Written by Theresa Rose on August 6, 2015

DES MOINES – Hot temperatures, low stream levels and cloudbursts are the perfect recipe for a fish kill.

“Historically, fish kills occur more frequently under these conditions, and we are very dry here in northwest Iowa,” says Ken Hessenius, supervisor of DNR’s Spencer field office. “We’ve also investigated a few fish kills in other parts of the state this week.

“For that reason, we want to encourage farmers, pesticide and manure applicators and homeowners to be extra careful when using chemicals, fertilizers and manure,” he added.

The dog days of summer, when heat and algal blooms cause oxygen levels to drop, cause fish and other aquatic organisms like crayfish and dragonfly larvae especially vulnerable to pollutants.

Anyone who handles chemicals or animal manure can take a few simple precautions to prevent downstream impacts.

Follow pesticide labels and manure management plans. Watch the application rate and observe setbacks from streams. “Some aerially sprayed chemicals are toxic to fish at concentrations of less than one part per billion, which is like adding a pinch of salt to a 10-ton bag of potato chips,” he said.

Check for discharges from chemical mixing stations or areas of livestock concentration to make sure nothing reaches the stream after a rain,” he says. “Keeping open lots scraped and clean will help.”

If you suspect a problem with runoff, contain it immediately to prevent pollutants from entering a stream. Check below the lot to see if runoff is reaching a ditch, stream pond or tile inlet.

Finally, report spills, runoff and fish kills as soon as possible to the nearest DNR field office or the 24-hour spill line at 515-725-8694. Spills must be reported within six hours of discovery, but the sooner they are reported, the sooner specialists at the DNR can help with advice on containment, reducing the impact on a stream.