State soil summary
Soil types in Montana
The most widespread soil series in Montana are Cabbart, Kevin, Cabba. Pick a county below, or enter a ZIP code for the county you live in.
- Well or moderately well drained
- 86% of mapped land
- Typical topsoil pH
- 7.2 neutral · most land 6.0–7.9
- Septic fields very limited
- 78% 3% not limited
- Subject to flooding
- 4% of land, any frequency
Montana counties
2 county reports, by population
| County | Most common soil | Well drained | Topsoil pH | Septic very limited |
|---|---|---|---|---|
| Yellowstone County | Cabbart | 93% | 7.5 | 76% |
| Gallatin County | Brocko | 78% | 7.0 | 67% |
What this means
What Montana soils mean for gardens, lawns and septic systems
For gardens
Typical topsoil in Montana is neutral: pH 7.2 (most land between 6.0 and 7.9), the range most vegetables, flowers and lawn grasses prefer.
Loamy topsoil (loam, silt loam and similar) covers 81% of the land: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is loam (23% of the land).
86% of the land is moderately well to excessively drained, which suits most garden plants.
For lawns and yards
On 64% 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 78% of the land in Montana very limited, 10% somewhat limited and 3% not limited (9% 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 | 1.9% |
| Somewhat excessively drained | 3.8% |
| Well drained | 79.4% |
| Moderately well drained | 1.2% |
| Somewhat poorly drained | 0.9% |
| Poorly drained | 1.0% |
| Very poorly drained | 0.6% |
| Not rated | 11.2% |
Septic absorption fields
Show as a table
| Category | Share of land |
|---|---|
| Not limited | 2.9% |
| Somewhat limited | 9.5% |
| Very limited | 78.4% |
| Not rated | 9.1% |
Topsoil pH
Show as a table
| Category | Share of land |
|---|---|
| Strongly acidic (below 5.5) | 2.5% |
| Moderately to slightly acidic (5.5–6.4) | 12.9% |
| Near neutral (6.5–7.3) | 41.8% |
| Alkaline (7.4 and up) | 33.6% |
| Not reported | 9.2% |
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
- Montana: 99,169,608 acres of mapped land in 56 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.