Soil series profile
Walla Walla soil series
Walla Walla is a well drained soil with a silt loam surface, mapped on 813,994 acres in 11 counties across 2 states. Hydrologic group B.
- Drainage class
- Well drained 100% of mapped acres
- Hydrologic group
- B >99% of mapped acres
- Typical topsoil pH
- 7.2 neutral · range 7.0–7.2
- Mapped area
- 814k acres in 11 counties, 2 states
Typical Walla Walla profile
Texture and pH by depth
Show as a table
| Depth | Texture | pH | Clay | Sand | Organic matter |
|---|---|---|---|---|---|
| 0–16 in (H1) | Silt loam | 7.2 | 14% | 14% | 2.5% |
| 16–41 in (H2) | Silt loam | 7.2 | 14% | 14% | 1.5% |
| 41–60 in (H3) | Silt loam | 8.2 | 14% | 14% | 0.25% |
What this means
What Walla Walla soil means for gardens, lawns and septic systems
For gardens
Typical topsoil in Walla Walla soils is neutral: pH 7.2 (most land between 7.0 and 7.2), the range most vegetables, flowers and lawn grasses prefer.
Loamy topsoil (loam, silt loam and similar) covers 100% of mapped Walla Walla acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is silt loam (>99% of mapped Walla Walla acres).
100% of mapped Walla Walla acres is moderately well to excessively drained, which suits most garden plants.
For lawns and yards
Most land is in hydrologic groups B and C, where rain soaks in at a moderate pace.
For a septic system
For conventional septic absorption fields, NRCS rates 42% of the acres in mapped Walla Walla soils very limited, 58% somewhat limited and 0% not limited.
Only a licensed site evaluation or perc test at the actual lot decides whether a system is allowed and which design.
Where Walla Walla soil is found
Mapped acres
Walla Walla is mapped in Washington and Oregon.
| County | Acres | Share of county land |
|---|---|---|
| Whitman County, WA | 187,732 | 14.0% |
| Umatilla County, OR | 157,048 | 9.2% |
| Walla Walla County, WA | 138,605 | 16.8% |
| Sherman County, OR | 109,200 | 24.1% |
| Adams County, WA | 61,769 | 5.1% |
| Columbia County, WA | 56,602 | 13.5% |
| Wasco County, OR | 38,591 | 3.2% |
| Garfield County, WA | 26,341 | 3.7% |
| Klickitat County, WA | 14,086 | 1.3% |
| Benton County, WA | 13,141 | 1.2% |
| Gilliam County, OR | 10,880 | 1.4% |
Septic absorption fields
NRCS rating, share of Walla Walla acres
Show as a table
| Category | Share of acres |
|---|---|
| Not limited | 0.0% |
| Somewhat limited | 58.1% |
| Very limited | 41.9% |
Drainage, water table and flooding
Share of Walla Walla acres
- Depth to seasonal high water table
- None reported within about 6.5 feet (median where reported).
- Flooding
- Not mapped as flooding on most acres.
- Slope
- Typically 4–35% (median 14%).
- Topsoil organic matter
- Median 2.5%.
Drainage class
Show as a table
| Category | Share of acres |
|---|---|
| Excessively drained | 0.0% |
| Somewhat excessively drained | 0.0% |
| Well drained | 100.0% |
| Moderately well drained | 0.0% |
| Somewhat poorly drained | 0.0% |
| Poorly drained | 0.0% |
| Very poorly drained | 0.0% |
Hydrologic soil group
Show as a table
| Category | Share of acres |
|---|---|
| A: fast infiltration (mostly sandy or gravelly) | 0.0% |
| B: moderate infiltration | 99.3% |
| C: slow infiltration | 0.7% |
| D: very slow infiltration (clayey, shallow or wet) | 0.0% |
| A/D: D as is, A if drained | 0.0% |
| B/D: D as is, B if drained | 0.0% |
| C/D: D as is, C if drained | 0.0% |
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
- All map unit components named Walla Walla (component kind "Series") in SSURGO: 813,994 acres.
- Method
- Shares are by mapped acres of Walla Walla components. The profile comes from the single largest Walla Walla component. Full methodology.