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Avoid Late Summer Fish Kills

  • 9/18/2017 9:08:00 AM
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Low stream levels, high temperatures and dry conditions set the stage for potential water quality issues and fish kills. Even small amounts of polluted runoff can affect fish and other aquatic organisms under these conditions.

Farmers and others who handle chemicals or animal manure can take a few simple precautions to prevent downstream impacts. “First check for discharges from chemical mixing stations or areas of livestock concentration to make sure nothing reaches the stream or a tile inlet after a rainfall,” says Ken Hessenius, supervisor of the DNR Spencer field office.

“Look for improperly stored manure, fertilizer, fuel or pesticide containers. Check them for leaks,” he adds. “Check for cut channels below open feedlots, a sign that runoff is moving and could reach a stream. Even organic matter such as milk or silage leachate can cause dissolved oxygen levels to drop, stressing fish.”

“Second, if you suspect a problem with runoff, contain it and prevent additional pollutants from adding to the runoff,” Hessenius said.

Producers with open feedlots can scrape and clean them frequently to prevent contaminated runoff. Adding clean water diversions such as berms or gutters around open feedlots, and providing manure storage can also help. Technical assistance is available from ISU Extension, county NRCS offices and DNR field offices.

Finally, report fish kills as soon as possible to the nearest DNR field office or the 24-hour spill line at 515-725-8694. Specialists at the DNR can help people trace the pollutant causing the fish kill and reduce the impact on a stream.