The State of Colorado's Lakes 2026

Cleanest lakes in Colorado

Cleanest combined nutrient and algae readings, 2026.

1. 1.Pueblo Reservoir — Pueblo County6.5 ft clarity · 15 µg/L P · 5 µg/L chl-a
2. 2.Willow Creek Reservoir — Grand County3.9 ft clarity · 76 µg/L P · 2 µg/L chl-a
3. 3.Wolford Mountain Reservoir — Grand County7.5 ft clarity · 13 µg/L P · 2 µg/L chl-a
4. 4.Grand Lake — Grand County8.7 ft clarity · 14 µg/L P · 3 µg/L chl-a
5. 5.Shadow Mountain Lake — Grand County7.9 ft clarity · 20 µg/L P · 5 µg/L chl-a
6. 6.Blue Mesa Reservoir — Gunnison County11.5 ft clarity · 35 µg/L P · 4 µg/L chl-a
7. 7.Dillon Reservoir — Summit County11.6 ft clarity · 46 µg/L P · 3 µg/L chl-a
8. 8.Deweese Reservoir — Custer County5.2 ft clarity · 42 µg/L P · 14 µg/L chl-a
9. 9.Windy Gap Reservoir — Grand County52 µg/L P · 3 µg/L chl-a
10. 10.Horse Creek Outlet Lake — Weld County460 µg/L P · 28 µg/L chl-a

Highest measured algae

Highest measured chlorophyll-a (algae) concentration.

1. 1.North Sterling Reservoir — Logan County198 µg/L chlorophyll-a
2. 2.Turks Pond — Baca County140 µg/L chlorophyll-a
3. 3.Prospect Lake — El Paso County81 µg/L chlorophyll-a
4. 4.Prospect Lake — Weld County43 µg/L chlorophyll-a
5. 5.Equestrian Park Pond — Douglas County36 µg/L chlorophyll-a
6. 6.Berkeley Lake — Denver County34 µg/L chlorophyll-a
7. 7.Prewitt Reservoir — Washington County32 µg/L chlorophyll-a
8. 8.Horse Creek Outlet Lake — Weld County28 µg/L chlorophyll-a
9. 9.Windsor Lake — Weld County25 µg/L chlorophyll-a
10. 10.Jackson Reservoir — Morgan County22 µg/L chlorophyll-a

Trending lakes

Improving

1. 1.Pueblo Reservoir — Pueblo County
2. 2.Lake Granby Dam Bottom — Grand County
3. 3.Willow Creek Reservoir — Grand County
4. 4.Grand Lake — Grand County
5. 5.Lake Nighthorse — La Plata County
6. 6.Blue Mesa Reservoir — Gunnison County
7. 7.Big Meadows Reservoir — Mineral County
8. 8.Vega Reservoir — Mesa County

Declining

1. 1.Prospect Lake — Weld County
2. 2.Jackson Reservoir — Morgan County
3. 3.Beaver Creek Reservoir — Rio Grande County
4. 4.Horse Creek Outlet Lake — Weld County
5. 5.Stagecoach Lake — Routt County
6. 6.Wolford Mountain Reservoir — Grand County
7. 7.Crystal Reservoir — Montrose County
8. 8.Catamount Lake Top — Routt County