Hydrologic Evaluation for Geothermal Development--An Example at Coso Hot Springs, California

Abstract

Adequate hydrologic evaluations are essential to determine the economic and environmental feasibility of a proposed geothermal development. The main economic concern is the availability of cooling water. The major environmental concerns are maintenance of surface and ground water character, effects of surface and ground water use and effects on surface manifestations. A study done at Coso Hot Springs, California, is an example of such an evaluation. It was found that the ground water reservoir is currently near hydrologic equilibrium and ground water extraction will cause water table lowering in Rose Valley. Projections to 2000 indicate that water use will exceed recharge by about two thousand acre-feet/year. Pumping may affect the spatial distribution of usable ground water. A baseline of natural variations in surface thermal manifestations must be established to assess changes due to geothermal production.