The State of Iowa's Lakes 2026

Cleanest lakes in Iowa

Cleanest combined nutrient and algae readings, 2026.

1. 1.West Okoboji Lake — Dickinson County15.7 ft clarity · 20 µg/L P · 2 µg/L chl-a
2. 2.Dale Maffitt Reservoir — Dallas County9.8 ft clarity · 20 µg/L P · 2 µg/L chl-a
3. 3.Blue Pit Lake — Cerro Gordo County17.1 ft clarity · 20 µg/L P · 2 µg/L chl-a
4. 4.Ada Hayden Heritage Park Lake — Story County6.8 ft clarity · 19 µg/L P · 5 µg/L chl-a
5. 5.Little Sioux Park Lake — Woodbury County5.7 ft clarity · 19 µg/L P · 6 µg/L chl-a
6. 6.Rudd Lake — Floyd County8.1 ft clarity · 14 µg/L P · 5 µg/L chl-a
7. 7.Slipbluff Lake — Decatur County9.0 ft clarity · 18 µg/L P · 5 µg/L chl-a
8. 8.Lacey Keosauqua Lake — Van Buren County7.1 ft clarity · 22 µg/L P · 5 µg/L chl-a
9. 9.Yenruogis Pond — Keokuk County9.9 ft clarity · 21 µg/L P · 6 µg/L chl-a
10. 10.Sand Lake — Marshall County6.4 ft clarity · 25 µg/L P · 4 µg/L chl-a

Highest measured algae

Highest measured chlorophyll-a (algae) concentration.

1. 1.Cedar Lake — Linn County125 µg/L chlorophyll-a
2. 2.Hannen Lake — Benton County120 µg/L chlorophyll-a
3. 3.Meyers Lake — Black Hawk County117 µg/L chlorophyll-a
4. 4.Rock Creek Max Depth Lake — Jasper County108 µg/L chlorophyll-a
5. 5.Littlefield Lake — Audubon County103 µg/L chlorophyll-a
6. 6.Alice Wyth Lake — Black Hawk County102 µg/L chlorophyll-a
7. 7.Lake Hendricks — Howard County99 µg/L chlorophyll-a
8. 8.Casey Lake — Tama County96 µg/L chlorophyll-a
9. 9.Desoto Bend Lake — Harrison County93 µg/L chlorophyll-a
10. 10.Lake Orient — Adair County92 µg/L chlorophyll-a

Trending lakes

Improving

1. 1.Dale Maffitt Reservoir — Dallas County
2. 2.Blue Pit Lake — Cerro Gordo County
3. 3.Lacey Keosauqua Lake — Van Buren County
4. 4.Yenruogis Pond — Keokuk County
5. 5.Storm Lake Max Depth — Buena Vista County
6. 6.Arrowhead Lake — Sac County
7. 7.Kent Park Lake — Johnson County
8. 8.Mormon Trail Lake — Adair County

Declining

1. 1.White Oak Lake — Mahaska County
2. 2.Hannen Lake — Benton County
3. 3.Briggs Woods Lake — Hamilton County
4. 4.Nelson Lake — Crawford County
5. 5.Grays Lake — Polk County
6. 6.Littlefield Lake — Audubon County
7. 7.Meyers Lake — Black Hawk County
8. 8.Diamond Lake — Poweshiek County