BasementSoil

Iowa: basement moisture and foundation risk by county

99 counties, ranked by our combined index. Highest combined risk is Butler County (69), lowest is Harrison County (27). The worst soil for foundation cracks specifically is in Wayne County.

Where in Iowa the ground is worse

Every county in the state, coloured by the soil values below. Click a county to open its report; switch what the colour means with the buttons. The pattern is geology, not administration — risk stops at the edge of a physiographic region, not at a county line.

Adair County, IA — combined 57/100, moisture 56, movement 52, water table 66Adams County, IA — combined 59/100, moisture 54, movement 61, water table 66Allamakee County, IA — combined 28/100, moisture 33, movement 19, water table 30Appanoose County, IA — combined 65/100, moisture 53, movement 69, water table 82Audubon County, IA — combined 57/100, moisture 52, movement 56, water table 66Benton County, IA — combined 56/100, moisture 54, movement 51, water table 66Black Hawk County, IA — combined 56/100, moisture 57, movement 37, water table 82Boone County, IA — combined 63/100, moisture 65, movement 58, water table 66Bremer County, IA — combined 51/100, moisture 56, movement 49, water table 46Buchanan County, IA — combined 55/100, moisture 56, movement 45, water table 66Buena Vista County, IA — combined 61/100, moisture 56, movement 53, water table 82Butler County, IA — combined 69/100, moisture 68, movement 52, water table 95Calhoun County, IA — combined 60/100, moisture 67, movement 34, water table 82Carroll County, IA — combined 62/100, moisture 66, movement 55, water table 66Cass County, IA — combined 55/100, moisture 54, movement 49, water table 66Cedar County, IA — combined 51/100, moisture 53, movement 36, water table 66Cerro Gordo County, IA — combined 69/100, moisture 67, movement 54, water table 95Cherokee County, IA — combined 32/100, moisture 33, movement 31, water table 30Chickasaw County, IA — combined 56/100, moisture 55, movement 51, water table 66Clarke County, IA — combined 52/100, moisture 52, movement 43, water table 66Clay County, IA — combined 51/100, moisture 53, movement 38, water table 66Clayton County, IA — combined 30/100, moisture 35, movement 22, water table 30Clinton County, IA — combined 55/100, moisture 55, movement 46, water table 66Crawford County, IA — combined 31/100, moisture 34, movement 38, water table 16Dallas County, IA — combined 50/100, moisture 56, movement 43, water table 46Davis County, IA — combined 57/100, moisture 51, movement 48, water table 82Decatur County, IA — combined 57/100, moisture 53, movement 55, water table 66Delaware County, IA — combined 29/100, moisture 34, movement 20, water table 30Des Moines County, IA — combined 51/100, moisture 52, movement 38, water table 66Dickinson County, IA — combined 55/100, moisture 53, movement 51, water table 66Dubuque County, IA — combined 33/100, moisture 37, movement 31, water table 30Emmet County, IA — combined 64/100, moisture 64, movement 42, water table 95Fayette County, IA — combined 49/100, moisture 54, movement 44, water table 46Floyd County, IA — combined 58/100, moisture 67, movement 39, water table 66Franklin County, IA — combined 63/100, moisture 65, movement 48, water table 82Fremont County, IA — combined 30/100, moisture 35, movement 22, water table 30Greene County, IA — combined 59/100, moisture 69, movement 40, water table 66Grundy County, IA — combined 57/100, moisture 53, movement 45, water table 82Guthrie County, IA — combined 51/100, moisture 54, movement 36, water table 66Hamilton County, IA — combined 63/100, moisture 68, movement 53, water table 66Hancock County, IA — combined 66/100, moisture 65, movement 57, water table 82Hardin County, IA — combined 64/100, moisture 67, movement 57, water table 66Harrison County, IA — combined 27/100, moisture 33, movement 28, water table 16Henry County, IA — combined 59/100, moisture 50, movement 68, water table 66Howard County, IA — combined 59/100, moisture 52, movement 52, water table 82Humboldt County, IA — combined 68/100, moisture 68, movement 57, water table 82Ida County, IA — combined 34/100, moisture 36, movement 34, water table 30Iowa County, IA — combined 58/100, moisture 56, movement 56, water