1701 121ST ST SE 2025-02-03 - Laserfiche WebLink

Buffer Enhancement Pla! Plan 1,128 Square Feet Common Name Scientific Name Size Spacing uLT Western red cedar Thuja plicata 1 gallon 10' 7 Douglas-fir Pseudotsuga menziesii 1 gallon 10' 6 Salmonberry Rubus spectabilis 1 gallon 5' 10 Baldhip rose Rosa gymnocarpa 1 gallon 5' 10 Osoberry Oemleria cerasiformis 1 gallon 5' 10 Swordfern Pol stichum munitum 1 gallon 5' 10 6.2 FLTNc nONS AND VALUES ASSESSMENT Pursuant to requirements set forth in EMC 19.37.073,critical areas studies shall assess the impacts of any alteration proposed for a critical area or buffer. The following assessment is intended to compare the current and post-development functions and values. 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 buffer of the on-site wetland but is characteristic of similar systems found throughout western Washington. 6.2.1 Existing Buffer Conditions The buffer enhancement area is currently forested with a native canopy and an understory dominated by invasive English holly, English ivy, and Himalayan blackberry. Small areas of native salmonberry and osoberry are present in the buffer but are being outcompeted by invasive species. In general, the invasive species in buffer areas limit the functions and values performed by the buffer. English ivy restricts the growth of woody species where it is dominant and thus the density of plants within the buffer. Dense woody vegetation adjacent to wetlands and streams help to reduce hydrologic flow rates as water moves through the system.When water slows,pollutants may fall out of suspension or be filtered from the water column by the dense plants. In areas where hydrologic flows are unimpeded, water enters the system more rapidly and with a higher concentration of pollutants. By reducing the presence of dense woody species in the buffer, the dominance of English ivy reduces the water quality and hydrologic functions provided to Wetland A, Silver Lake Creek, and Silver Lake. Both Himalayan blackberry and English ivy are reducing the structural diversity and species richness within buffer areas. Areas with lesser species richness afford fewer opportunities to wildlife. A diverse and native forest is most suitable to wildlife endemic to the ecoregion. Restricting the growth of new plants also limits structural diversity. In a healthy native forest, as new trees and shrubs grow large woody debris can accumulate, snags can form, and other opportunities for species with unique life histories can be prevented. By restricting the growth of native species on site, the dominance of invasive species also reduces the wildlife and habitat functions performed by the buffer. Charter Club Apartments 15 WRI#23061 V Critical Area Report&Mitigation Plan November 6, 2023