Soil series profile

Pewamo soil series

Pewamo is a very poorly drained soil with a silty clay loam surface, mapped on 1,795,144 acres in 92 counties across 4 states. Hydrologic group C/D.

#52 by mapped area fine Typic Argiaquolls (Mollisols)

Drainage class: Very poorly drained
Hydrologic group: C/D
Typical topsoil pH: 6.4
Mapped area: 1.8M

Typical Pewamo 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 Pewamo horizons (representative values)
Depth	Texture	pH	Clay	Sand	Organic matter
0–11 in (Ap)	Silty clay loam	6.4	30%	15%	4%
11–34 in (Btg1)	Silty clay	6.9	42%	16%	1.5%
34–47 in (Btg2)	Silty clay	7.2	42%	16%	1%
47–57 in (BCg)	Clay loam	7.4	35%	21%	0.75%
57–79 in (Cg)	Clay loam	7.8	33%	23%	0.5%

Representative values from the most extensive Pewamo map unit (Pewamo silty clay loam, 0 to 1 percent slopes, survey area IN053). 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 Pewamo soil means for gardens, lawns and septic systems

For gardens

Typical topsoil in Pewamo soils is slightly acidic: pH 6.4 (most land between 6.4 and 6.5), the range most vegetables, flowers and lawn grasses prefer.

Loamy topsoil (loam, silt loam and similar) covers >99% of mapped Pewamo acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is silty clay loam (90% of mapped Pewamo acres).

>99% of mapped Pewamo acres is somewhat poorly to very poorly drained, so soil stays soggy for long spells after rain and in wet seasons. Raised beds, plants that tolerate wet feet, and not working the soil while wet all help.

For lawns and yards

On >99% 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.

A seasonal high water table comes within 18 inches of the surface on >99% of mapped acres, 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 >99% of the acres in mapped Pewamo soils very limited, 0% somewhat limited and 0% not 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.

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

Where Pewamo soil is found

Mapped acres

Pewamo is mapped in Ohio, Indiana, Michigan and Wisconsin. The 60 counties with the most Pewamo acres:

Counties with the most mapped Pewamo soil
County	Acres	Share of county land
Grant County, IN	96,557	36.6%
Mercer County, OH	84,346	28.9%
Hancock County, OH	83,283	24.5%
Hardin County, OH	78,821	26.2%
Adams County, IN	72,761	33.6%
Allen County, IN	72,342	17.4%
Van Wert County, OH	71,419	27.3%
Huntington County, IN	68,628	28.1%
Wells County, IN	67,219	28.5%
Allen County, OH	65,984	25.6%
Delaware County, OH	63,197	22.3%
Auglaize County, OH	58,829	23.2%
Jay County, IN	52,440	21.4%
Marion County, OH	51,883	20.1%
Monroe County, MI	50,133	14.1%
Shelby County, OH	47,176	18.1%
Delaware County, IN	42,543	17.0%
Randolph County, IN	37,154	12.8%
Miami County, IN	34,546	14.4%
Wyandot County, OH	32,961	12.7%
Union County, OH	32,767	11.8%
Darke County, OH	32,370	8.5%
Lenawee County, MI	30,150	6.3%
Lake County, IN	29,800	9.4%
Licking County, OH	29,353	6.7%
Crawford County, OH	27,226	10.6%
Whitley County, IN	26,718	12.5%
Williams County, OH	24,250	9.0%
Blackford County, IN	23,546	22.3%
Morrow County, OH	22,782	8.8%
Wayne County, MI	21,794	5.6%
Howard County, IN	18,233	9.8%
Madison County, IN	16,445	5.7%
Wabash County, IN	16,010	6.1%
Washtenaw County, MI	15,867	3.5%
Richland County, OH	14,581	4.6%
Noble County, IN	14,287	5.5%
Logan County, OH	12,603	4.3%
Seneca County, OH	12,496	3.5%
Hillsdale County, MI	11,374	3.0%
Fairfield County, OH	11,021	3.4%
Porter County, IN	10,723	4.0%
Franklin County, OH	10,550	3.1%
Fulton County, OH	9,523	3.7%
Steuben County, IN	8,244	4.2%
Huron County, OH	7,459	2.4%
Lapeer County, MI	7,024	1.7%
Knox County, OH	6,745	2.0%
Allegan County, MI	5,873	1.1%
Defiance County, OH	4,756	1.8%
DeKalb County, IN	4,443	1.9%
Ionia County, MI	4,134	1.1%
Kent County, MI	4,083	0.7%
Putnam County, OH	4,036	1.3%
Calhoun County, MI	3,874	0.9%
St. Clair County, MI	3,424	0.7%
Van Buren County, MI	2,825	0.7%
Miami County, OH	1,947	0.7%
Ashland County, OH	1,850	0.7%
Kosciusko County, IN	1,799	0.5%

Septic absorption fields

NRCS rating, share of Pewamo acres

Not limited 0%

Somewhat limited 0%

Very limited >99%

Not rated <1%

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

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Septic tank absorption field rating across mapped Pewamo acres.
Category	Share of acres
Not limited	0.0%
Somewhat limited	0.0%
Very limited	99.4%
Not rated	0.6%

Drainage, water table and flooding

Share of Pewamo acres

Depth to seasonal high water table: About 6 inches (median where reported); within 18 inches on >99% of acres.
Flooding: Not mapped as flooding on most acres.
Slope: Typically 0–1% (median 0%).
Topsoil organic matter: Median 4%.

Drainage class

Excessively drained 0%

Somewhat excessively drained 0%

Well drained 0%

Moderately well drained 0%

Somewhat poorly drained 0%

Poorly drained 8%

Very poorly drained 91%

Not rated <1%

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

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Drainage class across mapped Pewamo acres.
Category	Share of acres
Excessively drained	0.0%
Somewhat excessively drained	0.0%
Well drained	0.0%
Moderately well drained	0.0%
Somewhat poorly drained	0.0%
Poorly drained	8.4%
Very poorly drained	91.0%
Not rated	0.6%

Hydrologic soil group

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

B: moderate infiltration 0%

C: slow infiltration 0%

D: very slow infiltration (clayey, shallow or wet) <1%

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 99%

Not rated <1%

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

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Hydrologic soil group across mapped Pewamo acres.
Category	Share of acres
A: fast infiltration (mostly sandy or gravelly)	0.0%
B: moderate infiltration	0.0%
C: slow infiltration	0.0%
D: very slow infiltration (clayey, shallow or wet)	0.4%
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	99.0%
Not rated	0.6%

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 Pewamo (component kind "Series") in SSURGO: 1,795,144 acres.
Method: Shares are by mapped acres of Pewamo components. The profile comes from the single largest Pewamo component. Full methodology.

Independent reference site. No government affiliation or endorsement.

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