Spiny Waterflea

Invasive SpeciesFound in 100 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 100 lakes. 100 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 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.

100

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
Pine Lake	Cook	MN	A	113 ft
Burntside Lake	St. Louis	MN	A	126 ft
Gunflint Lake	Cook	MN	A	200 ft
Flour Lake	Cook	MN	A	75 ft
Su18 Lake	Cook	MN	A	-
Mcfarland Lake	Cook	MN	A	-
Su19 Lake	Cook	MN	A	-
Little Gunflint Lake	Cook	MN	A	200 ft
Superior Lake	Cook	MN	A	-
Superior Lake	St. Louis	MN	A	-
Ls94 Lake	Lake	MN	A	-
Suseq32a Lake	St. Louis	MN	A	-
Seq044a Lake	Lake	MN	A	-
Suseq44a Lake	Lake	MN	A	-
Seq032a Lake	St. Louis	MN	A	-
Spider Lake	Vilas	WI	A	43 ft
Whitefish Lake	Douglas	WI	A	102 ft
Whitefish Lake	Douglas	WI	A	102 ft
Butternut Lake	Forest	WI	A	42 ft
Plum Lake	Vilas	WI	A	57 ft
Ike Walton Lake Deep	Vilas	WI	A	61 ft
Twin Falls Flowage Us Twin Falls Dam Lake	Florence	WI	A	50 ft
Stormy Lake	Vilas	WI	A	63 ft
Bardon Lake	Douglas	WI	A	102 ft
Ml-Thains Lake	Mille Lacs	MN	A	42 ft
Ml-Seventeen Lake	Aitkin	MN	A	42 ft
Ml Lake	Mille Lacs	MN	A	42 ft
Ml Lake	Mille Lacs	MN	A	42 ft
Ml-Vineland Lake	Mille Lacs	MN	A	42 ft
Ml-Peterson Lake	Mille Lacs	MN	A	42 ft
Ml-Malone Lake	Mille Lacs	MN	A	42 ft
Lake of the Woods	Lake of the Woods	MN	A	-
Greenwood Lake	Cook	MN	A	112 ft
Low: Mpca Co-Located Site Muskeg Bay Lake	Lake of the Woods	MN	A	-
Low: Mpca Co-Located Site Big Traverse Bay Lake	Lake of the Woods	MN	A	-
Low: Mpca Co-Located Site Lake	Lake of the Woods	MN	A	-
Ml-Nw Lake	Aitkin	MN	B	42 ft
Ml-Ce Lake	Aitkin	MN	B	42 ft
Ml-Se Lake	Mille Lacs	MN	B	42 ft
Ml-Nshore Lake	Aitkin	MN	B	42 ft
Ml-Ne Lake	Aitkin	MN	B	42 ft
Mille Lacs Lake	Aitkin	MN	B	42 ft
Devil Track Lake	Cook	MN	B	50 ft
Red Rock Lake	Cook	MN	B	64 ft
Sucker Lake	Lake	MN	B	111 ft
Namakan Lake	St. Louis	MN	B	150 ft
Snowbank Lake	Lake	MN	B	150 ft
Lake of the Woods	Lake of the Woods	MN	B	-

Showing 50 of 100 infested lakes.

Frequently Asked Questions

How many lakes have spiny waterflea?

Spiny Waterflea has been documented in 100 lakes, 88 in Minnesota and 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.

Source: EPA National Aquatic Resource Surveys, 2026.