ENVIRONMENT The environmental impact of geothermal development in California’s Imperial Valley For further information contact David W. Layton (422-0918). The Imperial Valley of California contains nearly one-third of the nation’s identified natural hot water resources. With its 475 000 acres of irrigated lands and warm climate, it is also one of our major agricultural resources. Development of the valley’s geothermal resources could be hinderedif the environmental impact provesto be unacceptable or if geothermal operations are incompatible with agriculture. LLNL’s Environmental! Sciences Division has undertaken the Imperial Valley Environmental Project (IVEP) to measure and assess the impact of geothermal development in the area. In 1975, the U.S. Energy Research and Development Administration (ERDA), predecessor to the Department of Energy, entered into a contract with the San Diego Gas and Electric Company to build and operate a geothermal test facility in the Salton Sea geothermal resource area. As part of this contract, ERDA agreed to sponsorfield studies for the collection of baseline environmental data ee and to assess the potential impact of future geothermal development in the Imperial Valley. LLNL was given responsibility for fulfilling this agreement on ERDA’s behalf, and the Imperial Valley Environmental Project (FVEP) wasinitiated. The main subject areas to be addressed were air and water quality, subsidence and induced seismicity, health and safety, ecosystems, and socioeconomics.! The assessment process We began our assessment by analyzing environmental data collected by private and public research groups. We then characterized various geothermal 19 NJU0co To technologies in terms of their consumption of natural resources and their production of liquid, solid, and gaseous by-products. Finally, we assessed potential adverse environmental and socioeconomic effects, and evaluated methods of prevention and mitigation. High-, medium-, and lowenergy-production scenarios were prepared to serve as a basis for the assessment of the range of effects that might be observed. Our analysis focused on the medium- production scenario, which assumes a growth of 100 MW/yr in energy-generating capacity begin- ning in 1982 (Fig. 1). Under such a scenario, the total energyproduction capacity would reach 3000 MW bythe year 2010 (5% of California's projected peak load for that year). The most important potential adverse effects addressed in our assessment were (a) air quality changesresulting from emissions of hydrogensulfide, (b) increases in