State soil summary
Soil types in Colorado
The most widespread soil series in Colorado are Valent, Ascalon, Wiley. Pick a county below, or enter a ZIP code for the county you live in.
- Well or moderately well drained
- 84% of mapped land
- Typical topsoil pH
- 7.2 neutral · most land 6.2–8.0
- Septic fields very limited
- 68% 6% not limited
- Subject to flooding
- 5% of land, any frequency
Colorado counties
11 county reports, by population
| County | Most common soil | Well drained | Topsoil pH | Septic very limited |
|---|---|---|---|---|
| El Paso County | Bresser | 92% | 7.0 | 49% |
| Denver County | Elyria | 63% | 7.2 | 46% |
| Arapahoe County | Bresser | 86% | 7.2 | 52% |
| Jefferson County | Nunn | 82% | 6.7 | 79% |
| Adams County | Weld | 90% | 7.2 | 35% |
| Douglas County | Sphinx | 83% | 6.7 | 78% |
| Larimer County | Boyle | 75% | 6.7 | 72% |
| Weld County | Ascalon | 88% | 7.2 | 34% |
| Boulder County | Nunn | 75% | 6.8 | 76% |
| Pueblo County | Manvel | 94% | 7.9 | 64% |
| Mesa County | Persayo | 70% | 7.9 | 69% |
What this means
What Colorado soils mean for gardens, lawns and septic systems
For gardens
Typical topsoil in Colorado is neutral: pH 7.2 (most land between 6.2 and 8.0), the range most vegetables, flowers and lawn grasses prefer.
Loamy topsoil (loam, silt loam and similar) covers 75% of the land: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is loam (20% of the land).
84% of the land is moderately well to excessively drained, which suits most garden plants.
For lawns and yards
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 septic systems
For conventional septic absorption fields, NRCS rates 68% of the land in Colorado very limited, 15% somewhat limited and 6% not limited (10% not rated, such as urban land, pits or water).
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.
Only a licensed site evaluation or perc test at the actual lot decides whether a system is allowed and which design.
Statewide mix
Share of all mapped land
Drainage
Show as a table
| Category | Share of land |
|---|---|
| Excessively drained | 5.1% |
| Somewhat excessively drained | 8.0% |
| Well drained | 70.2% |
| Moderately well drained | 0.9% |
| Somewhat poorly drained | 1.0% |
| Poorly drained | 1.5% |
| Very poorly drained | 0.5% |
| Not rated | 12.8% |
Septic absorption fields
Show as a table
| Category | Share of land |
|---|---|
| Not limited | 6.3% |
| Somewhat limited | 15.4% |
| Very limited | 68.0% |
| Not rated | 10.4% |
Topsoil pH
Show as a table
| Category | Share of land |
|---|---|
| Strongly acidic (below 5.5) | 3.7% |
| Moderately to slightly acidic (5.5–6.4) | 8.7% |
| Near neutral (6.5–7.3) | 42.6% |
| Alkaline (7.4 and up) | 30.7% |
| Not reported | 14.4% |
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
- Colorado: 66,885,491 acres of mapped land in 63 counties, pooled (not an average of county figures).
- 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.