Purple Loosestrife
Invasive SpeciesFound in 288 lakes
Purple Loosestrife appears on the {{stateName}} infested-waters lists for 288 surface waters. Boaters and anglers moving gear in or out of those lakes carry a clean-drain-dry obligation under state law. At 288 infested lakes, Purple Loosestrife is past the "containable" stage in the upper Midwest — every public boat-launch on uninfested water should now assume incoming boaters may be carrying it.
The presence of Purple Loosestrife does not directly change a lake's LakeGrade rubric score — the grade measures the water itself, not the species inhabiting it. But invasive presence is a meaningful adjacent signal worth reading alongside the grade.
Lakes with Purple Loosestrife
| Lake | County | State | Grade | Depth |
|---|---|---|---|---|
| Long Lake | Waushara | WI | A | 71 ft |
| Long Lake | Waupaca | WI | A | 76 ft |
| Long Lake | Burnett | WI | A | 41 ft |
| Long Lake | Fond du Lac | WI | A | 47 ft |
| Long Lake | Bayfield | WI | A | 28 ft |
| Chain Lake | Chippewa | WI | A | 74 ft |
| Spring Lake | Manitowoc | WI | A | 23 ft |
| Spider Lake | Vilas | WI | A | 43 ft |
| Silver Lake | Waukesha | WI | A | 40 ft |
| Silver Lake | Kenosha | WI | A | 44 ft |
| Silver Lake | Vilas | WI | A | - |
| Lac la Belle Lake | Waukesha | WI | A | 45 ft |
| Spencer Lake | Waupaca | WI | A | 53 ft |
| Goose Lake | Adams | WI | A | 18 ft |
| Wind Lake | Polk | WI | A | - |
| Weber Lake | Iron | WI | A | 39 ft |
| Pewaukee Lake | Waukesha | WI | A | 45 ft |
| Bear Lake | Oneida | WI | A | 20 ft |
| Bear Lake | Waupaca | WI | A | 62 ft |
| Bear Lake | Barron | WI | A | 87 ft |
| Lily Lake | Brown | WI | A | 19 ft |
| Pine Lake | Iron | WI | A | 41 ft |
| Planting Ground Lake | Oneida | WI | A | 37 ft |
| Lake Emily | Portage | WI | A | 35 ft |
| Rock Lake | Kenosha | WI | A | 33 ft |
| Birch Island Lake | Burnett | WI | A | - |
| Kusel Lake | Waushara | WI | A | 29 ft |
| Island Lake | Rusk | WI | A | 54 ft |
| Island Lake | Vilas | WI | A | 35 ft |
| Spirit Lake | Oneida | WI | A | 39 ft |
| Buffalo Lake | Oneida | WI | A | 27 ft |
| Booth Lake | Oneida | WI | A | 34 ft |
| Tiger Cat Flowage Lake | Sawyer | WI | A | 30 ft |
| Nagawicka Lake | Waukesha | WI | A | 90 ft |
| Shadow Lake | Waupaca | WI | A | 41 ft |
| Red Cedar Lake | Barron | WI | A | 53 ft |
| Turtle Lake | Walworth | WI | A | 30 ft |
| Porcupine Lake | Florence | WI | A | 20 ft |
| Pickerel Lake | Oconto | WI | A | - |
| Stone Lake | Washburn | WI | A | 49 ft |
| Mercer Lake | Oneida | WI | A | 23 ft |
| Ranch Lake | Oconto | WI | A | 44 ft |
| Big Mckenzie Lake | Washburn | WI | A | 71 ft |
| White Potato Lake | Oconto | WI | A | - |
| Tozer Lake | Washburn | WI | A | 53 ft |
| North Twin Lake | Polk | WI | A | 27 ft |
| Ottawa Lake | Waukesha | WI | A | - |
| Golden Lake | Waukesha | WI | A | 44 ft |
| Wolf Lake | Portage | WI | A | 17 ft |
| Lower Eau Claire Lake | Bayfield | WI | A | 41 ft |
Showing 50 of 288 infested lakes.
Frequently Asked Questions
How many lakes have purple loosestrife?
Purple Loosestrife has been documented in 288 lakes, 0 in Minnesota and 288 in Wisconsin.
Does purple loosestrife affect water quality?
Invasive species can significantly affect lake ecosystems. They may alter nutrient cycling, displace native species, and change water clarity. Lakes with purple loosestrife should be monitored for changes in water quality over time.
Source: EPA National Aquatic Resource Surveys, 2026.