County soil summary
Soil types in Washington County, Minnesota
The most widespread soils are Antigo, Chetek and Santiago; the most common drainage class is well drained (44% of the land), and typical topsoil pH is 6.1.
- Well or moderately well drained
- 73% of land · state 41%
- Typical topsoil pH
- 6.1 slightly acidic · state 6.5
- Septic fields very limited
- 83% of land · state 91%
- Subject to flooding
- 1% of land, any frequency · state 4%
Most common soils in Washington County
Share of mapped land
A county is a patchwork of many soils. These 8 cover 41% of the mapped land; 71 named soil series are mapped here in all.
| Soil | Share of land | Drainage | Topsoil pH |
|---|---|---|---|
| Antigo | 10.3% | Well drained | 5.7 |
| Chetek | 6.2% | Somewhat excessively drained | 6.2 |
| Santiago | 5.6% | Well drained | 5.9 |
| Mahtomedi | 5.3% | Excessively drained | 5.8 |
| Kingsley | 4.8% | Well drained | 6.1 |
| Urban landLand type, not a soil series | 3.1% | — | — |
| OstranderGeneral soil group, not a named series | 2.9% | — | — |
| Waukegan | 2.8% | Well drained | 6.5 |
What this means
What the soils in Washington County mean for gardens, lawns and septic systems
For your garden
Typical topsoil in Washington County is slightly acidic: pH 6.1 (most land between 5.5 and 6.5), the range most vegetables, flowers and lawn grasses prefer.
Loamy topsoil (loam, silt loam and similar) covers 66% of the land: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is silt loam (40% of the land).
73% of the land is moderately well to excessively drained, which suits most garden plants.
For your lawn and yard
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 83% of the land in Washington County very limited, 6% somewhat limited and 0% not limited (11% not rated, such as urban land, pits or water).
Statewide, 91% of the land is very limited, so Washington County is less restrictive than typical.
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.
Drainage
How long the soil stays wet
The most common drainage class is well drained (44%). 73% of the land is moderately well drained or better, compared with 41% across Minnesota.
Show as a table
| Category | Washington County | Minnesota |
|---|---|---|
| Excessively drained | 11.5% | 3.1% |
| Somewhat excessively drained | 8.8% | 3.9% |
| Well drained | 44.1% | 20.3% |
| Moderately well drained | 8.1% | 13.7% |
| Somewhat poorly drained | 5.5% | 12.3% |
| Poorly drained | 4.1% | 20.7% |
| Very poorly drained | 7.0% | 22.1% |
| Not rated | 10.8% | 4.1% |
Septic absorption fields
NRCS rating for conventional drain fields
The rating looks at the soil from 24 to 60 inches deep: permeability, depth to a seasonal water table or bedrock, flooding and slope. “Very limited” means at least one feature is unfavorable enough that a conventional field is hard to make work.
Show as a table
| Category | Washington County | Minnesota |
|---|---|---|
| Not limited | 0.0% | 0.0% |
| Somewhat limited | 5.7% | 4.4% |
| Very limited | 83.2% | 91.3% |
| Not rated | 11.1% | 4.3% |
Rain, runoff and water table
Hydrologic soil group, flooding, seasonal water table
Hydrologic soil group
How fast rain soaks in when the soil is already wet. Group A soaks in fastest, D slowest.
Show as a table
| Category | Washington County | Minnesota |
|---|---|---|
| A: fast infiltration (mostly sandy or gravelly) | 23.7% | 9.5% |
| B: moderate infiltration | 27.0% | 12.3% |
| C: slow infiltration | 18.0% | 16.9% |
| D: very slow infiltration (clayey, shallow or wet) | 1.9% | 4.4% |
| A/D: D as is, A if drained | 5.4% | 13.9% |
| B/D: D as is, B if drained | 8.2% | 14.0% |
| C/D: D as is, C if drained | 4.5% | 24.7% |
| Not rated | 11.1% | 4.3% |
Flooding
Show as a table
| Category | Washington County | Minnesota |
|---|---|---|
| No flooding | 92.5% | 92.4% |
| Rare or very rare | 0.0% | 0.2% |
| Occasional | 0.5% | 1.3% |
| Frequent or very frequent | 0.7% | 2.4% |
| Not reported | 6.3% | 3.7% |
Seasonal high water table
Show as a table
| Category | Washington County | Minnesota |
|---|---|---|
| Within 18 inches at some time of year | 18.2% | 52.0% |
| 18 inches to 3.3 feet | 5.7% | 15.0% |
| Deeper than 3.3 feet or none reported | 69.8% | 29.6% |
| Not reported | 6.3% | 3.3% |
Topsoil pH and texture
First mineral layer of each soil
Typical topsoil pH is 6.1 (slightly acidic); 80% of rated land falls between 5.5 and 6.5. Median topsoil organic matter is 3%.
Show as a table
| Category | Washington County | Minnesota |
|---|---|---|
| Strongly acidic (below 5.5) | 7.3% | 7.0% |
| Moderately to slightly acidic (5.5–6.4) | 52.8% | 27.3% |
| Near neutral (6.5–7.3) | 23.4% | 32.0% |
| Alkaline (7.4 and up) | 0.5% | 15.2% |
| Not reported | 15.9% | 18.6% |
Texture
Show as a table
| Category | Washington County | Minnesota |
|---|---|---|
| Sandy | 18.5% | 11.2% |
| Loamy (loam, silt loam and similar) | 65.6% | 66.1% |
| Clayey (40%+ clay) | 0.0% | 2.2% |
| Organic (muck or peat) | 4.8% | 16.2% |
| Not reported (rock, urban land, etc.) | 11.1% | 4.3% |
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
- Washington County, Minnesota (FIPS 27163): 248,413 acres of mapped land, 22,087 acres of open water excluded. State comparisons pool all mapped land in Minnesota.
- Method
- Shares are by mapped land area: each map unit’s acres in the county times each soil component’s percentage. Open water is excluded. Topsoil values use the first mineral horizon of each component. Full methodology.