County soil summary
Soil types in Waukesha County, Wisconsin
The most widespread soils are Fox, Casco and Ozaukee; the most common drainage class is well drained (45% of the land), and typical topsoil pH is 6.8.
- Well or moderately well drained
- 63% of land · state 65%
- Typical topsoil pH
- 6.8 neutral · state 5.9
- Septic fields very limited
- 90% of land · state 92%
- Subject to flooding
- 4% of land, any frequency · state 7%
Most common soils in Waukesha County
Share of mapped land
A county is a patchwork of many soils. These 8 cover 58% of the mapped land; 71 named soil series are mapped here in all.
| Soil | Share of land | Drainage | Topsoil pH |
|---|---|---|---|
| HochheimGeneral soil group, not a named series | 13.2% | — | — |
| Fox | 12.4% | Well drained | 6.2 |
| Casco | 8.1% | Somewhat excessively drained | 6.5 |
| Ozaukee | 6.9% | Moderately well drained | 6.6 |
| Houghton | 6.2% | Very poorly drained | Not reported |
| Theresa | 5.0% | Well drained | 7.0 |
| Pella | 2.9% | Poorly drained | 7.0 |
| Warsaw | 2.9% | Well drained | 6.5 |
What this means
What the soils in Waukesha County mean for gardens, lawns and septic systems
For your garden
Typical topsoil in Waukesha County is neutral: pH 6.8 (most land between 6.2 and 7.2), the range most vegetables, flowers and lawn grasses prefer.
Loamy topsoil (loam, silt loam and similar) covers 82% of the land: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is silt loam (42% of the land).
63% of the land is moderately well to excessively drained, which suits most garden plants.
For your lawn and yard
On 63% of the land, 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.
A seasonal high water table comes within 18 inches of the surface on 27% of the land, often in spring. Basements, sump pumps and lawns in low spots feel it first.
For a septic system
For conventional septic absorption fields, NRCS rates 90% of the land in Waukesha County very limited, 5% somewhat limited and 0% not limited (6% not rated, such as urban land, pits or water).
That is close to the state as a whole (92% very 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.
Drainage
How long the soil stays wet
The most common drainage class is well drained (45%). 63% of the land is moderately well drained or better, compared with 65% across Wisconsin.
Show as a table
| Category | Waukesha County | Wisconsin |
|---|---|---|
| Excessively drained | 2.2% | 8.5% |
| Somewhat excessively drained | 7.2% | 5.1% |
| Well drained | 45.2% | 36.1% |
| Moderately well drained | 7.8% | 15.1% |
| Somewhat poorly drained | 11.9% | 14.3% |
| Poorly drained | 10.4% | 7.4% |
| Very poorly drained | 12.4% | 11.3% |
| Not rated | 2.8% | 2.2% |
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 | Waukesha County | Wisconsin |
|---|---|---|
| Not limited | 0.0% | 0.0% |
| Somewhat limited | 4.8% | 4.9% |
| Very limited | 89.6% | 91.9% |
| Not rated | 5.6% | 3.2% |
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 | Waukesha County | Wisconsin |
|---|---|---|
| A: fast infiltration (mostly sandy or gravelly) | 3.2% | 19.7% |
| B: moderate infiltration | 25.6% | 19.8% |
| C: slow infiltration | 23.0% | 16.5% |
| D: very slow infiltration (clayey, shallow or wet) | 14.0% | 6.2% |
| A/D: D as is, A if drained | 6.4% | 10.7% |
| B/D: D as is, B if drained | 12.3% | 10.3% |
| C/D: D as is, C if drained | 7.5% | 13.3% |
| Not rated | 8.1% | 3.5% |
Flooding
Show as a table
| Category | Waukesha County | Wisconsin |
|---|---|---|
| No flooding | 93.9% | 91.3% |
| Rare or very rare | 0.0% | 0.4% |
| Occasional | 0.7% | 2.4% |
| Frequent or very frequent | 3.7% | 3.7% |
| Not reported | 1.7% | 2.2% |
Seasonal high water table
Show as a table
| Category | Waukesha County | Wisconsin |
|---|---|---|
| Within 18 inches at some time of year | 26.6% | 36.9% |
| 18 inches to 3.3 feet | 15.8% | 8.0% |
| Deeper than 3.3 feet or none reported | 55.9% | 53.1% |
| Not reported | 1.7% | 2.0% |
Topsoil pH and texture
First mineral layer of each soil
Typical topsoil pH is 6.8 (neutral); 80% of rated land falls between 6.2 and 7.2. Median topsoil organic matter is 3%.
Show as a table
| Category | Waukesha County | Wisconsin |
|---|---|---|
| Strongly acidic (below 5.5) | 0.0% | 18.5% |
| Moderately to slightly acidic (5.5–6.4) | 12.3% | 43.9% |
| Near neutral (6.5–7.3) | 70.7% | 26.0% |
| Alkaline (7.4 and up) | 0.6% | 0.5% |
| Not reported | 16.4% | 11.1% |
Texture
Show as a table
| Category | Waukesha County | Wisconsin |
|---|---|---|
| Sandy | 1.5% | 17.8% |
| Loamy (loam, silt loam and similar) | 82.0% | 66.3% |
| Clayey (40%+ clay) | 0.0% | 0.5% |
| Organic (muck or peat) | 10.9% | 12.1% |
| Not reported (rock, urban land, etc.) | 5.6% | 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
- Waukesha County, Wisconsin (FIPS 55133): 355,010 acres of mapped land, 16,520 acres of open water excluded. State comparisons pool all mapped land in Wisconsin.
- 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.