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Iowa soil by county

Across Iowa's mapped land, shrink-swell clay limits houses without basements on 32% and a shallow water table limits basements on 61%.

Highest clay shares: Adair County (91%), Adams County (88%), Madison County (88%), Taylor County (85%), Union County (85%). Highest water-table shares: Pocahontas County (93%), Calhoun County (91%), Hamilton County (91%), Kossuth County (90%), Humboldt County (90%).

Data as of September 22, 2026 · 99 counties

Adair County: 91%Adams County: 88%Allamakee County: 18%Appanoose County: 69%Audubon County: 30%Benton County: 33%Black Hawk County: 9%Boone County: 9%Bremer County: 4%Buchanan County: 2%Buena Vista County: 22%Butler County: 9%Calhoun County: 13%Carroll County: 18%Cass County: 49%Cedar County: 39%Cerro Gordo County: 6%Cherokee County: 27%Chickasaw County: 3%Clarke County: 74%Clay County: 32%Clayton County: 1%Clinton County: 15%Crawford County: 12%Dallas County: 17%Davis County: 74%Decatur County: 66%Delaware County: 4%Des Moines County: 57%Dickinson County: 10%Dubuque County: 9%Emmet County: 10%Fayette County: 1%Floyd County: 3%Franklin County: 13%Fremont County: 22%Greene County: 11%Grundy County: 59%Guthrie County: 62%Hamilton County: 32%Hancock County: 16%Hardin County: 17%Harrison County: 17%Henry County: 76%Howard County: 1%Humboldt County: 10%Ida County: 23%Iowa County: 57%Jackson County: 1%Jasper County: 40%Jefferson County: 71%Johnson County: 40%Jones County: 12%Keokuk County: 71%Kossuth County: 18%Lee County: 61%Linn County: 9%Louisa County: 38%Lucas County: 73%Lyon County: 18%Madison County: 88%Mahaska County: 71%Marion County: 71%Marshall County: 42%Mills County: 16%Mitchell County: 4%Monona County: 30%Monroe County: 72%Montgomery County: 36%Muscatine County: 20%O'Brien County: 47%Osceola County: 21%Page County: 63%Palo Alto County: 10%Plymouth County: 8%Pocahontas County: 13%Polk County: 13%Pottawattamie County: 14%Poweshiek County: 53%Ringgold County: 76%Sac County: 26%Scott County: 36%Shelby County: 21%Sioux County: 26%Story County: 9%Tama County: 42%Taylor County: 85%Union County: 85%Van Buren County: 70%Wapello County: 70%Warren County: 81%Washington County: 65%Wayne County: 77%Webster County: 27%Winnebago County: 18%Winneshiek County: 6%Woodbury County: 16%Worth County: 10%Wright County: 27%
Expansive clay: share of mapped land where shrink-swell clay limits houses without basementsunder 10%10-25%25-40%40-60%60%+
Adair County: 80%Adams County: 78%Allamakee County: 11%Appanoose County: 78%Audubon County: 29%Benton County: 73%Black Hawk County: 75%Boone County: 64%Bremer County: 78%Buchanan County: 78%Buena Vista County: 83%Butler County: 73%Calhoun County: 91%Carroll County: 41%Cass County: 46%Cedar County: 43%Cerro Gordo County: 75%Cherokee County: 36%Chickasaw County: 82%Clarke County: 78%Clay County: 77%Clayton County: 14%Clinton County: 44%Crawford County: 15%Dallas County: 60%Davis County: 80%Decatur County: 76%Delaware County: 53%Des Moines County: 80%Dickinson County: 75%Dubuque County: 25%Emmet County: 84%Fayette County: 59%Floyd County: 74%Franklin County: 72%Fremont County: 39%Greene County: 71%Grundy County: 67%Guthrie County: 66%Hamilton County: 91%Hancock County: 87%Hardin County: 57%Harrison County: 30%Henry County: 86%Howard County: 76%Humboldt County: 90%Ida County: 27%Iowa County: 69%Jackson County: 18%Jasper County: 55%Jefferson County: 87%Johnson County: 56%Jones County: 38%Keokuk County: 87%Kossuth County: 90%Lee County: 77%Linn County: 57%Louisa County: 70%Lucas County: 78%Lyon County: 37%Madison County: 77%Mahaska County: 88%Marion County: 77%Marshall County: 47%Mills County: 28%Mitchell County: 75%Monona County: 46%Monroe County: 77%Montgomery County: 40%Muscatine County: 50%O'Brien County: 64%Osceola County: 76%Page County: 63%Palo Alto County: 85%Plymouth County: 27%Pocahontas County: 93%Polk County: 52%Pottawattamie County: 25%Poweshiek County: 62%Ringgold County: 77%Sac County: 63%Scott County: 41%Shelby County: 21%Sioux County: 35%Story County: 64%Tama County: 49%Taylor County: 83%Union County: 78%Van Buren County: 82%Wapello County: 85%Warren County: 80%Washington County: 88%Wayne County: 80%Webster County: 88%Winnebago County: 82%Winneshiek County: 22%Woodbury County: 25%Worth County: 80%Wright County: 89%
High water table: share of mapped land where a shallow water table limits basementsunder 10%10-25%25-40%40-60%60%+

