Todd County Lake Quality
Minnesota, 17 lakes, average grade C (Fair)
Todd County's 17 graded lakes fall in the moderate-density bracket for Minnesota. The county-level average smooths over real differences — a single agricultural watershed near the southwest corner can pull the average down even if the rest of the county runs clean. Todd County averages to a C. The distribution behind that average matters more than the letter: a few stressed lakes versus many decent ones can produce the same average as the inverse.
The county's lakes lean shallow, which makes the grades sensitive to wind, sediment-resuspension, and any nutrient inputs from the watershed. The cleanest lake on the books is Mons Lake (A); the most-stressed is Guernsey Lake (D).
Quick Answers for Todd County
Planning a trip? Check special fishing regulations for Mons Lake, whether the fish are safe to eat, and the best times to fish — or browse the full Minnesota regulations index.
DNR Reports (63)
Minnesota DNR LakeFinder resources for lakes in Todd County. Showing 12 most recent — browse all reports →
- —Fisheries Lake Survey — TurtleFisheries Lake Survey · MN DNR LakeFinder
- —Fisheries Lake Survey — Pine IslandFisheries Lake Survey · MN DNR LakeFinder
- —Fisheries Lake Survey — OsakisFisheries Lake Survey · MN DNR LakeFinder
- —Fisheries Lake Survey — MooseFisheries Lake Survey · MN DNR LakeFinder
- —Fisheries Lake Survey — MonsFisheries Lake Survey · MN DNR LakeFinder
- —Fisheries Lake Survey — MapleFisheries Lake Survey · MN DNR LakeFinder
- —Fisheries Lake Survey — LongFisheries Lake Survey · MN DNR LakeFinder
- —Fisheries Lake Survey — Little SaukFisheries Lake Survey · MN DNR LakeFinder
- —Fisheries Lake Survey — Little BirchFisheries Lake Survey · MN DNR LakeFinder
- —Fisheries Lake Survey — LatimerFisheries Lake Survey · MN DNR LakeFinder
- —Fisheries Lake Survey — HorseshoeFisheries Lake Survey · MN DNR LakeFinder
- —Fisheries Lake Survey — GuernseyFisheries Lake Survey · MN DNR LakeFinder
All Lakes in Todd County
| Rank | Lake | Grade | Clarity | Max Depth | Phosphorus |
|---|---|---|---|---|---|
| 1 | Mons Lake | A | 15.4 ft | 80 ft | 11 µg/L |
| 2 | Little Birch Lake | A | 14 ft | 89 ft | 18 µg/L |
| 3 | Big Birch Lake | B | 13 ft | 81 ft | 25 µg/L |
| 4 | Horseshoe Lake | B | 10 ft | 24 ft | - |
| 5 | Long Lake | B | 10 ft | 63 ft | 25 µg/L |
| 6 | Long Lake | B | 14 ft | - | - |
| 7 | Turtle Lake | B | 12 ft | 39 ft | - |
| 8 | Fairy Lake | B | 14.2 ft | 37 ft | - |
| 9 | Pine Island Lake | B | 14.5 ft | 26 ft | - |
| 10 | Big Swan Lake | C | 8.9 ft | 45 ft | - |
| 11 | Moose Lake | C | 7 ft | 26 ft | - |
| 12 | Beauty Lake | C | 7 ft | 27 ft | - |
| 13 | Osakis Lake | C | 10.5 ft | 73 ft | 77 µg/L |
| 14 | Maple Lake | C | 6 ft | 23 ft | 51 µg/L |
| 15 | Latimer Lake | C | 5 ft | 30.5 ft | 58.5 µg/L |
| 16 | Little Sauk Lake | D | 3.9 ft | 29 ft | 72 µg/L |
| 17 | Guernsey Lake | D | 2.6 ft | 19 ft | 68 µg/L |
Source: EPA National Aquatic Resource Surveys, 2026.