons were extracted from CDWR 2016 to define the Northern Sacramento Valley Domestic-supply Aquifer study unit. These include the Enterprise, Millville, South Battle Creek, Bowman, Rosewood, Anderson, Bend, Antelope, Dye Creek, Los Molinos, and Red Bluff subbasins of the Sacramento Valley groundwater basin defined by CDWR 2003. 2018 S10: The Eastern San Joaquin Valley groundwater subbasin polygon from the CDWR 2018 source dataset was extracted to define the Northern San Joaquin Valley Domestic-supply Aquifer study unit. 2019 S11: The Desert Hot Springs, Mission Creek, Indio, and San Gorgonio groundwater subbasin polygons were extracted from the CDWR 2018 source dataset to define the Coachella Valley Domestic-supply Aquifer study unit. 2019 S12S13: Due to sampling constraints during the Corona virus pandemic, the S12 and S13 study units were condensed into a single study unit. The boundaries of the Merced, Modesto, and Turlock subbasin polygons (CDWR, 2018) were used to define the Modesto, Turlock, and Merced Basins Domestic-supply Aquifer study unit. The boundary of the Merced National Wildlife Refuge was excluded from a portion of the Merced subbasin. 20200623 S14: Several Sacramento Valley Basin subunits were extracted from CDWR 2018 to form the Butte, Sutter, and Yuba Basins and adjacent highlands Domestic-supply Aquifer study unit boundary. These include the Los Molinos, Vina, North Yuba, South Yuba, Sutter, Wyandotte Creek, and Butte subunits. Areas in the foothills of Los Molinos were also included using the county boundary minus areas that fell within the Northern Sacramento Valley Domestic-supply Aquifer study unit. 20210714 S15: The San Joaquin Valley-Kern County groundwater subbasin polygon from the CDWR 2018 source dataset was extracted to define the Kern Basin Domestic-supply Aquifer study unit. 202112 S16: The Gilroy-Hollister Valley and Gilroy-Hollister Valley Highlands groundwater units were selected from Johnson and Belitz, 2014 to form the Gilroy and Hollister Basins and adjacent highlands Domestic-supply Aquifer study unit. 20220329 Vector Simple FALSE 0 FALSE FALSE coordinate pair 0.6096 0.6096 meters D_North_American_1983 GRS_1980 6378137.0 298.257222101 Attribute Table Table containing attribute information associated with the data set. Producer defined Feature Class 0 FID Internal feature number. Esri Sequential unique whole numbers that are automatically generated. FID OID 4 0 0 Shape Feature geometry. Esri Coordinates defining the features. Shape Geometry 0 0 0 SU The study unit number and full name. Producer defined The study unit number and full name. SU String 150 0 0 AreaSqKm Area in square kilometers. Producer defined 1964 9843 AreaSqKm Double 19 0 0 Report_Ref References the USGS Data Series, Data Releases, or Scientific Investigation Report (SIR) that include more detailed information about the Study Unit. Study Units S14, S15, and S16 do not have associated reports at the time of this publication. Producer defined none A report for the study unit has not been published yet. Producer defined S1 Bennett, G.L., V, 2018, Status and understanding of groundwater quality in the North San Francisco Bay Shallow Aquifer study unit, 2012; California GAMA Priority Basin Project (ver. 1.1, February 2018): U.S. Geological Survey Scientific Investigations Report 2017-5051, 74 p., https://doi.org/10.3133/sir20175051. Producer defined S2 Burton, C.A., and Wright, M.T., 2018, Status and understanding of groundwater quality in the Monterey-Salinas Shallow Aquifer study unit, 2012-13: California GAMA Priority Basin Project (ver. 1.1, September 2018): U.S. Geological Survey Scientific Investigations Report 2018-5057, 116 p., https://doi.org/10.3133/sir20185057. Producer defined S3 Fram, M.S. and Shelton, J.L., 2018, Groundwater Quality in the Shallow Aquifers of the Madera–Chowchilla and Kings Subbasins, San Joaquin Valley, California: U.S. Geological Survey Open-File Report 2017–1162, 4 p., https://doi.org/10.3133/ofr20171162. Producer defined S4 Fram, M.S., 2017, Groundwater quality in the shallow aquifers of the Tulare, Kaweah, and Tule Groundwater Basins and adjacent highlands areas, Southern San Joaquin Valley, California: U.S. Geological Survey Fact Sheet 2017-3001, 4 p., https://doi.org/10.3133/fs2017300. Producer defined S5 Levy, Z.F., and Fram, M.S., 2021, Status and understanding of groundwater quality in the northern Sierra Nevada foothills domestic-supply aquifer study units, 2015–17—California GAMA Priority Basin Project: U.S. Geological Survey Scientific Investigations Report 2021–5019, 120 p., https://doi.org/10.3133/sir20215019. Producer defined S6 Levy, Z.F., and Fram, M.S., 2021, Status and understanding of groundwater quality in the northern Sierra Nevada foothills domestic-supply aquifer study units, 2015–17—California GAMA Priority Basin Project: U.S. Geological Survey Scientific Investigations Report 2021–5019, 120 p., https://doi.org/10.3133/sir20215019. Producer defined S7 Bennett, G.L., V, 2022, Status and understanding of groundwater quality in the Sacramento Metropolitan Domestic-Supply Aquifer study unit, 2017—California GAMA Priority Basin Project: U.S. Geological Survey Scientific Investigations Report 2022–5021, 52 p., https://doi.org/10.3133/sir20225021. Producer defined S8 Groover, K.D., and Goldrath, D.A., 2019, Groundwater quality in shallow aquifers in the western Mojave Desert, California: U.S. Geological Survey Fact Sheet 2019–3033, 4 p., https://doi.org/10.3133/fs20193033. Producer defined S9 Harkness, J.S., and Shelton, J.L., 2020, Groundwater quality in the Redding–Red Bluff shallow aquifer study unit of the northern Sacramento Valley, California: U.S. Geological Survey Fact Sheet 2020–3025, 4 p., https://doi.org/10.3133/fs20203025. Producer defined S10 Levy, Z.F., Balkan, M., and Shelton, J.L., 2021, Quality of groundwater used for domestic supply in the northern San Joaquin Valley, California: U.S. Geological Survey Fact Sheet 2021-3040, 4 p. https://doi.org/10.3133/fs20213040. Producer defined S11 Soldavini, A.L., Goldrath, D.A., Shelton, J.L., Johnson, T.D., and Watson, E., 2021, Groundwater-quality data in the Coachella Valley Domestic Supply Aquifer Study Unit, 2020: Results from the California GAMA Priority Basin Project (ver. 2.0, May 2022): U.S. Geological Survey data release, https://doi.org/10.5066/P9UYXI95. Producer defined S12 Balkan, M., Levy, Z.F., Dupuy, D.I., Shelton, J.L., Johnson, T.D., and Watson, E., 2021, Groundwater-quality data in the Modesto-Turlock-Merced Domestic-Supply Aquifer Study Unit, 2020-2021: Results from the California GAMA Priority Basin Project: U.S. Geological Survey data release, https://doi.org/10.5066/P96R55KQ. Producer defined Report_Ref String 5 0 0 StudyInfo StudyInfo String 254 0 0 Notes Notes String 254 0 0 USGS_SIte USGS_SIte String 254 0 0 SUNumber SUNumber Double 19 0 0 Photo Photo String 254 0 0 Data Data String 254 0 0 Shape_Leng Shape_Leng Double 19 0 0 Shape_Area Shape_Area Double 19 0 0 Area of feature in internal units squared. Esri Positive real numbers that are automatically generated. The entity and attribute information provided here describes the tabular data associated with the data set. Please review the detailed descriptions that are provided (the individual attribute descriptions) for information on the values that appear as fields/table entries of the data set. The entity and attribute information was generated by the individual and/or agency identified as the originator of the data set. Please review the rest of the metadata record for additional details and information. U.S. Geological Survey GS ScienceBase mailing address

