from today's Lexington Herald Leader...
Cool-water fish threatened by warming water
MANY MIGHT DIE IN PARTS OF CUMBERLAND RIVER
By Art Lander Jr.
Kentucky wildlife officials are worried that the warming waters in parts of the Cumberland River will trigger a major fish kill in one of the finest trout-fishing areas in the eastern United States.
Cool-water fish below the Wolf Creek Dam in south-central Kentucky -- including prized catches such as the striped bass, brown trout and rainbow trout -- face the greatest threat.
A major fish kill on the Cumberland tailwaters would be a devastating blow to anglers, erase years of intensive management efforts by fishery biologists, and strike a blow to local tourism economies already reeling from the loss of revenue from the drawdown of Lake Cumberland.
The 75-mile tailwaters, which flow through parts of Russell, Cumberland and Monroe counties to the Tennessee line east of Tompkinsville, are the state's premier trout fishery, supported by discharges of cool water from the depths of Lake Cumberland.
About 191,000 trout reared at the Cumberland National Fish Hatchery, just below Wolf Creek Dam, are released into the tailwaters annually, and each spring when discharge rates increase, striped bass migrate up the river from Cordell Hull Reservoir in Tennessee.
"We think the upper river is going to be OK. It's the lower section, below Burkesville, Ky., that we're worried about," said Benjy Kinman, director of fisheries for the Kentucky Department of Fish and Wildlife Resources.
Burkesville is about 35 river miles below Wolf Creek Dam, and 40 miles upstream of the Tennessee border.
A spring drought, unseasonably hot weather and the lowering of Lake Cumberland to elevation 680 to repair leaks in Wolf Creek Dam have caused lower than normal river levels and less cool water to be discharged.
"The cool water that's coming into the river is warming rapidly as it flows across shallow shoals downriver," said Kinman.
Normally, water temperatures in the tailwaters during June are in the mid 50s, and sometimes reach into the 60s during the heat of summer, but water temperatures above 65 degrees are life-threatening to trout.
"Last Friday the water in the river was 75.9 degrees at Cloyd's Landing (on Ky. 1424 in Cumberland County), and Tuesday it was 69 degrees at the Ky. 61 bridge (at Burkesville), and 75.6 degrees at McMillian's Ferry (at Ky. 214 in Monroe County)," Kinman said. "Trout can live three or four days in water above 75 degrees, but they become very stressed. There's no long-term survival at that temperature."
Kinman said water temperatures are being monitored daily, and emergency regulations are being considered that would increase the amount and size of fish that anglers could take. "We've received reports that hundreds of stressed fish have been observed in schools at the mouths of creeks, where 70-degree water is entering the river."
In an attempt to discharge more cool, oxygenated water into the river, the U.S. Army Corps of Engineers is opening two sluice gates in Wolf Creek Dam for 11/2 hours at a time, four times a day.
Opening the sluice gates causes cold water from near the lake bed to flow into a concrete basin and spray into the tailwaters. "This water is 6 degrees cooler than when they use the turbines," Kinman said. "They're forgoing the generation of electricity to help us out."
Kinman said he will ask the Corps of Engineers on Friday to slightly change the discharge rates in an attempt to offset the warming period between the opening of the sluice gates. "We'd like to try a change for about a week to see if it makes a difference in water temperatures."
The Cumberland River produces brown trout up to 21 pounds, thanks in part to the restrictive 20-inch minimum-size limit, and one-fish daily creel limit. The rainbow trout fishery has been revitalized in recent years because of a 15- to 20-inch slot limit that protects quality-size fish.
The tailwaters near McMillian's Ferry produce huge striped bass (fish up to 40 pounds are taken), and offers one of the best opportunities in the region to hook into a trophy-sized fish.
Fishery biologists are keeping their fingers crossed that some fish might escape. "Burkesville seems to be the cutoff point (where the warm water starts)," Kinman said. "We're hoping a lot of the big fish migrated upriver and have taken thermal refuge, but there's no way to check it out."
Anglers have reported observing schools of striped bass farther up the river than normal, and fishing in the upper sections of the tailwaters has been unusually good in recent weeks.
"What we need is a good rain in the headwaters of the lake (to increase discharges into the river)," Kinman said. "If there was localized heavy rainfall below the dam that brought a lot of warm water into the river at one time, it could be disastrous."