Continued groundwater use at rates in excess of natural recharge to the ground-water basins has caused significant overdrafts in some areas of the San Joaquin Valley. This study points out the need for careful consideration of pumping unit efficiency and water costs per acre-foot, per foot of lift. Farmers in areas of highly unstable pumping lifts may need to look for supplemental irrigation water or to reorganize their systems of farming.

This research, conducted in part under the Experiment Station Project RRF 2210, is also supported in part by grant funds from the Water Resources Center, University of California.