Crater Lake National Park, Oregon
The dominant drainage class is Somewhat excessively drained and the dominant hydrologic group is A (high infiltration, low 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 Crater Lake National Park, Oregon.
| 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 |
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.