The State of North Dakota's Lakes 2026

Cleanest lakes in North Dakota

Highest combined water-quality score, 2026.

1. 1.AWheaton Lake — Rolette County8.5 ft clarity · 26 µg/L P · 5 µg/L chl-a
2. 2.AJarvis Lake Center — Rolette County7.7 ft clarity · 20 µg/L P · 6 µg/L chl-a
3. 3.BGordon Center Lake — Rolette County8.2 ft clarity · 27 µg/L P · 9 µg/L chl-a
4. 4.BBelourt Outlet Lake — Rolette County3.0 ft clarity · 28 µg/L P · 13 µg/L chl-a
5. 5.BBelcourt Center Lake — Rolette County3.0 ft clarity · 38 µg/L P · 11 µg/L chl-a
6. 6.BBelcourt Inlet Lake — Rolette County3.3 ft clarity · 31 µg/L P · 11 µg/L chl-a
7. 7.BFree Peoples Lake — Benson County28 µg/L P
8. 8.BFort Totten Bay Lake — Benson County18 µg/L P
9. 9.CJamestown Reservoir — Stutsman County7.2 ft clarity · 527 µg/L P · 9 µg/L chl-a
10. 10.CLake Tschida — Grant County4.6 ft clarity · 33 µg/L P · 10 µg/L chl-a

Most-polluted lakes

Lowest combined water-quality score among monitored lakes.

1. 1.FSweetbriar Dam Lake — Morton County3.0 ft clarity · 353 µg/L P · 54 µg/L chl-a
2. 2.FMirror Lake — Adams County2.1 ft clarity · 388 µg/L P · 32 µg/L chl-a
3. 3.DNygren Dam Lake — Morton County2.6 ft clarity · 73 µg/L P · 25 µg/L chl-a
4. 4.DEpping-Springbrook Dam-Deepest Lake — Williams County4.9 ft clarity · 690 µg/L P · 20 µg/L chl-a
5. 5.DBowman-Haley Dam Lake — Bowman County3.9 ft clarity · 97 µg/L P · 13 µg/L chl-a
6. 6.CJamestown Reservoir — Stutsman County7.2 ft clarity · 527 µg/L P · 9 µg/L chl-a
7. 7.CLake Tschida — Grant County4.6 ft clarity · 33 µg/L P · 10 µg/L chl-a
8. 8.CDevils Lake — Benson County3.7 ft clarity · 313 µg/L P · 14 µg/L chl-a
9. 9.CLarimore Dam Lake — Grand Forks County3.0 ft clarity · 225 µg/L P · 13 µg/L chl-a
10. 10.CLake Ashtabula — Barnes County3.4 ft clarity · 291 µg/L P · 3 µg/L chl-a

Worst algae hotspots

Highest measured chlorophyll-a (algae) concentration.

1. 1.FBuffalo Lake — Pierce County220 µg/L chlorophyll-a
2. 2.NRJuanita Lake — Foster County154 µg/L chlorophyll-a
3. 3.FMchugh Slough Lake — Nelson County89 µg/L chlorophyll-a
4. 4.FMorrison Lake — Ramsey County86 µg/L chlorophyll-a
5. 5.NRKalmbach Lake — LaMoure County74 µg/L chlorophyll-a
6. 6.FSweetbriar Dam Lake — Morton County54 µg/L chlorophyll-a
7. 7.CCedar Lake — Slope County53 µg/L chlorophyll-a
8. 8.FHarmon Lake — Morton County49 µg/L chlorophyll-a
9. 9.FAntelope Lake — Pierce County44 µg/L chlorophyll-a
10. 10.NRSprague Lake — Sargent County43 µg/L chlorophyll-a

Trending lakes

Improving

1. 1.BPowers Lake — Mountrail County
2. 2.BFree Peoples Lake — Benson County
3. 3.BFort Totten Bay Lake — Benson County
4. 4.CDry Lake — Ramsey County
5. 5.CLake Tschida — Grant County
6. 6.CLarimore Dam Lake — Grand Forks County
7. 7.CBlacktail Dam Lake — Williams County
8. 8.CHomme Dam Lake — Walsh County

Declining

1. 1.FEastern Stump Lake — Nelson County
2. 2.FBuffalo Lake — Pierce County
3. 3.FAntelope Lake — Pierce County
4. 4.FMirror Lake — Adams County
5. 5.DLake Alice — Ramsey County
6. 6.DPelican Lake — Ramsey County
7. 7.DEast Devils Lake — Ramsey County
8. 8.DNygren Dam Lake — Morton County