Cleanest Lakes in Montana
Tally Lake in Flathead County leads the rankings on measured clarity and nutrients and 15.2 ft of clarity. Below are the top 22 cleanest monitored lakes in Montana, ranked on EPA nutrient and algae measurements.
Ranked List
| # | Lake | County | Clarity | Phosphorus | Algae |
|---|---|---|---|---|---|
| 1 | Tally Lake | Flathead | 15.2 ft | 4.7 µg/L | 0.8 µg/L |
| 2 | Whitefish Lake | Flathead | 22 ft | 2.8 µg/L | 0.9 µg/L |
| 3 | Swan Lake North End | Lake | - | 3.1 µg/L | 1.1 µg/L |
| 4 | Little Bitterroot Lake Center | Flathead | - | 4 µg/L | 1 µg/L |
| 5 | Inez Lake | Missoula | - | 7.1 µg/L | 1.8 µg/L |
| 6 | Alva Lake | Missoula | - | 4.7 µg/L | 0.7 µg/L |
| 7 | Cooney Reservoir | Carbon | 12.5 ft | 20 µg/L | 2.6 µg/L |
| 8 | East Bay Lake | Lake | - | 3 µg/L | - |
| 9 | Big Arm Bay Lake | Lake | - | 1.5 µg/L | - |
| 10 | Dickey Lake | Lincoln | - | 11.3 µg/L | 2.2 µg/L |
| 11 | Mcgilvray Lake | Flathead | - | 5.9 µg/L | 1.7 µg/L |
| 12 | Hanson-Doyle Lake | Flathead | - | 7.3 µg/L | 2.3 µg/L |
| 13 | Fish Lake | Lincoln | - | 8.1 µg/L | 2.3 µg/L |
| 14 | Bailey Lake | Flathead | - | 6.9 µg/L | 2 µg/L |
| 15 | Big Sky Lake | Missoula | - | 10 µg/L | 2.1 µg/L |
| 16 | Loon Lake | Lake | - | 6.7 µg/L | 2.2 µg/L |
| 17 | Mary Ronan Lake West | Lake | - | 33.6 µg/L | 4.7 µg/L |
| 18 | Foys Lake | Flathead | - | 15.8 µg/L | 4.1 µg/L |
| 19 | Rogers Lake | Flathead | - | 11.6 µg/L | 2.6 µg/L |
| 20 | Jette Lake | Lake | - | 16.6 µg/L | 4.7 µg/L |
| 21 | Mary Ronan Lake East | Lake | - | 15.8 µg/L | 3.5 µg/L |
| 22 | Lake Helena Outlet | Lewis and Clark | - | 115.5 µg/L | - |
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