Wisconsin Lake Water Quality
Water quality grades for 185 monitored lakes across 48 counties.
About 36% of New York's lakes pull an A — 67 top-bracket waters. That high A-share comes mostly from the cold, deep, kettle-formed lakes in the north of the state, which buffer themselves against nutrient inputs.
Trophically, oligotrophic lakes — cold, clear, low-nutrient — dominate the state's graded inventory. These are the deep glacial basins that buffer against nutrient inputs by sheer volume, and they hold most of New York's A-grade waters. St. Lawrence ranks highest on average county grade (A). Orange sits lowest. With only 48 counties in the state, the cross-county spread is narrower than the within-county spread for most lakes.
Lake Map
Reservoirs in Wisconsin
View all 60 reservoirs →60 of 185 Wisconsin lakes (32%) are man-made reservoirs in the USACE National Inventory of Dams. 36 carry a High or Significant hazard rating. The oldest matched dam dates to 1820.
EPA-Impaired Lakes in Wisconsin
View all 94 impaired lakes →94 of 185 Wisconsin lakes (51%) are officially listed as impaired under Clean Water Act §303(d) in the most recent EPA ATTAINS reporting cycle. 30 have an approved Total Maximum Daily Load (TMDL) restoration plan.
Counties
Top 25 Cleanest Lakes
| Rank | Lake | County | Grade | Clarity | Max Depth |
|---|---|---|---|---|---|
| 1 | Blue Mtn Lake | Hamilton | A | 21 ft | - |
| 2 | Brant Lake | Warren | A | 16.4 ft | - |
| 3 | Lake George | Warren | A | 26.7 ft | - |
| 4 | Loon Lake | Steuben | A | 14.8 ft | - |
| 5 | Lake Placid | Essex | A | 23.1 ft | - |
| 6 | Bradley Brook Reservoir | Madison | A | 20.7 ft | - |
| 7 | Friends Lake | Warren | A | 16.3 ft | - |
| 8 | Canandaigua Lake | Ontario | A | 17.6 ft | - |
| 9 | Oquaga Lake | Broome | A | 26.2 ft | - |
| 10 | Eagle Lake | Essex | A | 24.3 ft | - |
| 11 | Glen Lake | Warren | A | 16 ft | - |
| 12 | Lake Petonia | Chenango | A | 20.2 ft | - |
| 13 | Deruyter Reservoir | Madison | A | 17.6 ft | - |
| 14 | Chenango Lake | Chenango | A | 16.6 ft | - |
| 15 | Main Section Lake | Essex | A | 15.7 ft | - |
| 16 | Lake Sunnyside | Warren | A | 17.8 ft | - |
| 17 | Anawanda Lake | Sullivan | A | 18.4 ft | - |
| 18 | Keuka Lake | Yates | A | 23.6 ft | - |
| 19 | Lincoln Pond | Essex | A | 15.1 ft | - |
| 20 | Lake Bonaparte | Lewis | A | 15.8 ft | - |
| 21 | Skaneateles Lake | Onondaga | A | 27.4 ft | - |
| 22 | Mirror Lake | Essex | A | 22.6 ft | - |
| 23 | Lake Moraine | Madison | A | 20.3 ft | - |
| 24 | Lake Luzerne | Warren | A | 17.1 ft | - |
| 25 | Burden Lake | Rensselaer | A | 14.8 ft | - |
25 Lakes Needing Attention
| Rank | Lake | County | Grade | Clarity |
|---|---|---|---|---|
| 1 | Lake Lucille | Rockland | F | 2.3 ft |
| 2 | Java Lake | Wyoming | F | 2.1 ft |
| 3 | Lake Lacoma | Monroe | F | 3 ft |
| 4 | Deer River Flow Lake | Franklin | F | 3.3 ft |
| 5 | Buckingham Lake | Albany | F | 2.5 ft |
| 6 | Howlands Lake | Westchester | F | 3.1 ft |
| 7 | Truitt Pond | Chenango | F | 3.2 ft |
| 8 | Lake Lincolndale | Westchester | F | 2.8 ft |
| 9 | Orange Lake | Orange | F | 2.4 ft |
| 10 | Lk Ontario Lake | Monroe | D | - |
| 11 | Jamesville Reservoir | Onondaga | D | 5.3 ft |
| 12 | Stissing Pond | Dutchess | D | 5.9 ft |
| 13 | Duane Lake | Schenectady | D | 3.8 ft |
| 14 | Lake Carmel | Putnam | D | 5.6 ft |
| 15 | Seven Hills Lake | Putnam | D | 4.8 ft |
| 16 | Plymouth Reservoir | Chenango | D | 6.2 ft |
| 17 | Sleepy Hollow Lake | Greene | D | 5.9 ft |
| 18 | Kinderhook Lake | Columbia | D | 6.1 ft |
| 19 | Waneta Lake | Schuyler | D | 4.3 ft |
| 20 | Swamp Pond | Sullivan | D | 3.9 ft |
| 21 | Pleasant Lake | Oswego | D | 4.4 ft |
| 22 | Barger Pond | Putnam | D | 3.9 ft |
| 23 | Tomkins Lake | Rockland | D | 5.4 ft |
| 24 | Beaver Lake | Broome | D | 5.5 ft |
| 25 | Lake Waccabuc | Westchester | D | 5.7 ft |
Source: EPA National Aquatic Resource Surveys, 2026.