I’ve been in further contact with the DNR on last week’s Oak Creek fish kill in South Milwaukee, and I want to thank state biologist Will Wawrzyn for his continued help in providing information on the situation.
Here are his last two emails to me …
I am certain of one conclusion, the event was not caused by excessive heat or low flow conditions that the region experienced earlier this summer and contributed to fish kills throughout the state. …
There are some naturally occurring substances that may cause fish kills, most notably 4 relatively common algae species. However, these potentially toxic algae most often occur in eutrophic ponds, lakes and impoundments.
They are often visibly present as green surface scum or along wind-blown shorelines. These conditions were not observed along Oak Creek. Viral Hemorrhagic Septicemia (VHS) is a recent infectious disease that can be fatal to fish.
None of the fish I inspected displayed any of the symptoms of VHS.
At this point, unless sample results show some definitive killing agent or we receive information from another source about an illicit discharge, we may never know the cause.
I’ll keep you posted.