Big Pine Lake vs Ml-Nw Lake
Water quality, depth, fish species, and recreation comparison.
Big Pine Lake and Ml-Nw Lake both received the same overall water quality grade of A (Excellent). Both are in Aitkin County, Minnesota.
Big Pine Lake and Ml-Nw 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. These two are within a letter of each other on the rubric — Big Pine Lake (A) versus Ml-Nw Lake (A). The deciding factors for a recreational visitor are likely physical (depth, access, fish species) rather than water-quality differences.
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.
Big Pine Lake
Crystal clear, you can see 17 ft down.
Ml-Nw Lake
Moderate clarity, visible to about 9.4 ft.
Side-by-Side Metrics
| Metric | Big Pine Lake | Ml-Nw Lake |
|---|---|---|
| Overall Grade | A (Excellent) | A (Excellent) |
| Water Clarity | 17 ft | 9.4 ft |
| Phosphorus | 15 µg/L | 24 µg/L |
| Chlorophyll-a (Algae) | 1.6 µg/L | 5.7 µg/L |
| Maximum Depth | 78 ft | 42 ft |
| Surface Area | 638 acres | 128,250 acres |
| Public Access | Yes | Yes |
| Fish Species | 15 | 21 |
| Trophic State | oligotrophic | 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 (Big Pine Lake: 17 ft, Ml-Nw Lake: 9.4 ft) and what you want from the lake. Big Pine Lake has fewer fish species than Ml-Nw Lake.
Source: EPA National Aquatic Resource Surveys, 2026.