Duluth agrees to $202,000 package after 1.7 million‑gallon potable water release kills trout in Tischer Creek

DULUTH — City staff on Monday walked the Duluth City Council through an investigation into an August 2024 release that drained roughly 1.7 million gallons of potable water from an underground Woodland neighborhood reservoir into Tischer Creek and caused a substantial fish kill.

Ryan Granlund, a utility program coordinator in the public works utilities division, told the council the reservoir’s bottom drain is physically connected to the storm sewer network that discharges untreated to Tischer Creek. On the day of the release the stream was at base flow — about 0.19 cubic feet per second — while the release flowed at roughly 10.7 CFS. Granlund said the disinfectant concentration in the distributed water was about 1.6 parts per million, a normal level for drinking water but far above thresholds toxic to brook trout: “Chlorine toxicity levels are 0.038 parts per million for trout,” he said, explaining how the mismatch in flow and concentration produced lethal conditions for fish.

The city’s review, conducted with the Minnesota Pollution Control Agency (MPCA) and the Minnesota Department of Natural Resources (DNR), concluded the discharge produced substantial ecological harm. Granlund…