Every county in Iowa

Select a column heading to sort.
Adair County 91% 80% 0% 0 1958
Adams County 88% 78% 0% 1 1955
Allamakee County 18% 11% 0% 7 1972
Appanoose County 69% 78% 0% 0 1964
Audubon County 30% 29% 0% 0 1950
Benton County 33% 73% 0% 32 1964
Black Hawk County 9% 75% 0% 223 1966
Boone County 9% 64% 0% 6 1960
Bremer County 4% 78% 0% 48 1970
Buchanan County 2% 78% 0% 27 1973
Buena Vista County 22% 83% 0% 0 1964
Butler County 9% 73% 0% 71 1958
Calhoun County 13% 91% 0% 0 1958
Carroll County 18% 41% 0% 0 1964
Cass County 49% 46% 0% 1 1956
Cedar County 39% 43% 0% 8 1965
Cerro Gordo County 6% 75% 0% 13 1959
Cherokee County 27% 36% 0% 28 1958
Chickasaw County 3% 82% 0% 21 1966
Clarke County 74% 78% 0% 0 1975
Clay County 32% 77% 0% 64 1967
Clayton County 1% 14% 0% 33 1960
Clinton County 15% 44% 0% 31 1957
Crawford County 12% 15% 0% 0 1968
Dallas County 17% 60% 0% 7 2006
Davis County 74% 80% 0% 0 1973
Decatur County 66% 76% 0% 0 1970
Delaware County 4% 53% 0% 19 1967
Des Moines County 57% 80% 0% 108 1959
Dickinson County 10% 75% 0% 14 1979
Dubuque County 9% 25% 0% 24 1970
Emmet County 10% 84% 0% 6 1955
Fayette County 1% 59% 0% 22 1954
Floyd County 3% 74% 0% 47 1958
Franklin County 13% 72% 0% 1 1954
Fremont County 22% 39% 0% 119 1958
Greene County 11% 71% 0% 0 1954
Grundy County 59% 67% 0% 0 1962
Guthrie County 62% 66% 0% 2 1968
Hamilton County 32% 91% 0% 0 1953
Hancock County 16% 87% 0% 0 1961
Hardin County 17% 57% 0% 4 1956
Harrison County 17% 30% 2% 23 1954
Henry County 76% 86% 0% 0 1968
Howard County 1% 76% 0% 6 1960
Humboldt County 10% 90% 0% 1 1961
Ida County 23% 27% 0% 2 1952
Iowa County 57% 69% 0% 3 1969
Jackson County 1% 18% 0% 11 1970
Jasper County 40% 55% 0% 11 1965
Jefferson County 71% 87% 0% 0 1966
Johnson County 40% 56% 0% 8 1992
Jones County 12% 38% 0% 2 1970
Keokuk County 71% 87% 0% 0 1950
Kossuth County 18% 90% 0% 1 1962
Lee County 61% 77% 0% 18 1960
Linn County 9% 57% 0% 199 1978
Louisa County 38% 70% 0% 3 1966
Lucas County 73% 78% 0% 0 1962
Lyon County 18% 37% 0% 13 1967
Madison County 88% 77% 0% 0 1977
Mahaska County 71% 88% 0% 0 1965
Marion County 71% 77% 0% 1 1975
Marshall County 42% 47% 0% 0 1958
Mills County 16% 28% 0% 32 1972
Mitchell County 4% 75% 0% 9 1957
Monona County 30% 46% 81% 11 1956
Monroe County 72% 77% 0% 0 1970
Montgomery County 36% 40% 0% 2 1959
Muscatine County 20% 50% 0% 40 1970
O'Brien County 47% 64% 0% 3 1959
Osceola County 21% 76% 0% 2 1955
Page County 63% 63% 0% 1 1954
Palo Alto County 10% 85% 0% 2 1958
Plymouth County 8% 27% 4% 9 1971
Pocahontas County 13% 93% 0% 0 1950
Polk County 13% 52% 0% 202 1982
Pottawattamie County 14% 25% 0% 89 1967
Poweshiek County 53% 62% 0% 0 1971
Ringgold County 76% 77% 0% 0 1973
Sac County 26% 63% 0% 0 1957
Scott County 36% 41% 0% 268 1972
Shelby County 21% 21% 0% 1 1949
Sioux County 26% 35% 0% 32 1973
Story County 9% 64% 0% 12 1984
Tama County 42% 49% 0% 6 1957
Taylor County 85% 83% 0% 0 1951
Union County 85% 78% 0% 1 1962
Van Buren County 70% 82% 0% 1 1970
Wapello County 70% 85% 0% 7 1958
Warren County 81% 80% 0% 3 1985
Washington County 65% 88% 0% 0 1964
Wayne County 77% 80% 0% 0 1969
Webster County 27% 88% 0% 4 1957
Winnebago County 18% 82% 0% 0 1962
Winneshiek County 6% 22% 0% 28 1962
Woodbury County 16% 25% 65% 45 1959
Worth County 10% 80% 0% 2 1948
Wright County 27% 89% 0% 1 1960

How these shares are counted

Shares are of mapped land in USDA's soil survey (SSURGO), weighted by each soil's share of every map unit. Drought is the US Drought Monitor's D1-or-worse share on the September 22, 2026 map. Flood losses are FEMA NFIP records since 2016. Sources and methods.