Hydropower and Trout – A Winning Combination

Improved water quality means better fishing – especially in the tailwaters just below Hartwell Dam. With a modification to its turbines inside the dam, the Corps of Engineers turned the area just below the dam into a trout haven.

Like many southeastern reservoirs, Hartwell Lake has three distinct water layers that differ in temperature and chemistry. By late summer the “hypolimnion layer,” the cool bottom area of water in the reservoir, typically has low dissolved oxygen (DO). Since the water released through the dam for hydropower comes from this layer, the low oxygen content has a negative impact on the tailwater as it leaves the dam and enters Lake Russell. While trout prefer the colder water, the low oxygen content made it difficult for them to thrive. A modification to the turbines changed all that.

The Hartwell tailwater has always been of particular concern because of its status as a “put and take” rainbow trout fishery. When the Corps modified its turbines inside the Hartwell Dam, the area just below the dam became an excellent location for South Carolina and Georgia to increase their stocking of rainbow trout.

Recognizing an opportunity to improve fisheries habitat in the Hartwell tailwater through improving the quality of water released during hydropower generation, the Corps contacted the Tennessee Valley Authority (TVA) in 1997 to assist in identifying possible water quality improvements at the Hartwell Dam and power plant. After an on-site engineering study, the Corps followed TVA’s recommendations to install turbine hub baffles and 10-inch air supply pipes to four of the five generating units. These modifications, referred to as “turbine venting,” allow air to diffuse into the water as it flows past the turbines during generation. This results in a much-needed increase in dissolved oxygen levels in the tailwater.

Water quality information collected since installation of the hub baffles indicates that DO concentrations are being improved by at least 2 mg/l during the period when oxygen concentrations are low. As a result of these improvements, South Carolina Department of Natural Resources (SCDNR) and Georgia Department of Natural Resources (GADNR) expanded their stocking season and increased the number of trout stocked in the Hartwell tailwater.

“Stocking later than June was not an option in the past,” said Dan Rankin, SCDNR Regional fisheries Coordinator, “With the improvements from turbine venting, we are now able to stock trout as late as August and we have plans to stock right through the fall months.” In fact, Georgia and South Carolina Departments of Natural Resources now stock approximately 24,000, 9” to 12” rainbow trout annually and provide a viable and unique cold water fishery downstream from the Hartwell Dam.

The location of the Hartwell tailrace fishery makes it unique. Trout waters are located in the mountains, where water temperatures remain cool throughout the summer. The cool hypolimnetic water released during power generation makes a trout fishery possible in the piedmont. The same water once extremely low in DO (and a limiting factor for trout stocking) is now viable habitat with the addition of turbine venting.

A survey conducted by SCDNR in 1991 found that visitors participated in approximately 173,000 angler-hours of effort in the Hartwell tailwater and caught an estimated 172,995 fish, with the vast majority of these fish being rainbow trout. This study also valued the Hartwell tailwater fishery at approximately $800,000, based on angler’s expenditures.

The popularity of this fishery has expanded tremendously since the completion of the Lake Hartwell Tailrace Fishing Pier in January 2010. This pier, constructed by GADNR, is managed by the Corps. The funding came from a natural resource damage settlement with Schlumberger Technology Corporation, the responsible party for natural resource damages in Hartwell Lake. With completion of the pier, access to the Hartwell Tailrace fishery improved greatly. The tailrace is now accessible to all anglers, even those with disabilities.

Through cooperation to improve habitat, access and innovative management, SCDNR, GADNR, and the Corps have improved a unique fishery. When you think trout, you don’t have to travel to the mountains; you can catch them here in our backyard.

*For more information on the yearly physical changes of a lake, go to http://www.sas.usace.army.mil/lakes/hartwell/fishing.htm and select “Fact Sheet” under “Fishing Related Links”.

Jamie Sykes

About U.S. Army Corps of Engineers Savannah District

The U.S. Army Corps of Engineers Savannah District oversees a multimillion dollar military construction program at 11 Army and Air Force installations in Georgia and North Carolina. We also manage water resources across the Coastal Georgia region, including maintenance dredging of the Savannah and Brunswick harbors; operation of three hydroelectric dams and reservoirs along the upper Savannah River; and administration of an extensive stream and wetland permitting and mitigation program within the state of Georgia. Follow us on Twitter @SavannahCorps and on Facebook.com/SavannahCorps
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