Ruffe

Invasive SpeciesFound in 12 lakes

Ruffe is documented in 12 lakes across our dataset — 10 in Minnesota and 2 in Wisconsin. Each state's natural-resources agency maintains an official "infested waters" roster that triggers boat-launch decontamination protocols. 12 lakes — narrow enough that aggressive containment is still on the table. Most upper-Midwest invasives that established here did so quietly over a decade before anyone noticed, so a low number today is not a guarantee for tomorrow.

The presence of Ruffe 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 Ruffe

Lake	County	State	Grade	Depth
Teal Lake Deep	Cook	MN	A	-
Little Lake Deep	Cook	MN	A	-
Little Lake Inlet	Cook	MN	NR	-
Little Lake Landing	Cook	MN	NR	-
Superior Lake	Cook	MN	NR	-
Superior Lake	St. Louis	MN	NR	-
Duluth Lake	St. Louis	MN	NR	-
St. Louis Bay Lake	Douglas	MN	NR	-
Teal Lake Landing	Cook	MN	NR	-
Little Lake Culvert	Cook	MN	NR	-
St. Louis River Outlet Upstream of John A. Blatnik Memorial Bridge Lake	Douglas	WI	NR	-
Duluth Lake	Douglas	WI	NR	-

Frequently Asked Questions

How many lakes have ruffe?

Ruffe has been documented in 12 graded lakes: 10 in Minnesota, 2 in Wisconsin.

Does ruffe affect water quality?

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

Invasives Found With Ruffe

Eurasian Watermilfoil

Co-occurs in 9 lakes · 849 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

Spiny Waterflea

Co-occurs in 9 lakes · 78 total

White Perch

Co-occurs in 9 lakes · 9 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.