Underwater Dam and Embayment Aeration for Striped Bass Refuge

A submerged fabric dam was constructed underwater across the mouth of a small cove in a large reservoir. The dam trapped cool hypolimnetic water in the spring and prevented it from being withdrawn for hydropower releases throughout the summer. A liquid oxygen aeration system aerated the water trapped behind the dam. The purpose of the dam and aeration system was to provide an artificial refuge for striped bass. The bass have historically suffered in summer months from unsuitable dissolved oxygen (DO) and temperature conditions in the reservoir. The dam has promise for providing different aquatic conditions in portions of a large reservoir compared to the main reservoir body. Such dams, therefore, might be used to provide optimal conditions for both warmwater and coldwater species in the same reservoir. They could also provide an inexpensive alternative to aeration of an entire reservoir or changes in reservoir operation to furnish the desired aquatic conditions. Such dams, on a scale larger than described here, might also be used to allow hydropower projects to release cooler water later in the summer. Cooling the releases from a reservoir in warm months could help maintain a coldwater fishery in the tailwater and reduce stress on migrating fish such as salmon.