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LakeQuality
A storm cloud deck moving over Slim Lake at dusk, the last light breaking through low on the horizon

Starry Stonewort

Invasive speciesRecorded in 79 lakes

Starry stonewort is a relatively new invasive macroalga in the region. It forms thick, hard-to-control mats and is much more difficult to remove than the older invasive plants. Documented in 79 lakes so far — a number that has grown over the past five years. 79 infested lakes is enough to require active prevention work statewide. The species is established in pockets but not ubiquitous.

The presence of Starry Stonewort does not change a lake's clarity, phosphorus or algae readings, which measure the water itself, not the species living in it. Invasive presence is still worth reading alongside those numbers.

79
Lakes with records
50
Minnesota
29
Wisconsin

Lakes with Starry Stonewort

LakeCountyStateDepth
Clearwater LakeWrightMN73 ft
Long LakeKandiyohiMN46 ft
Long LakeHubbardMN135 ft
Benedict LakeHubbardMN91 ft
Leech LakeCassMN-
Moose LakeBeltramiMN71 ft
Turtle LakeBeltramiMN45 ft
Pokegama LakeItascaMN112 ft
West Sylvia LakeWrightMN97 ft
Pleasant LakeWrightMN74 ft
Bemidji LakeBeltramiMN76 ft
Rush LakeCrow WingMN105 ft
Wolf LakeBeltramiMN57 ft
Thunder LakeCassMN95 ft
Stump LakeBeltramiMN24 ft
Three Island LakeBeltramiMN25 ft
Beltrami LakeBeltramiMN50 ft
Minnewaska LakePopeMN32 ft
Garfield LakeHubbardMN32 ft
Middle Cullen LakeCrow WingMN48 ft
Pimushe LakeBeltramiMN40 ft
Steamboat Bay LakeCassMN150 ft
Boy Bay LakeCassMN-
Shingobee Bay LakeCassMN-
Portage Bay LakeCassMN-
Traders Bay LakeCassMN-
Headquarters Bay LakeCassMN-
Sucker Bay LakeCassMN-
Walker Bay LakeCassMN-
Agency Bay LakeCassMN-
Kabekona Bay LakeCassMN150 ft
Hen LakeCrow WingMN105 ft
Cass LakeBeltramiMN120 ft
Big Cedar Lake-North Site-Near West BendWashingtonWI105 ft
Geneva LakeWalworthWI135 ft
Big Wolf LakeHubbardMN57 ft
Green LakeWalworthWI57 ft
Green LakeWashingtonWI37 ft
Silver LakeKenoshaWI44 ft
Bear LakeWaupacaWI62 ft
Pike LakeWashingtonWI45 ft
Pewaukee LakeWaukeshaWI45 ft
Grass LakeShawanoWI52 ft
Lac la Belle LakeWaukeshaWI45 ft
Eagle Spring LakeWaukeshaWI8 ft
Lower Nemahbin LakeWaukeshaWI36 ft
Denoon LakeWaukeshaWI55 ft
Pine LakeShawanoWI35 ft
Pine LakeWaukeshaWI85 ft
Upper Nemahbin LakeWaukeshaWI60 ft

Showing 50 of 79 lakes with a record.

Frequently Asked Questions

How many lakes have starry stonewort?

Starry Stonewort is recorded in 79 measured lakes: 50 in Minnesota, 29 in Wisconsin. 79 of them carry a state infested-waters listing or an established population.

Does starry stonewort affect water quality?

An established invasive population can change how a lake works — altering nutrient cycling, displacing native species, and shifting water clarity. Clarity is the one to watch: filter-feeders can make water read clearer on a Secchi disk without any drop in nutrient loading, so a lake with starry stonewort is worth reading alongside its clarity number rather than through it.

Invasives Found With Starry Stonewort

Zebra Mussel

Co-occurs in 41 lakes · 609 total

Curly-Leaf Pondweed

Co-occurs in 28 lakes · 387 total

Zebra Mussel

Co-occurs in 27 lakes · 609 total

Purple Loosestrife

Co-occurs in 17 lakes · 242 total

Eurasian Watermilfoil

Co-occurs in 16 lakes · 792 total

Chinese Mystery Snail

Co-occurs in 16 lakes · 469 total

More on invasive species and lake health

Zebra Mussel Spread: How Many Lakes Are Affected?

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

Lake Water Quality Explained: What the Readings Mean

How nutrient and algae readings are read against EPA ecoregion condition classes, what each class means in the water, and why a clean reading 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.