State soils
California Soil Surveys
The short version
The most common soil here is Torriorthents, on about 3% of the land. Torripsamments and Lithic Torriorthents come next.
About 84% of the land drains well, and 5% stays wet for long stretches; groundwater comes within two feet of the surface under 4% of it.
USDA rates 89% of the land very limited for a standard septic drain field, and 73% very limited for homes with basements. That means extra cost or special design, not that it can't be done.
Worth knowing: 2% of the land floods occasionally or more, and bedrock lies within 40 inches under 50% of it.
Soils change over short distances, so look up an address below for the soil at that exact spot and the reasons behind each rating.
California has 122 USDA soil survey areas covering a wide range of landscapes and soil conditions. The most common soil order is Mollisols — grassland soils with a thick, dark, fertile topsoil rich in organic matter, making up roughly 26% of surveyed soils. Alfisols — moderately leached forest soils with a clay-enriched subsoil account for another 21%.
In terms of drainage, 58% of California soils are classified as well drained. Drainage class affects everything from septic system design to basement feasibility to garden planning. Use the survey area pages below to see drainage details for specific counties, or look up any address for an exact soil profile.
Soil Types
Mollisols
26% of surveyed soils
Fertile grassland soils with thick, dark topsoil. Among the best for agriculture, building, and gardening.
Alfisols
21% of surveyed soils
Moderately weathered forest soils with clay-enriched subsoil. Productive for agriculture, generally good for building and septic.
Entisols
19% of surveyed soils
Young soils with little development — found on floodplains, dunes, and steep slopes. Properties vary widely by setting.
Inceptisols
15% of surveyed soils
Young but developing soils found in mountains and river terraces. Variable properties — check drainage and bedrock depth.
Aridisols
6% of surveyed soils
Dry-climate soils with low organic matter. Often have caliche layers that make excavation difficult. Low shrink-swell is good for foundations.
Vertisols
4% of surveyed soils
High-clay soils that shrink and swell dramatically. Fertile but challenging for foundations and septic systems.
Ultisols
4% of surveyed soils
Strongly weathered clay soils of the Southeast. Acidic and naturally low in nutrients. Clay subsoil can slow drainage.
Andisols
1% of surveyed soils
Volcanic ash soils — light, porous, and fertile. Excellent drainage, but low density can complicate foundations.
Survey Areas
Alameda Area, CaliforniaAlameda County, California, Western PartAmador Area, CaliforniaAngeles National Forest Area, CaliforniaAntelope Valley Area, CaliforniaAnza-Borrego Area, California, Eastern PartAnza-Borrego Area, California, Western PartBenton-Owens Valley Area Parts of Inyo and Mono Counties, CaliforniaButte Area, California, Parts of Butte and Plumas CountiesButte Valley-Tule Lake Area, California, Parts of Siskiyou and Modoc CountiesCentral Sierra Foothills Area, California, Parts of Calaveras and Tuolumne CountiesChannel Islands Area, California, Parts of Santa Barbara and Los Angeles CountiesColeville-Bridgeport Area, Parts of Alpine and Mono Counties, CaliforniaColorado Desert Area, CaliforniaColusa County, CaliforniaContra Costa County, CaliforniaDeath Valley National Park Area, California and NevadaEastern Fresno Area, CaliforniaEastern Santa Clara Area, CaliforniaEastern Stanislaus Area, CaliforniaEdwards Air Force Base, California, Parts of Kern, Los Angeles, and San Bernardino CountiesEl Dorado Area, CaliforniaEldorado National Forest Area, California, Parts of Alpine, Amador, El Dorado, and Placer CountiesFish Lake and Deep Springs Valleys Area, CaliforniaFresno County, California, Western PartGlenn County, CaliforniaHigh Sierra Area, CaliforniaHumboldt County, Central Part, CaliforniaHumboldt County, South Part, CaliforniaHumboldt and Del Norte