The State of Wisconsin’s Lakes 2026

Cleanest lakes in Wisconsin

Highest combined water-quality score, 2026.

1. 1.AGeneva Lake — Walworth County20.2 ft clarity · 13 µg/L P
2. 2.ADeep Lake — Adams County15.5 ft clarity · 13 µg/L P
3. 3.ABeasley Lake — Waupaca County18.4 ft clarity · 15 µg/L P
4. 4.ABass Lake — Washburn County16.0 ft clarity · 12 µg/L P
5. 5.ABass Lake — Oconto County16.8 ft clarity · 11 µg/L P
6. 6.AExplosion Lake — Oconto County17.0 ft clarity · 16 µg/L P
7. 7.ASugar Camp Lake — Oneida County16.5 ft clarity · 10 µg/L P
8. 8.ALake Lucerne — Forest County18.5 ft clarity · 9 µg/L P
9. 9.ALake Metonga — Forest County22.0 ft clarity · 14 µg/L P
10. 10.ARound Lake — Sawyer County21.1 ft clarity · 14 µg/L P · 1 µg/L chl-a

Most-polluted lakes

Lowest combined water-quality score among monitored lakes.

1. 1.FLake Redstone — Sauk County2.0 ft clarity · 92 µg/L P
2. 2.FIndian Lake — Dane County0.7 ft clarity · 295 µg/L P
3. 3.FBig Eau Pleine Lake — Marathon County1.5 ft clarity · 131 µg/L P
4. 4.FBeaver Dam Lake — Dodge County1.0 ft clarity · 228 µg/L P
5. 5.FRice Lake — Dane County1.5 ft clarity · 197 µg/L P
6. 6.FLong Lake — Manitowoc County1.9 ft clarity · 90 µg/L P
7. 7.FAltoona Lake — Eau Claire County3.0 ft clarity · 100 µg/L P
8. 8.FEagle Lake — Racine County1.5 ft clarity · 113 µg/L P
9. 9.FMud Lake — Polk County2.0 ft clarity · 93 µg/L P
10. 10.FComus Lake — Walworth County1.5 ft clarity · 193 µg/L P

Worst algae hotspots

Highest measured chlorophyll-a (algae) concentration.

1. 1.DMilwaukee Harbor South Half Lake — Milwaukee County31 µg/L chlorophyll-a
2. 2.CMilwaukee Harbor North Half Lake — Milwaukee County26 µg/L chlorophyll-a
3. 3.CMilwaukee Harbor Lake — Milwaukee County26 µg/L chlorophyll-a
4. 4.DMilwaukee Harbor Lake — Milwaukee County23 µg/L chlorophyll-a
5. 5.CBig Round Lake — Polk County21 µg/L chlorophyll-a

Trending lakes

Improving

1. 1.ABig Bass Lake — Washburn County
2. 2.ADeep Lake — Adams County
3. 3.ABeasley Lake — Waupaca County
4. 4.ABass Lake — Oconto County
5. 5.AWhite Sand Lake Deep — Vilas County
6. 6.ALake Lucerne — Forest County
7. 7.ALake Metonga — Forest County
8. 8.ARound Lake — Sawyer County

Declining

1. 1.FLake Redstone — Sauk County
2. 2.FSilver Lake — Walworth County
3. 3.FBeaver Dam Lake — Dodge County
4. 4.FBear Lake — Douglas County
5. 5.FLong Lake — Price County
6. 6.FIsland Lake — Iron County
7. 7.FAltoona Lake — Eau Claire County
8. 8.FComus Lake — Walworth County