Humboldt County, Central Part, California
The most common soil here is Sproulish, on about 8% of the land: a gravelly silt loam, smooth, like flour. Canoecreek and Redwoodhouse come next.
About 81% of the land drains well, and 10% stays wet for long stretches; groundwater comes within two feet of the surface under 22% of it.
USDA rates 96% of the land very limited for a standard septic drain field, and 94% very limited for homes with basements. That means extra cost or special design, not that it can't be done.
Worth knowing: 5% of the land floods occasionally or more, and bedrock lies within 40 inches under 12% 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.
The soils you're most likely standing on
The biggest named soils in Humboldt County, Central Part, California, each drawn five feet deep from its official USDA description, in its recorded colors.
Dots mark gravel; white flecks mark lime. Shares are by acres across the survey area, and each mapped patch usually mixes several of these soils.
The biggest mapped areas
The dominant drainage class is Well drained and the dominant hydrologic group is C (slow infiltration, moderate runoff). The most common soil order is Alfisols — moderately leached forest soils with a clay-enriched subsoil. This report summarizes the major soil map units across the survey area to help you understand what to expect when buying, building, or gardening in Humboldt County, Central Part, California. Search your address to find the exact soil composition, drainage, and series details at your specific location.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Sproulish-Canoecreek-Redwohly complex, 30 to 50 percent slopes | 54K | Well drained | C | Very limited | Very limited |
| Canoecreek-Sproulish-Redwohly complex, 50 to 75 percent slopes | 50K | Well drained | B | Very limited | Very limited |
| Redwoodhouse-Yagercreek-Mailridge complex, 30 to 50 percent slopes | 32K | Well drained | C | Very limited | Very limited |
| Pasturerock-Coyoterock-Maneze complex, 15 to 50 percent slopes, dry | 28K | Well drained | C | Very limited | Very limited |
| Tannin-Burgsblock-Rockyglen complex, 30 to 50 percent slopes | 27K | Well drained | B | Very limited | Very limited |
| Scoutcamp-Rootcreek-Redcrest complex, 30 to 50 percent slopes | 25K | Well drained | C | Very limited | Very limited |
| Coppercreek-Slidecreek-Tectah complex, 30 to 50 percent slopes | 23K | Well drained | C | Very limited | Very limited |
| Tannin-Burgsblock-Rockyglen complex, 50 to 75 percent slopes | 19K | Well drained | B | Very limited | Very limited |
| Northbear-Caperidge-Taylorpeak complex, 30 to 50 percent slopes | 19K | Well drained | B | Very limited | Very limited |
| Sproulish, warm-Canoecreek-Redwohly, warm complex, 30 to 50 percent slopes | 18K | Well drained | C | Very limited | Very limited |
| Highyork-Elkcamp-Airstrip complex, 9 to 30 percent slopes | 17K | Somewhat poorly drained | C/D | Very limited | Very limited |
| Ferncat-Sleepyhollow-Oilcreek complex, 30 to 50 percent slopes | 14K | Well drained | C | Very limited | Very limited |
| Burgsblock-Coolyork-Tannin complex, 15 to 30 percent slopes | 14K | Well drained | B | Very limited | Very limited |
| Redwoodhouse-Yagercreek-Mailridge complex, 15 to 30 percent slopes | 13K | Well drained | C | Very limited | Very limited |
| Sproulish-Canoecreek-Redwohly complex, 15 to 30 percent slopes | 13K | Well drained | C | Very limited | Very limited |
| Slidecreek-Lackscreek-Coppercreek complex, 50 to 75 percent slopes | 13K | Well drained | C | Very limited | Very limited |
| Redwoodhouse-Yagercreek-Mailridge complex, 50 to 75 percent slopes | 13K | Well drained | B | Very limited | Very limited |
| Lepoil-Espa-Candymountain complex, 15 to 50 percent slopes | 12K | Well drained | B | Very limited | Very limited |
| Hydraquents-Wassents mucky silt loam, strongly saline, 0-3 percent slopes, very frequently flooded | 12K | Very poorly drained | D | Very limited | Very limited |
| Lepoil-Candymountain complex, 2 to 15 percent slopes | 11K | Well drained | B | Not limited | Very limited |
Soil Orders in This Area
The USDA classifies every soil into one of 12 soil orders. Here are the dominant orders found in this survey area.
What This Means
Building & Foundations
About 94% of soils are rated "very limited" for dwellings with basements. Specific challenges include steep slopes, poor drainage in some areas, flood-prone areas. A geotechnical assessment is recommended before building.
Septic Systems
About 96% of soils are rated "very limited" for septic absorption fields. Despite good drainage overall, limitations may stem from shallow bedrock, steep slopes, or seasonal conditions. Engineered or alternative systems are frequently required. Always get a professional perc test before purchasing land that needs septic.
Gardening & Agriculture
Well-drained soils on sloped terrain — good for most plants but watch for erosion. Terracing, contour planting, and mulching help retain moisture and topsoil. Drip irrigation is more effective than sprinklers on slopes.