Mason County, Washington
The dominant drainage class is Moderately well 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 Mason County, Washington.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Alderwood gravelly sandy loam, 8 to 15 percent slopes | 85K | Moderately well drained | B | Very limited | Very limited |
| Rough mountainous land, Tebo soil material | 46K | Excessively drained | Very limited | Very limited | |
| Grove gravelly sandy loam, 0 to 5 percent slopes | 44K | Somewhat excessively drained | A | Not limited | Very limited |
| Shelton gravelly sandy loam, 5 to 15 percent slopes | 41K | Moderately well drained | A | Very limited | Very limited |
| Hoodsport gravelly sandy loam, 5 to 15 percent slopes | 14K | Moderately well drained | B/D | Very limited | Very limited |
| Grove gravelly sandy loam, 5 to 15 percent slopes | 10K | Somewhat excessively drained | A | Somewhat limited | Very limited |
| Astoria silt loam, 15 to 30 percent slopes | 9K | Well drained | B | Very limited | Very limited |
| Cloquallum silt loam, 5 to 15 percent slopes | 9K | Moderately well drained | C | Very limited | Very limited |
| Hoodsport gravelly sandy loam, 30 to 45 percent slopes | 9K | Moderately well drained | B/D | Very limited | Very limited |
| Alderwood gravelly sandy loam, 15 to 30 percent slopes | 9K | Moderately well drained | B | Very limited | Very limited |
| Everett very gravelly sandy loam, 8 to 15 percent slopes | 8K | Somewhat excessively drained | A | Somewhat limited | Very limited |
| Rough mountainous land, Hoodsport soil material | 8K | Excessively drained | A | Very limited | Very limited |
| Water | 7K | Not rated | Not rated | ||
| Shelton gravelly sandy loam, 15 to 30 percent slopes | 7K | Moderately well drained | A | Very limited | Very limited |
| Everett very gravelly sandy loam, 15 to 30 percent slopes | 7K | Somewhat excessively drained | A | Very limited | Very limited |
| Harstine gravelly ashy sandy loam, 6 to 15 percent slopes | 6K | Moderately well drained | C | Very limited | Very limited |
| Rough broken land | 6K | Well drained | B | Very limited | Very limited |
| Hoodsport stony sandy loam, 5 to 15 percent slopes | 6K | Moderately well drained | B/D | Very limited | Very limited |
| Carstairs gravelly loam, 0 to 5 percent slopes | 6K | Excessively drained | A | Not limited | Very limited |
| Hoquiam silt loam, 5 to 15 percent slopes | 5K | Well drained | B | Somewhat limited | Somewhat limited |
What This Means
Building & Foundations
About 76% of soils are rated "very limited" for dwellings with basements. Specific challenges include steep slopes. A geotechnical assessment is recommended before building.
Septic Systems
About 96% 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.