Hydrogeologic Provinces for California based upon established groundwater basins and watershed polygons.
Ten hydrogeologic provinces of California are represented by a region-
class feature called "provinces" within this digital data set.  These
provinces were identified and defined in the USGS Water Resource
Investigation Report (WRIR) 03-4166 (Belitz and others, 2003) titled,
"Framework for a Ground-water Quality …