Soil series profile

Toomes soil series

Toomes is a well drained soil with a very stony loam surface, mapped on 251,809 acres in 17 counties in CA. Hydrologic group D.

#1393 by mapped area loamy Lithic Ruptic-Xerorthentic Xerochrepts (Inceptisols)

Drainage class: Well drained
Hydrologic group: D
Typical topsoil pH: 6.1
Mapped area: 252k

Typical Toomes 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 Toomes horizons (representative values)
Depth	Texture	pH	Clay	Sand	Organic matter
0–12 in (H1)	Very stony loam	6.1	18%	43%	1.5%
12–16 in (H2)	Unweathered bedrock	Not reported	Not reported	Not reported	Not reported

Representative values from the most extensive Toomes map unit (Toomes very rocky loam, 10 to 30 percent slopes, survey area CA645). 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 Toomes soil means for gardens, lawns and septic systems

For gardens

Typical topsoil in Toomes soils is slightly acidic: pH 6.1, the range most vegetables, flowers and lawn grasses prefer.

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

>99% of mapped Toomes 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 Toomes 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 Toomes soil is found

Mapped acres

Toomes is mapped in California.

Counties with the most mapped Toomes soil
County	Acres	Share of county land
Tehama County, CA	184,692	9.8%
Shasta County, CA	42,421	2.4%
Sonoma County, CA	6,980	0.7%
Santa Barbara County, CA	5,237	0.5%
Kern County, CA	3,504	0.1%
Solano County, CA	3,426	0.6%
Calaveras County, CA	1,592	0.2%
Tuolumne County, CA	1,592	0.1%
Fresno County, CA	725	0.0%
Napa County, CA	504	0.1%
San Joaquin County, CA	362	0.0%
Stanislaus County, CA	340	0.0%
Glenn County, CA	166	0.0%
Amador County, CA	85	0.0%
Los Angeles County, CA	32	0.0%
Ventura County, CA	32	0.0%
Sacramento County, CA	7	0.0%

Septic absorption fields

NRCS rating, share of Toomes acres

Not limited 0%

Somewhat limited 0%

Very limited >99%

Not rated <1%

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

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Septic tank absorption field rating across mapped Toomes acres.
Category	Share of acres
Not limited	0.0%
Somewhat limited	0.0%
Very limited	99.8%
Not rated	0.2%

Drainage, water table and flooding

Share of Toomes 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 16–40% (median 26%).
Topsoil organic matter: Median 1.5%.

Drainage class

Excessively drained 0%

Somewhat excessively drained 7%

Well drained 93%

Moderately well drained 0%

Somewhat poorly drained 0%

Poorly drained 0%

Very poorly drained 0%

Not rated <1%

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

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Drainage class across mapped Toomes acres.
Category	Share of acres
Excessively drained	0.0%
Somewhat excessively drained	6.9%
Well drained	92.9%
Moderately well drained	0.0%
Somewhat poorly drained	0.0%
Poorly drained	0.0%
Very poorly drained	0.0%
Not rated	0.2%

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) >99%

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 <1%

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

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Hydrologic soil group across mapped Toomes 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)	99.8%
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	0.2%

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 Toomes (component kind "Series") in SSURGO: 251,809 acres.
Method: Shares are by mapped acres of Toomes components. The profile comes from the single largest Toomes component. Full methodology.

Independent reference site. No government affiliation or endorsement.

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