Denver Federal Center, Building 810, Mail Stop 302

Denver CO 80225 United States 1-888-275-8747 sciencebase@usgs.gov Although this data set has been used by the U.S. Geological Survey, U.S. Department of the Interior, no warranty expressed or implied is made by the U.S. Geological Survey as to the accuracy of the data and related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the U.S. Geological Survey in the use of this data, software, or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Vector Digital Data Set (Polygon) https://doi.org/10.5066/P931PZRC None. No fees are applicable for obtaining the data set. 20230124 Elise Watson U.S. Geological Survey, SOUTHWEST REGION Physical Scientist mailing address

4165 Spruance Road

San Diego CA 92101-0821 US 619-225-6426 619-225-6436 ewatson@usgs.gov FGDC Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998 local time 20240809 14065900 1.0 FALSE GAMA_PBP_SAA_Study_Unit Boundaries 002 0.000 Projected GCS_WGS_1984 Linear Unit: Meter (1.000000) WGS_1984_Web_Mercator_Auxiliary_Sphere <ProjectedCoordinateSystem xsi:type='typens:ProjectedCoordinateSystem' xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' xmlns:xs='http://www.w3.org/2001/XMLSchema' xmlns:typens='http://www.esri.com/schemas/ArcGIS/3.3.0'><WKT>PROJCS[&quot;WGS_1984_Web_Mercator_Auxiliary_Sphere&quot;,GEOGCS[&quot;GCS_WGS_1984&quot;,DATUM[&quot;D_WGS_1984&quot;,SPHEROID[&quot;WGS_1984&quot;,6378137.0,298.257223563]],PRIMEM[&quot;Greenwich&quot;,0.0],UNIT[&quot;Degree&quot;,0.0174532925199433]],PROJECTION[&quot;Mercator_Auxiliary_Sphere&quot;],PARAMETER[&quot;False_Easting&quot;,0.0],PARAMETER[&quot;False_Northing&quot;,0.0],PARAMETER[&quot;Central_Meridian&quot;,0.0],PARAMETER[&quot;Standard_Parallel_1&quot;,0.0],PARAMETER[&quot;Auxiliary_Sphere_Type&quot;,0.0],UNIT[&quot;Meter&quot;,1.0],AUTHORITY[&quot;EPSG&quot;,3857]]</WKT><XOrigin>-20037700</XOrigin><YOrigin>-30241100</YOrigin><XYScale>148923141.92838538</XYScale><ZOrigin>-100000</ZOrigin><ZScale>10000</ZScale><MOrigin>-100000</MOrigin><MScale>10000</MScale><XYTolerance>0.001</XYTolerance><ZTolerance>0.001</ZTolerance><MTolerance>0.001</MTolerance><HighPrecision>true</HighPrecision><WKID>102100</WKID><LatestWKID>3857</LatestWKID></ProjectedCoordinateSystem> 20240905 13554000 20240905 13554000 Esri ArcGIS 13.3.0.52636 GAMA_PBP_SAA_Study_Unit Boundaries Shapefile 0.000 dataset EPSG 6.18.3(9.3.1.2) 0 20240905