North Twin Lake vs South Twin Lake
Water quality, depth, fish species, and recreation comparison.
North Twin Lake and South Twin Lake both received the same overall water quality grade of A (Excellent). Both are in Mahnomen County, Minnesota.
North Twin Lake and South Twin Lake are both in Minnesota — a same-state head-to-head where the comparison comes down to lake-specific differences in depth, watershed, and monitoring history rather than the broader state-level water-quality regime. The grades are close: North Twin Lake (A) and South Twin Lake (A) are within one letter of each other on the LakeGrade rubric. The per-parameter sub-grades below will show where the small differences actually live.
With grades 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.
North Twin Lake
Moderate clarity, visible to about 8.5 ft.
South Twin Lake
Good clarity, visible to about 10.2 ft.
Side-by-Side Metrics
| Metric | North Twin Lake | South Twin Lake |
|---|---|---|
| Overall Grade | A (Excellent) | A (Excellent) |
| Water Clarity | 8.5 ft | 10.2 ft |
| Phosphorus | 17 µg/L | 13.5 µg/L |
| Chlorophyll-a (Algae) | 5.9 µg/L | 3.1 µg/L |
| Maximum Depth | 16 ft | 29 ft |
| Surface Area | 966 acres | 1,127 acres |
| Public Access | No | Yes |
| Fish Species | 14 | 15 |
| Trophic State | mesotrophic | mesotrophic |
Bold value = better for that metric (lower phosphorus / chlorophyll = cleaner; higher Secchi / depth / species count = better).
Verdict
Both lakes earn the same Grade A. The tiebreakers come down to clarity (North Twin Lake: 8.5 ft, South Twin Lake: 10.2 ft) and what you want from the lake. North Twin Lake has fewer fish species than South Twin Lake.
Source: EPA National Aquatic Resource Surveys, 2026.