Size of zebra mussels

Hopefully by now, most people in Northwest Wisconsin are familiar with the troublesome zebra mussels that were discovered in Big McKenzie Lake in the fall of 2016. A lakeshore owner pulling out his dock found them and brought them to the Wisconsin Department of Natural Resoures for verification. They are now also inhabiting Middle McKenzie Lake.

This very invasive finger-nail sized mussel, with alternating white and brown stripes, creates problems by attaching to hard surfaces such as docks, rocks, boats, and even native clam species and crayfish. Clams can’t open their shells to feed and can die.

Zebra mussels reduce food sources for fish and other animals, decrease water quality which may cause more vegetative growth, and can cut feet. Because they multiply quickly and cannot be eliminated, they hamper boating, swimming, fishing, and hiking. One zebra mussel can produce up to 1 million eggs per season!

Cooperative efforts create results

The DNR conducted Environmental DNA (eDNA) sampling, which is the detection of DNA shed from an organism. This method is primarily used to determine the presence of AIS. It doesn’t tell how much there is or if it’s dead or alive. Ten total lakes were tested in Northwest Wisconsin, with Big McKenzie being the only one showing a positive hit. State, county, and federal staff along with many trained citizen volunteers conducted early detection surveys in other lakes. Those results also came back negative for zebra mussels in lakes outside the McKenzie Chain.

Staff and citizens will continue monitoring efforts throughout Washburn and Burnett counties in 2019 and conduct an early-detection survey of Lower McKenzie.

The Washburn County Lakes and Rivers Association (WCLRA) works with local and state agencies to educate consumers and monitor and sample for new infestations of the mussels and other invasive species.

Effective prevention against spread of zebra mussels

The first step to keep zebra mussels and other aquatic invasive species from being carried from one waterbody to another is for all boaters and water recreationists to look for and remove any plants, animals, or mud which may harbor unwanted “hitchhikers.” Also drain all water from boat and equipment, including the live well water.

Another step to prevent the spread of invasive species is to use the decontamination station, if one is provided at a boat launch, before entering and leaving the waterbody. It takes just a few minutes and is required per 2018 Washburn and Burnett County ordinance (Chapter 46, Article IV, Section 46-50).

Each station consists of instructions, a long-handled soft brush, a weed remover, goggles, and a gallon sprayer with a pre-mixed mild bleach and water solution. The mild solution kills microscopic zebra mussel larvae and other invasive species.

In Washburn County, the decontamination stations are currently installed at the McKenzie Chain, Bass (Casey township), Cable, Mathews, Long Lake, Nancy, Spooner, and Stone. More stations are anticipated this year.

Everyone boating, swimming or hiking around water is encouraged to watch for zebra mussels along the shore, on docks, or on swimming rafts. If you find any unusual or suspected aquatic invasive species or want to volunteer to get more involved, contact Kris Larsen, 715.468.4072, or Lisa Burns, 715.468.4654.

We appreciate the public’s awareness and efforts to keep our lakes healthy in Northwest Wisconsin! Join us at the Northwest Wisconsin Lakes Conference on June 21 at the Hayward Middle School.

For more information about zebra mussels and other activities of WCLRA, visit


(Copyright © 2019 APG Media)

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