Iowa Soil Drainage Rankings
How well does the soil drain across Iowa? We ranked every USDA survey area by the percentage of land classified as "well drained." Areas at the top of the list have soils where water moves through at a healthy rate — favorable for building, septic, and gardening. Areas at the bottom have more waterlogged or slowly-draining soils that may require engineered solutions.
The best-drained survey area is Crawford County, Iowa at 91% well-drained soils. The most drainage-challenged is Pocahontas County, Iowa at 5%. With 78% poorly-drained soils, properties in Pocahontas County, Iowa should budget for drainage engineering, alternative septic designs, or raised-bed gardening.
| # | Survey Area | Well Drained | Poorly Drained | Dominant Class |
|---|---|---|---|---|
| 1 | Crawford County, Iowa | 91% | 3% | Well drained |
| 2 | Shelby County, Iowa | 89% | 9% | Well drained |
| 3 | Allamakee County, Iowa | 86% | 5% | Well drained |
| 4 | Clayton County, Iowa | 83% | 7% | Well drained |
| 5 | Jackson County, Iowa | 79% | 8% | Well drained |
| 6 | Winneshiek County, Iowa | 76% | 13% | Well drained |
| 7 | Plymouth County, Iowa | 74% | 14% | Well drained |
| 8 | Ida County, Iowa | 72% | 18% | Well drained |
| 9 | Woodbury County, Iowa | 71% | 18% | Well drained |
| 10 | Pottawattamie County, Iowa | 71% | 21% | Well drained |
| 11 | Mills County, Iowa | 71% | 20% | Well drained |
| 12 | Dubuque County, Iowa | 69% | 6% | Well drained |
| 13 | Harrison County, Iowa | 68% | 21% | Well drained |
| 14 | Audubon County, Iowa | 68% | 28% | Well drained |
| 15 | Sioux County, Iowa | 65% | 31% | Well drained |
| 16 | Lyon County, Iowa | 64% | 22% | Well drained |
| 17 | Cherokee County, Iowa | 62% | 28% | Well drained |
| 18 | Cass County, Iowa | 60% | 22% | Well drained |
| 19 | Carroll County, Iowa | 57% | 41% | Well drained |
| 20 | Montgomery County, Iowa | 57% | 33% | Well drained |
| 21 | Cedar County, Iowa | 56% | 33% | Well drained |
| 22 | Scott County, Iowa | 56% | 32% | Well drained |
| 23 | Marshall County, Iowa | 56% | 29% | Well drained |
| 24 | Fremont County, Iowa | 55% | 32% | Well drained |
| 25 | Jones County, Iowa | 55% | 24% | Well drained |
| 26 | Tama County, Iowa | 51% | 33% | Well drained |
| 27 | Clinton County, Iowa | 50% | 35% | Well drained |
| 28 | Monona County, Iowa | 49% | 40% | Well drained |
| 29 | Jasper County, Iowa | 47% | 30% | Well drained |
| 30 | Polk County, Iowa | 43% | 44% | Well drained |
| 31 | Dallas County, Iowa | 43% | 44% | Well drained |
| 32 | Hardin County, Iowa | 41% | 51% | Well drained |
| 33 | Poweshiek County, Iowa | 41% | 29% | Well drained |
| 34 | Muscatine County, Iowa | 40% | 44% | Well drained |
| 35 | Johnson County, Iowa | 40% | 30% | Well drained |
| 36 | Delaware County, Iowa | 38% | 31% | Well drained |
| 37 | Guthrie County, Iowa | 37% | 26% | Well drained |
| 38 | O'Brien County, Iowa | 36% | 49% | Well drained |
| 39 | Sac County, Iowa | 35% | 47% | Well drained |
| 40 | Story County, Iowa | 35% | 58% | Poorly drained |
| 41 | Fayette County, Iowa | 35% | 35% | Well drained |
| 42 | Boone County, Iowa | 34% | 56% | Poorly drained |
| 43 | Grundy County, Iowa | 33% | 49% | Well drained |
| 44 | Linn County, Iowa | 32% | 38% | Well drained |
| 45 | Page County, Iowa | 32% | 39% | Well drained |
| 46 | Iowa County, Iowa | 30% | 34% | Moderately well drained |
