ChiefsPlanet - Weather Heat Kills Fish in Midwest

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A frog sits on a dead fish in a pond near Waterloo, Neb. on Tuesday, July 31, 2012. It is unclear what caused the fish to die but possible culprits are the low water levels due to the drought, high water temperatures due to the hot weather and a lack of oxygen in the water.

Drought and scorching heat are warming lakes, streams and rivers in the Midwest and Plains to temperatures seldom seen before.

In Chicago, Lake Michigan hit 82 degrees in late July: "I can't remember a shoreline water temperature going any higher in my 35 years here," reports Chicago meteorologist Tom Skilling of WGN, "which means a reading any higher takes us into record territory."

A customer in western Illinois complained to the water department in Moline that her "cold" water was coming out warm: "She said she went to every water faucet in her house," says Moline water division general manager Greg Swanson, "and wondered if something was wrong with her pipes."

"It's pretty unbelievable," adds Swanson, who said he'd never heard of such a complaint in his 35 years of working there. He says that at one point in late July the water temperature of the Mississippi River at Moline measured 91 degrees, the highest since records began in 1943.

Hottest Month on Record for Some Cities

By comparison, the water temperature in the Gulf of Mexico more than 1,200 miles to the south in Key West, Fla., was 87 Tuesday, according to the National Oceanic and Atmospheric Administration (NOAA).

Fish kills because of the warm water have been reported in Michigan, Missouri, Iowa and Minnesota.

"The hot, dry weather isn't just hard on humans, it's hard on fish, too," says Missouri Department of Conservation fisheries biologist Jake Allman.

"Most problems occur in ponds that are not deep enough for fish to retreat to cooler and more oxygen-rich water," Allman adds. "Hot water holds less oxygen than cool water. Shallow ponds get warmer than deeper ponds, and with little rain, area ponds are becoming shallower by the day. Evaporation rates are up to 11 inches per month in these conditions."

Drought Disaster 2012

In Michigan, "water temperatures of nearly 90 degrees were recorded in the lower Shiawassee River last week, which resulted in a small kill of northern pike as temperatures were beyond their physiological ability to handle these conditions," explains Gary Whelan, a fish production manager with the Michigan Department of Natural Resources.

"We expect to see more of these fish kills until there are major changes in this summer's weather," Whelan says.

In Minnesota, warm summer temperatures contributed to fish kills in the Big Sandy Lake system near McGregor, according to the Minnesota Department of Natural Resources.

Fishing Forecast

The warmth was kick-started last winter, says physical scientist George Leshkevich of NOAA's Great Lakes Environmental Research Laboratory, when the lakes stayed mostly ice-free because of unusually mild temperatures. A freak hot spell in March helped lake temperatures rise, too, he says.

Superior, the northernmost Great Lake, had an average water temperature last week of 68 degrees. At the same time in 2011 the lake was 56 degrees, which is close to average.

"We're right up there at or near record temperatures" for Superior, Leshkevich says.

In Kansas, the Little Arkansas River has been running about 5 degrees above average the past two months, says Andy Ziegler, director of the U.S. Geological Survey's South Central area. With highs averaging about 95 degrees, that's "pretty warm," he says.

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