Ordinance 2213-97 - Laserfiche WebLink

13. Fences shall not be permitted where they would restrict wildlife movement through environmentally sensitive areas/wildlife corridors. (SEPA Plant and Animal and Land and Shoreline Use Policies) 4.3.3 Mitigating Impacts on Streams, Fish, and Fish Habitat 1. Areas with soils suitable for large scale infiltration should be protected. Due to the construction of new impervious surfaces, stormwater volumes will increase significantly. Base flow reductions can only be mitigated by the use of infiltration systems for collected stormwater. Infiltration systems will be required whenever feasible, as determined by the Public Works Department, particularly for rooftop runoff. This study area, however, has few areas of soils suitable for large scale infiltration. The Associated Sand and Gravel property located south of Sievers-Duecy Blvd. is one area where stormwater is currently being infiltrated. Infiltration must continue to occur on that site. (SEPA Water, Plant and Animal, and Land and Shoreline Use Policies) 2. Assisting the conversion of riparian zones from deciduous to coniferous or mixed forest will improve the long-term fish and terrestrial habitat of these streams. While riparian corridors are currently providing needed ecological functions, most of these stands are dominated by red alder. Red alder is a relatively short-lived species, and alder snags and logs decay relatively rapidly. A forest stand including conifers would have a longer lived canopy and would provide longer-lasting woody debris to the channels. Natural regeneration of conifers within the riparian corridors is slow, and silvicultural treatments designed to encourage forest succession to conifers would eventually enhance wildlife habitat and stream conditions. Additional coniferous tree plantings shall be required in riparian corridors in conjunction with issuance of permits for development on sites containing these corridors when the Planning Director determines that the corridor can be enhanced, particularly on sites with solid stands of alder without any conifer seedlings. An enhancement plan must be reviewed and approved by the Planning Department prior to the issuance of any permits. The City encourages the voluntary enhancement of all sites. (SEPA Water, Plant and Animal, and Land and Shoreline Use Policies) 3. Where mitigation for impacts to streams is required, the applicant shall consider the following potential mitigation measures: • Evaluate fish access to the Puget Sound streams bearing or potentially bearing anadromous fish, including Japanese Gulch, Merrill and Ring Creek, Glenwood Creek, Powder Mill Gulch, and Pigeon Creek#2, and improve where appropriate. (SEPA Water, Plant and Animal, and Land and Shoreline Use Policies) • Restore the riparian vegetation immediately adjacent to Japanese Gulch stream north of Mukilteo Blvd. • Peak flow rates from the Boeing complex are partly mitigated by a series of detention ponds and biofiltration systems above Seaway Boulevard. Nevertheless, high flow rates have accelerated channel and bank erosion in Powder Mill Gulch stream. In the event that Boeing requests a permit for additional impervious surface, the City may require better regulation of outflow from the Boeing detention facility to reduce channel erosion rates in Powder Mill Gulch. 23