Rio Grande NF Area, Colorado, West Part, Parts of Archuleta, Conejos, Hinsdale, Mineral, Rio Grande, Saguache, and San Juan Counties
The most common soil here is Seitz, on about 11% of the land. Frisco and Leighcan come next.
About 88% of the land drains well, and 5% stays wet for long stretches; groundwater comes within two feet of the surface under 2% of it.
USDA rates 98% of the land very limited for a standard septic drain field, and 97% 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 61% 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 Rio Grande NF Area, Colorado, West Part, Parts of Archuleta, Conejos, Hinsdale, Mineral, Rio Grande, Saguache, and San Juan Counties, 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 Mollisols — grassland soils with a thick, dark, fertile topsoil rich in organic matter. 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 Rio Grande NF Area, Colorado, West Part, Parts of Archuleta, Conejos, Hinsdale, Mineral, Rio Grande, Saguache, and San Juan Counties. 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 |
|---|---|---|---|---|---|
| Frisco-Agneston association, 5 to 50 percent slopes | 141K | Well drained | A | Very limited | Very limited |
| Seitz cobbly loam, 15 to 60 percent slopes | 111K | Well drained | C | Very limited | Very limited |
| Cryoboralfs-Rock outcrop complex, 35 to 75 percent slopes | 106K | Well drained | C | Very limited | Very limited |
| Leighcan-Frisco association, 5 to 60 percent slopes | 72K | Well drained | A | Very limited | Very limited |
| Cryumbrepts-Rock outcrop-Rubble land complex, 20 to 80 percent slopes | 69K | Well drained | D | Very limited | Very limited |
| Mirror-Teewinot association, 8 to 45 percent slopes | 64K | Well drained | B | Very limited | Very limited |
| Rock outcrop and Rubble land | 64K | D | Very limited | Very limited | |
| Frisco-Scout association, 15 to 60 percent slopes | 64K | Well drained | A | Very limited | Very limited |
| Leighcan-Endlich association, 2 to 50 percent slopes | 59K | Well drained | A | Very limited | Very limited |
| Endlich-Hechtman association, 5 to 60 percent slopes | 58K | Well drained | B | Very limited | Very limited |
| Tellura, moist-Seitz association, 15 to 60 percent slopes | 56K | Well drained | C | Very limited | Very limited |
| Pergrin-Agneston-Hechtman association, 15 to 60 percent slopes | 53K | Well drained | B | Very limited | Very limited |
| Cryaquolls-Cryoborolls association, 0 to 20 percent slopes | 52K | Poorly drained | C | Very limited | Very limited |
| Seitz-Winz association, 8 to 60 percent slopes | 48K | Well drained | C | Very limited | Very limited |
| Seitz cobbly loam, dry, 15 to 60 percent slopes | 45K | Well drained | C | Very limited | Very limited |
| Cryoborolls-Cryochrepts-Rock outcrop complex, 15 to 80 percent slopes | 37K | Well drained | C | Very limited | Very limited |
| Cryochrepts-Rock outcrop association, 5 to 70 percent slopes | 36K | Well drained | C | Very limited | Very limited |
| Tellura-Gothic association, 2 to 45 percent slopes | 34K | Well drained | C | Very limited | Very limited |
| Bowen, cool-Agneston association, 15 to 50 percent slopes | 33K | Well drained | C | Very limited | Very limited |
| Embargo-Tellura association, 12 to 50 percent slopes | 32K | Well drained | D | 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 97% of soils are rated "very limited" for dwellings with basements. Specific challenges include shallow bedrock, steep slopes, poor drainage in some areas, flood-prone areas. A geotechnical assessment is recommended before building.
Septic Systems
About 98% 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.