| 47 | Greene County, Iowa | 28% | 64% | Poorly drained |
| 48 | Franklin County, Iowa | 26% | 55% | Poorly drained |
| 49 | Ringgold County, Iowa | 24% | 64% | Somewhat poorly drained |
| 50 | Cerro Gordo County, Iowa | 23% | 57% | Poorly drained |
| 51 | Monroe County, Iowa | 23% | 56% | Somewhat poorly drained |
| 52 | Decatur County, Iowa | 22% | 65% | Somewhat poorly drained |
| 53 | Floyd County, Iowa | 22% | 55% | Somewhat poorly drained |
| 54 | Clarke County, Iowa | 22% | 70% | Somewhat poorly drained |
| 55 | Mitchell County, Iowa | 22% | 56% | Somewhat poorly drained |
| 56 | Benton County, Iowa | 22% | 37% | Moderately well drained |
| 57 | Wayne County, Iowa | 22% | 75% | Somewhat poorly drained |
| 58 | Madison County, Iowa | 22% | 34% | Moderately well drained |
| 59 | Lucas County, Iowa | 22% | 74% | Somewhat poorly drained |
| 60 | Union County, Iowa | 21% | 47% | Moderately well drained |
| 61 | Howard County, Iowa | 21% | 56% | Somewhat poorly drained |
| 62 | Adair County, Iowa | 21% | 38% | Moderately well drained |
| 63 | Davis County, Iowa | 20% | 69% | Somewhat poorly drained |
| 64 | Louisa County, Iowa | 20% | 49% | Poorly drained |
| 65 | Worth County, Iowa | 20% | 66% | Poorly drained |
| 66 | Butler County, Iowa | 19% | 52% | Poorly drained |
| 67 | Warren County, Iowa | 19% | 46% | Moderately well drained |
| 68 | Dickinson County, Iowa | 18% | 58% | Somewhat poorly drained |
| 69 | Winnebago County, Iowa | 18% | 63% | Poorly drained |
| 70 | Marion County, Iowa | 17% | 32% | Moderately well drained |
| 71 | Van Buren County, Iowa | 17% | 58% | Somewhat poorly drained |
| 72 | Lee County, Iowa | 17% | 55% | Somewhat poorly drained |
| 73 | Appanoose County, Iowa | 17% | 76% | Somewhat poorly drained |
| 74 | Des Moines County, Iowa | 16% | 51% | Moderately well drained |
| 75 | Keokuk County, Iowa | 16% | 36% | Moderately well drained |
| 76 | Adams County, Iowa | 15% | 45% | Moderately well drained |
| 77 | Bremer County, Iowa | 15% | 66% | Somewhat poorly drained |
| 78 | Buena Vista County, Iowa | 15% | 58% | Poorly drained |
| 79 | Henry County, Iowa | 14% | 48% | Moderately well drained |
| 80 | Wapello County, Iowa | 14% | 49% | Moderately well drained |
| 81 | Taylor County, Iowa | 13% | 57% | Somewhat poorly drained |
| 82 | Emmet County, Iowa | 13% | 67% | Poorly drained |
| 83 | Chickasaw County, Iowa | 13% | 64% | Poorly drained |
| 84 | Osceola County, Iowa | 12% | 57% | Somewhat poorly drained |
| 85 | Jefferson County, Iowa | 12% | 53% | Moderately well drained |
| 86 | Buchanan County, Iowa | 12% | 55% | Poorly drained |
| 87 | Clay County, Iowa | 12% | 66% | Poorly drained |
| 88 | Hancock County, Iowa | 11% | 73% | Poorly drained |
| 89 | Washington County, Iowa | 11% | 38% | Moderately well drained |
| 90 | Palo Alto County, Iowa | 11% | 68% | Poorly drained |
| 91 | Wright County, Iowa | 10% | 73% | Poorly drained |
| 92 | Mahaska County, Iowa | 9% | 33% | Moderately well drained |
| 93 | Black Hawk County, Iowa | 9% | 51% | Poorly drained |
| 94 | Webster County, Iowa | 9% | 76% | Poorly drained |
| 95 | Hamilton County, Iowa | 8% | 72% | Poorly drained |
| 96 | Humboldt County, Iowa | 8% | 69% | Poorly drained |
| 97 | Kossuth County, Iowa | 7% | 77% | Poorly drained |
| 98 | Calhoun County, Iowa | 7% | 75% | Poorly drained |
| 99 | Pocahontas County, Iowa | 5% | 78% | Poorly drained |