98-percent peak efficiency in oxygen absorption. Toetz, Wilhm, and Summerfelt (1972) provided a
review of the impacts of aeration/oxygenation systems on biological components along with an
extensive bibliography of selected abstracts.
The hypolimnetic aeration or oxygenation cases referenced above were on a variety of
reservoirs. Since then, oxygenation systems have been designed and installed at several reservoirs in
the Tennessee Valley Authority and Corps of Engineers. These systems have been designed to
increase release DO and minimize mixing between the hypolimnion and epilimnion. An oxygenation
system for the Richard B. Russell Reservoir on the Savannah River in Georgia was designed to deliver
150 tons of oxygen per day to maintain release DO at 6 mg/L in the hydropower releases without
increasing the release temperature (USAED, Savannah 1981; Gallagher 1984). Even more recently,
TVA developed an innovative system using ordinary garden soaker hoses as the delivery diffuser and
flexible ABS piping for a supply and floatation system (Mobley and Brock 1996).
Aeration or oxygenation is a technique designed to increase the in-reservoir and release oxygen
concentration. Some designs can accomplish this without impacting the thermal stratification. Other
designs because of vertical mixing induced by the aeration system may partially destratify the reservoir.
In most cases, the objective is to add oxygen without creating mixing cells in the lake that induce
destratification. The design approach consists of defining the hypolimnetic oxygen degradation rate, the
volume of water requiring treatment, and the amount of oxygen required to meet in-reservoir or release
oxygen objectives. The actual system selection will depend upon the operational objects. Several
aeration/oxygenation systems have been installed in Bureau of Reclamation, TVA, and CE projects.
The most recent installations have been at TVA reservoir using a relatively inexpensive porous-hose
delivery system. Summary information on aeration/oxygenation systems is presented in Table 4.5.1.