Rocky Mountain National Park, Colorado, Parts of Boulder, Grand, and Larimer Counties
The dominant drainage class is Somewhat excessively drained and the dominant hydrologic group is D (very slow infiltration, high runoff). 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 Rocky Mountain National Park, Colorado, Parts of Boulder, Grand, and Larimer Counties.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Rock outcrop-Rubble land complex, 30 to 200 percent slopes | 47K | D | Very limited | Very limited | |
| Trailridge-Mummy complex, 20 to 60 percent slopes | 23K | Somewhat excessively drained | D | Very limited | Very limited |
| Fallriver-Hiamovi complex, 10 to 55 percent slopes | 21K | Somewhat excessively drained | A | Very limited | Very limited |
| Fallriver gravelly sandy loam, 10 to 45 percent slopes | 21K | Somewhat excessively drained | A | Very limited | Very limited |
| Fallriver-Rock outcrop complex, 30 to 70 percent slopes | 15K | Somewhat excessively drained | A | Very limited | Very limited |
| Hiamovi-Rock outcrop complex, 15 to 80 percent slopes | 13K | Somewhat excessively drained | D | Very limited | Very limited |
| Trailridge-Archrock complex, 10 to 40 percent slopes | 13K | Somewhat excessively drained | D | Very limited | Very limited |
| Ypsilon gravelly coarse sandy loam, 20 to 50 percent slopes | 9K | Somewhat excessively drained | A | Very limited | Very limited |
| Tonahutu very gravelly sandy loam, 15 to 30 percent slopes | 7K | Well drained | B | Very limited | Very limited |
| Catamount-Bullwark-Rock outcrop complex, 10 to 40 percent slopes | 7K | Somewhat excessively drained | D | Very limited | Very limited |
| Tileston very cobbly sandy loam, 10 to 40 percent slopes | 7K | Well drained | B | Very limited | Very limited |
| Onahu-Terric Cryofibrists-Trailridge complex, 2 to 35 percent slopes | 6K | Poorly drained | B/D | Very limited | Very limited |
| Enentah very stony loam, 10 to 40 percent slopes | 6K | Somewhat excessively drained | A | Very limited | Very limited |
| Galuche-Rock outcrop complex, 20 to 90 percent slopes | 5K | Somewhat excessively drained | D | Very limited | Very limited |
| Mummy gravelly sandy loam, 10 to 35 percent slopes | 4K | Somewhat excessively drained | A | Very limited | Very limited |
| Nanita extremely gravelly loamy coarse sand, 30 to 60 percent slopes | 4K | Somewhat excessively drained | A | Very limited | Very limited |
| Hiamovi-Rock outcrop complex, 5 to 40 percent slopes | 4K | Somewhat excessively drained | D | Very limited | Very limited |
| Archrock-Fallriver association, 15 to 50 percent slopes | 4K | Somewhat excessively drained | B | Very limited | Very limited |
| Nanita very gravelly sandy loam, 10 to 60 percent slopes | 4K | Somewhat excessively drained | A | Very limited | Very limited |
| Archrock-Onahu-Rock outcrop complex, 10 to 75 percent slopes | 4K | Somewhat excessively drained | B | Very limited | Very limited |
What This Means
Building & Foundations
About 100% of soils are rated "very limited" for dwellings with basements. Specific challenges include shallow bedrock, steep slopes, poor drainage in some areas, sandy or gravelly soils with low bearing capacity. A geotechnical assessment is recommended before building.
Septic Systems
About 100% of soils are rated "very limited" for septic absorption fields. The well-drained soils may actually drain too fast for standard leach fields, allowing effluent to reach groundwater. Engineered or alternative systems are frequently required. Always get a professional perc test before purchasing land that needs septic.
Gardening & Agriculture
Soils tend to drain very quickly, meaning nutrients and water don't stick around long. Raised beds with amended soil, drip irrigation, and heavy mulching will give the best results. Compost is your best friend here — it improves water retention dramatically.