South Long Lake vs Upper South Long Lake
Water quality, depth, fish species, and recreation comparison.
South Long Lake and Upper South Long Lake read the same on nutrients and algae. Both are in Crow Wing County, Minnesota.
Both South Long Lake and Upper South Long 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. These two sit close on the readings, South Long Lake versus Upper South Long Lake. The deciding factors for a recreational visitor are likely physical (depth, access, fish species) rather than water-quality differences.
With readings this close, the choice between the two lakes turns on non-water-quality factors: depth, fish species, public access, distance from home. The per-lake pages below cover all of those.
South Long Lake
Moderate clarity, visible to about 9 ft.
Upper South Long Lake
Murky, only visible to about 6 ft.
Side-by-Side Metrics
| Metric | South Long Lake | Upper South Long Lake |
|---|---|---|
| Water Clarity | 9 ft Better | 6 ft |
| Phosphorus | 24 µg/L | 16 µg/L Better |
| Chlorophyll-a (Algae) | 8.8 µg/L | 8.5 µg/L Better |
| Maximum Depth | 47 ft | 47 ft |
| Surface Area | 1,309 acres | 804 acres |
| Public Access | Yes | Yes |
| Fish Species | 17 Better | 16 |
| 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.
Swap a lake
Compare South Long Lake or Upper South Long Lake against a different lake.
Verdict
Both lakes earn the same Grade C. The tiebreakers come down to clarity (South Long Lake: 9 ft, Upper South Long Lake: 6 ft) and what you want from the lake. South Long Lake supports more documented fish species.
Source: EPA National Aquatic Resource Surveys, 2026.