LAKE TANEYCOMO — The oxygen levels in cold water rushing through power-generating turbines at Table Rock Dam in southwest Missouri are so low that the multimillion trout fishery at Lake Taneycomo downstream is in danger, state conservation officials said.
The Springfield News-Leader reports that the problem is especially acute in late summer and fall, when oxygen levels coming out of the dam can drop as low as 2 parts per million or less. Missouri Conservation Department fisheries biologist Shane Bush said the fish need at least 6 parts per million to thrive.
"The fish don't eat," he said. "It affects how quick they grow and they really get lethargic. Fish that are hooked won't fight well, and if they're released they're usually exhausted to the point they might not recover. They often die."
Lake Taneycomo has been declared an "impaired waterway" since 2008 because of the oxygen levels.
A 2004 Missouri Department of Conservation report estimated that the trout fishery contributes nearly $15 million a year to the local economy.
The federal Environmental Protection Agency has ordered the Missouri Department of Natural Resources to turn in a final report, including public comments, by the end of the year. The 90-page report will detail details the oxygen problem and some potential solutions.
Bush said a large tank of liquid oxygen is being used to oxygenate water at the Shepherd of the Hills Hatchery adjacent to Table Rock Dam. The water then flows into Lake Taneycomo.
"In October and November, when oxygen in water from the dam is typically at its lowest, fish congregate at our hatchery water outflows," Bush said. "It's not an exaggeration — it looks like you can walk across the backs of those fish that are there breathing oxygen we diffused into our water."
The problem goes away in the winter when oxygen-rich surface water at Table Rock Lake mixes with the deep oxygen-depleted water. Bush said oxygen levels get up to 10 or 12 parts per million in February through March.
"You'll really notice the difference in how hard a fish fights," he said. "They also look a lot healthier and fatter."