Updated Aug 2026
North Dakota Lake Water Quality
Water quality grades for 149 monitored lakes across 48 counties.
North Dakota has 149 graded lakes in our dataset, sampled across 48 counties, drawing on monitoring by the North Dakota Department of Environmental Quality plus federal and volunteer measurements. A-grade lakes are scarce in North Dakota: about 2% of the dataset. Most lakes here sit in C or D — productive, often shallow, frequently algal in late summer.
Eutrophic conditions dominate — nutrient-loaded, productive, with algal pressure that shows up most years in late summer. These lakes tend to be shallow, agricultural-watershed, and over-warmed by the time July ends. Rolette ranks highest on average county grade (B). Pierce sits lowest. With only 48 counties in the state, the cross-county spread is narrower than the within-county spread for most lakes.
Grade Distribution
All 149 North Dakota lakes in the index: 91 (61.1%) carry an A–F grade and 58 (38.9%) are not rated, because they lack enough recent nutrient or algae sampling to support a letter.
Where to stay near North Dakota
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Top-Graded North Dakota Lakes
The highest water-quality grades in North Dakota — clarity, depth, and A-F grade at a glance.
Lake Map
Explore North Dakota Lakes
North Dakota reports, fishing & travel
North Dakota's cleanest and most-polluted lakes, ranked A–F
Species activity outlook by water temperature and season
Where to stay at North Dakota's top lakes, each with its grade
Best-graded lakes within 50 miles of Fargo
Best-graded lakes within 50 miles of Bismarck
Best-graded lakes within 50 miles of Devils Lake
Reservoirs in North Dakota
View all 86 reservoirs →86 of 149 North Dakota lakes (58%) are man-made reservoirs in the USACE National Inventory of Dams. 49 carry a High or Significant hazard rating. The oldest matched dam dates to 1890.
EPA-Impaired Lakes in North Dakota
View all 40 impaired lakes →40 of 149 North Dakota lakes (27%) are officially listed as impaired under Clean Water Act §303(d) in the most recent EPA ATTAINS reporting cycle. 20 have an approved Total Maximum Daily Load (TMDL) restoration plan.
North Dakota Fishing & Recreation
Licenses, regulations, records, and where to fish across North Dakota.
Counties
All 48 North Dakota counties, ranked by average lake water quality. Compare them against every county nationwide in the county rankings, browse the full directory of graded lakes, or pick a different state.
North Dakota Lake Water Quality Dataset (2026)
Every graded North Dakota lake in one spreadsheet — A–F grade, water clarity, phosphorus, chlorophyll-a, trophic state, size, public access, and a link to each lake's report card.
Top 25 Cleanest Lakes
25 lakes25 graded lakes
| # | Lake | County | Grade | Clarity | Trophic | Access |
|---|---|---|---|---|---|---|
| 1 | ALake Darling | Renville | A | 4.9 ft | Mesotrophic | ✓ Public |
| 2 | AWheaton Lake | Rolette | A | 8.5 ft | Mesotrophic | Not recorded |
| 3 | AJarvis Lake Center | Rolette | A | 7.7 ft | Mesotrophic | Not recorded |
| 4 | BSweetwater Lake | Ramsey | B | 3 ft | Eutrophic | Not recorded |
| 5 | BGordon Center Lake | Rolette | B | 8.2 ft | Eutrophic | Not recorded |
| 6 | BPowers Lake Dredge Site | Mountrail | B | 3.9 ft | Eutrophic | ✓ Public |
| 7 | BPowers Lake | Mountrail | B | 5.6 ft | Eutrophic | Not recorded |
| 8 | BBelourt Outlet Lake | Rolette | B | 3 ft | Eutrophic | Not recorded |
| 9 | BBelcourt Center Lake | Rolette | B | 3 ft | Eutrophic | Not recorded |
