Unknown County Lake Quality
Minnesota, 5 lakes — no lake here has enough monitoring data for a grade
Only 5 lakes in Unknown County carry an active grade. The county-level summary is therefore representative of those specific lakes, not necessarily of every water body in the county.
Many of the county's lakes are deep glacial basins — over 50 feet at their deepest point — which gives them thermal stratification and a buffer against summer warming. Birch Lake (grade —) is the cleanest in the county.
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Quick Answers for Unknown County
Planning a trip? Check special fishing regulations for Birch Lake, whether the fish are safe to eat, and the best times to fish — or browse the full Minnesota regulations index.
Fishing in Unknown County
DNR Reports (6)
Minnesota DNR LakeFinder resources for lakes in Unknown County. browse all reports →
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — AshdickFisheries Lake Survey · MN DNR LakeFinder
- —Fisheries Lake Survey — OttertrackFisheries Lake Survey · MN DNR LakeFinder
- —Fisheries Lake Survey — ClearwaterFisheries Lake Survey · MN DNR LakeFinder
- —Fisheries Lake Survey — BirchFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Clearwater (1828)Aquatic Plant Report · MN DNR LakeFinder
- —Public Water Access Sites — ClearwaterPublic Water Access Sites · MN DNR LakeFinder
All Lakes in Unknown County
5 lakes · 0 graded, 5 not rated0 graded lakes · 5 not rated, hidden
| # | Lake | Grade | Clarity | Phosphorus | Algae | Trophic | Max Depth | Access |
|---|---|---|---|---|---|---|---|---|
| NRBirch LakeUnknown | NR | 15 ft | No recent samples | No recent samples | No recent samples | 34 ft | Carry-in | |
| NRCarp LakeUnknown | NR | 8.5 ft | No recent samples | No recent samples | No recent samples | 34 ft | Carry-in | |
| NRSeed LakeUnknown | NR | 7 ft | No recent samples | No recent samples | No recent samples | No recent samples | Carry-in | |
| NRSwamp LakeUnknown | NR | 16.2 ft | No recent samples | No recent samples | No recent samples | 50 ft | Carry-in | |
| NRMountain LakeUnknown | NR | 19 ft | No recent samples | No recent samples | No recent samples | 130 ft | ✓ Public |
NR = not rated: there is not enough recent sampling to support a letter. That is EPA Integrated Reporting Category 3 (insufficient information), not a failing grade. How grading works.
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Other Counties in Minnesota
See how Unknown County stacks up in the national county water-quality rankings, or browse the full directory of graded lakes across all 49 states and 2 Canadian provinces.
Source: EPA National Aquatic Resource Surveys, 2026.