Empirical estimates of benefits from groundwater management are reported for an area in California with heavy reliance on groundwater supplies. Benefits are quite sensitive to the water demand schedule and interest rate but less sensitive to other parameters. I However,i n all cases considered the increases in welfare from groundwater management are less than ten percent. Tax revenues received under a system of pump taxes are four to five times as large as the benefits from management. Thus, groundwater users gain under a system of quotas but may suffer substantial welfare losses under pump taxes.