2320 106TH ST SW 2025-07-21 - Laserfiche WebLink

the areas mapped as wetland are saturated to the surface for more than 12.5 percent of the growing season, thereby fulfilling wetland hydrology criteria. Non -Wetland Adjacent to Wetland A Dominant vegetation within the non -wetland areas adjacent to the on -site wetland is characterized by the following species: red alder (Alnus rubra, Fac), salmonberry (Rubus spectabilis, Fac), Himalayan blackberry (Rubus armeniucus, Facq, English ivy (Hedera helix, FacU), and sword fern (Polystichum munitum, FacU). The upland areas also support sporadic Douglas fir (Pseudolsuga menziesii, Facq and western red cedar (Thuja plicala, Fac) trees. The underlying soils are typically very dark grayish brown (1 OYR 3/2) sandy loam in the upper five inches with brown (IOYR 4/3) gravelly sandy loam in the sub -layers. The soils were slightly moist at the time of the site investigation. Based on the lack of positive field indicators for hydrophytic vegetation, hydric soils, and saturation, the areas mapped as non -wetland are not saturated to the surface for more than 12.5 percent of the growing season, thereby not fulfilling wetland hydrology criteria. WETLAND FUNCTIONS AND VALUES ASSESSMENT Methodology The methodology for this functions and values assessment is based on professional opinion developed through past field analyses and interpretation. This assessment pertains specifically to the on -site wetland and stream system, but is typical for assessments of similar systems common to Western Washington. Functional Components Wetlands in Western Washington perform a variety of ecosystem functions. Included among the most important functions provided by wetlands are stormwater control, water quality improvement, fish and wildlife habitat, aesthetic value, recreational opportunities and education. The most commonly assessed functions and their descriptions are listed below. Assessments of these functions for the project site are provided in the "Analysis" section of this report. Hydrologic Functions Wetlands often function as natural water storage areas during periods of precipitation and flooding. By storing water that otherwise might be channeled into open flow systems, wetlands can attenuate or modify potentially damaging effects of storm events, reducing erosion and peak flows to downstream systems. Additionally, the soils underlying wetlands are often less permeable, providing long-term storage of stormwater or floodflow and controlling baseflows of downstream systems. Stormwater storage capacity and floodflow attenuation are generally a function of the size of the wetland and their topographic characteristics. Water Qualify Surface water quality improvement is another evaluated function. Surface runoff during periods of precipitation increases the potential for sediments and pollutants to enter surface Critical Area Study and Buffer Averaging Plan March 16, 2016 C & D Land Go. 10611i Street SW 5 4VRI #15111