Colorado River Indian Reservation, Parts of La Paz County, Arizona, and Riverside and San Bernardino Counties, California
The most common soil here is Superstition, on about 10% of the land: a sand, loose sand that holds almost no water. Glenbar and Gilman come next.
About 89% of the land drains well.
USDA rates 78% of the land very limited for a standard septic drain field, and 79% very limited for homes with basements. That means extra cost or special design, not that it can't be done.
Worth knowing: 4% of the land floods occasionally or more, and bedrock lies within 40 inches under 7% 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 Colorado River Indian Reservation, Parts of La Paz County, Arizona, and Riverside and San Bernardino Counties, 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 A (high infiltration, low runoff). The most common soil order is Entisols — young soils with little profile development, often on floodplains or steep slopes. 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 Colorado River Indian Reservation, Parts of La Paz County, Arizona, and Riverside and San Bernardino Counties, 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 |
|---|---|---|---|---|---|
| Superstition-Rositas association, 0 to 15 percent slopes | 37K | Somewhat excessively drained | A | Not limited | Very limited |
| Badland-Torriorthents-Torripsamments complex, 10 to 60 percent slopes | 24K | A | Very limited | Very limited | |
| Gunsight very gravelly sandy loam, 15 to 60 percent slopes | 18K | Somewhat excessively drained | B | Very limited | Very limited |
| Glenbar silt loam | 16K | Well drained | C | Very limited | Very limited |
| Laposa-Rock outcrop complex, 15 to 75 percent slopes | 15K | Well drained | B | Very limited | Very limited |
| Gilman fine sandy loam | 12K | Well drained | B | Very limited | Somewhat limited |
| Carrizo extremely gravelly coarse sand, 0 to 3 percent slopes | 12K | Excessively drained | A | Very limited | Very limited |
| Lagunita loamy sand, strongly saline, 0 to 5 percent slopes | 11K | Somewhat excessively drained | A | Very limited | Very limited |
| Superstition gravelly loamy fine sand, 0 to 3 percent slopes | 9K | Somewhat excessively drained | A | Not limited | Very limited |
| Gilman fine sandy loam, strongly saline, 0 to 3 percent slopes | 8K | Well drained | B | Very limited | Somewhat limited |
| Glenbar silt loam, strongly saline, 0 to 3 percent slopes | 8K | Well drained | B | Very limited | Somewhat limited |
| Chuckawalla-Gunsight association, 1 to 45 percent slopes | 7K | Well drained | B | Not limited | Very limited |
| Agualt sandy loam | 6K | Well drained | B | Very limited | Very limited |
| Vint sandy loam | 6K | Well drained | A | Very limited | Somewhat limited |
| Holtville silty clay loam | 5K | Well drained | C | Very limited | Very limited |
| Cherioni-Rock outcrop complex, 25 to 70 percent slopes | 5K | Well drained | D | Very limited | Very limited |
| Glenbar silty clay loam | 4K | Well drained | C | Very limited | Very limited |
| Holtville silty clay loam, strongly saline, 0 to 3 percent slopes | 4K | Well drained | C | Very limited | Very limited |
| Cibola sandy loam | 4K | Well drained | C | Very limited | Very limited |
| Gadsden clay, strongly saline | 4K | Well drained | C | Very 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 79% of soils are rated "very limited" for dwellings with basements. Specific challenges include shallow bedrock, steep slopes, flood-prone areas. A geotechnical assessment is recommended before building.
Septic Systems
About 78% 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.