Beltrami Lake vs Three Island Lake
Water quality, depth, fish species, and recreation comparison.
Beltrami Lake and Three Island Lake read the same on nutrients and algae. Both are in Beltrami County, Minnesota.
Both Beltrami Lake and Three Island 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, Beltrami Lake versus Three Island 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.
Beltrami Lake
Good clarity, visible to about 11.2 ft.
Three Island Lake
Good clarity, visible to about 11.8 ft.
Side-by-Side Metrics
| Metric | Beltrami Lake | Three Island Lake |
|---|---|---|
| Water Clarity | 11.2 ft | 11.8 ft Better |
| Phosphorus | 15 µg/L Better | 17 µg/L |
| Chlorophyll-a (Algae) | 4.3 µg/L | 4.1 µg/L Better |
| Maximum Depth | 50 ft Better | 25 ft |
| Surface Area | 726 acres | 729 acres |
| Public Access | Yes | Yes |
| Fish Species | 16 | 17 Better |
| 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 Beltrami Lake or Three Island Lake against a different lake.
Verdict
Both lakes earn the same Grade A. The tiebreakers come down to clarity (Beltrami Lake: 11.2 ft, Three Island Lake: 11.8 ft) and what you want from the lake. Beltrami Lake has fewer fish species than Three Island Lake.
Source: EPA National Aquatic Resource Surveys, 2026.