By Nathan HerringJune 26, 2013
TULSA, Okla. - The stream below Tenkiller Dam in Oklahoma is home to a popular trout fishery; however, during the 2011 drought, low dissolved oxygen levels, and high water temperatures resulted in a fish kill of both trout and other types of fish.
As a result of a multi-agency effort, a two-part mechanical solution was developed to prevent further fish kills below the dam.
"What happens is that below the dam, the water level gets so low and the temperature gets so hot that there's no oxygen to support the fishery so the fish basically suffocate," said Richard Thatcher, Oklahoma Wildlife Department director.
The new mechanical solution ensures that in times of stress there will be enough oxygenated water coming into the area, he said.
Although one of the congressionally authorized purposes of Tenkiller Lake is for fish and wildlife, there is no water allocated in the lake for that purpose and all water storage is contracted to other users. The Oklahoma Department of Wildlife and Conservation relies on limited donated storage to release water for the fishery. The mechanical system will help ODWC better utilize that donated storage.
The first part of the new system is a low flow pipe that transports water from the surge tank at the hydropower plant to the steam. Prior to the low flow pipe, there was only one mechanism to release water for the trout fishery, and it had a minimum release of 150 cubic feet per second. At certain times, this was more water than ODWC wanted released.
"This will allow for smaller and better releases of donated water so that we have higher dissolved oxygen levels, lower water temperatures and more water available downstream," said Kent Dunlap, Tulsa District chief of natural resources.
With the low flow pipe, as little as 50 cubic feet can be released, unlike the earlier mechanism which would waste thousands of gallons of water.
"You couldn't control it," said Col. Michael Teague, Tulsa District commander. "It's like opening the garage door when you want to let your dog out."
Another benefit of the low flow pipe is that it will be controlled from the Fort Gibson powerhouse so releases can be changed around the clock. In the past, when the gates were used for releases late in the day, the releases needed to continue until personnel arrived in the morning to close the gates.
The second part of the mechanical system is a Supersaturated Dissolved Oxygen System, or SDOX, that will target an isolated pool below the powerhouse where the 2011 fish kill occurred. ODWC can operate the system when the dissolved oxygen levels reach critical lows in that area.
"It's able to oxygenate the water in the sluice pool area when we have really critical low dissolved oxygen times," Dunlap said.
He compared the SDOX to an elephant gun in that you don't use it often, but when you do it is definitely needed.
The low flow pipe system and SDOX were the result of a partnership between the Corps of Engineers, ODWC, and Southwestern Power Administration, a partnership which Teague called critical to the project.
"All of the agencies had different concerns and also different resources they could contribute to the project," he said. "No agency could have done it alone."
In addition the mechanical system, ODWC has placed dissolved oxygen monitors along the stream.
"This will allow us to collect very important data in the future to see what the situation is, how the fishery is being affected and when we need to implement these measures that we have in place to keep the fish alive," he said.
The oxygen monitoring, combined with the low flow pipe and SDOX, will help to ensure that the fishery continues to thrive.
"Thousands of people come to the area each year to fish," Thatcher said. "Not only is it important to the local economy, but it's also great for people to come and just enjoy the beautiful surroundings out here."