Fisheries Biologists Watching Water Temps in Lake Cumberland

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Fisheries Biologists Watching Water Temps in Lake Cumberland

7/17/09

Frankfort, Kentucky - The cold air that blankets Kentucky each December, January and February is uncomfortable for most people. Few of us enjoy pulling on extra clothes, driving in snow or being cooped up inside during winter.

Although we might not like winter, the cold water being stored in Lake Cumberland at that time of year is important to the health and survival of trout, striped bass and walleye in the lake and its tailwater the following summer.

"That winter water stored in the lake is the habitat for the trout in Cumberland tailwater and for the striped bass and walleye in the lake," said Dave Dreves, fisheries research biologist for the Kentucky Department of Fish and Wildlife Resources. "There is a finite amount of this winter-stored cold water after April."

Fisheries biologists are concerned about the amount of winter-stored cold water that remains in the lake this year. Heavy rains in May and June have drained a significant amount of cold water from the lake, as the U.S. Army Corps of Engineers siphoned water from the Lake Cumberland's colder lower reaches in an effort to prevent the lake from rising too high.

Corps officials are keeping the lake at an elevation of 680 feet above mean sea level to relieve pressure on Wolf Creek Dam while repairs are underway. The normal summer pool for Lake Cumberland is 723 feet.

The lower water level effectively reduces amount of important cool water being stored in the lake. Releasing colder water and replacing it with warmer water compounds an already delicate situation.

John Williams, southeastern fishery district biologist for Kentucky Fish and Wildlife, said fish are already reacting to the change. "According to the fishing guides, the striped bass are already moving down toward the dam - where there is better water quality in the summer," Williams said. "This usually doesn't happen until August."

This situation worries Williams because the worst part of the year isn't here yet. "We are still two months away from the critical time," he said. "That deeper, oxygenated, cool water gradually depletes as you go through summer. Fish and other organisms consume it."

Typically, September is the critical month for maintaining oxygen levels at the temperatures preferred by trout, walleye and striped bass. These fish cannot survive without enough dissolved oxygen in the water. Fish also prefer a certain temperature range. If the water grows too warm in the lake, the walleye and striped bass could seek deeper water that does not have adequate oxygen. In the tailwater, trout can overstress if the water temperatures climb too high.

Williams fished earlier this week for striped bass in Lake Cumberland and did well. The fish he caught were in good condition.

The rainbow and brown trout living in the Cumberland River below Wolf Creek Dam also utilize similar water temperatures as striped bass in the lake.

During the past two summers, water temperatures in the lower section of the Cumberland River from roughly Burkesville downstream to the Tennessee line warmed to the point of stress for trout.

Water temperatures are better so far this year. "The water temperatures recently were 56 degrees at the dam and 62 to 63 degrees at Burkesville," Dreves explained. "If it stays like this for the rest of the summer, it will be good for the trout. It was above 68 degrees at Burkesville at this time last summer."

Trout stress in water greater than 70 degrees. The warmer water in the lower part of Cumberland River pushes trout upstream toward to dam to find cooler water. This concentration of fish is good for anglers, but bad for growth of trout.

"There are some skinny fish in the river right now, and some that look okay," Dreves said. "We are doing really well on catch rates, but growth rates and body conditions are down a little from 2006."

As the weather becomes drier, water temperatures in the river could become a problem. Dry weather increases water temperatures in Cumberland River because less water is released through Wolf Creek Dam.

"If we continue to have a cool summer, that would help tremendously," Dreves said. "Everything is good right now. We just hope it holds out."

Author Lee McClellan is an award-winning associate editor for Kentucky Afield magazine, the official publication of the Kentucky Department of Fish and Wildlife Resources. He is a life-long hunter and angler, with a passion for smallmouth bass fishing.


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