Ground water in the Twenty-Nine Palms Indian Reservation and vicinity, San Bernardino County, California

The Twenty-Nine Palms Indian Reservation is in San Bernardino County, California. Movement of ground water in the area is impeded locally by faults which act as ground-water barriers. There are indications that a fault probably crosses the reservation in an east-west direction; such a fault may interfere with ground-water pumping. The water-table altitude near the northern boundary of the reservation is estimated to be 120 to 130 feet below land surface datum; the aquifer thickness in the area is unknown. Pumping-test results for wells near the reservation show specific capacities ranging from 9.2 to 70.0 gallons per minute per foot of drawdown. Wells drilled on the reservation would probably fall within this range. Sodium concentrations, which may pose a hazard to those who must restrict its intake, and excessive fluoride are present in water samples from wells near the reservation. High sodium and fluoride concentrations are probably present in water in the saturated material underlying the reservation. (USGS)