Soil series profile
Cotharin soil series
Cotharin is a well drained soil with a loam surface, mapped on 35,999 acres in 2 counties in CA. Hydrologic group D.
- Drainage class
- Well drained >99% of mapped acres
- Hydrologic group
- D 97% of mapped acres
- Typical topsoil pH
- 7.0 neutral · range 7.0–7.0
- Mapped area
- 36k acres in 2 counties, 1 state
Typical Cotharin profile
Texture and pH by depth
Show as a table
| Depth | Texture | pH | Clay | Sand | Organic matter |
|---|---|---|---|---|---|
| 0–1 in (Oe) | Slightly decomposed plant material | 6.0 | Not reported | Not reported | 3% |
| 1–9 in (A) | Loam | 7.0 | 23% | 37% | 2.5% |
| 9–11 in (AC) | Loam | 7.0 | 23% | 40% | 2.5% |
| 11–21 in (Cr) | Weathered bedrock | Not reported | 0% | Not reported | 0% |
What this means
What Cotharin soil means for gardens, lawns and septic systems
For gardens
Typical topsoil in Cotharin soils is neutral: pH 7.0, the range most vegetables, flowers and lawn grasses prefer.
Loamy topsoil (loam, silt loam and similar) covers 97% of mapped Cotharin acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is loam (97% of mapped Cotharin acres).
100% of mapped Cotharin acres is moderately well to excessively drained, which suits most garden plants.
For lawns and yards
On 97% 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 97% of the acres in mapped Cotharin soils very limited, 0% somewhat limited and 0% not limited (3% 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.
Where Cotharin soil is found
Mapped acres
Cotharin is mapped in California.
| County | Acres | Share of county land |
|---|---|---|
| Ventura County, CA | 20,270 | 3.2% |
| Los Angeles County, CA | 15,729 | 0.5% |
Septic absorption fields
NRCS rating, share of Cotharin acres
Show as a table
| Category | Share of acres |
|---|---|
| Not limited | 0.0% |
| Somewhat limited | 0.0% |
| Very limited | 96.6% |
| Not rated | 3.4% |
Drainage, water table and flooding
Share of Cotharin 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 32–52% (median 52%).
- Topsoil organic matter
- Median 2.5%.
Drainage class
Show as a table
| Category | Share of acres |
|---|---|
| Excessively drained | 0.0% |
| Somewhat excessively drained | 0.4% |
| Well drained | 99.6% |
| 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 | 0.0% |
| C: slow infiltration | 0.0% |
| D: very slow infiltration (clayey, shallow or wet) | 96.6% |
| 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 | 3.4% |
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
- All map unit components named Cotharin (component kind "Series") in SSURGO: 35,999 acres.
- Method
- Shares are by mapped acres of Cotharin components. The profile comes from the single largest Cotharin component. Full methodology.