Safest Lakes to Swim In in Colorado
9 lakes in Colorado qualify as safest for swimming, all hold grade A or B and report chlorophyll-a (algae) under 10 µg/L. Always check local advisories on the day you swim.
Ranked List
| # | Lake | County | Grade | Clarity | Phosphorus | Algae |
|---|---|---|---|---|---|---|
| 1 | Crystal Reservoir | Montrose | A | 15.4 ft | 15.7 µg/L | - |
| 2 | Lake Granby | Grand | A | 12.7 ft | 17 µg/L | 1.7 µg/L |
| 3 | Pueblo Reservoir | Pueblo | B | 6.7 ft | 10 µg/L | 5 µg/L |
| 4 | Wolford Mountain Reservoir | Grand | B | 8.3 ft | 10 µg/L | 1.9 µg/L |
| 5 | Grand Lake | Grand | B | 8.9 ft | 14 µg/L | 2.7 µg/L |
| 6 | Summit Lake | Jackson | B | 12.1 ft | 20 µg/L | - |
| 7 | Blue Mesa Reservoir | Gunnison | B | 11.5 ft | 35 µg/L | 4.9 µg/L |
| 8 | Windy Gap Reservoir | Grand | B | - | 52.5 µg/L | 3 µg/L |
| 9 | Shadow Mountain Lake | Grand | B | 7.8 ft | 20 µg/L | 5.1 µg/L |