Characterization of the aquatic environment in Lake Mead near the proposed Spring Canyon pumped-storage project, and assessment of potential aquatic impacts

A pumped storage system consists of an upper reservoir and lower reservoir separated by an elevation difference. During low demand energy periods such as nights and weekends water is pumped from the lower to the upper reservoir using available energy from conventional steam electric power plants. During high energy demand periods, such as mornings and afternoons of weekdays, upper reservoir water is allowed to drop back down through the same system of water conduits and turbines, generating electricity to conveniently meet abrupt electrical energy requirements. The same water turbines thus act both as pumps and as conventional hydroelectric turbines. Because energy demands of electrical consumers vary considerably on a daily basis, the ability to economically store large amounts of energy during off - peak periods is of great advantage to utilities. Pumped-storage tends to stabilize a power generation and distribution system (Feickeisen 1979). Conventional steam electric power plants (fossil or nuclear fueled) operate more efficiently and have a longer life when they are run continuously rather than cycled to meet rapidly charging power demands. Pumped storage systems allow for a more continuous, efficient operation of base - load steam electric plants. Increasing populations in the Southwestern United States have resulted in increased peaking energy requirements. Following a decade of energy studies conducted by the Bureau of Reclamation and other Federal and non - Federal agencies, it was determined that pumped storage offered the best opportunity for meeting energy peaking needs while complementing large base-load steam electric plants. Some 200 potential pumped storage sites in Arizona, Nevada and southern California had been identified by 1982, and in \u27the same year, after an extensive screening process, the Bureau of Reclamation selected Spring Canyon as the preferred pumped storage site (USBR 1987). A total of 20 utility companies and power marketing agencies in Arizona, southern Nevada and southern California, are participating with the Bureau of Reclamation in a joint Spring Canyon Investigation that includes determination of potential environmental impacts, among other aspects. Contingent upon study findings, construction could begin in 1992 and be completed as early as 1997 (USBR 1987). The present study involves the aquatic environment of Lake Mead and addresses potential aquatic impacts of the Spring Canyon Pumped Storage Powerplant. The report is designed to aid the Bureau of Reclamation in development of a Draft Environmental Statement in 1988. The objectives were to evaluate the area of Lake Mead near the proposed pumped storage site (Virgin Canyon) and to predict the biological, hydrological and limnological conditions prevailing within Lake Mead and the Spring Canyon forebay (upper reservoir) once the project is operational. Items specifically considered include appraisal of existing conditions and impact assessment for the following: water temperature, water movements, dissolved oxygen, pH, conductivity and salinity, water transparency and light penetration, nutrients and chlorophyll, zooplankton, benthic macroinvertebrates, and fish (early life history stages and adults)