The State of North Dakota’s Lakes 2026

Cleanest lakes in North Dakota

Highest combined water-quality score, 2026.

1. 1.ASpiritwood Lake — Stutsman County31.0 ft clarity · 6 µg/L chl-a
2. 2.ALake Upsilon — Rolette County11.2 ft clarity · 2 µg/L chl-a
3. 3.ATwin Lakes — LaMoure County14.1 ft clarity · 3 µg/L chl-a
4. 4.ARound Lake — McHenry County12.1 ft clarity · 2 µg/L chl-a
5. 5.AQacmainstfbk Lake — Mercer County10 µg/L P · 7 µg/L chl-a
6. 6.BVelva Sportsmans Dam Lake — Ward County13.6 ft clarity · 6 µg/L chl-a
7. 7.BDavis Dam Lake — Slope County7.5 ft clarity · 5 µg/L chl-a
8. 8.BArroda Lake — Oliver County6.7 ft clarity · 3 µg/L chl-a
9. 9.BKota Ray Dam Lake — Williams County7.7 ft clarity · 4 µg/L chl-a
10. 10.BSkjermo Lake — Divide County7.7 ft clarity · 2 µg/L chl-a

Most-polluted lakes

Lowest combined water-quality score among monitored lakes.

1. 1.FMorrison Lake — Ramsey County1.9 ft clarity · 565 µg/L P · 86 µg/L chl-a
2. 2.FMchugh Slough Lake — Nelson County1.6 ft clarity · 389 µg/L P · 89 µg/L chl-a
3. 3.FBuffalo Lake — Pierce County0.3 ft clarity · 220 µg/L chl-a
4. 4.FSprague Lake — Sargent County1.6 ft clarity · 43 µg/L chl-a
5. 5.FDead Colt Creek Dam Lake — Ransom County3.3 ft clarity · 32 µg/L chl-a
6. 6.FJuanita Lake — Foster County1.0 ft clarity · 154 µg/L chl-a
7. 7.FKalmbach Lake — LaMoure County0.7 ft clarity · 74 µg/L chl-a
8. 8.FSweetbriar Dam Lake — Morton County3.0 ft clarity · 54 µg/L chl-a
9. 9.FSweet Briar Dam-Mid Reservoir — Morton County3.0 ft clarity · 37 µg/L chl-a
10. 10.FCedar Lake — Slope County1.3 ft clarity · 53 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.FJuanita 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.DEast Stump Lake — Nelson County75 µg/L chlorophyll-a
6. 6.FKalmbach Lake — LaMoure County74 µg/L chlorophyll-a
7. 7.FSweetbriar Dam Lake — Morton County54 µg/L chlorophyll-a
8. 8.FCedar Lake — Slope County53 µg/L chlorophyll-a
9. 9.FHarmon Lake — Morton County49 µg/L chlorophyll-a
10. 10.DAntelope Lake — Pierce County44 µg/L chlorophyll-a

Trending lakes

Improving

1. 1.AEpping-Springbrook Dam-Littoral Lake — Williams County
2. 2.BHomme Dam Lake — Walsh County
3. 3.CLake Tschida — Grant County
4. 4.CFordville Dam Lake — Grand Forks County
5. 5.CPowers Lake — Mountrail County
6. 6.CLake Tschida — Grant County
7. 7.CLake Tschida — Grant County
8. 8.CPowers Lake Dredge Site — Mountrail County

Declining

1. 1.FBuffalo Lake — Pierce County
2. 2.FGordon Beach Lake — Rolette County
3. 3.FMirror Lake — Adams County
4. 4.FEastern Stump Lake — Nelson County
5. 5.DAntelope Lake — Pierce County
6. 6.DLake Alice — Ramsey County
7. 7.DLake Irvine — Ramsey County
8. 8.DJamestown Reservoir — Stutsman County