Multilevel Outlet Works at Four Existing Reservoirs

Design and performance of four multilevel outlet works constructed by the Bureau of Reclamation are analyzed. The four reservoirs (Cachuma, Casitas, Folsom, and Whiskeytown) have been in operation from 6 yr to 13 yr and present some variation in water quality situations and outlet designs. Cachuma and Casitas are thermally stratified during summer. Taste and odor requirements have governed the withdrawal level selection, but chlorine demand, temperature, and dissolved oxygen are considered. Modifications were made at Folsom to allow withdrawal of reservoir water from upper and lower levels. Salmon spawning requirements downstream from Folsom fix the maximum water temperature at 58○ F. Selective withdrawal at Whiskeytown Dam plan for temperature control of releases to Clear Creek, a salmon spawning stream.