This polygon shapefile depicts hydrological basins and sub-basins as defined by the California Department of Water Resources, and are designated on the basis of geological and hydrological conditions such as the occurrence of alluvial or unconsolidated deposits. When practical, large basins are also subdivided by political boundaries, as in the Central Valley. Basins are named and numbered per the convention of the Department of Water Resources. This dataset is intended to aid assessment of the groundwater basins along the Russian River. Circuit Rider Productions and National Oceanic and Atmospheric Administration (2002). Hydrologic Basins: Russian River Watershed, California, 1998-2002. Circuit Rider Productions. Available at: http://purl.stanford.edu/nc328hx9429 The State Water Resources Control Board traced selected formations from 250K USGS geologic maps onto mylar sheets. Because the USGS maps are regarded as high-quality maps and because of the integrity of mylar, it could be said that the resulting digitized coverage maintains good accuracy. Some of the tracings on the mylar, however, seemed a bit jagged and, in some cases, problems with horizontal rectification between USGS quads and the mylars were solved by repositioning tics. The coverage is, therefore, only of moderate quality. This layer is presented in the WGS84 coordinate system for web display purposes. Downloadable data are provided in native coordinate system or projection.