Is Lake St Louis Safe for Swimming?
Lake St Louis in St. Charles County, Missouri is not rated for water quality — its monitoring record does not meet the evidence bar. Not rated for swimming — there is not enough monitoring data to judge this lake. Water clarity: 2.7 ft visibility. Phosphorus: 50 µg/L. Chlorophyll-a (algae): 74.3 µg/L. Always check local health department advisories before swimming.
Key Metrics
| Metric | Value |
|---|---|
| Overall Grade | NR (Not rated) |
| Water Clarity (Secchi Depth) | 2.7 ft |
| Phosphorus | 50 μg/L |
| Chlorophyll-a (Algae) | 74.3 μg/L |
| Location | St. Charles County, Missouri |
How does Lake St Louis compare?
Lake St Louis is not rated for water quality — it does not have enough recent summer sampling for a letter grade, so it is not compared with the Missouri state average.
Water clarity (Secchi depth) sits at 2.7 feet. That signals heavy algae or sediment, often tied to high phosphorus from runoff. Algae levels (chlorophyll-a) measure 74.3 µg/L — elevated; risk of harmful algal bloom advisories increases at this concentration.
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