Effects of Artificial Aeration on Lake Ecology

Summer stratification in small mountain trout-fishery lakes restricts trout habitat to the thin layer of surface water. As atmospheric temperatures increase during later summer months, the epilimnion waters reach temperatures intolerable for trout. A technique of managing trout-fishery lakes, through introduction of compressed air, was studied at Lake Roberts in southern New Mexico during the summer of 1969. Research was conducted to determine the feasibility of induced aeration to control nutrient stratification and dissipation of high-bottom concentrations of hydrogen sulfide. The oxygenation efficiency of the induced aeration system was evaluated, and further research required for optimum development of the systems as management tools for trout-fishery lakes is discussed.

Artificial circulation and hypolimnetic aeration are management techniques for oxygenating eutrophic lakes subject to water quality problems, algal blooms, and fishkills. Artificial circulation is achieved by injecting diffused air into lower waters, by mechanical pumping of water from one depth stratum to another, or by inducing turbulence at the surface using large axial-flow pumps. In contrast, hypolimnetic aeration by air or oxygen injection affects primarily bottom waters. In some instances low dissolved oxygen concentrations persist in the metalimnion. In general, both methods lower the concentrations of reduced compounds in lake waters, providing benefits for water supply systems. Aeration may cause supersaturation of nitrogen gas, thereby raising the potential danger of gas bubble disease in downstream fishes.