Best Swimming Lakes in Wisconsin
The best lakes for swimming in Wisconsin. Grade A and B water quality, public beach access, and clean water. Ranked by clarity, safety, and accessibility.
Recreation rankings need public-access, beach and launch, depth, and fish-survey data, which currently cover Wisconsin lakes. Water-quality grades themselves span all 49 states and 2 Canadian provinces LakeQuality covers.
| Rank | Lake | County | State | Grade | Clarity | Beaches | Area |
|---|---|---|---|---|---|---|---|
| 1 | Green Lake | Green Lake | WI | A | 13.5 ft | 3 | 7,920 acres |
| 2 | Geneva Lake | Walworth | WI | A | 21 ft | 6 | 5,401 acres |
| 3 | Lake St Croix | St. Croix | WI | B | 5.6 ft | 6 | 7,696 acres |
| 4 | Clear Lake | Oneida | WI | B | — | 2 | 873 acres |
| 5 | Long Lake | Fond du Lac | WI | B | 9.1 ft | 2 | 423 acres |
| 6 | Rock Lake | Jefferson | WI | B | 12 ft | 2 | 1,365 acres |
Frequently Asked Questions
Which lakes are safest for swimming in Wisconsin?
The safest swimming lakes have Grade A or B water quality, meaning low algae levels, high water clarity, and minimal risk of harmful algae blooms. All lakes on this list have public beach access and excellent water quality scores.
How is swimming safety determined?
Swimming safety is based on three factors: water clarity (Secchi depth), phosphorus levels (which fuel algae growth), and chlorophyll-a concentration (a measure of actual algae present). Grade A and B lakes have the lowest risk of harmful algae blooms.
Top Picks: Swimming Lakes
Source: EPA National Aquatic Resource Surveys, 2026.