The Dynamics Of Hot Water Discharge Lakes

Across the continent, savvy anglers recognize the potential of plying the tepid waters that flow from power plants. In Minnesota, for example, anglers venture to the “Hot Pond” at Lake Pokegama near Grand Rapids to catch open-water bass when most folks are drilling holes in the ice. Likewise, warm effluent from a power plant on the Mississippi River near Monticello, Minnesota, draws smallmouth bass and walleye. And the heated waters of North Dakota’s Nelson Lake yield scores of crappie and the state’s biggest largemouth bass during the dead of winter. In Texas, more than 50 electric-plant cooling reservoirs offer excellent fishing in artificially warmed waters, including Lake Monticello, where a former state record bass was caught. From New York to New Mexico, similar opportunities exist.

The Scene

In the nation’s heartland, some Kansas anglers spend winter days pursuing their favorite quarries at La Cygne and Coffey County lakes. La Cygne is a 2,600-acre cooling reservoir for the Kansas City Power and Light Company’s coal-burning plant, about 40 miles south of Kansas City. Coffey County’s 5,090 acres lie about two miles north of Burlington, Kansas, and it cools the generators at the Wolf Creek Nuclear Power Plant. Coffey’s average depth is 21 feet and its deepest spot plunges into 90 feet of water.

Both are flatland reservoirs with miles of riprap jetties and shorelines. There also are submerged humps, roadbeds, bridges, rockpiles, manmade reefs, farm pond dams, stumps, brushpiles, and an assortment of aquatic vegetation. Anglers new to Coffey and La Cygne and many other discharge lakes should be warned that much of the shoreline is an eyesore, and the noise pollution is distracting. Huge towers with plumes of smoke and steam set a surreal scene, particularly when fog rolls off the water.

The Coldwater Connection at Hotwater Lakes

Most anglers hold the mistaken notion that the best areas are within the plume of the warm water that the power plants create. Several winters ago, a group of anglers began probing coldwater lairs at La Cygne and Coffey, and these areas yielded excellent numbers of largemouth and smallmouth bass, white bass, and wipers, along with occasional crappies, catfish, and more. Coldwater areas often outproduced warm ones, especially when the lakes hosted many anglers who believed that the most catchable bass lived in warm water.

Moreover, the smallmouth bass anglers typically catch in Coffey County’s cool waters are bigger and healthier-looking than those in warm sections. According to Leonard Jirak, a fishery biologist with the Kansas Department of Wildlife and Parks who helps manage Coffey, the reason for this phenomenon is that Coffey County’s shad population is small. He notes that the Wolf Creek Nuclear Operating Corporation tries to minimize shad numbers to keep them from clogging the power plant’s cooling-water intake screen. Jirak concludes: “Since there’s no surplus of forage-sized shad, predators in the warm waters have an increased metabolism but not enough food to match it. For maintaining their condition, they’re better off in colder waters.”