Utility of layer aeration for reservoir and lake management

Abstract

Layer aeration (U.S. Pat. 4,724,086) is a process that manipulates the heat and oxygen mass of a thermally stratified water body to create a desirable physical/chemical depth profile. Unlike destratification, layer aeration creates an aerobic cool, isothermal layer(s) bounded by several functional thermoclines. The process also enhances stratification and habitat structure. Unlike hypolimnetic aeration, the method redistributes available heat and oxygen and avoids the potentially adverse effects of nitrogen super-saturation, increased diffusional transport to the epilimnion, and metalimnetic anoxia. This paper discusses the chemical, physical, and biological effects of layer aeration in two Connecticut lakes. In Mulberry Reservoir, layer aeration reduced summer phosphorus accumulation by over one-third of pretreatment levels and improved hypolimnetic oxygen levels. Application to Glen Reservoir lowered ferrous iron concentrations and improved dissolved oxygen concentrations. Although further research is needed to document long-term benefits, layer aeration provides another option for treating systems for hypolimnetic oxygen depletion and related symptoms. Implications for managing recreational lakes and water supply reservoirs are discussed. © 1988 North American Lake Management Society.