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LakeQuality

Zebra Mussel

Invasive SpeciesFound in 667 lakes

Zebra mussels are the most consequential invasive in the upper Midwest lake system. They are small, fast-reproducing bivalves that filter enormous volumes of water, increase clarity in a misleading way (filtered water reads clearer on a Secchi disk), and disrupt the food web by stripping the planktonic base. A 667-lake footprint means Zebra Mussel prevention has shifted from "stop the spread" to "manage the new normal." Watercraft-inspection programs at boat launches and shoreline-management practices on individual lakes are doing most of the active prevention work.

On our A–F scale specifically: an A-grade lake with zebra mussels is partially "credited" for clarity that the mussels — not the underlying nutrient regime — produce. Reading both the grade and the invasive flag together gives a truer picture.

667
Total Lakes
496
Minnesota
171
Wisconsin

Lakes with Zebra Mussel

LakeCountyStateGradeDepth
Lobster LakeDouglasMNA65 ft
Clearwater LakeWrightMNA73 ft
Lower Hay LakeCrow WingMNA100 ft
Latoka LakeDouglasMNA108 ft
Little Birch LakeToddMNA89 ft
North Long LakeCrow WingMNA97 ft
Mud LakeBeckerMNA34 ft
Big LakeBeltramiMNA35 ft
Big LakeSherburneMNA48 ft
Pelican LakeOtter TailMNA55 ft
Pelican LakeCrow WingMNA104 ft
Round LakeAitkinMNA125 ft
Round LakeCrow WingMNA51 ft
Whitefish LakeCrow WingMNA138 ft
Horseshoe LakeCrow WingMNA56 ft
Long LakeKandiyohiMNA46 ft
Long LakeOtter TailMNA128 ft
Long LakeBeckerMNA61 ft
Long LakeHubbardMNA135 ft
Long LakeOtter TailMNA73 ft
Dead LakeOtter TailMNA65 ft
Maple LakeDouglasMNA78 ft
Detroit LakeBeckerMNA89 ft
Sallie LakeBeckerMNA50 ft
Deer LakeOtter TailMNA26 ft
Chippewa LakeDouglasMNA95 ft
Lida LakeOtter TailMNA58 ft
Cowdry LakeDouglasMNA52 ft
Ossawinnamakee LakeCrow WingMNA63 ft
Florida LakeKandiyohiMNA40 ft
Clear LakeCrow WingMNA63 ft
Spectacle LakeIsantiMNA51.5 ft
Marion LakeDakotaMNA21 ft
Eagle LakeHubbardMNA77 ft
Eagle LakeKandiyohiMNA67 ft
Eagle LakeOtter TailMNA46 ft
Darling LakeDouglasMNA62 ft
Ida LakeDouglasMNA106 ft
Ida LakeBeckerMNA20 ft
Star LakeOtter TailMNA94 ft
Upper Maple LakeWrightMNA76 ft
Fish LakeOtter TailMNA69 ft
Benedict LakeHubbardMNA91 ft
Sand LakeItascaMNA60 ft
Little Pine LakeCrow WingMNA36 ft
Woman LakeCassMNA-
Andrusia LakeBeltramiMNA60 ft
Green LakeKandiyohiMNA110 ft
Girl LakeCassMNA81 ft
Upper Gull LakeCassMNA54 ft

Showing 50 of 667 infested lakes.

Frequently Asked Questions

How many lakes have zebra mussel?

Zebra Mussel has been documented in 667 graded lakes: 496 in Minnesota, 171 in Wisconsin.

Does zebra mussel affect water quality?

Invasive species can significantly affect lake ecosystems. They may alter nutrient cycling, displace native species, and change water clarity. Lakes with zebra mussel should be monitored for changes in water quality over time.

Invasives Found With Zebra Mussel

Eurasian Watermilfoil

Co-occurs in 160 lakes · 849 total

Curly-Leaf Pondweed

Co-occurs in 131 lakes · 420 total

Banded Mystery Snail

Co-occurs in 80 lakes · 362 total

Purple Loosestrife

Co-occurs in 72 lakes · 275 total

Chinese Mystery Snail

Co-occurs in 69 lakes · 494 total

Starry Stonewort

Co-occurs in 45 lakes · 95 total

More on invasive species and lake health

Zebra Mussel Spread: How Many Lakes Are Affected?

Zebra mussel counts from the lakes LakeQuality grades, the counties that show up most often, and the Clean, Drain, Dry rules that still matter.

Lake Water Quality Grades Explained: What A–F Means

How lakes are graded A–F on nutrients and algae using EPA ecoregion condition classes, what each letter means in the water, and why an A is not a clearance.

What to Check Before Buying Lakefront Property

Before you buy lakefront, check the water: clarity trend, nutrient impairment, algae advisories, invasive species, and depth — a data-backed checklist.

Source: EPA National Aquatic Resource Surveys, 2026.