Oxygen Diffusers to Create and Maintain Summer Fish Habitat
Mark Mobley, Ed Shallenberger, Marc W. Beutel, Paul Gantzer, and Brian Sak
Abstract.—Habitat for striped bass Morone saxatilis, hybrid striped bass, salmonids, and other coolwater and coldwater fishes can be limiting in stratified reservoirs during summer and early autumn as surface water temperatures increase above tolerable ranges and deeper waters are depleted of dissolved oxygen (DO). Usable habitat can be increased in these reservoirs using oxygen diffusers to increase DO concentrations in the cooler, deeper waters. Several oxygen diffuser systems are currently in operation. Some of the systems were originally designed to increase DO in hydropower reservoir releases, but have also created fish habitat as a result of the diffuser system’s efficient oxygen transfer capabilities in the reservoir. Several other systems are operated to improve water quality in the reservoir for water supply, and two systems have specific fish habitat maintenance goals. Improvements in DO for fish have been obtained at Calaveras Reservoir, California by the San Francisco Public Utility Commission, and fish studies at this reservoir are currently underway. In North Twin Lake, Washington, the Colville Confederated Tribes and Washington State University have documented improved trout habitat and reduced sulfide concentrations. Oxygenation of cool, deep water is now a proven technology that can alleviate summertime thermal and oxygen stress on striped bass and hybrid striped bass and can minimize habitat-related mortalities. The technology is being implemented specifically for striped bass with a large installation in J. Strom Thurmond Reservoir, South Carolina, for the Savannah District of the U. S. Army Corps of Engineers.