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Hybrid Eurasian/Northern Watermilfoil

Invasive speciesRecorded in 130 lakes

Hybrid Eurasian/Northern Watermilfoil appears on state infested-waters lists for 130 surface waters. Boaters and anglers moving gear in or out of those lakes carry a clean-drain-dry obligation under state law. With 130 documented lakes, Hybrid Eurasian/Northern Watermilfoil sits in the middle of the invasion curve — established enough that prevention requires real coordination, not so widespread that containment is hopeless.

The presence of Hybrid Eurasian/Northern Watermilfoil 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.

130
Lakes with records
130
Wisconsin

Lakes with Hybrid Eurasian/Northern Watermilfoil

LakeCountyStateDepth
Green LakeGreen LakeWI236 ft
Lake BeulahWalworthWI58 ft
Powers LakeKenoshaWI33 ft
Round LakeSawyerWI74 ft
Green LakeWashingtonWI37 ft
Potter LakeWalworthWI26 ft
Pickerel LakeForestWI19 ft
Silver LakeKenoshaWI44 ft
Silver LakeWaukeshaWI40 ft
Silver LakeWausharaWI50 ft
Plum LakeVilasWI57 ft
Round LakeShawanoWI39 ft
Round LakeOcontoWI31 ft
Cedar LakeManitowocWI21 ft
Deep LakeAdamsWI49 ft
Bass LakeFlorenceWI16 ft
Bass LakeOcontoWI40 ft
Kusel LakeWausharaWI29 ft
Berry LakeOcontoWI27 ft
Marl LakeWausharaWI35 ft
Long LakeFond du LacWI47 ft
Crooked LakeAdamsWI56 ft
Lilly LakeKenoshaWI22 ft
Rock LakeJeffersonWI60 ft
Pike LakeWashingtonWI45 ft
Pleasant LakeWausharaWI24 ft
Pleasant LakeWalworthWI29 ft
Lake MorrisWausharaWI40 ft
Kelly LakeOcontoWI41 ft
Camelot LakeAdamsWI24 ft
Bark LakeWashingtonWI34 ft
Grass LakeShawanoWI52 ft
Lake EmilyPortageWI35 ft
Jordan LakeAdamsWI92 ft
Loon LakeShawanoWI22 ft
Little Hills LakeWausharaWI20 ft
Lake KeesusWaukeshaWI42 ft
Hartlaub LakeManitowocWI60 ft
Gilbert LakeWausharaWI65 ft
Bahr LakeShawanoWI44 ft
Lake RipleyJeffersonWI44 ft
Eagle Spring LakeWaukeshaWI8 ft
Oconomowoc LakeWaukeshaWI60 ft
Druid LakeWashingtonWI53 ft
Crane LakeForestWI25 ft
Whitewater LakeWalworthWI35 ft
Krohns LakeKewauneeWI38 ft
Crystal LakeMarquetteWI60 ft
Mcginnis LakeAdamsWI28 ft
Forest LakeFond du LacWI32 ft

Showing 50 of 130 lakes with a record.

Frequently Asked Questions

How many lakes have hybrid eurasian/northern watermilfoil?

Hybrid Eurasian/Northern Watermilfoil is recorded in 130 measured lakes: 130 in Wisconsin. 130 of them carry a state infested-waters listing or an established population.

Does hybrid eurasian/northern watermilfoil 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 hybrid eurasian/northern watermilfoil is worth reading alongside its clarity number rather than through it.

Invasives Found With Hybrid Eurasian/Northern Watermilfoil

Curly-Leaf Pondweed

Co-occurs in 94 lakes · 387 total

Banded Mystery Snail

Co-occurs in 78 lakes · 341 total

Zebra Mussel

Co-occurs in 59 lakes · 609 total

Chinese Mystery Snail

Co-occurs in 48 lakes · 469 total

Purple Loosestrife

Co-occurs in 44 lakes · 242 total

Rusty Crayfish

Co-occurs in 25 lakes · 233 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.