Soil series profile
Rockly soil series
Rockly is a well drained soil with a very cobbly loam surface, mapped on 335,321 acres in 21 counties across 3 states. Hydrologic group D.
- Drainage class
- Well drained >99% of mapped acres
- Hydrologic group
- D >99% of mapped acres
- Typical topsoil pH
- 6.7 neutral · range 6.7–6.8
- Mapped area
- 335k acres in 21 counties, 3 states
Typical Rockly profile
Texture and pH by depth
Show as a table
| Depth | Texture | pH | Clay | Sand | Organic matter |
|---|---|---|---|---|---|
| 0–3 in (A) | Very cobbly loam | 6.7 | 8% | 45% | 3% |
| 3–6 in (Bw) | Very cobbly loam | 6.5 | 9% | 45% | 1.5% |
| 6–16 in (R) | Bedrock | Not reported | Not reported | Not reported | Not reported |
What this means
What Rockly soil means for gardens, lawns and septic systems
For gardens
Typical topsoil in Rockly soils is neutral: pH 6.7 (most land between 6.7 and 6.8), the range most vegetables, flowers and lawn grasses prefer.
Loamy topsoil (loam, silt loam and similar) covers >99% of mapped Rockly acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is very gravelly loam (45% of mapped Rockly acres).
>99% of mapped Rockly acres is moderately well to excessively drained, which suits most garden plants.
For lawns and yards
On >99% of mapped acres, 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 >99% of the acres in mapped Rockly soils very limited, 0% somewhat limited and 0% not 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.
Only a licensed site evaluation or perc test at the actual lot decides whether a system is allowed and which design.
Where Rockly soil is found
Mapped acres
Rockly is mapped in Oregon, Washington and Idaho.
| County | Acres | Share of county land |
|---|---|---|
| Spokane County, WA | 62,707 | 5.6% |
| Grant County, OR | 50,128 | 2.4% |
| Klickitat County, WA | 41,083 | 3.8% |
| Morrow County, OR | 25,306 | 2.3% |
| Malheur County, OR | 23,672 | 0.4% |
| Wheeler County, OR | 21,510 | 2.2% |
| Umatilla County, OR | 19,508 | 1.1% |
| Adams County, ID | 17,028 | 6.2% |
| Union County, OR | 15,856 | 1.3% |
| Wasco County, OR | 15,327 | 1.3% |
| Wallowa County, OR | 8,654 | 0.6% |
| Gilliam County, OR | 7,455 | 1.0% |
| Jefferson County, OR | 5,520 | 0.5% |
| Baker County, OR | 4,427 | 0.3% |
| Asotin County, WA | 4,303 | 1.2% |
| Garfield County, WA | 3,992 | 0.6% |
| Lincoln County, WA | 2,587 | 0.2% |
| Columbia County, WA | 1,663 | 0.4% |
| Washington County, ID | 1,119 | 0.2% |
| Walla Walla County, WA | 981 | 0.1% |
| Whitman County, WA | 118 | 0.0% |
Septic absorption fields
NRCS rating, share of Rockly acres
Show as a table
| Category | Share of acres |
|---|---|
| Not limited | 0.0% |
| Somewhat limited | 0.0% |
| Very limited | 99.1% |
| Not rated | 0.9% |
Drainage, water table and flooding
Share of Rockly 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 3–55% (median 11%).
- Topsoil organic matter
- Median 2%.
Drainage class
Show as a table
| Category | Share of acres |
|---|---|
| Excessively drained | 0.0% |
| Somewhat excessively drained | 0.0% |
| Well drained | 99.1% |
| Moderately well drained | 0.0% |
| Somewhat poorly drained | 0.0% |
| Poorly drained | 0.0% |
| Very poorly drained | 0.0% |
| Not rated | 0.9% |
Hydrologic soil group
Show as a table
| Category | Share of acres |
|---|---|
| A: fast infiltration (mostly sandy or gravelly) | 0.0% |
| B: moderate infiltration | 0.0% |
| C: slow infiltration | 0.0% |
| D: very slow infiltration (clayey, shallow or wet) | 99.1% |
| 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% |
| Not rated | 0.9% |
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
- All map unit components named Rockly (component kind "Series") in SSURGO: 335,321 acres.
- Method
- Shares are by mapped acres of Rockly components. The profile comes from the single largest Rockly component. Full methodology.