Soil series profile
Capay soil series
Capay is a moderately well drained soil with a clay surface, mapped on 245,213 acres in 20 counties in CA. Hydrologic group C.
- Drainage class
- Moderately well drained 91% of mapped acres
- Hydrologic group
- C 78% of mapped acres
- Typical topsoil pH
- 7.2 neutral · range 6.4–7.5
- Mapped area
- 245k acres in 20 counties, 1 state
Typical Capay profile
Texture and pH by depth
Show as a table
| Depth | Texture | pH | Clay | Sand | Organic matter |
|---|---|---|---|---|---|
| 0–5 in (Ap) | Clay | 7.1 | 54% | 18% | 1.9% |
| 5–21 in (Bk) | Silty clay | 7.9 | 55% | 3% | 1.4% |
| 21–32 in (Bkss1) | Silty clay | 8.4 | 51% | 5% | 0.9% |
| 32–40 in (Bkss2) | Silty clay | 8.3 | 45% | 7% | 0.5% |
| 40–50 in (B'k1) | Silty clay loam | 8.3 | 38% | 18% | 0.4% |
| 50–62 in (B'k2) | Silty clay loam | 8.2 | 38% | 18% | 0.4% |
| 62–81 in (2B'k3) | Clay loam | 8.3 | 36% | 33% | 0.2% |
| 81–88 in (2B'k4) | Sandy clay loam | 8.3 | 24% | 58% | 0.15% |
| 88–102 in (2B'k5) | Fine sandy loam | 8.1 | 13% | 70% | 0.12% |
What this means
What Capay soil means for gardens, lawns and septic systems
For gardens
Typical topsoil in Capay soils is neutral: pH 7.2 (most land between 6.4 and 7.5), the range most vegetables, flowers and lawn grasses prefer.
Clayey topsoil covers 81% of mapped Capay acres. Clay holds water and nutrients but drains slowly and compacts if worked wet: add compost, avoid tilling soggy soil and consider raised beds. The most common surface texture is clay (48% of mapped Capay acres).
91% of mapped Capay acres is moderately well to excessively drained, which suits most garden plants.
For lawns and yards
On 95% 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 95% of the acres in mapped Capay soils very limited, 0% somewhat limited and 0% not limited (5% 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.
Flooding is mapped on 70% of the acres (3% occasional, 7% frequent).
Only a licensed site evaluation or perc test at the actual lot decides whether a system is allowed and which design.
Where Capay soil is found
Mapped acres
Capay is mapped in California.
| County | Acres | Share of county land |
|---|---|---|
| Yolo County, CA | 40,453 | 6.2% |
| Sutter County, CA | 36,530 | 9.4% |
| San Joaquin County, CA | 36,360 | 4.1% |
| Colusa County, CA | 36,150 | 4.9% |
| Solano County, CA | 32,483 | 6.2% |
| Stanislaus County, CA | 26,297 | 2.7% |
| Contra Costa County, CA | 18,287 | 4.0% |
| Glenn County, CA | 12,490 | 1.5% |
| Yuba County, CA | 1,667 | 0.4% |
| Merced County, CA | 1,148 | 0.1% |
| Sacramento County, CA | 1,001 | 0.2% |
| San Luis Obispo County, CA | 952 | 0.1% |
| Alameda County, CA | 692 | 0.1% |
| Monterey County, CA | 423 | 0.0% |
| Santa Clara County, CA | 137 | 0.0% |
| Calaveras County, CA | 45 | 0.0% |
| Tuolumne County, CA | 45 | 0.0% |
| San Benito County, CA | 42 | 0.0% |
| Butte County, CA | 5 | 0.0% |
| Napa County, CA | 3 | 0.0% |
Septic absorption fields
NRCS rating, share of Capay acres
Show as a table
| Category | Share of acres |
|---|---|
| Not limited | 0.0% |
| Somewhat limited | 0.0% |
| Very limited | 95.4% |
| Not rated | 4.6% |
Drainage, water table and flooding
Share of Capay acres
- Depth to seasonal high water table
- About 4.4 feet (53 in) (median where reported).
- Flooding
- Mapped as flooding on 70% of acres (3% occasional, 7% frequent).
- Slope
- Typically 0–1% (median 0%).
- Topsoil organic matter
- Median 1.5%.
Drainage class
Show as a table
| Category | Share of acres |
|---|---|
| Excessively drained | 0.0% |
| Somewhat excessively drained | 0.0% |
| Well drained | 0.0% |
| Moderately well drained | 91.1% |
| Somewhat poorly drained | 4.9% |
| Poorly drained | 0.0% |
| Very poorly drained | 0.0% |
| Not rated | 4.0% |
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 | 77.5% |
| D: very slow infiltration (clayey, shallow or wet) | 17.9% |
| 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 | 4.6% |
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 Capay (component kind "Series") in SSURGO: 245,213 acres.
- Method
- Shares are by mapped acres of Capay components. The profile comes from the single largest Capay component. Full methodology.