Soil series profile

Highmore soil series

Highmore is a well drained soil with a silt loam surface, mapped on 776,556 acres in 15 counties in SD. Hydrologic group C.

#284 by mapped area fine-silty Typic Argiustolls (Mollisols)

Drainage class: Well drained
Hydrologic group: C
Typical topsoil pH: 6.4
Mapped area: 777k

Typical Highmore 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 Highmore horizons (representative values)
Depth	Texture	pH	Clay	Sand	Organic matter
0–6 in (H1)	Silt loam	6.7	23%	10%	3%
6–21 in (H2)	Silty clay loam	7.5	30%	7%	1.5%
21–60 in (H3)	Silt loam	7.9	26%	7%	0.5%

Representative values from the most extensive Highmore map unit (Highmore-Mobridge silt loams, 0 to 4 percent slopes, survey area SD603). 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 Highmore soil means for gardens, lawns and septic systems

For gardens

Typical topsoil in Highmore soils is slightly acidic: pH 6.4 (most land between 6.4 and 6.7), the range most vegetables, flowers and lawn grasses prefer.

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

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

For lawns and yards

On 86% 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 86% of the acres in mapped Highmore soils very limited, 14% 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 Highmore soil is found

Mapped acres

Highmore is mapped in South Dakota.

Counties with the most mapped Highmore soil
County	Acres	Share of county land
Charles Mix County, SD	133,107	19.2%
Hughes County, SD	122,368	26.1%
Brule County, SD	110,769	13.4%
Buffalo County, SD	110,769	13.4%
Potter County, SD	103,859	18.8%
Sully County, SD	97,980	15.3%
Douglas County, SD	35,487	12.8%
Hyde County, SD	31,519	5.7%
Walworth County, SD	20,007	4.5%
Aurora County, SD	6,254	1.4%
Jerauld County, SD	2,745	0.8%
Hand County, SD	1,631	0.2%
Beadle County, SD	26	0.0%
Hanson County, SD	17	0.0%
Hutchinson County, SD	17	0.0%

Septic absorption fields

NRCS rating, share of Highmore acres

Not limited 0%

Somewhat limited 14%

Very limited 86%

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

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Septic tank absorption field rating across mapped Highmore acres.
Category	Share of acres
Not limited	0.0%
Somewhat limited	14.1%
Very limited	85.9%

Drainage, water table and flooding

Share of Highmore 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 2%).
Topsoil organic matter: Median 3%.

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

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Drainage class across mapped Highmore 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 15%

C: slow infiltration 86%

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

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Hydrologic soil group across mapped Highmore acres.
Category	Share of acres
A: fast infiltration (mostly sandy or gravelly)	0.0%
B: moderate infiltration	14.5%
C: slow infiltration	85.5%
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 Highmore (component kind "Series") in SSURGO: 776,556 acres.
Method: Shares are by mapped acres of Highmore components. The profile comes from the single largest Highmore component. Full methodology.

Independent reference site. No government affiliation or endorsement.

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