Eurasian Watermilfoil
Invasive SpeciesFound in 849 lakes
Eurasian watermilfoil is a submerged aquatic plant that forms dense surface-canopy mats, crowding out native vegetation and limiting boat access. Documented in 849 lakes in our dataset. A 849-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 |
|---|---|---|---|---|
| Clearwater Lake | Wright | MN | A | 73 ft |
| Clearwater Lake | Crow Wing | MN | A | 54 ft |
| Little Birch Lake | Todd | MN | A | 89 ft |
| North Long Lake | Crow Wing | MN | A | 97 ft |
| Big Lake | Sherburne | MN | A | 48 ft |
| Birch Lake | Ramsey | MN | A | - |
| Birch Lake | Wright | MN | A | 52 ft |
| Washburn Lake | Cass | MN | A | 111 ft |
| Otter Lake | Ramsey | MN | A | 21 ft |
| Ossawinnamakee Lake | Crow Wing | MN | A | 63 ft |
| Florida Lake | Kandiyohi | MN | A | 40 ft |
| Spectacle Lake | Isanti | MN | A | 51.5 ft |
| Marion Lake | Dakota | MN | A | 21 ft |
| Mantrap Lake | Hubbard | MN | A | - |
| Fish Lake | Chisago | MN | A | 57 ft |
| Snail Lake | Ramsey | MN | A | 30 ft |
| Green Lake | Kandiyohi | MN | A | 110 ft |
| Girl Lake | Cass | MN | A | 81 ft |
| Charlotte Lake | Wright | MN | A | 46 ft |
| Leech Lake | Cass | MN | A | - |
| Bass Lake | Crow Wing | MN | A | 27 ft |
| Crooked Lake | Crow Wing | MN | A | 54 ft |
| Portage Lake | Crow Wing | MN | A | 37 ft |
| Cedar Lake | Wright | MN | A | 108 ft |
| Turtle Lake | Ramsey | MN | A | 28 ft |
| Mitchell Lake | Sherburne | MN | A | 33 ft |
| Alexander Lake | Morrison | MN | A | 64 ft |
| Henderson Lake | Kandiyohi | MN | A | 57 ft |
| Minnewashta Lake | Carver | MN | A | 70 ft |
| Lawrence Lake | Cass | MN | A | 71 ft |
| Courthouse Lake | Carver | MN | A | 57 ft |
| Kimball Lake | Crow Wing | MN | A | 77 ft |
| Big Marine Lake | Washington | MN | A | - |
| West Sylvia Lake | Wright | MN | A | 97 ft |
| Upper Mission Lake | Crow Wing | MN | A | 36 ft |
| Pleasant Lake | Wright | MN | A | 74 ft |
| Pulaski Lake | Wright | MN | A | - |
| Roosevelt Lake | Cass | MN | A | 129 ft |
| Bay Lake | Crow Wing | MN | A | 74 ft |
| White Bear Lake | Washington | MN | A | 83 ft |
| Le Homme Dieu Lake | Douglas | MN | A | 85 ft |
| Shamineau Lake | Morrison | MN | A | 52 ft |
| Pine Lake | Crow Wing | MN | A | 16.9 ft |
| Lac Lavon Lake | Dakota | MN | A | 32 ft |
| Geneva Lake | Douglas | MN | A | 63 ft |
| South Lindstrom Lake | Chisago | MN | A | 34 ft |
| Holland Lake | Dakota | MN | A | 55 ft |
| East Sylvia Lake | Wright | MN | A | 78 ft |
| O'Brien Lake | Dakota | MN | A | - |
| Piersons Lake | Carver | MN | A | 40 ft |
Showing 50 of 849 infested lakes.
Frequently Asked Questions
How many lakes have eurasian watermilfoil?
Eurasian Watermilfoil has been documented in 849 graded lakes: 472 in Wisconsin, 376 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 278 lakes · 420 total
Co-occurs in 213 lakes · 494 total
Co-occurs in 208 lakes · 362 total
Co-occurs in 160 lakes · 667 total
Co-occurs in 152 lakes · 667 total
Co-occurs in 146 lakes · 275 total
More on invasive species and lake health
Zebra mussel counts from the lakes LakeQuality grades, the counties that show up most often, and the Clean, Drain, Dry rules that still matter.
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.
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.