table 66Jackson County, IA — combined 46/100, moisture 52, movement 38, water table 46Jasper County, IA — combined 60/100, moisture 57, movement 49, water table 82Jefferson County, IA — combined 54/100, moisture 50, movement 39, water table 82Johnson County, IA — combined 54/100, moisture 54, movement 45, water table 66Jones County, IA — combined 54/100, moisture 52, movement 47, water table 66Keokuk County, IA — combined 53/100, moisture 55, movement 41, water table 66Kossuth County, IA — combined 60/100, moisture 65, movement 48, water table 66Lee County, IA — combined 58/100, moisture 49, movement 64, water table 66Linn County, IA — combined 45/100, moisture 53, movement 33, water table 46Louisa County, IA — combined 48/100, moisture 56, movement 39, water table 46Lucas County, IA — combined 58/100, moisture 53, movement 48, water table 82Lyon County, IA — combined 33/100, moisture 33, movement 36, water table 30Madison County, IA — combined 59/100, moisture 57, movement 57, water table 66Mahaska County, IA — combined 53/100, moisture 57, movement 53, water table 46Marion County, IA — combined 54/100, moisture 55, movement 32, water table 82Marshall County, IA — combined 65/100, moisture 65, movement 53, water table 82Mills County, IA — combined 29/100, moisture 34, movement 22, water table 30Mitchell County, IA — combined 51/100, moisture 53, movement 52, water table 46Monona County, IA — combined 32/100, moisture 34, movement 31, water table 30Monroe County, IA — combined 52/100, moisture 49, movement 47, water table 66Montgomery County, IA — combined 61/100, moisture 53, movement 68, water table 66Muscatine County, IA — combined 53/100, moisture 56, movement 40, water table 66O'Brien County, IA — combined 31/100, moisture 35, movement 35, water table 16Osceola County, IA — combined 35/100, moisture 34, movement 41, water table 30Page County, IA — combined 60/100, moisture 50, movement 58, water table 82Palo Alto County, IA — combined 57/100, moisture 68, movement 35, water table 66Plymouth County, IA — combined 34/100, moisture 35, movement 35, water table 30Pocahontas County, IA — combined 59/100, moisture 64, movement 34, water table 82Polk County, IA — combined 61/100, moisture 53, movement 57, water table 82Pottawattamie County, IA — combined 33/100, moisture 34, movement 35, water table 30Poweshiek County, IA — combined 58/100, moisture 54, movement 57, water table 66Ringgold County, IA — combined 56/100, moisture 53, movement 52, water table 66Sac County, IA — combined 57/100, moisture 54, movement 54, water table 66Scott County, IA — combined 55/100, moisture 53, movement 51, water table 66Shelby County, IA — combined 28/100, moisture 34, movement 29, water table 16Sioux County, IA — combined 27/100, moisture 33, movement 27, water table 16Story County, IA — combined 57/100, moisture 64, movement 41, water table 66Tama County, IA — combined 50/100, moisture 53, movement 34, water table 66Taylor County, IA — combined 59/100, moisture 53, movement 52, water table 82Union County, IA — combined 52/100, moisture 49, movement 45, water table 66Van Buren County, IA — combined 60/100, moisture 52, movement 57, water table 82Wapello County, IA — combined 54/100, moisture 50, movement 40, water table 82Warren County, IA — combined 52/100, moisture 54, movement 39, water table 66Washington County, IA — combined 46/100, moisture 53, movement 36, water table 46Wayne County, IA — combined 61/100, moisture 53, movement 70, water table 66Webster County, IA — combined 62/100, moisture 66, movement 43, water table 82Winnebago County, IA — combined 59/100, moisture 67, movement 43, water table 66Winneshiek County, IA — combined 53/100, moisture 54, movement 41, water table 66Woodbury County, IA — combined 32/100, moisture 35, movement 29, water table 30Worth County, IA — combined 66/100, moisture 68, movement 51, water table 82Wright County, IA — combined 60/100, moisture 67, movement 35, water table 82
  • Low (0–27)
  • Moderate (28–49)
  • Elevated (50–74)
  • High (75–100)

County boundaries: US Census TIGER (public domain), simplified for display. Colours are our index from USDA SSURGO fields where loaded, otherwise from our regional model — each county page states which. How the index is calculated.

