County soil summary
Soil types in St. Louis County, Missouri
The most widespread soils are Harvester, Menfro and Winfield; the most common drainage class is moderately well drained (25% of the land), and typical topsoil pH is 5.7.
- Well or moderately well drained
- 53% of land · state 67%
- Typical topsoil pH
- 5.7 moderately acidic · state 6.0
- Septic fields very limited
- 63% of land · state 93%
- Subject to flooding
- 19% of land, any frequency · state 20%
Most common soils in St. Louis County
Share of mapped land
A county is a patchwork of many soils. These 8 cover 79% of the mapped land; 65 named soil series are mapped here in all.
| Soil | Share of land | Drainage | Topsoil pH |
|---|---|---|---|
| Urban landLand type, not a soil series | 33.1% | — | — |
| Harvester | 14.1% | Moderately well drained | 5.1 |
| Menfro | 13.0% | Well drained | 5.5 |
| Winfield | 7.4% | Moderately well drained | 5.6 |
| Goss | 4.0% | Well drained | 6.0 |
| Fishpot | 3.0% | Somewhat poorly drained | 5.7 |
| Freeburg | 2.6% | Somewhat poorly drained | 6.2 |
| Peers | 1.9% | Somewhat poorly drained | 7.7 |
What this means
What the soils in St. Louis County mean for gardens, lawns and septic systems
For your garden
Typical topsoil in St. Louis County is moderately acidic: pH 5.7 (most land between 5.1 and 7.6). Many vegetables grow well here, and some gardens benefit from a little lime. Test before adding any.
Loamy topsoil (loam, silt loam and similar) covers 62% of the land: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is silt loam (54% of the land).
For your lawn and yard
On 57% of the land, rain soaks in slowly (hydrologic groups C and D, including dual groups that are D until drained). Expect runoff and puddles after heavy rain: core-aerate compacted lawns and keep ground sloping away from foundations.
For a septic system
For conventional septic absorption fields, NRCS rates 63% of the land in St. Louis County very limited, 3% somewhat limited and 0% not limited (34% not rated, such as urban land, pits or water).
Statewide, 93% of the land is very limited, so St. Louis County is less restrictive than typical.
Where the soil is very limited (slow permeability, a high water table, flooding, shallow bedrock or steep slopes), alternative systems such as mound or sand-filter designs are common and cost more.
Flooding is mapped on 19% of the land (9% occasional, 9% frequent).
Only a licensed site evaluation or perc test at the actual lot decides whether a system is allowed and which design.
Drainage
How long the soil stays wet
The most common drainage class is moderately well drained (25%). 53% of the land is moderately well drained or better, compared with 67% across Missouri.
Show as a table
| Category | St. Louis County | Missouri |
|---|---|---|
| Excessively drained | 0.7% | 1.0% |
| Somewhat excessively drained | 3.4% | 7.9% |
| Well drained | 23.7% | 29.2% |
| Moderately well drained | 25.4% | 28.8% |
| Somewhat poorly drained | 10.3% | 18.1% |
| Poorly drained | 1.7% | 13.0% |
| Very poorly drained | 0.2% | 0.6% |
| Not rated | 34.6% | 1.5% |
Septic absorption fields
NRCS rating for conventional drain fields
The rating looks at the soil from 24 to 60 inches deep: permeability, depth to a seasonal water table or bedrock, flooding and slope. “Very limited” means at least one feature is unfavorable enough that a conventional field is hard to make work.
Show as a table
| Category | St. Louis County | Missouri |
|---|---|---|
| Not limited | 0.0% | 0.0% |
| Somewhat limited | 2.7% | 6.1% |
| Very limited | 63.4% | 92.9% |
| Not rated | 33.9% | 1.0% |
Rain, runoff and water table
Hydrologic soil group, flooding, seasonal water table
Hydrologic soil group
How fast rain soaks in when the soil is already wet. Group A soaks in fastest, D slowest.
Show as a table
| Category | St. Louis County | Missouri |
|---|---|---|
| A: fast infiltration (mostly sandy or gravelly) | 1.2% | 3.8% |
| B: moderate infiltration | 7.5% | 15.7% |
| C: slow infiltration | 42.6% | 27.6% |
| D: very slow infiltration (clayey, shallow or wet) | 3.6% | 31.2% |
| A/D: D as is, A if drained | 0.0% | 0.0% |
| B/D: D as is, B if drained | 1.5% | 2.9% |
| C/D: D as is, C if drained | 8.9% | 17.2% |
| Not rated | 34.7% | 1.6% |
Flooding
Show as a table
| Category | St. Louis County | Missouri |
|---|---|---|
| No flooding | 81.0% | 80.2% |
| Rare or very rare | 0.1% | 4.1% |
| Occasional | 9.2% | 9.4% |
| Frequent or very frequent | 9.2% | 6.1% |
| Not reported | 0.6% | 0.2% |
Seasonal high water table
Show as a table
| Category | St. Louis County | Missouri |
|---|---|---|
| Within 18 inches at some time of year | 7.3% | 27.8% |
| 18 inches to 3.3 feet | 30.5% | 29.2% |
| Deeper than 3.3 feet or none reported | 62.1% | 42.9% |
| Not reported | 0.0% | 0.1% |
Topsoil pH and texture
First mineral layer of each soil
Typical topsoil pH is 5.7 (moderately acidic); 80% of rated land falls between 5.1 and 7.6. Median topsoil organic matter is 2.2%.
Show as a table
| Category | St. Louis County | Missouri |
|---|---|---|
| Strongly acidic (below 5.5) | 13.6% | 22.1% |
| Moderately to slightly acidic (5.5–6.4) | 28.2% | 45.6% |
| Near neutral (6.5–7.3) | 16.3% | 28.6% |
| Alkaline (7.4 and up) | 7.2% | 2.1% |
| Not reported | 34.7% | 1.6% |
Texture
Show as a table
| Category | St. Louis County | Missouri |
|---|---|---|
| Sandy | 0.7% | 1.0% |
| Loamy (loam, silt loam and similar) | 61.5% | 94.6% |
| Clayey (40%+ clay) | 3.3% | 2.8% |
| Organic (muck or peat) | 0.0% | 0.0% |
| Not reported (rock, urban land, etc.) | 34.6% | 1.6% |
Sources & data dates
- Source
- USDA NRCS Soil Survey Geographic Database (SSURGO), queried through Soil Data Access. Public domain.
- Data date
- SSURGO as published on November 3, 2026 (most recent survey area update October 26, 2026). NRCS refreshes SSURGO each October.
- Scope
- St. Louis County, Missouri (FIPS 29189): 364,744 acres of mapped land, 13,003 acres of open water excluded. State comparisons pool all mapped land in Missouri.
- Method
- Shares are by mapped land area: each map unit’s acres in the county times each soil component’s percentage. Open water is excluded. Topsoil values use the first mineral horizon of each component. Full methodology.