The State of Wisconsin's Lakes 2026

Cleanest lakes in Wisconsin

Cleanest combined nutrient and algae readings, 2026.

1. 1.Big Cedar Lake-North Site-Near West Bend — Washington County11.8 ft clarity · 18 µg/L P · 4 µg/L chl-a
2. 2.Green Lake — Green Lake County13.5 ft clarity · 38 µg/L P · 4 µg/L chl-a
3. 3.Lake Beulah — Walworth County10.0 ft clarity · 13 µg/L P · 3 µg/L chl-a
4. 4.Geneva Lake — Walworth County21.0 ft clarity · 13 µg/L P · 2 µg/L chl-a
5. 5.Powers Lake — Kenosha County10.0 ft clarity · 17 µg/L P · 3 µg/L chl-a
6. 6.Lac Courte Oreilles Lake — Sawyer County12.2 ft clarity · 15 µg/L P · 2 µg/L chl-a
7. 7.Whitefish Lake — Sawyer County13.5 ft clarity · 14 µg/L P · 2 µg/L chl-a
8. 8.Round Lake — Sawyer County21.1 ft clarity · 14 µg/L P · 1 µg/L chl-a
9. 9.Indian Lake — Sawyer County6.5 ft clarity · 23 µg/L P · 4 µg/L chl-a
10. 10.Big Lake — Shawano County8.0 ft clarity · 15 µg/L P · 3 µg/L chl-a

Highest measured algae

Highest measured chlorophyll-a (algae) concentration.

No qualifying lakes with sufficient data.

Trending lakes

Improving

1. 1.Green Lake — Green Lake County
2. 2.Lake Beulah — Walworth County
3. 3.Powers Lake — Kenosha County
4. 4.Lac Courte Oreilles Lake — Sawyer County
5. 5.Whitefish Lake — Sawyer County
6. 6.Round Lake — Sawyer County
7. 7.Big Lake — Shawano County
8. 8.Ashegon Lake — Sawyer County

Declining

1. 1.Lake Redstone — Sauk County
2. 2.Beaver Dam Lake — Dodge County
3. 3.Rice Lake — Dane County
4. 4.Rice Lake — Walworth County
5. 5.Hidden Valley Lake — Lafayette County
6. 6.Bear Lake — Bayfield County
7. 7.Butternut Lake — Barron County
8. 8.Altoona Lake — Eau Claire County