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LakeQuality
Pink and orange afterglow over the treeline on Slim Lake after sunset

Updated August 2026

The State of North Dakota's Lakes 2026

Of 143 lakes in North Dakota, 20.7% sit in EPA's favourable condition classes for nutrients and algae and 36.8% in its poorer ones. Wheaton Lake is the cleanest; 35 lakes (24.5%) are on an official impaired-waters list.

Data Report

143
Monitored lakes sampled
C
Average readings
20.7%
low nutrient and algae readings
24.5%
On impaired list

North Dakota nutrient and algae readings

Cleanest lakes in North Dakota

Cleanest combined nutrient and algae readings, 2026.

  1. 1.Wheaton Lake — Rolette County8.5 ft clarity · 26 µg/L P · 5 µg/L chl-a
  2. 2.Jarvis Lake Center — Rolette County7.7 ft clarity · 20 µg/L P · 6 µg/L chl-a
  3. 3.Gordon Center Lake — Rolette County8.2 ft clarity · 27 µg/L P · 9 µg/L chl-a
  4. 4.Belourt Outlet Lake — Rolette County3.0 ft clarity · 28 µg/L P · 13 µg/L chl-a
  5. 5.Belcourt Center Lake — Rolette County3.0 ft clarity · 38 µg/L P · 11 µg/L chl-a
  6. 6.Belcourt Inlet Lake — Rolette County3.3 ft clarity · 31 µg/L P · 11 µg/L chl-a
  7. 7.Free Peoples Lake — Benson County28 µg/L P
  8. 8.Fort Totten Bay Lake — Benson County18 µg/L P
  9. 9.Jamestown Reservoir — Stutsman County7.2 ft clarity · 527 µg/L P · 9 µg/L chl-a
  10. 10.Lake Tschida — Grant County4.6 ft clarity · 33 µg/L P · 10 µg/L chl-a

Highest measured algae

Highest measured chlorophyll-a (algae) concentration.

  1. 1.Buffalo Lake — Pierce County220 µg/L chlorophyll-a
  2. 2.Juanita Lake — Foster County154 µg/L chlorophyll-a
  3. 3.Mchugh Slough Lake — Nelson County89 µg/L chlorophyll-a
  4. 4.Morrison Lake — Ramsey County86 µg/L chlorophyll-a
  5. 5.Kalmbach Lake — LaMoure County74 µg/L chlorophyll-a
  6. 6.Sweetbriar Dam Lake — Morton County54 µg/L chlorophyll-a
  7. 7.Cedar Lake — Slope County53 µg/L chlorophyll-a
  8. 8.Harmon Lake — Morton County49 µg/L chlorophyll-a
  9. 9.Antelope Lake — Pierce County44 µg/L chlorophyll-a
  10. 10.Sprague Lake — Sargent County43 µg/L chlorophyll-a

Trending lakes

Improving

  1. 1.Powers Lake — Mountrail County
  2. 2.Free Peoples Lake — Benson County
  3. 3.Fort Totten Bay Lake — Benson County
  4. 4.Dry Lake — Ramsey County
  5. 5.Lake Tschida — Grant County
  6. 6.Larimore Dam Lake — Grand Forks County
  7. 7.Blacktail Dam Lake — Williams County
  8. 8.Homme Dam Lake — Walsh County

Declining

  1. 1.Eastern Stump Lake — Nelson County
  2. 2.Buffalo Lake — Pierce County
  3. 3.Antelope Lake — Pierce County
  4. 4.Mirror Lake — Adams County
  5. 5.Lake Alice — Ramsey County
  6. 6.Pelican Lake — Ramsey County
  7. 7.East Devils Lake — Ramsey County
  8. 8.Nygren Dam Lake — Morton County

Impaired waters in North Dakota

35 lakes appear on the EPA/state 303(d) impaired-waters list (19 formally listed, 19 with a cleanup plan/TMDL).

Nutrients (phosphorus, nitrogen) · 33Oxygen depletion (low DO) · 17Sediment / turbidity · 10Turbidity · 2Mercury · 1Salinity / chlorides · 1

Explore North Dakota lakes

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Species activity outlook by water temperature and season

North Dakota Lake Trips

Where to stay at North Dakota's top lakes, each with its readings

Lakes near Fargo

Cleanest lakes within 50 miles of Fargo

Lakes near Bismarck

Cleanest lakes within 50 miles of Bismarck

Lakes near Devils Lake

Cleanest lakes within 50 miles of Devils Lake

Readings combine total phosphorus, total nitrogen, chlorophyll-a, and turbidity from the EPA Water Quality Portal and state agencies. See the full methodology, the national State of America’s Lakes report, or all North Dakota lakes.

Cite this report: LakeQuality, “The State of North Dakota's Lakes 2026”.