Birch Lake vs Tamarack Bay Lake
Water quality, depth, fish species, and recreation comparison.
Birch Lake has a higher water quality grade (A, Excellent) than Tamarack Bay Lake (C, Fair). Both are in Cass County, Minnesota.
Both Birch Lake and Tamarack Bay 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. The grades are meaningfully apart: Birch Lake grades a A while Tamarack Bay Lake grades a C. That two-letter spread reflects real underlying differences — different watershed inputs, different depth profiles, or different monitoring rigor.
For a recreational visitor, the wider grade gap is decisive — Birch 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?
Birch Lake
Good clarity, visible to about 14 ft.
Tamarack Bay Lake
Good clarity, visible to about 11.5 ft.
Side-by-Side Metrics
| Metric | Birch Lake | Tamarack Bay Lake |
|---|---|---|
| Overall Grade | A (Excellent) | C (Fair) |
| Water Clarity | 14 ft | 11.5 ft |
| Phosphorus | 12 µg/L | 26 µg/L |
| Chlorophyll-a (Algae) | 4 µg/L | 4.6 µg/L |
| Maximum Depth | 45 ft | 69.8 ft |
| Surface Area | 1,267 acres | 56,471 acres |
| Public Access | Yes | Yes |
| Fish Species | 14 | 20 |
| Trophic State | mesotrophic | mesotrophic |
Bold value = better for that metric (lower phosphorus / chlorophyll = cleaner; higher Secchi / depth / species count = better).
Verdict
Birch Lake wins on overall water quality with a Grade A versus Tamarack Bay Lake's Grade C. Water clarity: 14 ft vs 11.5 ft. For more fish-species variety, Tamarack Bay Lake edges ahead with 20 documented species.
Source: EPA National Aquatic Resource Surveys, 2026.