Spiny Waterflea

Invasive SpeciesFound in 78 lakes

Spiny waterflea is a small zooplankton invasive that disrupts the food web by competing with native zooplankton — the base of the food chain for many small fish. Documented in 78 lakes. 78 infested lakes is enough to require active prevention work statewide. The species is established in pockets but not ubiquitous.

The presence of Spiny Waterflea does not directly change a lake's letter grade — the grade measures the water itself, not the species living in it. Invasive presence is still worth reading alongside the grade.

Total Lakes

Minnesota

Wisconsin

Lakes with Spiny Waterflea

Lake	County	State	Grade	Depth
Clearwater Lake	Cook	MN	A	65 ft
Trout Lake	Cook	MN	A	77 ft
Devil Track Lake	Cook	MN	A	50 ft
Fall Lake	Lake	MN	A	32 ft
Burntside Lake	St. Louis	MN	A	126 ft
Gunflint Lake	Cook	MN	A	200 ft
Flour Lake	Cook	MN	A	75 ft
Mcfarland Lake	Cook	MN	A	8 ft
Greenwood Lake	Cook	MN	A	112 ft
Ml-Nw Lake	Aitkin	MN	A	42 ft
Ml-Seventeen Lake	Aitkin	MN	A	42 ft
Teal Lake Deep	Cook	MN	A	-
Ml-Vineland Lake	Mille Lacs	MN	A	42 ft
Little Lake Deep	Cook	MN	A	-
Ml-Malone Lake	Mille Lacs	MN	A	42 ft
Ml-Ne Lake	Aitkin	MN	A	42 ft
Snowbank Lake	Lake	MN	B	150 ft
Spider Lake	Vilas	WI	B	43 ft
Plum Lake	Vilas	WI	B	57 ft
Whitefish Lake	Douglas	WI	B	102 ft
Butternut Lake	Forest	WI	B	42 ft
Lake Waubesa	Dane	WI	B	38 ft
East Twin Lake	St. Louis	MN	C	22 ft
Big Traverse Bay Lake	Lake of the Woods	MN	C	-
Lake of the Woods	Lake of the Woods	MN	C	-
Lake of the Woods	Lake of the Woods	MN	C	-
Ml-Thains Lake	Mille Lacs	MN	C	42 ft
Ml-Ce Lake	Aitkin	MN	C	42 ft
Ml-Se Lake	Mille Lacs	MN	C	42 ft
Ml-Peterson Lake	Mille Lacs	MN	C	42 ft
Ml-Garrison Lake	Aitkin	MN	C	42 ft
Ml-Nshore Lake	Aitkin	MN	C	42 ft
Lake of the Woods	Lake of the Woods	MN	C	-
Lake of the Woods	Lake of the Woods	MN	C	-
Lake of the Woods	Lake of the Woods	MN	C	-
Low Lake	Lake of the Woods	MN	C	-
Low Lake	Lake of the Woods	MN	C	-
Low Lake	Lake of the Woods	MN	C	-
Bardon Lake	Douglas	WI	C	102 ft
Lake of the Woods	Lake of the Woods	MN	D	-
Lake Kegonsa	Dane	WI	D	32 ft
Lake Mendota	Dane	WI	D	83 ft
Kabetogama Lake	St. Louis	MN	NR	80 ft
Rainy Lake	Koochiching	MN	NR	161 ft
Rainy Lake	St. Louis	MN	NR	161 ft
Namakan Lake	St. Louis	MN	NR	150 ft
Kabetogama Lake	St. Louis	MN	NR	80 ft
Kabetogama Lake	St. Louis	MN	NR	80 ft
Sand Point Lake	St. Louis	MN	NR	184 ft
Crane Lake	St. Louis	MN	NR	80 ft

Showing 50 of 78 infested lakes.

Frequently Asked Questions

How many lakes have spiny waterflea?

Spiny Waterflea has been documented in 78 graded lakes: 66 in Minnesota, 12 in Wisconsin.

Does spiny waterflea affect water quality?

Invasive species can significantly affect lake ecosystems. They may alter nutrient cycling, displace native species, and change water clarity. Lakes with spiny waterflea should be monitored for changes in water quality over time.

Invasives Found With Spiny Waterflea

Zebra Mussel

Co-occurs in 38 lakes · 667 total

Eurasian Watermilfoil

Co-occurs in 22 lakes · 849 total

Chinese Mystery Snail

Co-occurs in 10 lakes · 494 total

New Zealand Mud Snail

Co-occurs in 9 lakes · 9 total

Faucet Snail

Co-occurs in 9 lakes · 41 total

Round Goby

Co-occurs in 9 lakes · 18 total

More on invasive species and lake health

Zebra Mussel Spread: How Many Lakes Are Affected?

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

Lake Water Quality Grades Explained: What A–F Means

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.

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.