Area, CaliforniaImperial County, California, Imperial Valley AreaIntermountain Area, Parts of Lassen, Modoc, Shasta, and Siskiyou Counties, CaliforniaInyo County Area, CaliforniaInyo National Forest, Eastern Part, California and NevadaInyo National Forest, Western Part, CaliforniaJoshua Tree National Park, CaliforniaKern County, California, Northwestern PartKern County, California, Southeastern PartKern County, California, Southwest PartKern County, Northeastern Part, and Southeastern Part of Tulare County, CaliforniaKings County, CaliforniaKlamath National Forest Area, Parts of Siskiyou County, California, and Jackson County, OregonLake County, CaliforniaLassen National Forest, California, Parts of Lassen, Plumas, Butte, Shasta, and Siskiyou CountiesLassen Volcanic National Park, CaliforniaLos Angeles County, California, Southeastern PartLos Angeles County, California, West San Fernando Valley AreaLos Padres National Forest Area, CaliforniaMadera Area, CaliforniaMarin County, CaliforniaMarine Corps Air Ground Combat Center at Twentynine Palms, CaliforniaMariposa County Area, CaliforniaMendocino County, Eastern Part and Southwestern Part of Trinity County, CaliforniaMendocino County, Western Part, CaliforniaMendocino National Forest Area, CaliforniaMerced Area, CaliforniaMerced County, California, Western PartModoc County, California, Alturas AreaModoc National Forest Area, CaliforniaMojave Desert Area, CaliforniaMojave Desert Area, Northeast Part, CaliforniaMojave Desert Area, Northwest Part, CaliforniaMojave Desert Area, West Central Part, CaliforniaMojave National Preserve Area, CaliforniaMonterey County, CaliforniaNapa County, CaliforniaNational Training Center, Fort Irwin, CaliforniaNevada County Area, CaliforniaNorthern Santa Barbara Area, CaliforniaOrange County and Part of Riverside County, CaliforniaPalo Verde Area, CaliforniaPinnacles National Monument, CaliforniaPlacer County, California, Western PartPlumas National Forest Area, CaliforniaRedwood National and State Parks, CaliforniaRiverside County, Coachella Valley Area, CaliforniaRogue River National Forest Area, CaliforniaSacramento County, CaliforniaSalton Sea Area, CaliforniaSan Benito County, CaliforniaSan Bernardino County Southwestern Part, CaliforniaSan Bernardino County, California, Mojave River AreaSan Bernardino National Forest Area, CaliforniaSan Diego County Area, CaliforniaSan Joaquin County, CaliforniaSan Luis Obispo County, California, Carrizo Plain AreaSan Luis Obispo County, California, Coastal PartSan Luis Obispo County, California, Paso Robles AreaSan Mateo Area, CaliforniaSan Mateo County, Eastern Part, and San Francisco County, CaliforniaSanta Barbara County, California, South Coastal PartSanta Clara Area, California, Western PartSanta Cruz County, CaliforniaSanta Monica Mountains National Recreation AreaSequoia National Forest Parts of Fresno, Kern and Tulare Counties, CaliforniaSequoia and Kings Canyon National Parks, CaliforniaShasta County Area, CaliforniaShasta-Trinity National Forest Area, Parts of Humboldt, Siskiyou, Shasta, Tehama, and Trinity Counties, CaliforniaSierra National Forest Area Parts of Fresno, CaliforniaSierra Valley Area, California, Parts of Sierra, Plumas, and Lassen CountiesSiskiyou County, California, Central PartSix Rivers National Forest Area, CaliforniaSolano County, CaliforniaSonoma County, CaliforniaStanislaus County, California, Northern PartStanislaus County, California, Western PartStanislaus National Forest, California, PartsSurprise Valley-Home Camp Area, California and NevadaSusanville Area, Parts of Lassen and Plumas Counties, CaliforniaSutter County, CaliforniaTahoe Basin Area, California and NevadaTahoe National Forest Area, CaliforniaTehama County, CaliforniaToiyabe National Forest Area, CaliforniaTrinity County, California, Weaverville AreaTulare County, California, Central PartTulare County, Western Part, CaliforniaVentura Area, CaliforniaWestern Riverside Area, CaliforniaYolo County, CaliforniaYosemite National Park, CaliforniaYuba County, California