Illinois: basement moisture and foundation risk by county
102 counties, ranked by our combined index. Highest combined risk is Crawford County (64), lowest is Jo Daviess County (27). The worst soil for foundation cracks specifically is in Williamson County.
| County | Index | Moisture | Cracks | Water table | Region |
|---|---|---|---|---|---|
| Crawford County | 64 | 52 | 68 | 82 | Dissected till plain with a claypan |
| Lawrence County | 64 | 53 | 67 | 82 | Dissected till plain with a claypan |
| Gallatin County | 63 | 54 | 62 | 82 | Dissected till plain with a claypan |
| Jasper County | 63 | 54 | 62 | 82 | Dissected till plain with a claypan |
| Jackson County | 62 | 53 | 61 | 82 | Dissected till plain with a claypan |
| Jersey County | 62 | 49 | 65 | 82 | Dissected till plain with a claypan |
| Shelby County | 62 | 56 | 56 | 82 | Wisconsinan till plain |
| Effingham County | 61 | 54 | 66 | 66 | Dissected till plain with a claypan |
| Williamson County | 61 | 53 | 69 | 66 | Dissected till plain with a claypan |
| Clinton County | 60 | 50 | 57 | 82 | Dissected till plain with a claypan |
| Fulton County | 60 | 54 | 52 | 82 | Wisconsinan till plain |
| Johnson County | 60 | 51 | 67 | 66 | Dissected till plain with a claypan |
| Menard County | 60 | 56 | 50 | 82 | Wisconsinan till plain |
| Pope County | 60 | 52 | 57 | 82 | Dissected till plain with a claypan |
| Wabash County | 60 | 52 | 66 | 66 | Dissected till plain with a claypan |
| Washington County | 60 | 50 | 57 | 82 | Dissected till plain with a claypan |
| Cumberland County | 59 | 53 | 61 | 66 | Dissected till plain with a claypan |
| Marion County | 59 | 53 | 50 | 82 | Dissected till plain with a claypan |
| Vermilion County | 59 | 53 | 51 | 82 | Wisconsinan till plain |
| Cass County | 58 | 53 | 47 | 82 | Wisconsinan till plain |
| Kankakee County | 58 | 54 | 57 | 66 | Wisconsinan till plain |
| Madison County | 58 | 51 | 52 | 82 | Dissected till plain with a claypan |
| Montgomery County | 58 | 53 | 59 | 66 | Dissected till plain with a claypan |
| Fayette County | 57 | 51 | 58 | 66 | Dissected till plain with a claypan |
| Greene County | 57 | 54 | 43 | 82 | Wisconsinan till plain |
| Kendall County | 57 | 57 | 52 | 66 | Wisconsinan till plain |
| Lake County | 57 | 57 | 52 | 66 | Wisconsinan till plain |
| Macoupin County | 57 | 54 | 42 | 82 | Dissected till plain with a claypan |
| Monroe County | 57 | 49 | 61 | 66 | Dissected till plain with a claypan |
| Perry County | 57 | 53 | 55 | 66 | Dissected till plain with a claypan |
| Will County | 57 | 54 | 56 | 66 | Wisconsinan till plain |
| Winnebago County | 57 | 56 | 52 | 66 | Wisconsinan till plain |
| Bond County | 56 | 52 | 42 | 82 | Dissected till plain with a claypan |
| Boone County | 56 | 52 | 53 | 66 | Wisconsinan till plain |
| Brown County | 56 | 53 | 41 | 82 | Wisconsinan till plain |
| Coles County | 56 | 56 | 49 | 66 | Wisconsinan till plain |
| Edwards County | 56 | 54 | 41 | 82 | Dissected till plain with a claypan |
| Hamilton County | 56 | 53 | 43 | 82 | Dissected till plain with a claypan |
| Henry County | 56 | 53 | 53 | 66 | Wisconsinan till plain |
| Jefferson County | 56 | 50 | 45 | 82 | Dissected till plain with a claypan |
| Knox County | 56 | 53 | 52 | 66 | Wisconsinan till plain |
| Lee County | 56 | 55 | 50 | 66 | Wisconsinan till plain |
| Pulaski County | 56 | 53 | 54 | 66 | Dissected till plain with a claypan |
| Schuyler County | 56 | 55 | 51 | 66 | Wisconsinan till plain |
| Tazewell County | 56 | 53 | 54 | 66 | Wisconsinan till plain |
| Clark County | 55 | 56 | 45 | 66 | Wisconsinan till plain |
| Hancock County | 55 | 53 | 38 | 82 | Wisconsinan till plain |
| Pike County | 55 | 53 | 39 | 82 | Wisconsinan till plain |
| Saline County | 55 | 51 | 40 | 82 | Dissected till plain with a claypan |
| Union County | 55 | 50 | 55 | 66 | Dissected till plain with a claypan |
| White County | 55 | 49 | 54 | 66 | Dissected till plain with a claypan |
| Alexander County | 54 | 53 | 48 | 66 | Dissected till plain with a claypan |
| Clay County | 54 | 51 | 49 | 66 | Dissected till plain with a claypan |
| Edgar County | 54 | 55 | 57 | 46 | Wisconsinan till plain |
| Kane County | 54 | 56 | 42 | 66 | Wisconsinan till plain |
| Sangamon County | 54 | 53 | 48 | 66 | Wisconsinan till plain |
| Whiteside County | 54 | 53 | 34 | 82 | Wisconsinan till plain |
| Bureau County | 53 | 56 | 38 | 66 | Wisconsinan till plain |
| Cook County | 53 | 53 | 31 | 82 | Wisconsinan till plain |
| Franklin County | 53 | 54 | 43 | 66 | Dissected till plain with a claypan |
| Iroquois County | 53 | 57 | 38 | 66 | Wisconsinan till plain |
| Mercer County | 53 | 56 | 39 | 66 | Wisconsinan till plain |
| Ogle County | 53 | 57 | 38 | 66 | Wisconsinan till plain |
| Piatt County | 53 | 54 | 41 | 66 | Wisconsinan till plain |
| Richland County | 53 | 51 | 46 | 66 | Dissected till plain with a claypan |
| St. Clair County | 53 | 50 | 49 | 66 | Dissected till plain with a claypan |
| Wayne County | 53 | 54 | 43 | 66 | Dissected till plain with a claypan |
| Adams County | 52 | 53 | 39 | 66 | Wisconsinan till plain |
| Christian County | 52 | 53 | 30 | 82 | Wisconsinan till plain |
| De Witt County | 52 | 52 | 55 | 46 | Wisconsinan till plain |
| Ford County | 52 | 56 | 35 | 66 | Wisconsinan till plain |
| LaSalle County | 52 | 55 | 39 | 66 | Wisconsinan till plain |
| Morgan County | 52 | 57 | 34 | 66 | Wisconsinan till plain |
| Randolph County | 52 | 53 | 42 | 66 | Dissected till plain with a claypan |
| Stark County | 52 | 54 | 38 | 66 | Wisconsinan till plain |
| Calhoun County | 51 | 49 | 44 | 66 | Dissected till plain with a claypan |
| Champaign County | 51 | 52 | 39 | 66 | Wisconsinan till plain |
| DuPage County | 51 | 55 | 48 | 46 | Wisconsinan till plain |
| Logan County | 51 | 53 | 38 | 66 | Wisconsinan till plain |
| Marshall County | 51 | 54 | 36 | 66 | Wisconsinan till plain |
| Massac County | 51 | 51 | 39 | 66 | Dissected till plain with a claypan |
| McLean County | 51 | 57 | 32 | 66 | Wisconsinan till plain |
| Putnam County | 51 | 54 | 37 | 66 | Wisconsinan till plain |
| Rock Island County | 51 | 52 | 38 | 66 | Wisconsinan till plain |
| Warren County | 51 | 52 | 39 | 66 | Wisconsinan till plain |
| DeKalb County | 50 | 53 | 34 | 66 | Wisconsinan till plain |
| Livingston County | 50 | 53 | 34 | 66 | Wisconsinan till plain |
| McDonough County | 50 | 53 | 35 | 66 | Wisconsinan till plain |
| McHenry County | 50 | 56 | 45 | 46 | Wisconsinan till plain |
| Peoria County | 50 | 56 | 44 | 46 | Wisconsinan till plain |
| Scott County | 50 | 57 | 30 | 66 | Wisconsinan till plain |
| Douglas County | 49 | 53 | 31 | 66 | Wisconsinan till plain |
| Grundy County | 49 | 55 | 29 | 66 | Wisconsinan till plain |
| Hardin County | 49 | 49 | 37 | 66 | Dissected till plain with a claypan |
| Mason County | 49 | 53 | 31 | 66 | Wisconsinan till plain |
| Moultrie County | 49 | 53 | 32 | 66 | Wisconsinan till plain |
| Henderson County | 48 | 52 | 30 | 66 | Wisconsinan till plain |
| Macon County | 47 | 56 | 34 | 46 | Wisconsinan till plain |
| Woodford County | 46 | 56 | 31 | 46 | Wisconsinan till plain |
| Stephenson County | 34 | 37 | 34 | 30 | Driftless Area |
| Carroll County | 28 | 33 | 20 | 30 | Driftless Area |
| Jo Daviess County | 27 | 34 | 16 | 30 | Driftless Area |
Values from USDA NRCS SSURGO where available, otherwise our regional model — each county page states which. Methodology.
The physiographic regions inside Illinois
State lines are political; soil follows geology. These are the distinct ground types inside Illinois 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.
60 counties: Adams County, Boone County, Brown County, Bureau County, Cass County, Champaign County, Christian County, Clark County, Coles County, Cook County, De Witt County, DeKalb County, Douglas County, DuPage County, Edgar County, Ford County, Fulton County, Greene County, Grundy County, Hancock County, Henderson County, Henry County, Iroquois County, Kane County, Kankakee County, Kendall County, Knox County, LaSalle County, Lake County, Lee County, Livingston County, Logan County, Macon County, Marshall County, Mason County, McDonough County, McHenry County, McLean County, Menard County, Mercer County, Morgan County, Moultrie County, Ogle County, Peoria County, Piatt County, Pike County, Putnam County, Rock Island County, Sangamon County, Schuyler County, Scott County, Shelby County, Stark County, Tazewell County, Vermilion County, Warren County, Whiteside County, Will County, Winnebago County, Woodford 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.
39 counties: Alexander County, Bond County, Calhoun County, Clay County, Clinton County, Crawford County, Cumberland County, Edwards County, Effingham County, Fayette County, Franklin County, Gallatin County, Hamilton County, Hardin County, Jackson County, Jasper County, Jefferson County, Jersey County, Johnson County, Lawrence County, Macoupin County, Madison County, Marion County, Massac County, Monroe County, Montgomery County, Perry County, Pope County, Pulaski County, Randolph County, Richland County, Saline County, St. Clair County, Union County, Wabash County, Washington County, Wayne County, White County, Williamson 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.
3 counties: Carroll County, Jo Daviess County, Stephenson County
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