Is Mark Twain Lake by Hwy J Safe for Swimming?
Mark Twain Lake by Hwy J in Ralls County, Wisconsin has a water quality grade of C (Fair). Generally safe for swimming, moderate water quality. Water clarity: 3.7 ft visibility. Phosphorus: 33.6 µg/L. Chlorophyll-a (algae): 14.6 µg/L. Always check local health department advisories before swimming.
Key Metrics
| Metric | Value |
|---|---|
| Overall Grade | C (Fair) |
| Water Clarity (Secchi Depth) | 3.7 ft |
| Phosphorus | 33.6 μg/L |
| Chlorophyll-a (Algae) | 14.6 μg/L |
| Location | Ralls County, Wisconsin |
How does Mark Twain Lake by Hwy J compare?
With an overall water quality grade of C, Mark Twain Lake by Hwy J matches or beats the Wisconsin state average of Grade C. It ranks #1 of 4 lakes in Ralls County by water quality score.
Water clarity (Secchi depth) sits at 3.7 feet. That falls into moderate clarity — typical for lakes with some nutrient enrichment. Algae levels (chlorophyll-a) measure 14.6 µg/L — moderate; acceptable for swimming on most days, but worth checking advisories.