Is Lake St Louis Safe for Swimming?
Lake St Louis in St. Charles County, Missouri has limited nutrient and algae sampling on record. Chlorophyll-a in the monitoring record runs high enough that algae is a factor. A water-quality reading is not a swimming clearance. The state water agency and county health departments post current advisories; check them before you swim.. 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 |
|---|---|
| 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 does not have enough recent summer sampling to compare 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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