The DNR ‘s Spencer field office investigated the fish kill Wednesday morning, finding dead crawdads and fish of different sizes and species in the stream. The stream flows into Rat Creek, a tributary of Otter Creek, located between Ashton and George in the eastern part of the county.
The DNR staff took field tests of water samples. Field results ruled out excessive manure and fertilizer as causes of the kill. Pending lab results, aerial spraying is the most probable cause of the kill, following three aerial applicators flying the area Tuesday. This is the second recent Lyon County fish kill likely due to aerial spraying.
Some pesticides can be toxic to fish and other aquatic organisms in very small amounts, counted in parts of chemical per billion parts of water. The University of Michigan compares one ppb with a pinch of salt in 10 tons of potato chips or one second in nearly 32 years.
Report fish kills to the DNR’s 24-hour spill line at 515-281-8694, or to the regional DNR field office during business hours at www.iowadnr.gov/InsideDNR/DNRStaffOffices/EnvironmentalFieldOffices.aspx. Quick reporting can help the DNR trace the pollutant source and reduce environmental damage.