Soil series profile

Henneke soil series

Henneke is a well drained soil with a gravelly loam surface, mapped on 195,587 acres in 23 counties in CA. Hydrologic group D.

#1864 by mapped area clayey-skeletal Lithic Argixerolls (Mollisols)

Drainage class
Well drained
51% of mapped acres
Hydrologic group
D
85% of mapped acres
Typical topsoil pH
6.9
neutral · range 6.7–7.3
Mapped area
196k
acres in 23 counties, 1 state

Typical Henneke profile

Texture and pH by depth

Typical Henneke soil profile by depth 0 in 10 in 20 in 0–7 in · H1 · pH 6.7 · 24% clay Gravelly loam 7–15 in · H2 · pH 7.5 · 39% clay Very gravelly clay loam 15–25 in · H3 Bedrock
Depth to scale. More strongly shaded layers hold more clay. Horizon names are the soil survey's (A = topsoil, B = subsoil, C = parent material).
Show as a table
Typical Henneke horizons (representative values)
Depth Texture pH Clay Sand Organic matter
0–7 in (H1) Gravelly loam 6.7 24% 39% 4.5%
7–15 in (H2) Very gravelly clay loam 7.5 39% 30% 1.25%
15–25 in (H3) Bedrock Not reported Not reported Not reported Not reported

Representative values from the most extensive Henneke map unit (Henneke gravelly loam, 30 to 75 percent slopes, survey area CA055). Other map units of this series vary within the series range.

Hands holding dark garden soil
Stock photo for illustration, not a sample of this soil series. Credit on the Sources & method page.

What this means

What Henneke soil means for gardens, lawns and septic systems

For gardens

Typical topsoil in Henneke soils is neutral: pH 6.9 (most land between 6.7 and 7.3), the range most vegetables, flowers and lawn grasses prefer.

Loamy topsoil (loam, silt loam and similar) covers 92% of mapped Henneke acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is gravelly loam (53% of mapped Henneke acres).

42% of mapped Henneke acres is excessively or somewhat excessively drained: water moves through fast, so gardens need more frequent watering in dry spells.

For lawns and yards

On 92% 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 92% of the acres in mapped Henneke soils very limited, 0% somewhat limited and 0% not limited (8% not rated, such as urban land, pits or water).

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 Henneke soil is found

Mapped acres

Henneke is mapped in California.

Counties with the most mapped Henneke soil
County Acres Share of county land
Napa County, CA 49,390 11.2%
Lake County, CA 26,404 3.0%
Tehama County, CA 21,006 1.1%
Colusa County, CA 19,531 2.6%
Sonoma County, CA 12,061 1.2%
Alameda County, CA 10,494 2.2%
Glenn County, CA 10,223 1.2%
San Luis Obispo County, CA 10,149 0.6%
Mendocino County, CA 8,509 0.4%
Monterey County, CA 6,754 0.3%
San Benito County, CA 4,461 0.5%
Santa Clara County, CA 3,811 0.5%
Stanislaus County, CA 3,761 0.4%
Marin County, CA 3,631 1.1%
Mariposa County, CA 2,471 0.3%
Shasta County, CA 861 0.0%
Amador County, CA 540 0.1%
Placer County, CA 462 0.1%
Yolo County, CA 407 0.1%
Trinity County, CA 198 0.1%
Kings County, CA 183 0.0%
Fresno County, CA 176 0.0%
Kern County, CA 10 0.0%

Septic absorption fields

NRCS rating, share of Henneke acres

Not limited 0%
Somewhat limited 0%
Very limited 92%
Not rated 8%
Septic tank absorption field rating across mapped Henneke acres. Scale 0 to 100% of mapped land.
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Septic tank absorption field rating across mapped Henneke acres.
CategoryShare of acres
Not limited0.0%
Somewhat limited0.0%
Very limited92.3%
Not rated7.7%

Drainage, water table and flooding

Share of Henneke 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 27–53% (median 48%).
Topsoil organic matter
Median 4.5%.

Drainage class

Excessively drained 27%
Somewhat excessively drained 15%
Well drained 51%
Moderately well drained 0%
Somewhat poorly drained 0%
Poorly drained 0%
Very poorly drained 0%
Not rated 7%
Drainage class across mapped Henneke acres. Scale 0 to 100% of mapped land.
Show as a table
Drainage class across mapped Henneke acres.
CategoryShare of acres
Excessively drained26.7%
Somewhat excessively drained15.3%
Well drained51.3%
Moderately well drained0.0%
Somewhat poorly drained0.0%
Poorly drained0.0%
Very poorly drained0.0%
Not rated6.6%

Hydrologic soil group

A: fast infiltration (mostly sandy or gravelly) 0%
B: moderate infiltration 0%
C: slow infiltration 8%
D: very slow infiltration (clayey, shallow or wet) 85%
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 8%
Hydrologic soil group across mapped Henneke acres. Scale 0 to 100% of mapped land.
Show as a table
Hydrologic soil group across mapped Henneke acres.
CategoryShare of acres
A: fast infiltration (mostly sandy or gravelly)0.0%
B: moderate infiltration0.0%
C: slow infiltration7.5%
D: very slow infiltration (clayey, shallow or wet)84.9%
A/D: D as is, A if drained0.0%
B/D: D as is, B if drained0.0%
C/D: D as is, C if drained0.0%
Not rated7.7%

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 Henneke (component kind "Series") in SSURGO: 195,587 acres.
Method
Shares are by mapped acres of Henneke components. The profile comes from the single largest Henneke component. Full methodology.

Independent reference site. No government affiliation or endorsement.

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