CountyIndexMoistureCracksWater tableRegion
Butler County69685295Des Moines Lobe and prairie potholes
Cerro Gordo County69675495Des Moines Lobe and prairie potholes
Humboldt County68685782Des Moines Lobe and prairie potholes
Hancock County66655782Des Moines Lobe and prairie potholes
Worth County66685182Des Moines Lobe and prairie potholes
Appanoose County65536982Dissected till plain with a claypan
Marshall County65655382Des Moines Lobe and prairie potholes
Emmet County64644295Des Moines Lobe and prairie potholes
Hardin County64675766Des Moines Lobe and prairie potholes
Boone County63655866Des Moines Lobe and prairie potholes
Franklin County63654882Des Moines Lobe and prairie potholes
Hamilton County63685366Des Moines Lobe and prairie potholes
Carroll County62665566Des Moines Lobe and prairie potholes
Webster County62664382Des Moines Lobe and prairie potholes
Buena Vista County61565382Wisconsinan till plain
Montgomery County61536866Dissected till plain with a claypan
Polk County61535782Wisconsinan till plain
Wayne County61537066Dissected till plain with a claypan
Calhoun County60673482Des Moines Lobe and prairie potholes
Jasper County60574982Wisconsinan till plain
Kossuth County60654866Des Moines Lobe and prairie potholes
Page County60505882Dissected till plain with a claypan
Van Buren County60525782Dissected till plain with a claypan
Wright County60673582Des Moines Lobe and prairie potholes
Adams County59546166Dissected till plain with a claypan
Greene County59694066Des Moines Lobe and prairie potholes
Henry County59506866Dissected till plain with a claypan
Howard County59525282Wisconsinan till plain
Madison County59575766Wisconsinan till plain
Pocahontas County59643482Des Moines Lobe and prairie potholes
Taylor County59535282Dissected till plain with a claypan
Winnebago County59674366Des Moines Lobe and prairie potholes
Floyd County58673966Des Moines Lobe and prairie potholes
Iowa County58565666Wisconsinan till plain
Lee County58496466Dissected till plain with a claypan
Lucas County58534882Dissected till plain with a claypan
Poweshiek County58545766Wisconsinan till plain
Adair County57565266Wisconsinan till plain
Audubon County57525666Wisconsinan till plain
Davis County57514882Dissected till plain with a claypan
Decatur County57535566Dissected till plain with a claypan
Grundy County57534582Wisconsinan till plain
Palo Alto County57683566Des Moines Lobe and prairie potholes
Sac County57545466Wisconsinan till plain
Story County57644166Des Moines Lobe and prairie potholes
Benton County56545166Wisconsinan till plain
Black Hawk County56573782Wisconsinan till plain
Chickasaw County56555166Wisconsinan till plain
Ringgold County56535266Dissected till plain with a claypan
Buchanan County55564566Wisconsinan till plain
Cass County55544966Wisconsinan till plain
Clinton County55554666Wisconsinan till plain
Dickinson County55535166Wisconsinan till plain
Scott County55535166Wisconsinan till plain
Jefferson County54503982Dissected till plain with a claypan
Johnson County54544566Wisconsinan till plain
Jones County54524766Wisconsinan till plain
Marion County54553282Wisconsinan till plain
Wapello County54504082Dissected till plain with a claypan
Keokuk County53554166Wisconsinan till plain
Mahaska County53575346Wisconsinan till plain
Muscatine County53564066Wisconsinan till plain
Winneshiek County53544166Wisconsinan till plain
Clarke County52524366Dissected till plain with a claypan
Monroe County52494766Dissected till plain with a claypan
Union County52494566Dissected till plain with a claypan
Warren County52543966Wisconsinan till plain
Bremer County51564946Wisconsinan till plain
Cedar County51533666Wisconsinan till plain
Clay County51533866Wisconsinan till plain
Des Moines County51523866Dissected till plain with a claypan
Guthrie County51543666Wisconsinan till plain
Mitchell County51535246Wisconsinan till plain
Dallas County50564346Wisconsinan till plain
Tama County50533466Wisconsinan till plain
Fayette County49544446Wisconsinan till plain
Louisa County48563946Wisconsinan till plain
Jackson County46523846Wisconsinan till plain
Washington County46533646Wisconsinan till plain
Linn County45533346Wisconsinan till plain
Osceola County35344130Loess hills
Ida County34363430Loess hills
Plymouth County34353530Loess hills
Dubuque County33373130Driftless Area
Lyon County33333630Loess hills
Pottawattamie County33343530Loess hills
Cherokee County32333130Loess hills
Monona County32343130Loess hills
Woodbury County32352930Loess hills
Crawford County31343816Loess hills
O'Brien County31353516Loess hills
Clayton County30352230Driftless Area
Fremont County30352230Loess hills
Delaware County29342030Driftless Area
Mills County29342230Loess hills
Allamakee County28331930Driftless Area
Shelby County28342916Loess hills
Harrison County27332816Loess hills
Sioux County27332716Loess hills

