Soil series profile
Evanston soil series
Evanston is a well drained soil with a loam surface, mapped on 632,809 acres in 42 counties across 4 states. Hydrologic group B.
- Drainage class
- Well drained >99% of mapped acres
- Hydrologic group
- B 92% of mapped acres
- Typical topsoil pH
- 7.2 neutral · range 7.2–7.2
- Mapped area
- 633k acres in 42 counties, 4 states
Typical Evanston profile
Texture and pH by depth
Show as a table
| Depth | Texture | pH | Clay | Sand | Organic matter |
|---|---|---|---|---|---|
| 0–3 in (H1) | Loam | 7.2 | 21% | 42% | 3% |
| 3–15 in (H2) | Clay loam | 7.6 | 28% | 38% | 2% |
| 15–60 in (H3) | Sandy clay loam | 7.9 | 23% | 50% | 0.75% |
What this means
What Evanston soil means for gardens, lawns and septic systems
For gardens
Typical topsoil in Evanston soils is neutral: pH 7.2, the range most vegetables, flowers and lawn grasses prefer.
Loamy topsoil (loam, silt loam and similar) covers 99% of mapped Evanston acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is loam (84% of mapped Evanston acres).
>99% of mapped Evanston 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 8% of the acres in mapped Evanston soils very limited, 90% somewhat limited and <1% not limited (1% not rated, such as urban land, pits or water).
Only a licensed site evaluation or perc test at the actual lot decides whether a system is allowed and which design.
Where Evanston soil is found
Mapped acres
Evanston is mapped in Montana, Wyoming, Colorado and Utah.
| County | Acres | Share of county land |
|---|---|---|
| Laramie County, WY | 174,571 | 10.2% |
| Chouteau County, MT | 71,601 | 2.8% |
| Toole County, MT | 54,056 | 5.0% |
| Valley County, MT | 53,140 | 1.6% |
| Phillips County, MT | 40,599 | 1.1% |
| Petroleum County, MT | 27,606 | 2.6% |
| Liberty County, MT | 25,226 | 2.8% |
| Hill County, MT | 24,969 | 1.4% |
| Platte County, WY | 22,425 | 1.7% |
| Carbon County, WY | 16,159 | 0.4% |
| Pondera County, MT | 15,141 | 1.4% |
| Gunnison County, CO | 13,299 | 1.0% |
| Cascade County, MT | 11,096 | 0.7% |
| Sublette County, WY | 10,971 | 0.4% |
| Rosebud County, MT | 7,967 | 0.2% |
| Eagle County, CO | 7,924 | 1.6% |
| Park County, WY | 7,636 | 0.5% |
| Fergus County, MT | 7,316 | 0.3% |
| Teton County, MT | 4,832 | 0.4% |
| Sweet Grass County, MT | 4,723 | 0.4% |
| Albany County, WY | 3,966 | 0.2% |
| Saguache County, CO | 3,766 | 0.3% |
| Pitkin County, CO | 3,229 | 2.2% |
| Garfield County, CO | 2,971 | 0.2% |
| Roosevelt County, MT | 2,208 | 0.1% |
| Uinta County, WY | 1,927 | 0.1% |
| Summit County, UT | 1,425 | 0.2% |
| Wheatland County, MT | 1,094 | 0.1% |
| Daggett County, UT | 785 | 0.4% |
| Park County, MT | 733 | 0.0% |
| McCone County, MT | 597 | 0.0% |
| Broadwater County, MT | 550 | 0.1% |
| Larimer County, CO | 467 | 0.0% |
| Hinsdale County, CO | 439 | 0.1% |
| Glacier County, MT | 398 | 0.0% |
| Converse County, WY | 335 | 0.0% |
| Sweetwater County, WY | 139 | 0.0% |
| Lincoln County, WY | 74 | 0.0% |
| Blaine County, MT | 51 | 0.0% |
| Golden Valley County, MT | 42 | 0.0% |
| Garfield County, MT | 3 | 0.0% |
| Stillwater County, MT | 1 | 0.0% |
Septic absorption fields
NRCS rating, share of Evanston acres
Show as a table
| Category | Share of acres |
|---|---|
| Not limited | 0.2% |
| Somewhat limited | 90.4% |
| Very limited | 8.3% |
| Not rated | 1.1% |
Drainage, water table and flooding
Share of Evanston 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 2–11% (median 3%).
- 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 | 99.5% |
| Moderately well drained | 0.0% |
| Somewhat poorly drained | 0.0% |
| Poorly drained | 0.0% |
| Very poorly drained | 0.0% |
| Not rated | 0.5% |
Hydrologic soil group
Show as a table
| Category | Share of acres |
|---|---|
| A: fast infiltration (mostly sandy or gravelly) | 0.0% |
| B: moderate infiltration | 92.4% |
| C: slow infiltration | 6.9% |
| 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% |
| Not rated | 0.7% |
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 Evanston (component kind "Series") in SSURGO: 632,809 acres.
- Method
- Shares are by mapped acres of Evanston components. The profile comes from the single largest Evanston component. Full methodology.