
Nelson County Lake Quality
North Dakota, 37 lakes, average grade F (Algae-prone)
Nelson County's 37 monitored lakes fall in the moderate-density bracket for North Dakota. 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. 4 of those lakes carry an A–F grade. The county-level summary describes that subset, not every water body listed. The county average is F — the most-stressed bracket in our rubric. Most monitored lakes here show persistent nutrient loading and algal pressure.
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 Lake Laretta (D); the most-stressed is Western Stump Lake (F).
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Quick Answers for Nelson County
Planning a trip? Check special fishing regulations for Lake Laretta — or check the official North Dakota fishing regulations.
All Lakes in Nelson County
37 lakes · 4 graded, 33 not rated4 graded lakes · 33 not rated, hidden
| # | Lake | Grade | Clarity | Phosphorus | Algae | Trophic | Access |
|---|---|---|---|---|---|---|---|
| 1 | DLake LarettaNelson | D | 3.3 ft | 253.5 µg/L | 21.7 µg/L | No recent samples | Not recorded |
| 2 | FWestern Stump LakeNelson | F | 4.3 ft | 165.5 µg/L | 36.7 µg/L | No recent samples | Not recorded |
| 3 | FEastern Stump LakeNelson | F | 4.7 ft | 148.5 µg/L | 39.1 µg/L | No recent samples | ✓ Public |
| 4 | FMchugh Slough LakeNelson | F | 1.6 ft | 416 µg/L | 88.7 µg/L | No recent samples | Not recorded |
| NRWest Stump LakeNelson | NR | 9.8 ft | No recent samples | 20.1 µg/L | No recent samples | ✓ Public | |
| NREast Stump LakeNelson | NR | 8.5 ft | No recent samples | 37.9 µg/L | No recent samples | Not recorded | |
| NRWhitman Dam LakeNelson | NR | 12 ft | No recent samples | No recent samples | No recent samples | ✓ Public | |
| NRTolna Dam LakeNelson | NR | 4.9 ft | No recent samples | No recent samples | No recent samples | ✓ Public | |
| NRMcville Dam LakeNelson | NR | 6.9 ft | No recent samples | No recent samples | No recent samples | ✓ Public | |
| NRJohnson LakeNelson | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NROttofy LakeNelson | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRMannie LakeNelson | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRBasswood LakeNelson | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRDahl SloughNelson | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRBerkland SloughNelson | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NROlsen SloughNelson | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRBitter LakeNelson | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRCoon LakeNelson | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRSwan LakeNelson | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRRose LakeNelson | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRJones LakeNelson | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRRose LakeNelson | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRFiske LakeNelson | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRClear LakeNelson | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRStella LakeNelson | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRDeer LakeNelson | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRTwin LakesNelson | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRLake PickardNelson | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRHorseshoe LakeNelson | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRLambs LakeNelson | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRHarrison LakeNelson | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRTwin LakesNelson | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRRugh LakeNelson | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRHorseshoe LakeNelson | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRHillesland LakeNelson | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NROmild SloughNelson | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRMatson SloughNelson | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded |
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 North Dakota
See how Nelson County stacks up in the national county water-quality rankings, or browse the full directory of graded lakes across all United States (49 states), Canada (Ontario, Québec, Nova Scotia, British Columbia and Newfoundland and Labrador), and 38 other country hubs..
Source: EPA National Aquatic Resource Surveys, 2026.