Crater Lake National Park, Oregon

Survey Area OR682• Oregon

The dominant drainage class is Somewhat excessively drained and the dominant hydrologic group is A (high infiltration, low runoff). The most common soil order is Andisols — soils formed in volcanic ash, very light and porous. 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 Crater Lake National Park, Oregon. 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
Castlecrest gravelly ashy sandy loam, 2 to 10 percent slopes	23K	Somewhat excessively drained	A	Not limited	Very limited
Llaorock-Castlecrest complex, 15 to 30 percent slopes	17K	Somewhat excessively drained	A	Very limited	Very limited
Water	13K			Not rated	Not rated
Castlecrest-Llaorock complex, 2 to 25 percent slopes	12K	Somewhat excessively drained	A	Very limited	Very limited
Umak paragravelly ashy fine sandy loam, 0 to 7 percent slopes	10K	Excessively drained	A	Not limited	Very limited
Unionpeak-Castlecrest-Sunnotch complex, 0 to 15 percent slopes	9K	Somewhat excessively drained	A	Not limited	Very limited
Llaorock-Castlecrest complex, 0 to 15 percent slopes	6K	Somewhat excessively drained	A	Somewhat limited	Very limited
Castlecrest ashy loamy sand, dry, 0 to 15 percent slopes	6K	Somewhat excessively drained	A	Not limited	Very limited
Llaorock-Castlecrest-Rock outcrop complex, 30 to 60 percent south slopes	6K	Somewhat excessively drained	A	Very limited	Very limited
Castlecrest ashy loamy sand, low, 0 to 7 percent slopes	6K	Somewhat excessively drained	A	Not limited	Very limited
Timbercrater-Llaorock-Castlecrest complex, 30 to 60 percent slopes	5K	Excessively drained	A	Very limited	Very limited
Llaorock-Castlecrest-Rock outcrop complex, 30 to 60 percent north slopes	5K	Somewhat excessively drained	A	Very limited	Very limited
Timbercrater-Castlecrest-Unionpeak complex, dry, 15 to 30 percent slopes	3K	Somewhat excessively drained	A	Very limited	Very limited
Castlecrest-Badland complex, 60 to 100 percent slopes	3K	Somewhat excessively drained	A	Very limited	Very limited
Cleetwood, thin surface-Cleetwood-Dyarock complex, 2 to 20 percent slopes	3K	Excessively drained	A	Not limited	Very limited
Collier ashy loamy sand, dry, 0 to 10 percent slopes	3K	Somewhat excessively drained	A	Not limited	Very limited
Unionpeak-Castlecrest-Llaorock complex, 15 to 30 percent slopes	3K	Somewhat excessively drained	A	Very limited	Very limited
Timbercrater-Sunnotch-Castlecrest complex, 0 to 10 percent slopes	3K	Somewhat excessively drained	A	Not limited	Very limited
Grousehill-Llaorock complex, 5 to 35 percent slopes	3K	Moderately well drained	C/D	Very limited	Very limited
Umak paragravelly ashy fine sandy loam, dry, 0 to 10 percent slopes	3K	Excessively drained	A	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.

Andisols

Volcanic ash soils — light, porous, and fertile. Excellent drainage, but low density can complicate foundations.

Entisols

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

Histosols

Organic peat and muck soils formed in wetlands. Very poor for building (compressible) and septic. Often in regulated wetlands.

What This Means

Building & Foundations

About 40% of soils have significant building limitations, while the rest are generally suitable. Check specific sites carefully — conditions vary across the area.

Septic Systems

About 90% 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.