Eurasian Watermilfoil
Invasive SpeciesFound in 859 lakes
Eurasian watermilfoil is a submerged aquatic plant that forms dense surface-canopy mats, crowding out native vegetation and limiting boat access. Documented in 859 lakes in our dataset. A 859-lake footprint means Eurasian Watermilfoil 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.
A milfoil-infested lake can still grade well on water-clarity measurements — the plant itself does not cloud the water — but recreational use is meaningfully affected, and that is not captured in the underlying water-quality rubric.
Lakes with Eurasian Watermilfoil
| Lake | County | State | Grade | Depth |
|---|---|---|---|---|
| North Long Lake | Crow Wing | MN | A | 97 ft |
| Ossawinnamakee Lake | Crow Wing | MN | A | 63 ft |
| Birch Lake | Wright | MN | A | 52 ft |
| Girl Lake | Cass | MN | A | 81 ft |
| Charlotte Lake | Wright | MN | A | 46 ft |
| Crooked Lake | Crow Wing | MN | A | 54 ft |
| Alexander Lake | Morrison | MN | A | 64 ft |
| Kimball Lake | Crow Wing | MN | A | 77 ft |
| West Sylvia Lake | Wright | MN | A | 97 ft |
| Courthouse Lake | Carver | MN | A | 57 ft |
| Pulaski Lake | Wright | MN | A | - |
| Bay Lake | Crow Wing | MN | A | 74 ft |
| Sturgeon Lake | Pine | MN | A | 40 ft |
| Holland Lake | Dakota | MN | A | 55 ft |
| East Sylvia Lake | Wright | MN | A | 78 ft |
| Sugar Lake | Wright | MN | A | 69 ft |
| Bad Axe Lake | Hubbard | MN | A | 39 ft |
| Carlos Lake | Douglas | MN | A | 163 ft |
| Ruth Lake | Crow Wing | MN | A | 39 ft |
| Sturgeon Lake | Pine | MN | A | 40 ft |
| Walker Bay Lake | Cass | MN | A | - |
| Agency Bay Lake | Cass | MN | A | - |
| Big Lake | Sherburne | MN | A | 48 ft |
| Kabekona Bay Lake | Cass | MN | A | 150 ft |
| Superior Lake | Cook | MN | A | - |
| Superior Lake | St. Louis | MN | A | - |
| Geneva Lake | Walworth | WI | A | 135 ft |
| Deep Lake | Adams | WI | A | 49 ft |
| Beasley Lake | Waupaca | WI | A | 47 ft |
| Explosion Lake | Oconto | WI | A | - |
| White Sand Lake Deep | Vilas | WI | A | 63 ft |
| Lake Lucerne | Forest | WI | A | 73 ft |
| Lake Metonga | Forest | WI | A | 79 ft |
| Round Lake | Sawyer | WI | A | 74 ft |
| Round Lake | Waupaca | WI | A | 67 ft |
| Round Lake | Oconto | WI | A | 31 ft |
| Clear Lake | Sawyer | WI | A | 32 ft |
| Clear Lake | Lincoln | WI | A | 45 ft |
| Razorback Lake | Vilas | WI | A | 35 ft |
| Little Spider Lake | Vilas | WI | A | 23 ft |
| North Lake | Florence | WI | A | 43 ft |
| Pike Lake | Polk | WI | A | 33 ft |
| Wolf Lake | Adams | WI | A | 58 ft |
| Archibald Lake | Oconto | WI | A | 50 ft |
| North Twin Lake | Polk | WI | A | 27 ft |
| Eagle Lake | Bayfield | WI | A | 52 ft |
| Stone Lake | Washburn | WI | A | 49 ft |
| Big Lake | Vilas | WI | A | 30 ft |
| Upper Kaubashine Lake | Oneida | WI | A | 56 ft |
| Squash Lake | Oneida | WI | A | 74 ft |
Showing 50 of 859 infested lakes.
Frequently Asked Questions
How many lakes have eurasian watermilfoil?
Eurasian Watermilfoil has been documented in 859 graded lakes: 481 in Wisconsin, 377 in Minnesota, 1 in North Dakota.
Does eurasian watermilfoil affect water quality?
Invasive species can significantly affect lake ecosystems. They may alter nutrient cycling, displace native species, and change water clarity. Lakes with eurasian watermilfoil should be monitored for changes in water quality over time.
Invasives Found With Eurasian Watermilfoil
Co-occurs in 289 lakes · 432 total
Co-occurs in 217 lakes · 493 total
Co-occurs in 215 lakes · 363 total
Co-occurs in 162 lakes · 688 total
Co-occurs in 158 lakes · 688 total
Co-occurs in 154 lakes · 278 total
Source: EPA National Aquatic Resource Surveys, 2026.