Cleanest Lakes in St. Louis County, Missouri
Simpson Park Lake in St. Louis County leads the rankings with a water quality grade of D and 1.8 ft of clarity. Below are the top 9 cleanest monitored lakes in St. Louis County, Missouri, ranked by EPA water quality score.
Ranked List
| # | Lake | County | Grade | Clarity | Phosphorus | Algae |
|---|---|---|---|---|---|---|
| 1 | Simpson Park Lake | St. Louis | D | 1.8 ft | 73 µg/L | 23.3 µg/L |
| 2 | Simpson Park Lake | St. Louis | D | 2.5 ft | 36 µg/L | 43.6 µg/L |
| 3 | Mallard Lake | St. Louis | F | 1.9 ft | 84 µg/L | 32.2 µg/L |
| 4 | Creve Coeur Lake | St. Louis | F | 1.6 ft | 101 µg/L | 35.4 µg/L |
| 5 | Koeneman Park Lake | St. Louis | F | 3.1 ft | 270.8 µg/L | 35.9 µg/L |
| 6 | Spanish Lake | St. Louis | F | 1.6 ft | 347.8 µg/L | 62.6 µg/L |
| 7 | Creve Coeur Lake Nr. Boat Ramp | St. Louis | F | 1.2 ft | 100 µg/L | 92.9 µg/L |
| 8 | Bee Tree Lake | St. Louis | F | 0.6 ft | 263 µg/L | 296.4 µg/L |
| 9 | Tilles Park Reservoir | St. Louis | F | - | 434.5 µg/L | 66.5 µg/L |