MANKATO, Minn. — Zebra mussels have been found in the Minnesota River, and if they’re not yet in the rivers around Mankato, they soon will be.

The Department of Natural Resources announced Thursday it has confirmed zebra mussels in a western stretch of the Minnesota River and has found some larvae as far down as New Ulm.

Because there is no barrier, the invasive mussels will make their way down the 335-mile river and its confluence with the Mississippi River in the Twin Cities.

The discovery of mussels comes on the heels of confirmation of invasive big carp and grass carp in the Minnesota River in the past year.

Based on individual captures in 2016 and 2017, the Minnesota River also will be added to the Infested Waters List for bighead carp and grass carp from Granite Falls to the confluence with the Mississippi.

The DNR already has been in contact with some of the businesses, such as commercial anglers and bait harvesters, that would be affected by this designation. Changes in those regulated commercial activities on the Minnesota River will now match Mississippi River regulations. Related Articles Mike Lynch’s Skywatch: Roll down the big river of stars

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“We consider these designations carefully, especially when they affect businesses and people,” DNR invasive carp coordinator Nick Frohnauer said in a statement. “The tipping point was the recent capture of a large bighead carp with eggs. Although it’s just a few individuals, both male and female fish have been captured. This designation is a precautionary tool to help minimize risks.”

Last September, the DNR confirmed zebra mussels in Lac qui Parle, a Minnesota River reservoir. Recent DNR surveys confirmed adult zebra mussels behind the Granite Falls Dam and zebra mussel larvae, called veligers, at four of seven sites on the Minnesota River from Montevideo to near New Ulm.

No veligers were detected at survey sites near St. Peter, Chaska, Minneapolis or St. Paul.

Zebra mussels, bighead carp and grass carp are not native to Minnesota. Zebra mussels can compete with native species for food and habitat, cut the feet of swimmers, reduce the performance of boat motors and cause expensive damage to water intake pipes. Invasive carp can compete with native species for food, dramatically reduce aquatic vegetation and diminish water quality.

To protect the state’s waters from the spread of invasive species and the environmental, recreational and economic damage they cause, Minnesota law requires boaters and anglers to:

Clean watercraft of aquatic plants and prohibited invasive species.

Drain all water by removing drain plugs and keeping them out during transport.

Dispose of unwanted bait in the trash.

Some invasive species are small and difficult to see at the access. To remove or kill them, take one or more of the following precautions before moving to another water body, especially after leaving infested waters: