Soils in St. Clair County, Illinois
St. Clair County, Illinois has 89,576 acres of well-drained soil across 158 distinct soil map units. The map below shows every NRCS soil map unit inside the county boundary.
St. Clair County, Illinois at a glance
| Well-drained land | 89,576 acres |
|---|---|
| Share of mapped soil that is well drained | 20.8% |
| Poorly drained land | 259,265 acres |
| Most common drainage class | Somewhat poorly drained — 187,858 acres |
| Distinct soil map units | 158 |
| Largest soil map unit | Wakeland silt loam, 0 to 2 percent slopes, frequently flooded — 32,949 acres |
| Share with hydrologic soil group A or B (high infiltration) | 15.6% |
| Typical shallowest annual water table | 15 in below the surface |
St. Clair County, Illinois is home to 250,708 residents. Land Owl's soils layer records the following within the county boundary — Well-drained land: 89,576 acres. Share of mapped soil that is well drained: 20.8%. Poorly drained land: 259,265 acres. Most common drainage class: Somewhat poorly drained — 187,858 acres. Distinct soil map units: 158. Largest soil map unit: Wakeland silt loam, 0 to 2 percent slopes, frequently flooded — 32,949 acres. Share with hydrologic soil group A or B (high infiltration): 15.6%. Typical shallowest annual water table: 15 in below the surface. Every feature shown on the map above is clickable, and the figures on this page are derived from the same data the map renders, so they always agree. A free Land Owl account adds parcel boundaries, ownership records, flood zones, wetlands and topography over the same view.
Frequently asked questions
- What are the soils like in St. Clair County, Illinois?
- The USDA soil survey maps 89,576 acres of St. Clair County, Illinois as well drained and 259,265 acres as poorly drained. Drainage class and hydrologic soil group are the two properties that most often decide whether a rural lot can take a septic system and a driveway.
- Is this soil map free to use?
- Yes. This map is free to view. A free Land Owl account unlocks the other data layers, parcel boundaries and ownership records.
- Where does this data come from?
- Land Owl maps soils from the USDA Natural Resources Conservation Service SSURGO soil survey. SSURGO describes soil MAP UNITS at survey scale — it is a screening tool for shortlisting land, not a substitute for a site-specific soil evaluation or a septic percolation test, both of which your health department will want before it permits a system.
- Can I use this soil map to tell whether land will perc?
- It is the right place to start and the wrong place to finish. Drainage class and hydrologic soil group tell you which parcels are worth a site visit, but a health department permits a septic system on a percolation test dug on the actual lot, not on the survey.
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