Koochiching County Lake Quality
Minnesota, 7 lakes, average grade D (Poor)
Koochiching County has 7 graded lakes — a thin enough sample that one or two stressed lakes can move the county average noticeably. Use the per-lake pages below for what actually matters. On average, Koochiching County lakes grade D, with phosphorus loading and reduced clarity showing up across most of the dataset.
A meaningful share of Koochiching's lakes break 50 feet of depth, which matters because deep lakes hold cooler water all summer and resist the resuspended-sediment problems that plague shallow basins. The county's best-graded lake is Rainy Lake (C).
Quick Answers for Koochiching County
Planning a trip? Check special fishing regulations for Rainy Lake, whether the fish are safe to eat, and the best times to fish — or browse the full Minnesota regulations index.
DNR Reports (6)
Minnesota DNR LakeFinder resources for lakes in Koochiching County. browse all reports →
- —Fisheries Lake Survey — RainyFisheries Lake Survey · MN DNR LakeFinder
- —Fisheries Lake Survey — BartlettFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Bartlett (1966)Aquatic Plant Report · MN DNR LakeFinder
- —Fish Stocking History — BartlettFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — BartlettPublic Water Access Sites · MN DNR LakeFinder
- —Public Water Access Sites — RainyPublic Water Access Sites · MN DNR LakeFinder
All Lakes in Koochiching County
| Rank | Lake | Grade | Clarity | Max Depth | Phosphorus |
|---|---|---|---|---|---|
| 1 | Rainy Lake | C | 7.5 ft | 161 ft | - |
| 2 | Bartlett Lake | C | 4 ft | 16 ft | 37 µg/L |
| 3 | Rainy Lake | D | 3.6 ft | 161 ft | - |
| 4 | Rainy Lake | D | 6.6 ft | 161 ft | - |
| 5 | Rainy Lake | D | 4.9 ft | 161 ft | - |
| 6 | Rainy Lake | D | 3.6 ft | 161 ft | - |
| 7 | Rainy Lake | D | 5.2 ft | 161 ft | - |
Source: EPA National Aquatic Resource Surveys, 2026.