Volume 2: Draft Gorst Planned Action Environmental Impact Statement

GORST PLANNED ACTION EIS | AFFECTED ENVIRONMENT, SIGNIFICANT IMPACTS, AND MITIGATION MEASURESHydrology and Water QualityThe lower reach of Gorst Creek, Gorst tributary 1, and Gorst tributary 2, in the UGA is channelized with a riparianbuffer that is constrained by rural residences and commercial development along SR 3 and SR 16. Water quality inthe UGA is moderate with periods of elevated bacteria in Gorst Creek but is improving (City of Bremerton 2011).All waters in the Gorst UGA drain to Sinclair Inlet. Commercial development on the eastside of the highway is builtup to the edge of the wetland areas of Sinclair Inlet. Sinclair Inlet has a history of poor water quality withcommercial shellfish harvesting closed since the 1960s. Sinclair Inlet contains tidally influenced waters that mixslowly with the more open waters of Puget Sound. Because of its slow mixing rates, shallow depths and proximityto land use activities along the shoreline, Sinclair Inlet is extremely susceptible to pollution. Sinclair Inlet does notmeet the water quality standards for mercury and polychlorinated biphenyls (PCB) and is placed in Water QualityAssessment Category 5 and Ecology’s 303(d) List of Impaired Waters (Ecology 2012).Floodplains and ShorelineFloodplains are mapped based on FEMA information in the Gorst UGA along Gorst Creek, Gorst tributary 1, Gorsttributary 2, and in the waterfront along the shoreline of Sinclair Inlet (Figure 3.2-2 Gorst Creek Watershed:Floodplain and Shoreline). In the Gorst UGA, floodplain connectivity is fragmented by commercial developmentand SR 3. (FEMA floodplain mapping and its potential effect on development in the County including the Gorstvicinity is also being considered in a separate Kitsap County Alternatives Futures study undergoing review.)Gorst tributary 2 drains the north portion of the UGA near the mine site. This tributary in combination with hillsideseepage contributes to flood of residences and businesses including the Navy City Metals Recycling.Flooding problems and drainage infrastructure deficiencies are identified at 16 sites in and just outside of GorstUGA (Figure 3.2-3 Gorst Identified Infrastructure Existing Drainage Deficiencies). Sites included Elite Exterior andBetos Tires, development along W. Belfair Valley Road, and Peninsula Subaru. Elite Exterior has frequent floodingwhen high tides coincide with storm events. Businesses and residences along W. Belfair Valley Road haveexperienced increased flooding from high groundwater in combination with hill slope seepage and insufficientstormwater conveyance from degraded roadside ditches. Peninsula Subaru has drainage issues associated withundersized stormwater drain pipes and culverts with sink holes and slumps occurring on the property.Shorelines regulated under the Shoreline Management include Sinclair Inlet and Gorst Creek. The shorelinejurisdiction extends 200 feet landward of these waters which are mostly developed including riprap banks alongSinclair Inlet.Draft | June 2013 3-16