Soil series profile
Scism soil series
Scism is a well drained soil with a silt loam surface, mapped on 97,819 acres in 4 counties in ID. Hydrologic group C.
- Drainage class
- Well drained 100% of mapped acres
- Hydrologic group
- C 100% of mapped acres
- Typical topsoil pH
- 7.9 moderately alkaline · range 7.9–7.9
- Mapped area
- 98k acres in 4 counties, 1 state
Typical Scism profile
Texture and pH by depth
Show as a table
| Depth | Texture | pH | Clay | Sand | Organic matter |
|---|---|---|---|---|---|
| 0–3 in (A) | Silt loam | 7.9 | 15% | 14% | 1.5% |
| 3–25 in (Bk) | Silt loam | 8.4 | 15% | 14% | 0.75% |
| 25–29 in (Bkqm) | Cemented sandy loam | 8.4 | 19% | 62% | 0.25% |
| 29–60 in (C) | Loam | 8.4 | 15% | 44% | 0.25% |
What this means
What Scism soil means for gardens, lawns and septic systems
For gardens
Typical topsoil in Scism soils is moderately alkaline: pH 7.9. Acid-loving plants such as blueberries and azaleas struggle without amended beds, and some trees and shrubs show iron chlorosis (yellow leaves with green veins).
Loamy topsoil (loam, silt loam and similar) covers 100% of mapped Scism acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is silt loam (81% of mapped Scism acres).
100% of mapped Scism acres is moderately well to excessively drained, which suits most garden plants.
For lawns and yards
On 100% 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 100% of the acres in mapped Scism 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 Scism soil is found
Mapped acres
Scism is mapped in Idaho.
| County | Acres | Share of county land |
|---|---|---|
| Owyhee County, ID | 36,277 | 0.9% |
| Canyon County, ID | 28,658 | 8.9% |
| Ada County, ID | 24,702 | 4.3% |
| Elmore County, ID | 8,182 | 0.7% |
Septic absorption fields
NRCS rating, share of Scism acres
Show as a table
| Category | Share of acres |
|---|---|
| Not limited | 0.0% |
| Somewhat limited | 0.0% |
| Very limited | 100.0% |
Drainage, water table and flooding
Share of Scism 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 1–10% (median 3%).
- 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 | 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 | 0.0% |
| C: slow infiltration | 100.0% |
| 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 Scism (component kind "Series") in SSURGO: 97,819 acres.
- Method
- Shares are by mapped acres of Scism components. The profile comes from the single largest Scism component. Full methodology.