3.1.1 Description |
Bainbridge Island comprises 281,574 linear ft of shoreline (Table A-1). A total of 21 alongshore cells were used to define nine Management Areas (MAs), composed of 201 individual shoreline reaches around the Island (Figure 3). Shoreline reaches are distributed by geomorphic class as follows: spit/backshore (76), high bluff (54), low bank (33), marsh/lagoon (33), and rocky shore (5) (Figure 4). The smallest management area on Bainbridge Island is Manzanita Bay (MA-9; 10 reaches, 18,879 linear ft), and the longest is Point White – Battle Point (MA-8; 38 reaches, 51,650 ft). Sediment sources and wave exposure classes are shown in Figure B-1.
Overhanging riparian vegetation covers approximately 27% (76,399 linear ft) of the entire Bainbridge Island shoreline (Table A-1, Figure B-2). Within the Island’s 200-ft riparian zone (over 50 million ft2), naturally vegetated surfaces (coniferous and deciduous trees, shrubs, and wetlands) compose 54% of land cover, whereas impervious surfaces (e.g., roads, roofs) represent 23% of the riparian zone land cover (Table A-1, Figure B-3).
Overall, 82% of Bainbridge Island shorelines are currently in residential, recreational, commercial, or industrial use (Best 2003). The development pattern is dominated by single-family residences, although the Island’s shorelines host two state parks and many local parks, a fish-pen aquaculture operation, a ferry terminal, a ferry maintenance and repair facility, marinas, mixed-use development, and a Superfund site (a former creosote wood treatment plant and ship yard) (Best 2003). Related impacts are shown in Figure B-4.
Approximately 48% of Bainbridge Island’s shoreline is modified by armoring, with most of this represented by vertical rip rap or vertical concrete structures (Table A-1, Figure B-5). In total, 25% of the shoreline has armoring that encroaches into the intertidal zone. A total of 2,931 point modifications were recorded along Bainbridge Island shorelines (unpublished data, COBI 2002), at an average density of 10.4 structures per 1,000 ft (Table A-1, Figure B-6). The most common structures were stairs (526), followed by buoys (495), upland structures at the waterline (341), and docks (330).
The Island-wide distributions of subtidal/intertidal marine vegetation, forage-fish spawning areas, salmon-bearing streams, and geoduck and clam resources are shown in Figures B-7, B-8, and B-9.
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