St. Clair County, Missouri
The most common soil here is Goss, on about 12% of the land: a gravelly silt loam, smooth, like flour. Barden and Barco come next.
About 64% of the land drains well, and 7% stays wet for long stretches; groundwater comes within two feet of the surface under 10% of it.
USDA rates 96% of the land very limited for a standard septic drain field, and 59% very limited for homes with basements. That means extra cost or special design, not that it can't be done.
Worth knowing: 7% of the land floods occasionally or more, and bedrock lies within 40 inches under 39% of it.
Soils change over short distances, so look up an address below for the soil at that exact spot and the reasons behind each rating.
The soils you're most likely standing on
The biggest named soils in St. Clair County, Missouri, each drawn five feet deep from its official USDA description, in its recorded colors.
Dots mark gravel; white flecks mark lime. Shares are by acres across the survey area, and each mapped patch usually mixes several of these soils.
The biggest mapped areas
The dominant drainage class is Well drained and the dominant hydrologic group is C (slow infiltration, moderate runoff). The most common soil order is Alfisols — moderately leached forest soils with a clay-enriched subsoil. This report summarizes the major soil map units across the survey area to help you understand what to expect when buying, building, or gardening in St. Clair County, Missouri. Search your address to find the exact soil composition, drainage, and series details at your specific location.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Barden silt loam, 1 to 5 percent slopes | 54K | Moderately well drained | D | Very limited | Very limited |
| Hector fine sandy loam, 5 to 25 percent slopes, stony | 44K | Well drained | D | Very limited | Very limited |
| Barco fine sandy loam, 2 to 5 percent slopes | 32K | Well drained | C | Somewhat limited | Very limited |
| Gasconade-Rock outcrop complex, 3 to 35 percent slopes | 27K | Somewhat excessively drained | D | Very limited | Very limited |
| Goss gravelly silt loam, 8 to 15 percent slopes | 25K | Well drained | C | Somewhat limited | Very limited |
| Goss gravelly silt loam, 3 to 8 percent slopes | 24K | Well drained | C | Not limited | Very limited |
| Bolivar fine sandy loam, 2 to 5 percent slopes | 19K | Well drained | C | Somewhat limited | Very limited |
| Deepwater silt loam, 2 to 5 percent slopes | 17K | Moderately well drained | C | Somewhat limited | Very limited |
| Water | 16K | Subaqueous | Not rated | Not rated | |
| Collinsville fine sandy loam, 2 to 20 percent slopes | 15K | Somewhat excessively drained | D | Very limited | Very limited |
| Goss very gravelly silt loam, 15 to 35 percent slopes, very stony | 14K | Well drained | C | Very limited | Very limited |
| Bolivar fine sandy loam, 5 to 9 percent slopes | 12K | Well drained | C | Very limited | Very limited |
| Barco fine sandy loam, 5 to 9 percent slopes | 12K | Well drained | C | Somewhat limited | Very limited |
| Hartwell silt loam, 0 to 1 percent slopes | 10K | Somewhat poorly drained | C/D | Very limited | Very limited |
| Eldorado gravelly silt loam, 3 to 8 percent slopes | 10K | Well drained | B | Not limited | Very limited |
| Kenoma silt loam, 1 to 3 percent slopes | 10K | Moderately well drained | D | Very limited | Very limited |
| Verdigris silt loam, 0 to 1 percent slopes, occasionally flooded | 10K | Well drained | B | Very limited | Very limited |
| Useful silt loam, 3 to 8 percent slopes | 8K | Moderately well drained | C | Somewhat limited | Very limited |
| Liberal silt loam, 3 to 8 percent slopes | 6K | Moderately well drained | D | Very limited | Very limited |
| Quarles silt loam, 0 to 2 percent slopes, rarely flooded | 6K | Poorly drained | C/D | Very limited | Very limited |
Soil Orders in This Area
The USDA classifies every soil into one of 12 soil orders. Here are the dominant orders found in this survey area.
What This Means
Building & Foundations
About 59% of soils are rated "very limited" for dwellings with basements. Specific challenges include shallow bedrock, steep slopes, poor drainage in some areas, flood-prone areas. A geotechnical assessment is recommended before building.
Septic Systems
About 96% of soils are rated "very limited" for septic absorption fields. Despite good drainage overall, limitations may stem from shallow bedrock, steep slopes, or seasonal conditions. Engineered or alternative systems are frequently required. Always get a professional perc test before purchasing land that needs septic.
Gardening & Agriculture
Well-drained soils on sloped terrain — good for most plants but watch for erosion. Terracing, contour planting, and mulching help retain moisture and topsoil. Drip irrigation is more effective than sprinklers on slopes.