Big Fish Lake vs Sauk Lake
Water quality, depth, fish species, and recreation comparison.
Big Fish Lake has a higher water quality grade (A, Excellent) than Sauk Lake (D, Poor). Both are in Stearns County, Minnesota.
Both Big Fish Lake and Sauk Lake sit in Minnesota. A same-state comparison strips out the state-level water-quality regime as a variable: any grade differences here are about the lakes themselves, not the agencies grading them. Big Fish Lake (A) is materially cleaner than Sauk Lake (D). A gap that wide is unlikely to close in a single year of remediation work; it reflects multi-decade differences in the lakes themselves.
For a recreational visitor, the wider grade gap is decisive — Big Fish Lake is the better water-quality choice. For a researcher, the gap is the interesting part: what is different about the two watersheds, and which of those differences is mutable?
Big Fish Lake
Crystal clear, you can see 20 ft down.
Sauk Lake
Murky, only visible to about 3.9 ft.
Side-by-Side Metrics
| Metric | Big Fish Lake | Sauk Lake |
|---|---|---|
| Overall Grade | A (Excellent) | D (Poor) |
| Water Clarity | 20 ft | 3.9 ft |
| Phosphorus | 9 µg/L | 52 µg/L |
| Chlorophyll-a (Algae) | 1.8 µg/L | 22.3 µg/L |
| Maximum Depth | 70 ft | 61 ft |
| Surface Area | 557 acres | 2,126 acres |
| Public Access | Yes | Yes |
| Fish Species | 15 | 18 |
| Trophic State | oligotrophic | eutrophic |
Bold value = better for that metric (lower phosphorus / chlorophyll = cleaner; higher Secchi / depth / species count = better).
Verdict
Big Fish Lake wins on overall water quality with a Grade A versus Sauk Lake's Grade D. Water clarity: 20 ft vs 3.9 ft. For more fish-species variety, Sauk Lake edges ahead with 18 documented species.
Source: EPA National Aquatic Resource Surveys, 2026.