Soil series profile

Galva soil series

Galva is a well drained soil with a silty clay loam surface, mapped on 709,537 acres in 15 counties across 2 states. Hydrologic group C.

#328 by mapped area fine-silty Typic Hapludolls (Mollisols)

Drainage class: Well drained
Hydrologic group: C
Typical topsoil pH: 5.7
Mapped area: 710k

Typical Galva 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 Galva horizons (representative values)
Depth	Texture	pH	Clay	Sand	Organic matter
0–6 in (Ap)	Silty clay loam	5.7	32%	4%	4%
6–17 in (A)	Silty clay loam	6.5	33%	3%	3.5%
17–31 in (Bw)	Silty clay loam	7.0	29%	5%	1.5%
31–45 in (BC)	Silt loam	7.8	22%	11%	0.25%
45–79 in (C)	Silt loam	8.0	24%	8%	0.25%

Representative values from the most extensive Galva map unit (Galva silty clay loam, 2 to 5 percent slopes, survey area IA149). 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 Galva soil means for gardens, lawns and septic systems

For gardens

Typical topsoil in Galva soils is moderately acidic: pH 5.7. Many vegetables grow well here, and some gardens benefit from a little lime. Test before adding any.

Loamy topsoil (loam, silt loam and similar) covers 100% of mapped Galva acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is silty clay loam (100% of mapped Galva acres).

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

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.

For a septic system

For conventional septic absorption fields, NRCS rates 99% of the acres in mapped Galva soils very limited, 1% 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 Galva soil is found

Mapped acres

Galva is mapped in Iowa and Minnesota.

Counties with the most mapped Galva soil
County	Acres	Share of county land
Cherokee County, IA	137,917	37.5%
Plymouth County, IA	136,292	24.7%
O'Brien County, IA	117,631	32.1%
Sioux County, IA	105,362	21.5%
Sac County, IA	55,139	15.0%
Lyon County, IA	52,767	14.1%
Ida County, IA	50,110	18.2%
Buena Vista County, IA	22,634	6.2%
Osceola County, IA	12,009	4.7%
Woodbury County, IA	10,518	1.9%
Rock County, MN	8,072	2.6%
Clay County, IA	770	0.2%
Nobles County, MN	299	0.1%
Murray County, MN	16	0.0%
Pipestone County, MN	2	0.0%

Septic absorption fields

NRCS rating, share of Galva acres

Not limited 0%

Somewhat limited 1%

Very limited 99%

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

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Septic tank absorption field rating across mapped Galva acres.
Category	Share of acres
Not limited	0.0%
Somewhat limited	1.2%
Very limited	98.8%

Drainage, water table and flooding

Share of Galva acres

Depth to seasonal high water table: None reported within about 6.5 feet (median where reported).
Flooding: Not mapped as flooding on most acres.
Slope: Typically 1–4% (median 4%).
Topsoil organic matter: Median 4%.

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 Galva acres. Scale 0 to 100% of mapped land.

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Drainage class across mapped Galva 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 1%

C: slow infiltration 99%

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%

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

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Hydrologic soil group across mapped Galva acres.
Category	Share of acres
A: fast infiltration (mostly sandy or gravelly)	0.0%
B: moderate infiltration	1.2%
C: slow infiltration	98.8%
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%

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 Galva (component kind "Series") in SSURGO: 709,537 acres.
Method: Shares are by mapped acres of Galva components. The profile comes from the single largest Galva component. Full methodology.

Independent reference site. No government affiliation or endorsement.

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