Water resources data for the 1991 water year for California consist of records of stage, discharge, and water quality of streams; stage and contents in lakes and reservoirs; and water levels and water quality in wells. Volume 5 contains water levels for 1,069 observation wells and water-quality data for 276 monitoring wells and 2 springs. These data represent that part of the National Water Data System opera?ted by the U.S. Geological Survey and cooperating State and Federal agencies in California.