DNR launches online fish kill reporting tool for Otter Tail lakes

Anglers, lake homeowners and boaters around Otter Tail Lake, Big Pine Lake and North Lida Lake now have a faster way to flag fish die-offs before the problem spreads or points to a larger water-quality issue. The Minnesota Department of Natural Resources said May 11 that Minnesotans who see multiple dead fish in one area should use its new online reporting form, which the agency prefers because it speeds up and simplifies the response.

The state’s duty officer line remains open 24 hours a day, seven days a week at 651-649-5451 or 800-422-0798. Isaiah Tolo, the DNR’s fish health supervisor, said public reports are an important way the agency learns about fish mortality and help staff coordinate timely water and fish sampling and other response actions when needed.

When filing a report, the DNR said it is especially helpful to note the types of fish and their general sizes. That detail can help staff tell whether a cluster of dead fish looks like a localized die-off or something more serious that needs a broader response from state agencies.

The DNR classifies these events as fish kills or fish die-offs, both of which involve multiple fish deaths in one area. State employees must report events as small as 25 fish, and some incidents can involve thousands of fish from one or more species. The agency said fish kills are typically tied to an acute pollution event or industrial process, while fish die-offs are more often linked to environmental conditions.

Low dissolved oxygen is the most common factor in both fish kills and fish die-offs, according to the DNR. Other causes can include disease, fish stranded in isolated water, spawning stress, high temperatures, low water levels, sewage or wastewater releases, chemical spills and pollutant runoff. Rapid oxygen drops or prolonged low oxygen can lead fish to gasp at the surface before large die-offs follow. The DNR said hundreds of fish mortality events may occur across Minnesota each year.

In Otter Tail and Wilkin counties, the Fergus Falls area fisheries office manages 250 fishing lakes and 150 miles of rivers and streams, including work on the Otter Tail, Pelican and Red rivers. That local reach makes quick reporting especially important when dead fish appear on heavily used lakes, where early notice can shape how fast the DNR and other agencies react. Reported fish kills are posted weekly in the Environmental Quality Board Monitor.