Birch Lake vs Town Line Lake
Water quality, depth, fish species, and recreation comparison.
Birch Lake reads lower on nutrients and algae than Town Line Lake. Both are in Cass County, Minnesota.
Both Birch Lake and Town Line Lake sit in Minnesota. A same-state comparison strips out the state-level water-quality regime as a variable: any differences in the readings here are about the lakes themselves, not the agencies sampling them. Birch Lake reads materially cleaner than Town Line Lake on nutrients and algae. 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 gap in the readings is decisive: Birch Lake has the lower nutrient and algae numbers. 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.
Town Line Lake
Murky, only visible to about 6.6 ft.
Side-by-Side Metrics
| Metric | Birch Lake | Town Line Lake |
|---|---|---|
| Water Clarity | 14 ft Better | 6.6 ft |
| Phosphorus | 12 µg/L | 11 µg/L Better |
| Chlorophyll-a (Algae) | 4 µg/L | 2.1 µg/L Better |
| Maximum Depth | 45 ft Better | 11 ft |
| Surface Area | 1,267 acres | 698 acres |
| Public Access | Yes | Yes |
| Fish Species | 14 Better | 8 |
| Trophic State | mesotrophic | mesotrophic |
A green ✓ marks the better value for that metric (lower phosphorus / chlorophyll = cleaner; higher Secchi / depth / species count = better). Surface area and trophic state carry no tick — a bigger lake is not a better lake.
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Verdict
Birch Lake reads lower on nutrients and algae than Town Line Lake. Water clarity: 14 ft vs 6.6 ft. For fishing diversity, Birch Lake also leads with 14 species.
Source: EPA National Aquatic Resource Surveys, 2026.