Soil series profile

Theresa soil series

Theresa is a well drained soil with a silt loam surface, mapped on 151,409 acres in 14 counties in WI. Hydrologic group C.

#2438 by mapped area fine-loamy Typic Hapludalfs (Alfisols)

Drainage class: Well drained
Hydrologic group: C
Typical topsoil pH: 7.0
Mapped area: 151k

Typical Theresa profile

Texture and pH by depth

Depth to scale. More strongly shaded layers hold more clay. Horizon names are the soil survey's (A = topsoil, B = subsoil, C = parent material).

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Typical Theresa horizons (representative values)
Depth	Texture	pH	Clay	Sand	Organic matter
0–8 in (Ap)	Silt loam	7.0	15%	30%	2%
8–11 in (BE)	Silt loam	7.0	12%	30%	1%
11–16 in (Bt1)	Silty clay loam	6.5	30%	18%	0.75%
16–35 in (2Bt2)	Gravelly clay loam	7.5	27%	35%	0.25%
35–79 in (2Cd)	Gravelly sandy loam	8.2	5%	50%	0.25%

Representative values from the most extensive Theresa map unit (Theresa silt loam, 2 to 6 percent slopes, eroded, survey area WI039). Other map units of this series vary within the series range.

Stock photo for illustration, not a sample of this soil series. Credit on the Sources & method page.

What this means

What Theresa soil means for gardens, lawns and septic systems

For gardens

Typical topsoil in Theresa soils is neutral: pH 7.0, the range most vegetables, flowers and lawn grasses prefer.

Loamy topsoil (loam, silt loam and similar) covers 98% of mapped Theresa acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is silt loam (97% of mapped Theresa acres).

100% of mapped Theresa acres is moderately well to excessively drained, which suits most garden plants.

For lawns and yards

On 98% 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 7% of the acres in mapped Theresa soils very limited, 91% somewhat limited and 0% not limited (2% 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.

Generated from the mapped numbers above using fixed rules, not a site visit. See how these notes are written.

Where Theresa soil is found

Mapped acres

Theresa is mapped in Wisconsin.

Counties with the most mapped Theresa soil
County	Acres	Share of county land
Fond du Lac County, WI	39,236	8.5%
Washington County, WI	32,568	11.9%
Dodge County, WI	23,767	4.3%
Waukesha County, WI	17,821	5.0%
Sheboygan County, WI	17,162	5.2%
Jefferson County, WI	10,470	2.9%
Calumet County, WI	6,247	3.1%
Ozaukee County, WI	1,834	1.2%
Manitowoc County, WI	1,648	0.4%
Racine County, WI	296	0.1%
Brown County, WI	197	0.1%
Winnebago County, WI	143	0.1%
Milwaukee County, WI	18	0.0%
Kenosha County, WI	2	0.0%

Septic absorption fields

NRCS rating, share of Theresa acres

Not limited 0%

Somewhat limited 91%

Very limited 7%

Not rated 2%

Septic tank absorption field rating across mapped Theresa acres. Scale 0 to 100% of mapped land.

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Septic tank absorption field rating across mapped Theresa acres.
Category	Share of acres
Not limited	0.0%
Somewhat limited	90.9%
Very limited	7.1%
Not rated	1.9%

Drainage, water table and flooding

Share of Theresa 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 4–9% (median 4%).
Topsoil organic matter: Median 2%.

Drainage class

Excessively drained 0%

Somewhat excessively drained 0%

Well drained 100%

Moderately well drained 0%

Somewhat poorly drained 0%

Poorly drained 0%

Very poorly drained 0%

Drainage class across mapped Theresa acres. Scale 0 to 100% of mapped land.

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Drainage class across mapped Theresa acres.
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

A: fast infiltration (mostly sandy or gravelly) 0%

B: moderate infiltration 0%

C: slow infiltration 98%

D: very slow infiltration (clayey, shallow or wet) 0%

A/D: D as is, A if drained 0%

B/D: D as is, B if drained 0%

C/D: D as is, C if drained 0%

Not rated 2%

Hydrologic soil group across mapped Theresa acres. Scale 0 to 100% of mapped land.

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Hydrologic soil group across mapped Theresa acres.
Category	Share of acres
A: fast infiltration (mostly sandy or gravelly)	0.0%
B: moderate infiltration	0.0%
C: slow infiltration	98.1%
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	1.9%

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 Theresa (component kind "Series") in SSURGO: 151,409 acres.
Method: Shares are by mapped acres of Theresa components. The profile comes from the single largest Theresa component. Full methodology.

Independent reference site. No government affiliation or endorsement.

Full narrative description: USDA Official Soil Series Description for Theresa.