Values from USDA NRCS SSURGO where available, otherwise our regional model — each county page states which. Methodology.

The physiographic regions inside Iowa

State lines are political; soil follows geology. These are the distinct ground types inside Iowa and why each behaves the way it does.

Wisconsinan till plain

The classic American basement belt. Below the topsoil sits dense till that water barely penetrates, so infiltrating water travels sideways along it until it meets the first vertical obstruction — typically a basement wall.

39 counties: Adair County, Audubon County, Benton County, Black Hawk County, Bremer County, Buchanan County, Buena Vista County, Cass County, Cedar County, Chickasaw County, Clay County, Clinton County, Dallas County, Dickinson County, Fayette County, Grundy County, Guthrie County, Howard County, Iowa County, Jackson County, Jasper County, Johnson County, Jones County, Keokuk County, Linn County, Louisa County, Madison County, Mahaska County, Marion County, Mitchell County, Muscatine County, Polk County, Poweshiek County, Sac County, Scott County, Tama County, Warren County, Washington County, Winneshiek County

Des Moines Lobe and prairie potholes

The youngest glaciation in the Midwest, so the landscape has not yet developed a drainage network. Without artificial drainage much of it would be wetland. A house in a depression and a house 300 m away on a rise have genuinely different risk — this is where a county average tells you least.

22 counties: Boone County, Butler County, Calhoun County, Carroll County, Cerro Gordo County, Emmet County, Floyd County, Franklin County, Greene County, Hamilton County, Hancock County, Hardin County, Humboldt County, Kossuth County, Marshall County, Palo Alto County, Pocahontas County, Story County, Webster County, Winnebago County, Worth County, Wright County

Dissected till plain with a claypan

The claypan is a hard clay layer a few tens of centimetres under the lawn. Water sits on it and spreads sideways. The typical symptom is seepage through the upper part of the wall rather than at the floor.

19 counties: Adams County, Appanoose County, Clarke County, Davis County, Decatur County, Des Moines County, Henry County, Jefferson County, Lee County, Lucas County, Monroe County, Montgomery County, Page County, Ringgold County, Taylor County, Union County, Van Buren County, Wapello County, Wayne County

Loess hills

Loess is permeable and the water table is deep, but it is prone to erosion and to collapse under load when wetted — a different failure mode from expansive clay. A broken downspout can undermine a loess footing.

15 counties: Cherokee County, Crawford County, Fremont County, Harrison County, Ida County, Lyon County, Mills County, Monona County, O'Brien County, Osceola County, Plymouth County, Pottawattamie County, Shelby County, Sioux County, Woodbury County

Driftless Area

The region the ice sheets missed. Slope, permeable loess, deep water table. Soil-driven basement risk is low here; the problems are surface runoff arriving from the hillside rather than groundwater pushing in.

4 counties: Allamakee County, Clayton County, Delaware County, Dubuque County

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