County soil summary
Soil types in Oklahoma County, Oklahoma
The most widespread soils are Stephenville, Harrah and Darnell; the most common drainage class is well drained (66% of the land), and typical topsoil pH is 6.3.
- Well or moderately well drained
- 81% of land · state 87%
- Typical topsoil pH
- 6.3 slightly acidic · state 6.5
- Septic fields very limited
- 72% of land · state 77%
- Subject to flooding
- 16% of land, any frequency · state 14%
Most common soils in Oklahoma County
Share of mapped land
A county is a patchwork of many soils. These 8 cover 66% of the mapped land; 62 named soil series are mapped here in all.
| Soil | Share of land | Drainage | Topsoil pH |
|---|---|---|---|
| Urban landLand type, not a soil series | 14.9% | — | — |
| Stephenville | 14.5% | Well drained | 5.8 |
| Harrah | 11.1% | Well drained | 5.9 |
| Darnell | 7.3% | Excessively drained | 6.4 |
| Renthin | 7.0% | Well drained | 6.7 |
| Newalla | 4.0% | Moderately well drained | 5.3 |
| Grainola | 3.6% | Well drained | 7.5 |
| Ashport | 3.1% | Well drained | 7.0 |
What this means
What the soils in Oklahoma County mean for gardens, lawns and septic systems
For your garden
Typical topsoil in Oklahoma County is slightly acidic: pH 6.3 (most land between 5.8 and 7.5), the range most vegetables, flowers and lawn grasses prefer.
Loamy topsoil (loam, silt loam and similar) covers 63% of the land: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is fine sandy loam (36% of the land).
81% of the land is moderately well to excessively drained, which suits most garden plants.
For your lawn and yard
On 66% 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 72% of the land in Oklahoma County very limited, 19% somewhat limited and 0% not limited (9% not rated, such as urban land, pits or water).
That is close to the state as a whole (77% very limited).
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 16% of the land (7% occasional, 6% 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 well drained (66%). 81% of the land is moderately well drained or better, compared with 87% across Oklahoma.
Show as a table
| Category | Oklahoma County | Oklahoma |
|---|---|---|
| Excessively drained | 7.7% | 2.0% |
| Somewhat excessively drained | 1.8% | 5.7% |
| Well drained | 65.6% | 68.0% |
| Moderately well drained | 6.1% | 11.6% |
| Somewhat poorly drained | 3.1% | 8.8% |
| Poorly drained | 0.0% | 1.4% |
| Very poorly drained | 0.1% | 0.3% |
| Not rated | 15.6% | 2.3% |
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 | Oklahoma County | Oklahoma |
|---|---|---|
| Not limited | 0.0% | 1.1% |
| Somewhat limited | 19.0% | 15.4% |
| Very limited | 72.2% | 77.2% |
| Not rated | 8.9% | 6.2% |
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 | Oklahoma County | Oklahoma |
|---|---|---|
| A: fast infiltration (mostly sandy or gravelly) | 5.5% | 11.4% |
| B: moderate infiltration | 28.2% | 27.5% |
| C: slow infiltration | 19.0% | 20.9% |
| D: very slow infiltration (clayey, shallow or wet) | 46.8% | 32.5% |
| A/D: D as is, A if drained | 0.2% | 0.2% |
| B/D: D as is, B if drained | 0.0% | 0.4% |
| C/D: D as is, C if drained | 0.0% | 4.5% |
| Not rated | 0.2% | 2.6% |
Flooding
Show as a table
| Category | Oklahoma County | Oklahoma |
|---|---|---|
| No flooding | 83.6% | 85.4% |
| Rare or very rare | 4.1% | 2.5% |
| Occasional | 6.7% | 7.2% |
| Frequent or very frequent | 5.6% | 4.7% |
| Not reported | 0.0% | 0.2% |
Seasonal high water table
Show as a table
| Category | Oklahoma County | Oklahoma |
|---|---|---|
| Within 18 inches at some time of year | 1.0% | 9.6% |
| 18 inches to 3.3 feet | 1.9% | 6.8% |
| Deeper than 3.3 feet or none reported | 97.1% | 83.5% |
| Not reported | 0.0% | 0.1% |
Topsoil pH and texture
First mineral layer of each soil
Typical topsoil pH is 6.3 (slightly acidic); 80% of rated land falls between 5.8 and 7.5. Median topsoil organic matter is 2%.
Show as a table
| Category | Oklahoma County | Oklahoma |
|---|---|---|
| Strongly acidic (below 5.5) | 3.0% | 9.9% |
| Moderately to slightly acidic (5.5–6.4) | 41.8% | 31.4% |
| Near neutral (6.5–7.3) | 23.8% | 31.4% |
| Alkaline (7.4 and up) | 7.7% | 19.4% |
| Not reported | 23.8% | 7.9% |
Texture
Show as a table
| Category | Oklahoma County | Oklahoma |
|---|---|---|
| Sandy | 11.7% | 10.0% |
| Loamy (loam, silt loam and similar) | 63.1% | 78.7% |
| Clayey (40%+ clay) | 1.5% | 3.4% |
| Organic (muck or peat) | 0.0% | 0.0% |
| Not reported (rock, urban land, etc.) | 23.8% | 7.9% |
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
- Oklahoma County, Oklahoma (FIPS 40109): 450,543 acres of mapped land, 9,259 acres of open water excluded. State comparisons pool all mapped land in Oklahoma.
- 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.