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.

This digital data set contains the locations, water-level altitude, and water-level differences of 70 wells selected to document water-level changes between fall 2004 and spring 2005 in the Anza-Terwilliger area of Riverside County, California. The winter of 2005 was one of the wettest periods on record. Links to the U.S. Geological Survey National Water Information Systems Website (NWISWeb) have been established to interactively view recent water-level information via the internet by clicking on a specific well.

This digital data set contains the locations, water-level altitude, and water-level differences of 70 wells selected to document water-level changes between fall 2004 and spring 2005 in the Anza-Terwilliger area of Riverside County, California. The winter of 2005 was one of the wettest periods on record. Links to the U.S. Geological Survey National Water Information Systems Website (NWISWeb) have been established to interactively view recent water-level information via the internet by clicking on a specific well.

This data set represents the extent of the California Coastal Basin aquifers in California.

This data set represents the extent of the California Coastal Basin aquifers in California.

This data set represents the extent of the Central Valley aquifer system in California.

This data set represents the extent of the Central Valley aquifer system in California.

This digital geospatial dataset documents the fault traces in the Anza and Terwilliger area of southwest Riverside County, California, that were modified from Moyle (1971) by Woolfenden and Bright (1988, figure 8). The fault information is used to help assess ground-water level changes in the area of Anza and Terwilliger between 2004 and 2005.

This digital geospatial dataset documents the fault traces in the Anza and Terwilliger area of southwest Riverside County, California, that were modified from Moyle (1971) by Woolfenden and Bright (1988, figure 8). The fault information is used to help assess ground-water level changes in the area of Anza and Terwilliger between 2004 and 2005.

This digital dataset defines the spring 1961 water-table altitude for the California's Central Valley. It was used to initiate the water-level altitudes for the upper zones of the transient hydrologic model of the Central Valley flow system. The Central Valley encompasses an approximate 50,000 square-kilometer region of California. The complex hydrologic system of the Central Valley is simulated using the USGS numerical modeling code MODFLOW-FMP (Schmid and others, 2009). This simulation is referred to here as the Central Valley Hydrologic Model (CVHM) (Faunt, 2009). Utilizing MODFLOW-FMP, the CVHM simulates groundwater and surface-water flow, irrigated agriculture, land subsidence, and other key processes in the Central Valley on a monthly basis from 1961-2003. The starting heads are based on the water-table and potentiometric surface developed by Williamson and others (1989). Maps of the spring 1961 water-table and hydraulic head in the lower pumped zone are shown in Figure 31 of Williamson and others (1989). The CVHM is the most recent regional-scale model of the Central Valley developed by the U.S. Geological Survey (USGS).The CVHM was developed as part of the USGS Groundwater Resources Program (Faunt, 2009. See "Foreword", Chapter A, page iii, for details).