Soil series profile
Casco soil series
Casco is a somewhat excessively drained soil with a loam surface, mapped on 225,176 acres in 71 counties across 4 states. Hydrologic group B.
- Drainage class
- Somewhat excessively drained 82% of mapped acres
- Hydrologic group
- B 97% of mapped acres
- Typical topsoil pH
- 6.5 slightly acidic · range 6.5–6.5
- Mapped area
- 225k acres in 71 counties, 4 states
Typical Casco profile
Texture and pH by depth
Show as a table
| Depth | Texture | pH | Clay | Sand | Organic matter |
|---|---|---|---|---|---|
| 0–5 in (Ap) | Loam | 6.5 | 15% | 44% | 2% |
| 5–17 in (Bt) | Clay loam | 7.5 | 27% | 35% | 0.25% |
| 17–79 in (2C) | Stratified sand to gravel | 7.9 | 3% | 93% | 0.25% |
What this means
What Casco soil means for gardens, lawns and septic systems
For gardens
Typical topsoil in Casco soils is slightly acidic: pH 6.5, the range most vegetables, flowers and lawn grasses prefer.
Loamy topsoil (loam, silt loam and similar) covers 98% of mapped Casco acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is loam (78% of mapped Casco acres).
82% of mapped Casco acres is excessively or somewhat excessively drained: water moves through fast, so gardens need more frequent watering in dry spells.
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 98% of the acres in mapped Casco soils very limited, 0% somewhat limited and 0% not limited (2% 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 Casco soil is found
Mapped acres
Casco is mapped in Wisconsin, Illinois, Ohio and Indiana. The 60 counties with the most Casco acres:
| County | Acres | Share of county land |
|---|---|---|
| Waukesha County, WI | 28,914 | 8.1% |
| Sheboygan County, WI | 24,503 | 7.5% |
| Washington County, WI | 22,570 | 8.2% |
| Walworth County, WI | 21,735 | 6.1% |
| Fond du Lac County, WI | 14,142 | 3.1% |
| McHenry County, IL | 14,005 | 3.8% |
| Kewaunee County, WI | 10,018 | 4.6% |
| Jefferson County, WI | 9,458 | 2.7% |
| Racine County, WI | 8,154 | 3.8% |
| Ozaukee County, WI | 7,786 | 5.2% |
| Kenosha County, WI | 5,582 | 3.2% |
| Rock County, WI | 4,888 | 1.1% |
| Dodge County, WI | 4,859 | 0.9% |
| Kane County, IL | 4,373 | 1.3% |
| LaSalle County, IL | 3,054 | 0.4% |
| Outagamie County, WI | 2,940 | 0.7% |
| Pickaway County, OH | 2,837 | 0.9% |
| Champaign County, OH | 2,636 | 1.0% |
| Logan County, OH | 2,440 | 0.8% |
| Marquette County, WI | 2,134 | 0.7% |
| Brown County, WI | 2,020 | 0.7% |
| Noble County, IN | 1,982 | 0.8% |
| Bureau County, IL | 1,928 | 0.4% |
| Dane County, WI | 1,821 | 0.2% |
| Winnebago County, WI | 1,648 | 0.6% |
| Clark County, OH | 1,636 | 0.6% |
| Warren County, OH | 1,591 | 0.6% |
| Hamilton County, OH | 1,371 | 0.5% |
| Montgomery County, IN | 1,251 | 0.4% |
| Lake County, IL | 1,234 | 0.4% |
| Carroll County, IN | 1,206 | 0.5% |
| Kendall County, IL | 967 | 0.5% |
| Door County, WI | 941 | 0.3% |
| Milwaukee County, WI | 770 | 0.5% |
| Miami County, OH | 761 | 0.3% |
| Ross County, OH | 599 | 0.1% |
| Tazewell County, IL | 540 | 0.1% |
| Highland County, OH | 496 | 0.1% |
| Butler County, OH | 489 | 0.2% |
| Cook County, IL | 461 | 0.1% |
| Greene County, OH | 451 | 0.2% |
| Manitowoc County, WI | 412 | 0.1% |
| Stephenson County, IL | 394 | 0.1% |
| Scioto County, OH | 321 | 0.1% |
| Bartholomew County, IN | 280 | 0.1% |
| Will County, IL | 262 | 0.0% |
| DuPage County, IL | 251 | 0.1% |
| Clinton County, OH | 250 | 0.1% |
| Shelby County, OH | 201 | 0.1% |
| Stark County, IL | 199 | 0.1% |
| Waushara County, WI | 186 | 0.0% |
| Fayette County, OH | 172 | 0.1% |
| Parke County, IN | 162 | 0.1% |
| Columbia County, WI | 137 | 0.0% |
| Randolph County, IN | 112 | 0.0% |
| Boone County, IL | 111 | 0.1% |
| Green County, WI | 105 | 0.0% |
| Clermont County, OH | 86 | 0.0% |
| Carroll County, IL | 60 | 0.0% |
| Sauk County, WI | 56 | 0.0% |
Septic absorption fields
NRCS rating, share of Casco acres
Show as a table
| Category | Share of acres |
|---|---|
| Not limited | 0.0% |
| Somewhat limited | 0.0% |
| Very limited | 97.9% |
| Not rated | 2.1% |
Drainage, water table and flooding
Share of Casco acres
- Depth to seasonal high water table
- About 5.8 feet (69 in) (median where reported).
- Flooding
- Not mapped as flooding on most acres.
- Slope
- Typically 4–25% (median 9%).
- Topsoil organic matter
- Median 2%.
Drainage class
Show as a table
| Category | Share of acres |
|---|---|
| Excessively drained | 0.0% |
| Somewhat excessively drained | 82.2% |
| Well drained | 17.0% |
| Moderately well drained | 0.0% |
| Somewhat poorly drained | 0.0% |
| Poorly drained | 0.0% |
| Very poorly drained | 0.0% |
| Not rated | 0.9% |
Hydrologic soil group
Show as a table
| Category | Share of acres |
|---|---|
| A: fast infiltration (mostly sandy or gravelly) | 1.3% |
| B: moderate infiltration | 96.6% |
| C: slow infiltration | 0.0% |
| 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% |
| Not rated | 2.1% |
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 Casco (component kind "Series") in SSURGO: 225,176 acres.
- Method
- Shares are by mapped acres of Casco components. The profile comes from the single largest Casco component. Full methodology.