Herald-Whig

Fox Valley Lake lowered eight feet to kill off weeds, help fish

By Herald-Whig
Posted: Jan. 5, 2017 10:10 am

KAHOKA, Mo. -- Fishermen, boaters and picnickers familiar with Fox Valley Lake north of Kahoka might be a little surprised to see how the lake looks.

The 108-acre body of water is 8 feet lower than normal -- and will remain at that level until the beginning of March.

It is all part of an ambitious plan by the Missouri Department of Conservation to kill off weeds that are keeping the largemouth bass population from reaching its full potential.

Chris Williamson, a fisheries management biologist for the DOC, said the winter drawdown is an experiment aimed at solving a problem specific to this particular public lake.

Since Fox Valley Lake was built in the early 1980s, Williamson said, "it's always had very clear water."

While clear water "is pretty to look at," he noted, it creates some issues for certain fish species populating the lake, which is 30 feet deep in places.

"Bass and bluegill and crappie are all sight feeders, and they all rely on ambush" to catch minnows and other prey they use for food, Williamson said. "If the water is too clear, the prey can see them as well."

Ultra-clear water also allows a lot of light to reach the bottom of the lake, which promotes plant growth -- something that has been happening with great frequency at Fox Valley Lake.

"There's just a lot of submerged aquatic plants in the lake every year," Williamson said. "If we get too much of that, then there's too many places for the prey fish to hide. So the bass have to spend more time looking for food, and they spend a lot more energy to get that food."

As a result, many of the largemouth bass in Fox Valley Lake tend to be small in size, averaging just 10 to 12 inches in length.

By drawing down the lake 8 feet during the height of winter, the DOC hopes to kill off most of the lake's weeds, since most of the nuisance plant species only grow about 8 feet tall.

"A lot of those plants can't take the freezing temperature," Williamson said. "So by drawing down the lake and exposing those plants to air and the freezing temperatures, we're going to set those plants back for several years. And by reducing the coverage of plants, we are essentially increasing the bass' efficiency at feeding."

Williamson hopes by making it easier for bass to catch small fish, the bass will thrive and eventually reach the 15- to 18-inch size "where anglers really like to catch them."

The drawdown began Dec. 5 when a valve was opened in a spillway on the lake's dam. By Dec. 19, Williamson said, the lake had fallen 8 feet, exposing most of the submerged plants.

Williamson said the lake is expected to remain at the lower level until around March 1 when the valve will be shut, allowing rainfall to refill the lake naturally.

"The lake should be back to normal by April -- assuming it rains," Williamson said.

The lake and its surrounding conservation area -- more than 2,000 acres in all -- will remain open to the public throughout the drawdown. "The boat ramp is still accessible," Williamson said.