The Santa Clara Valley Water Conservation District includes 138,000 acres of the Santa Clara Valley, California, of which 120,700 acres are cultivated lands, roads, and cities which are watered by approximately 2,000 pumping wells. During the period of deficient rainfall, 1916–1934, prior to Santa Clara Valley water Conservation District's spreading operations, the average water‐level in wells dropped about 108 feet.Attention of those interested in ground‐water conservation has been focussed on this area because of the successful organization of the Santa Clara Valley Water Conservation District, the recovery of water‐level due to water‐spreading operations, the contamination of ground‐water around San Francisco Bay, and the sinking of land‐surface over an area of about 200 square miles, forming a trough‐like depression with maximum lowering in 1937 at San Jo