Zebra Mussel Spread: How Many Lakes Are Affected?
Zebra mussels are one of the most damaging invasive species in the upper Midwest. They filter massive volumes of water, altering nutrient cycles and starving native mussels and plankton. Here is what the data shows across Minnesota and Wisconsin.
By the Numbers
694
Zebra Mussel Lakes
861
Eurasian Milfoil Lakes
1,692
Any Invasive Species
45%
Lakes Affected
Most Affected Counties
| County | Zebra Mussel Lakes |
|---|---|
| Otter Tail County, MN | 61 |
| Crow Wing County, MN | 44 |
| Douglas County, MN | 43 |
| Waukesha County, WI | 38 |
| Cass County, MN | 36 |
| Becker County, MN | 31 |
| Wright County, MN | 21 |
| Walworth County, WI | 21 |
| Stearns County, MN | 20 |
| St. Louis County, MN | 19 |
| Itasca County, MN | 19 |
| Kandiyohi County, MN | 16 |
| Ramsey County, MN | 15 |
| Hennepin County, MN | 14 |
| Beltrami County, MN | 14 |
What Can You Do?
- Clean — remove all aquatic plants, animals, and mud from boats and equipment
- Drain — all water from livewells, bilge, and motors before leaving the launch
- Dry — allow boats to dry completely between lakes (Wisconsin requires 5 days or decontamination)
- Report — if you find zebra mussels on a lake not listed, report to your state DNR
View all invasive species data → · Full zebra mussel lake list →