St. Charles County, Missouri
The most common soil here is Menfro, on about 7% of the land: a silt loam, smooth, like flour. Harvester and Goss come next.
About 28% of the land drains well, and 34% stays wet for long stretches; groundwater comes within two feet of the surface under 39% of it.
USDA rates 88% of the land very limited for a standard septic drain field, and 72% very limited for homes with basements. That means extra cost or special design, not that it can't be done.
Worth knowing: 37% of the land floods occasionally or more, and bedrock lies within 40 inches under 3% 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. Charles 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 Moderately well drained and the dominant hydrologic group is D (very slow infiltration, high 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. Charles 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 |
|---|---|---|---|---|---|
| Harvester-Urban land complex, 2 to 9 percent slopes | 30K | Moderately well drained | C | Somewhat limited | Very limited |
| Water | 23K | Subaqueous | Not rated | Not rated | |
| Armster silt loam, 2 to 7 percent slopes | 20K | Moderately well drained | D | Very limited | Very limited |
| Goss very gravelly silt loam, 14 to 45 percent slopes | 20K | Well drained | C | Very limited | Very limited |
| Portage clay, 0 to 2 percent slopes, occasionally flooded, frequently ponded | 17K | Very poorly drained | D | Very limited | Very limited |
| Carlow silty clay loam, 0 to 2 percent slopes, occasionally flooded | 14K | Poorly drained | D | Very limited | Very limited |
| Lowmo silt loam, 0 to 2 percent slopes, occasionally flooded | 13K | Well drained | B | Very limited | Very limited |
| Hatton silt loam, 5 to 9 percent slopes | 13K | Moderately well drained | D | Very limited | Very limited |
| Peers silty clay loam, 0 to 2 percent slopes, occasionally flooded | 12K | Somewhat poorly drained | C/D | Very limited | Very limited |
| Gatewood-Gasconade-Crider complex, 15 to 50 percent slopes | 10K | Moderately well drained | D | Very limited | Very limited |
| Harvester-Urban land complex, 9 to 14 percent slopes | 10K | Moderately well drained | C | Somewhat limited | Very limited |
| Mexico silt loam, 1 to 4 percent slopes, eroded | 10K | Poorly drained | D | Very limited | Very limited |
| SansDessein silty clay, 0 to 2 percent slopes, occasionally flooded | 10K | Poorly drained | C/D | Very limited | Very limited |
| Keswick silt loam, 9 to 14 percent slopes, eroded | 10K | Somewhat poorly drained | C/D | Very limited | Very limited |
| Weller silt loam, 5 to 9 percent slopes | 9K | Moderately well drained | D | Very limited | Very limited |
| Urban land-Orthents complex, 1 to 9 percent slopes | 9K | Not rated | Not rated | ||
| Menfro silt loam, 5 to 9 percent slopes, eroded | 8K | Well drained | C | Somewhat limited | Very limited |
| Menfro silt loam, 9 to 14 percent slopes, eroded | 8K | Well drained | B | Somewhat limited | Somewhat limited |
| Dockery silt loam, 0 to 2 percent slopes, occasionally flooded | 6K | Somewhat poorly drained | B/D | Very limited | Very limited |
| DeSioux loam, 0 to 2 percent slopes, rarely flooded | 6K | Well drained | B | Very limited | Somewhat 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 72% 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 88% 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.