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Zebra Mussels and You: Spread, Impacts, and Prevention

Since 2000, 31 Minnesota lakes have been infested with zebra mussels due to spread overland by recreational boaters, anglers and divers. That's an average of 2.1 lakes per year. With over 10,000 lakes, 1.5 million anglers and over 866,000 registered boats moving frequently between waters, you'd think that they'd be more widespread. Media reports of new infestations and the damage they leave in their wake have made most people aware of this harmful aquatic invader. Minnesota has been at the forefront of thwarting the spread of zebra mussels, and media outlets have quickly taken up the story of their spread.

What boaters need to do to be hitchhiker free:

  • CLEAN aquatic plants, zebra mussels and other prohibited invasive species and mud off watercraft, trailer, motor, and equipment before leaving any water access.
  • DRAIN water from boat, bilge, motor, live well and portable bait containers before leaving any water access. Drain plug must be removed at water access and drain plugs and other water draining devices must remain open while trailering or transporting boats.
  • DISPOSE of unwanted bait, including minnows, leeches, and worms, in the trash. It is illegal to release bait into a waterbody or release aquatic animals from one waterbody to another. If you want to keep your bait, you must refill the bait container with bottled or tap water.
  • DRY everything for at least five days OR spray with high pressure and/or hot water (120F/50C for 2 minutes or 140F for at least 10 seconds).

These basic but effective steps can prevent future zebra mussel infestations.

Spread this message to fellow boaters to help ensure that we stop this invasive species throughout the state. Report any new sightings of zebra mussels to the DNR and stay vigilant as we all work to protect our waters.

So, what makes this little mollusk a threat and why should you be concerned?

Close up of a single zebra mussel.

Zebra mussels (Dreissena polymorpha) are small mollusks native to waters of Eastern Europe and Western Russia. In their native region, they are subject to natural predation by bird and fish species that limit populations. Here in North America however, these predators don't exist, and native species cannot keep mussel infestations in check.* Without predators, zebra mussels thrive, rapidly invading water bodies they are spread to. Despite their quick population growth, zebra mussels cannot move themselves between unconnected water systems as they are a largely immobile animal. This means human activities and movement between lakes is the main way they spread to new waters.

Zebra mussels create a variety of problems where they invade. Ecologically speaking, zebra mussels have the potential to completely alter water chemistry of a lake, river or stream due to their high filtration capacity. Despite their small size, a single adult zebra mussel can filter up to a liter of water each day; this process effectively removes nutrients from the water. Considering the size of infestations, commonly 20,000-30,000 mussels per square meter, they can significantly deplete nutrients in the water. This alteration changes habitat and can limit the availability of food for fish and other aquatic species.

Zebra mussels also can affect human recreation and infrastructure. Bottoms of infested waters often become covered in a thick layer of zebra mussels sharp enough to cut the feet of swimmers and dogs. Zebra mussels have also been known to clog drinking water pipes up to 36 inches in diameter. These impacts make the zebra mussel a threat to our ecosystems and have, in turn, become an economic issue. Since they arrived, the cost of zebra mussel control reaches millions of dollars annually.

While people are largely responsible for the current infestations, prevention is possible. With continued public education and enforcement of boating regulations we can eliminate overland transport of this invader.

Early detection is important. Find out how you can help detect and track aquatic invasive species with Extension and the Minnesota Aquatic Invasive Species Research Center.

Marte Kitson, AIS Extension Educator, Minnesota Sea Grant, 218-726-8305,

*Molloy et al. Natural enemies of zebra mussels: Predators, parasites, and ecological competitors. Fisheries Science. Volume 5, Issue 1, 1997. Web. Accessed 8/26/14.

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