Soil series profile

Bohannon soil series

Bohannon is a well drained soil with a gravelly loam surface, mapped on 503,574 acres in 10 counties in OR. Hydrologic group B.

#555 by mapped area fine-loamy Andic Haplumbrepts (Inceptisols)

Drainage class: Well drained
Hydrologic group: B
Typical topsoil pH: 5.3
Mapped area: 504k

Typical Bohannon 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 Bohannon horizons (representative values)
Depth	Texture	pH	Clay	Sand	Organic matter
0–1 in (Oi)	Slightly decomposed plant material	4.5	15%	35%	75%
1–12 in (H1)	Gravelly loam	5.3	20%	42%	5%
12–25 in (H2)	Cobbly loam	5.3	24%	39%	1.5%
25–35 in (H3)	Weathered bedrock	Not reported	Not reported	Not reported	Not reported

Representative values from the most extensive Bohannon map unit (Bohannon gravelly loam, 50 to 90 percent slopes, survey area OR637). 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 Bohannon soil means for gardens, lawns and septic systems

For gardens

Typical topsoil in Bohannon soils is strongly acidic: pH 5.3. Most vegetables and lawn grasses do best around 6.0 to 7.0, so lime is often needed; blueberries, azaleas and rhododendrons like it as it is.

Loamy topsoil (loam, silt loam and similar) covers 100% of mapped Bohannon acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is gravelly loam (95% of mapped Bohannon acres).

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

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 100% of the acres in mapped Bohannon 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 Bohannon soil is found

Mapped acres

Bohannon is mapped in Oregon.

Counties with the most mapped Bohannon soil
County	Acres	Share of county land
Lane County, OR	175,161	11.2%
Coos County, OR	105,752	12.8%
Lincoln County, OR	104,455	19.8%
Douglas County, OR	79,241	4.4%
Polk County, OR	18,570	4.5%
Benton County, OR	14,788	3.8%
Curry County, OR	4,195	0.4%
Tillamook County, OR	788	0.1%
Yamhill County, OR	437	0.1%
Linn County, OR	187	0.0%

Septic absorption fields

NRCS rating, share of Bohannon acres

Not limited 0%

Somewhat limited 0%

Very limited 100%

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

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Septic tank absorption field rating across mapped Bohannon acres.
Category	Share of acres
Not limited	0.0%
Somewhat limited	0.0%
Very limited	100.0%

Drainage, water table and flooding

Share of Bohannon 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 38–75% (median 65%).
Topsoil organic matter: Median 5%.

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

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Drainage class across mapped Bohannon 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 95%

C: slow infiltration 5%

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

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Hydrologic soil group across mapped Bohannon acres.
Category	Share of acres
A: fast infiltration (mostly sandy or gravelly)	0.0%
B: moderate infiltration	95.4%
C: slow infiltration	4.6%
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 Bohannon (component kind "Series") in SSURGO: 503,574 acres.
Method: Shares are by mapped acres of Bohannon components. The profile comes from the single largest Bohannon component. Full methodology.

Independent reference site. No government affiliation or endorsement.

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