Warmer temperatures in the City of Lakes set off natural cycle of fish kills

If you’ve been noticing some not-so-pleasant smells around the lakes in Minneapolis, don’t be alarmed. As strange as it sounds, the warmer temperatures and the appearance of dead fish and decomposing plants around the lakes have a direct correlation.

“Every spring, the rise in water temperatures and ensuing decrease in oxygen available for the fish, combined with the stress from spawning, can lead to fish kills,” said Deb Pilger, Director of Environmental Management for the Minneapolis Park and Recreation Board (MPRB).

This year, due to colder springtime temperatures, the process is occurring later in the season.

What happens after a fish kill

The MPRB reports fish kills to the Minnesota Department of Natural Resources (DNR), where fish are tested if DNR staff believe they were killed by factors other than those mentioned above. Species affected are usually sunfish, crappies and bullheads and occasionally, largemouth bass and northern pike.

“Typically, people who own homes or cabins with lakeshore access are aware of the fish kill odor,” said Pilger. “But Minneapolis lakes have paths and trails that offer such great access, more people notice it.”

“We try to keep an eye out for fish kills in spring and summer and make sure we remove fish from the shoreline in a timely manner,” she added.

Key points about spring fish kills:

  • Fish kills and plant decomposition occur annually 
  • Lakes across Minnesota – not just in Minneapolis – experience fish kills
  • Seasonal fish kills do not affect a lake’s water quality for swimming or boating. They do not affect water quality for other fish or the ability to eat or consume fish from the lake


Robin Smothers
Minneapolis Park and Recreation Board
Phone: 612-230-6410
Email: rsmothers@minneapolisparks.org