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Fish kills more likely under current stream conditions
Posted: 06/21/2012

Low stream levels, high temperatures and dry conditions set the stage for potential stream problems and fish kills. Even small amounts of polluted runoff can cause problems for fish and other aquatic organisms under these conditions.

“We’ve responded to two fish kills in eastern Iowa during the last week,” said Dennis Ostwinkle, supervisor of the DNR Washington field office. “We have extremely low stream conditions in southeast Iowa and other parts of the state. High temperatures and low oxygen levels in the water stress fish, leaving them vulnerable to pollutants washed into the water.”

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

Second, if you suspect a problem with runoff, it’s important to contain the runoff or prevent pollutants from entering it,” Hessenius said. “Iowa State Extension has test kits available that can be used to check for ammonia levels, a key indicator of possible pollution problems from manure or fertilizer.” 

Test kits and more information are available through about 20 county Iowa State University Extension and Outreach offices. Find test kit locations, a fact sheet and video on the IMMA G website at www.agronext.iastate.edu/immag/smallfeedlotsdairy.

Finally, report fish kills as soon as possible to the nearest DNR field office or the 24-hour spill line at 515-281-8694. Specialists at the DNR can help people trace the pollutant causing the fish kill and reduce the impact on a stream.

On the Delaware-Dubuque county line, DNR specialists checked Coffey Creek and found partially decayed large white suckers and a few creek chubs after a landowner reported a fish kill on June 15. The specialists concluded a pollutant was the likely cause of the fish kill, but were unable to identify the pollutant because the fish had been dead for about five days and any traces of pollutant had disappeared from the water.

In a separate incident, DNR biologists and environmental specialists concluded that a fish kill at Lake Odessa was due to natural causes. The DNR checked the Mississippi backwater in Louisa County on Monday, checking for dissolved oxygen levels again on Tuesday. The dead fish were predominantly large gizzard shad, which are particularly susceptible to temperature fluctuations.

For more information contact Dennis Ostwinkle at 319-653-2135 or Dennis.Ostwinkle@dnr.iowa.gov.



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