Is Long Lake Safe for Swimming?
Long Lake in Washington County, Minnesota has a water quality grade of D (Poor). Swimming not recommended, poor water quality with high algae risk. Water clarity: 2.8 ft visibility. Phosphorus: 47.5 µg/L. Chlorophyll-a (algae): 26 µg/L. Always check local health department advisories before swimming.
Key Metrics
| Metric | Value |
|---|---|
| Overall Grade | D (Poor) |
| Water Clarity (Secchi Depth) | 2.8 ft |
| Phosphorus | 47.5 μg/L |
| Chlorophyll-a (Algae) | 26 μg/L |
| Maximum Depth | 60 ft |
| Location | Washington County, Minnesota |
How does Long Lake compare?
With an overall water quality grade of D, Long Lake falls below the Minnesota state average of Grade C. It ranks #63 of 83 lakes in Washington County by water quality score.
Water clarity (Secchi depth) sits at 2.8 feet. That signals heavy algae or sediment, often tied to high phosphorus from runoff. Algae levels (chlorophyll-a) measure 26 µg/L — elevated; risk of harmful algal bloom advisories increases at this concentration.