Crater Lake National Park, Oregon
The most common soil here is Castlecrest, on about 32% of the land: a paragravelly ashy loamy sand, gritty and loose. Llaorock and Umak come next.
About 89% of the land drains well; groundwater comes within two feet of the surface under 3% of it.
USDA rates 92% of the land very limited for a standard septic drain field, and 43% very limited for homes with basements. That means extra cost or special design, not that it can't be done.
Worth knowing: bedrock lies within 40 inches under 8% 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 Crater Lake National Park, Oregon, 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 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.
What This Means
Building & Foundations
About 43% of soils have significant building limitations, while the rest are generally suitable. Check specific sites carefully — conditions vary across the area.
Septic Systems
About 92% 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.