| 10 | BBelcourt Inlet Lake | Rolette | B | 3.3 ft | Eutrophic | Not recorded |
| 11 | BLake Metigoshe | Bottineau | B | 5.4 ft | Eutrophic | ✓ Public |
| 12 | BNorth Lemmon Lake | Adams | B | 5.7 ft | Mesotrophic | ✓ Public |
| 13 | BKota Ray Dam Lake | Williams | B | 7.7 ft | Mesotrophic | ✓ Public |
| 14 | BLake Audubon | McLean | B | 4.7 ft | Eutrophic | ✓ Public |
| 15 | BWood Lake | Benson | B | No recent samples | Oligotrophic | ✓ Public |
| 16 | BFree Peoples Lake | Benson | B | No recent samples | Eutrophic | Not recorded |
| 17 | BFort Totten Bay Lake | Benson | B | No recent samples | Mesotrophic | Not recorded |
| 18 | BMission Bay Lake | Benson | B | No recent samples | Eutrophic | Not recorded |
| 19 | BClausen Springs Lake | Barnes | B | No recent samples | Eutrophic | ✓ Public |
| 20 | CDry Lake | Ramsey | C | 2.8 ft | Eutrophic | Not recorded |
| 21 | CE A Patterson Lake | Stark | C | 6 ft | Eutrophic | ✓ Public |
| 22 | CJamestown Reservoir | Stutsman | C | 7.2 ft | Eutrophic | ✓ Public |
| 23 | CLake Darling | Renville | C | 9.8 ft | Mesotrophic | ✓ Public |
| 24 | CLake Tschida | Grant | C | 4.6 ft | Eutrophic | ✓ Public |
| 25 | CDevils Lake | Benson | C | 3.7 ft | Eutrophic | Not recorded |
25 Lakes Needing Attention
25 lakes25 graded lakes
| # | Lake | County | Grade | Clarity |
|---|---|---|---|---|
| 1 | FHarmon Lake | Morton | F | No recent samples |
| 2 | FMirror Lake | Adams | F | 2.1 ft |
| 3 | FSweet Briar Dam-Mid Reservoir | Morton | F | 3 ft |
| 4 | FSweetbriar Dam Lake | Morton | F | 3 ft |
| 5 | FAntelope Lake | Pierce | F | 3.5 ft |
| 6 | FBuffalo Lake | Pierce | F | 0.3 ft |
| 7 | FMchugh Slough Lake | Nelson | F | 1.6 ft |
| 8 | FEastern Stump Lake | Nelson | F | 4.7 ft |
| 9 | FMorrison Lake | Ramsey | F | 1.9 ft |
| 10 | FWestern Stump Lake | Nelson | F | 4.3 ft |
| 11 | DFrettum Dam Lake | Kidder | D | 2.6 ft |
| 12 | DCherry Lake | Kidder | D | 2.2 ft |
| 13 | DClearwater Lake | Mountrail | D | 2.1 ft |
| 14 | DTioga Dam Lake | Williams | D | 2.2 ft |
| 15 | DWhite Earth Dam Lake | Mountrail | D | 3 ft |
| 16 | DBader Lake | Stutsman | D | 1.3 ft |
| 17 | DStanley Reservoir | Mountrail | D | 1.1 ft |
| 18 | DBowman-Haley Dam Lake | Bowman | D | 3.9 ft |
| 19 | DGascoyne Lake | Bowman | D | 1.3 ft |
| 20 | DLarson Lake | Hettinger | D | 4.8 ft |
| 21 | DCastle Rock Dam Lake | Hettinger | D | 3.8 ft |
| 22 | DOdland Dam Lake | Golden Valley | D | 1.5 ft |
| 23 | DFroelich Dam Lake | Sioux | D | 3.9 ft |
| 24 | DEpping-Springbrook Dam-Deepest Lake | Williams | D | 4.9 ft |
| 25 | DNygren Dam Lake | Morton | D | 2.6 ft |
Lake Match
Which lake suits how you actually use one?
Six questions — swimming, fishing, quiet, cabins, drive time — and a shortlist of graded lakes that fit, with the water quality behind each one.
Source: EPA National Aquatic Resource Surveys and the EPA Water Quality Portal.
More on lake water quality
The top-graded lake in every state we cover, picked grade-first with water clarity as the tie-breaker — plus the states whose winner is still not clean.
State-by-state Secchi champions: the clearest measured lake in each U.S. state we grade, which is not the same as the cleanest nutrient grade.
A data snapshot of the lakes we grade: how the A–F distribution breaks down, the clearest and the greenest states, and where the water is improving.
How lakes are graded A–F on nutrients and algae using EPA ecoregion condition classes, what each letter means in the water, and why an A is not a clearance.