Base of fresh ground water approximately 3,000 micromhos in the Sacramento Valley and Sacramento-San Joaquin Delta, California

The study area consists of about 6,600 square miles; about 5,500 square miles of the floor of the Sacramento Valley, and about 1,100 square miles of the Sacramento-San Joaquin Delta.  The Sacramento Valley, as defined by Bryan (1923, p. 8), extends from Red Bluff 145 miles southward to Suisun Bay.  It is bounded on the east by the Sierra Nevada, on the northeast by the Cascade Range, on the northwest by the Klamath Mountains, and the west by the Coast Ranges.  Southward the valley merges with the Delta and the San Joaquin Valley.  The width of the Sacramento Valley varies from about 30 miles near Red Bluff to about 60 miles on the south, and averages about 40 miles.  The southern boundary of the study area coincides with the northern boundary used in an earlier study be Page (1971, 1973a).