Hydrogeologic Data from the Cahuilla Valley and Terwilliger Valley Groundwater Basins, Riverside County, California, 2022 (ver. 2.0, August 2025)

The U.S. Geological Survey (USGS) entered into a cooperative study with the California Department of Water Resources and the Ramona Band of Cahuilla to characterize the hydrogeology of the Cahuilla Valley and Terwilliger Valley groundwater basins and surrounding water-bearing units, with the ultimate goal of developing a calibrated integrated hydrologic model to manage the groundwater supplies on a sustainable basis. A three-dimensional geologic framework model (GFM) was developed to quantify the structural geometry and distribution of water-bearing units in the groundwater basins, using borehole lithology and hydraulic information, geologic maps, and gravity-derived depth-to-basement information. This dataset includes (1) tabular data of selected boreholes with their location and construction information, (2) borehole lithology information, (3) a geographic information systems (GIS) shapefile of a cellular array containing interpolated elevations and thicknesses of modeled geologic units from the GFM in the format of a polygon feature class, (4) and a table of summary textural classes for the alluvial fill unit from borehole logs and summary textural classes used in geologic framework model.
Version History Summary
Version 1: August 2022
Version 2: August 2025