The U.S. Geological Survey, Water Resources, in cooperation with Federal, State, and local agencies, obtains a large amount of data pertaining to the ground-water resources of California each water year (October 1?September 30). These data constitute a valuable database for developing an improved understanding of the water resources of the State. This Fact Sheet serves as an index to ground-water data for water year 2002. The 2-page report contains a map of California showing the number of wells (by county) with available water-level and waterquality data for water year 2002 and instructions for obtaining this and other ground-water information contained in the databases of the U.S. Geological Survey, Water Resources, California District.