I got the following update today on the Oak Creek fish kill from Wisconsin Department of Natural Resources senior fisheries biologist Will Wawrzyn … and, while disappointing, it’s not surprising.
The upshot: Test results from the Milwaukee Metropolitan Sewerage District are back, and we’ll likely never know what led the death of hundreds of fish in Oak Creek near 16th and Rawson Avenues in South Milwaukee on August 15.
From the update …
The MMSD maintains an extensive monitoring network in local streams and near-shore Lake Michigan and produce high quality data. I appreciate the assistance they provided during this investigation.
Unfortunately, those results do not suggest any killing agent or decreasing trends in water quality between sample sites. While the list of analytes is extensive, there is an almost infinite number and type of potential killing agents that could have caused the kill. All of the results were within the range of water quality criteria or standards protective of fish and other aquatic life. Unless we hear of an after the fact report by others that may suggest what caused the fish kill, we may never know. I am confident that the fish kill was not caused by natural factors. Extended dry conditions and lack of runoff preceding the incident suggests it was not caused by non-point sources of pollution but most likely a discharge or spill of a toxic substances.
My recommendation if for fisheries staff to conduct brief synoptic electrofishing surveys at multiple sites in the near future to assess short-term impacts of the fish kill and gage the recruitment or repopulation of fish from un-impacted reaches, and make qualitative observations of other aquatic life along the impacted stream reach.
I’ll keep you posted on this, if there are any updates to provide. I hope there are — that we can figure out what happened here and make sure it doesn’t happen again. Here is my previous post on this.