San Juan County, Washington
The dominant drainage class is Well drained and the dominant hydrologic group is C/D (varies with drainage). 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 San Juan County, Washington.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Cady-Rock Outcrop complex, 5 to 30 percent slopes | 11K | Well drained | D | Very limited | Very limited |
| Doebay-Cady-Rock Outcrop complex, 10 to 30 percent slopes | 11K | Well drained | C | Very limited | Very limited |
| Cady-Doebay-Rock Outcrop complex, 25 to 75 percent slopes | 7K | Well drained | D | Very limited | Very limited |
| Coveland loam, 0 to 5 percent slopes | 6K | Somewhat poorly drained | C/D | Very limited | Very limited |
| Roche-Killebrew-Rock Outcrop complex, 5 to 35 percent slopes | 5K | Moderately well drained | C/D | Very limited | Very limited |
| Roche-Killebrew complex, 2 to 10 percent slopes | 4K | Moderately well drained | C/D | Very limited | Very limited |
| Doebay, moist-Cady-Rock Outcrop complex, 10 to 30 percent slopes | 4K | Well drained | C | Very limited | Very limited |
| Mitchellbay gravelly sandy loam, 5 to 15 percent slopes | 4K | Somewhat poorly drained | C/D | Very limited | Very limited |
| Mitchellbay gravelly sandy loam, 0 to 5 percent slopes | 4K | Somewhat poorly drained | C/D | Very limited | Very limited |
| Pickett-Kahboo-Rock Outcrop complex, 25 to 75 percent slopes | 4K | Well drained | B | Very limited | Very limited |
| Haro-Hiddenridge-Rock Outcrop complex, 5 to 30 percent slopes | 3K | Well drained | D | Very limited | Very limited |
| Doebay-Morancreek complex, 5 to 25 percent slopes | 3K | Well drained | C | Very limited | Very limited |
| Mitchellbay-Sholander-Bazal complex, 0 to 8 percent slopes | 3K | Somewhat poorly drained | C/D | Very limited | Very limited |
| Coveland-Mitchellbay complex, 2 to 15 percent slopes | 3K | Somewhat poorly drained | C/D | Very limited | Very limited |
| Turtleback-Cady-Rock Outcrop complex, 25 to 75 percent slopes | 2K | Well drained | A | Very limited | Very limited |
| Everett sandy loam, warm, 3 to 20 percent slopes | 2K | Somewhat excessively drained | A | Somewhat limited | Very limited |
| Whidbey-Hoypus complex, 2 to 15 percent slopes | 2K | Moderately well drained | B/D | Very limited | Very limited |
| Beaches-Endoaquents, tidal-Xerorthents association, 0 to 5 percent slopes | 2K | Very limited | Very limited | ||
| Mitchellbay-Rock Outcrop-Killebrew complex, 3 to 15 percent slopes | 2K | Somewhat poorly drained | C/D | Very limited | Very limited |
| Deadmanbay-Morancreek complex, 2 to 15 percent slopes | 2K | Somewhat poorly drained | C/D | Very limited | Very limited |
What This Means
Building & Foundations
About 97% of soils are rated "very limited" for dwellings with basements. Specific challenges include steep slopes, poor drainage in some areas, flood-prone areas. A geotechnical assessment is recommended before building.
Septic Systems
About 100% of soils are rated "very limited" for septic absorption fields. Despite good drainage overall, limitations may stem from shallow bedrock, steep slopes, or seasonal conditions. Engineered or alternative systems are frequently required. Always get a professional perc test before purchasing land that needs septic.
Gardening & Agriculture
Well-drained soils on sloped terrain — good for most plants but watch for erosion. Terracing, contour planting, and mulching help retain moisture and topsoil. Drip irrigation is more effective than sprinklers on slopes.