Sammamish
silt loam

Mapping Symbol: Sh

The Sammamish series consists of somewhat poorly drained soils that formed in alluvium in the stream valleys at elevations from sea level to 50 feet. Slopes are 0 to 2%. The annual precipitation is 50 inches. The frost-free season is about 200 days.

Typical Profile:
Depth from Surface:
0 to 60 Inches: Very dark grayish brown, grayish brown, dark grayish brown, and olive gray stratified silt loam, loamy sand, and
fine sandy loam

Permeability: Moderate

Rooting Depth: 60 inches +

Depth to Seasonal High Water Table: 2 to 4 feet

Available Water Holding Capacity: High

Runoff Potential: Slow 

Erosion and Slippage Hazard: Slight

Flooding Potential: Moderate 

Use and Management: Primary uses of this soil are for row crops and pasture. Pasture forage yields are 2.0 tons/acre/year for undrained soils and 5.0 tons/acre/year for drained soils. Douglas-fir, Western Red Cedar, Western Hemlock, Red Alder, and Bigleaf Maple are important tree species. This soil has moderate equipment limitations because of its potential for wetness Windthrow hazard is considered moderate while competition from invasive plants is considered a severe limitation. The Sammamish soil has moderate to severe recreational and severe engineering limitations due to its flooding potential and poor drainage.

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