Rocky Mountain National Park, Colorado, Parts of Boulder, Grand, and Larimer Counties

Survey Area CO651• Colorado

The dominant drainage class is Somewhat excessively drained and the dominant hydrologic group is D (very slow infiltration, high runoff). The most common soil order is Inceptisols — young soils with minimal horizon development but more than Entisols. 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. 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
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

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.

Inceptisols

Young but developing soils found in mountains and river terraces. Variable properties — check drainage and bedrock depth.

Mollisols

Fertile grassland soils with thick, dark topsoil. Among the best for agriculture, building, and gardening.

Entisols

Young soils with little development — found on floodplains, dunes, and steep slopes. Properties vary widely by setting.

Alfisols

Moderately weathered forest soils with clay-enriched subsoil. Productive for agriculture, generally good for building and septic.

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.