Cleanest Lakes in Iowa
West Okoboji Lake in Dickinson County leads the rankings with a water quality grade of A and 15.7 ft of clarity. Below are the top 50 cleanest monitored lakes in Iowa, ranked by EPA water quality score.
Ranked List
| # | Lake | County | Grade | Clarity | Phosphorus | Algae |
|---|---|---|---|---|---|---|
| 1 | West Okoboji Lake | Dickinson | A | 15.7 ft | - | 2.6 µg/L |
| 2 | Blue Pit Lake | Cerro Gordo | A | 17.1 ft | - | 4 µg/L |
| 3 | Nine Eagles Lake | Decatur | A | 11 ft | - | 3.3 µg/L |
| 4 | Terra Park Lake | Polk | A | 11.5 ft | - | 4.7 µg/L |
| 5 | Dale Maffitt Reservoir | Dallas | B | 9.8 ft | - | 2.5 µg/L |
| 6 | Rudd Lake | Floyd | B | 8.1 ft | - | 4.5 µg/L |
| 7 | Slipbluff Lake | Decatur | B | 9 ft | - | 4.5 µg/L |
| 8 | Lacey Keosauqua Lake | Van Buren | B | 7.1 ft | - | 4.7 µg/L |
| 9 | Yenruogis Pond | Keokuk | B | 9.9 ft | - | 6.2 µg/L |
| 10 | Ada Hayden Heritage Park Lake | Story | B | 6.8 ft | - | 5.3 µg/L |
| 11 | Lambach Lake | Scott | B | 7.9 ft | - | 5.1 µg/L |
| 12 | Sand Lake | Marshall | B | 6.4 ft | - | 3.6 µg/L |
| 13 | Arrowhead Lake | Sac | C | 5.6 ft | - | 7.1 µg/L |
| 14 | Railroad Lake | Scott | C | 5.1 ft | - | 8.3 µg/L |
| 15 | Mariposa Lake | Jasper | C | 5.1 ft | - | 8.9 µg/L |
| 16 | Mormon Trail Lake | Adair | C | 6.2 ft | - | 9.7 µg/L |
| 17 | Willow Lake | Harrison | C | 4.8 ft | - | 9.5 µg/L |
| 18 | Lake Wapello | Davis | C | 7.5 ft | - | 13 µg/L |
| 19 | Oldham Lake | Monona | C | 5.1 ft | - | 8.5 µg/L |
| 20 | Little Sioux Park Lake | Woodbury | C | 5.7 ft | - | 5.7 µg/L |
| 21 | Green Castle Lake | Marshall | C | 4.6 ft | - | 6.9 µg/L |
| 22 | Poll Miller Park Lake | Lee | C | 5.9 ft | - | 7.7 µg/L |
| 23 | Kent Park Lake | Johnson | C | 4.8 ft | - | 11.8 µg/L |
| 24 | Upper Gar Lake | Dickinson | C | 3.9 ft | - | 13.1 µg/L |
| 25 | Big Spirit Lake | Dickinson | C | 5.5 ft | - | 16.3 µg/L |
| 26 | Newell Pit Lake | Buena Vista | C | 4.1 ft | - | 12 µg/L |
| 27 | Lost Grove Lake | Scott | C | 3.9 ft | - | 15.8 µg/L |
| 28 | Blue Grass Lake | Scott | C | 4.5 ft | - | 12.7 µg/L |
| 29 | Lake Petocka | Polk | C | 3.3 ft | - | 9.3 µg/L |
| 30 | Lake of the Hills | Scott | C | 5.1 ft | - | 16.8 µg/L |
| 31 | Storm Lake Max Depth | Buena Vista | D | 1.7 ft | - | 12.1 µg/L |
| 32 | Lost Island Lake | Palo Alto | D | 2.6 ft | - | 19.1 µg/L |
| 33 | Lake Minnewashta | Dickinson | D | 2.8 ft | - | 19 µg/L |
| 34 | Pleasant Creek Lake | Linn | D | 3.6 ft | - | 26.5 µg/L |
| 35 | East Okoboji Lake | Dickinson | D | 3.9 ft | - | 25.3 µg/L |
| 36 | Mitchell Lake | Black Hawk | D | 2.3 ft | - | 18.7 µg/L |
| 37 | Cold Springs Lake | Cass | D | 4.8 ft | - | 21.6 µg/L |
| 38 | Bob White Lake | Wayne | D | 0.6 ft | - | 10.1 µg/L |
| 39 | Moorehead Lake | Ida | D | 3.7 ft | - | 20.7 µg/L |
| 40 | Rathbun Lake | Appanoose | D | 3 ft | - | 15.3 µg/L |
| 41 | Dog Creek Lake | O'Brien | D | 3.4 ft | - | 25 µg/L |
| 42 | Hickory Grove Lake | Story | D | 3.6 ft | - | 24.1 µg/L |
| 43 | Stolley Pit Lake | Clay | D | 2.7 ft | - | 17.3 µg/L |
| 44 | Thomas Mitchell Lake | Polk | D | 3.3 ft | - | 13.2 µg/L |
| 45 | Nodaway Lake | Adair | D | 2.8 ft | - | 27.6 µg/L |
| 46 | Loch Ayr Lake | Ringgold | D | 2 ft | - | 29.7 µg/L |
| 47 | Nelson Lake | Crawford | D | 3.8 ft | - | 30.6 µg/L |
| 48 | Clear Lake | Cerro Gordo | D | 2.1 ft | - | 26.4 µg/L |
| 49 | Hooper Pond Lake | Warren | D | 2.5 ft | - | 25.1 µg/L |
| 50 | Black Pit Lake | Cerro Gordo | D | 5.6 ft | - | 40.9 µg/L |