Generalized use classification for groundwater sites in California with publicly available water-quality data in the U.S. Geological Survey National Water Information System (NWIS) data archive (ver. 1.1, April 2025)

The U.S. Geological Survey Water Data for the Nation (WDFN; U.S. Geological Survey, 2025) data archive contains publicly available water-quality data for approximately 21,000 groundwater wells and springs in California. This data release publishes site type information and a generalized use classification for each site. The generalized use category is derived from, but is not equivalent to, the use of site and use of water fields from the WDFN data archive. The use of site and use of water fields in the WDFN data archive are not publicly available. The 21,000 groundwater wells and springs were categorized into seven generalized use categories: 1) domestic, 2) irrigation, 3) production, 4) water supply, other, 5) observation, 6) other, and 7) unknown. A similar classification system was used by Jurgens and others (2021) to categorize sites sampled by the USGS for the California State Water Resources Control Boards' (SWRCB) Groundwater Ambient Monitoring and Assessment Program Priority Basin Project (GAMA-PBP). The classification presented here only uses information from the use of site and use of water fields in the WDFN data archive; the classification presented by Jurgens and others (2021) considered additional information collected by the GAMA-PBP about the sites. The SWRCB's GAMA Groundwater Information System (GAMAGIS) also serves USGS WDFN data, along with data from other federal, state, and local agency sources. The generalized use categories in this data release are compatible with use categories defined in SWRCB GAMAGIS. Prior to publication of this data release, SWRCB GAMAGIS classified all groundwater sites in WDFN, except those sampled by the GAMA-PBP, as "water supply, other", which resulted in erroneous characterization of approximately 98 percent of the sites. The generalized use classification provided in this data release greatly improves the accuracy of site characterization, while still complying with Federal policies concerning release of location information for some types of sites.

Version 1.0 posted September 14, 2022
Version 1.1 posted April 14, 2025

References: Jurgens, B.C., Stork, S.V., and Fram, M.S., 2021, Water use information for sites sampled by the California Groundwater Ambient Monitoring and Assessment Program Priority Basin Project (GAMA-PBP), 2004-2021 (ver. 4.0, April 2025): U.S. Geological Survey data release, https://doi.org/10.5066/P9EHLFZM.