3.2.7 Rich Passage Management Area (MA7)
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Qualitative Rating = Low/Moderate Impact
Mean CF Score (Normalized) = -0.30 (Range: -0.68 to 0.00)
Median CF Score (Normalized) = -0.33
Number of Reaches = 16
Mean EF Score = 17.6 (Range: 10 to 27)
Median EF Score = 17
Description
MA-6 comprises 20,345 ft of shoreline that encompasses all of Blakely Harbor, including part of Restoration Point (Table A-1, Figure 2). Blakely Harbor is an embayment comprising 16 reaches broken into the following categories: spit/backshore (7), low bank (6), rocky shore (2), and marsh/lagoon (1) (Figure B‑50). MA-6 is defined by two drift cells with westerly alongshore drift that terminate at the head of Blakely Harbor, with the log pond area lacking appreciable alongshore drift (Figure 3). The first drift cell begins at a divergence zone located at a point on the northern margin of Blakely Harbor and moves west into the harbor; this short stretch of shoreline has scarce sediment abundance and encompasses a small reach with rocky shore (Figure B-51). The second drift cell begins at Restoration Point, a rocky headland with scarce sediment abundance and no appreciable alongshore drift, and moves northwest into Blakely Harbor. Relative to wave exposure, shorelines along the southern stretch of MA-6 are considered “semi-protected,” whereas the interior of Blakely Harbor is considered “protected” to “very protected” (Figure B-51). Blakely Harbor receives upland flows from five watersheds with low levels of land use and high forest cover: WRIA unnumbered 56 (TIA 1%), WRIA unnumbered 77 (TIA 2%), WRIA 15.0332 (TIA <1%), Macs Dam Creek (WRIA 15.0331; TIA <1%), and unnumbered 65 (TIA <1%).
Overhanging riparian vegetation covers approximately 29% of the MA-6 shoreline (Table A-1, Figure B-56). Within the 200-ft riparian zone, naturally vegetated surfaces (coniferous and deciduous trees, shrubs, and wetlands) compose 59% of land cover, whereas impervious surfaces (e.g., roads, roofs) represent 19% of land cover (Figure B-55).
Historically, Blakely Harbor was the home of a large commercial sawmill, which included a log rafting pond in the upper reaches of the bay that was constructed with a large stone jetty that constricted tidal flows (Figure B-54). This area is now parkland with public shoreline access, recreational trails, and plans for an interpretive center. The remainder of MA-6 shoreline has single-family residential development. Only 22% of the shoreline is modified by armoring and 17% of the shoreline has armoring that encroaches into the intertidal zone, the lowest values for any MA on Bainbridge Island (Table A-1, Figure B-52).
A total of 132 point modifications were recorded along MA-6 shorelines (unpublished data, COBI 2002), at an average of 6.5 modifications per 1000 ft, among the lowest on Bainbridge Island (Table A-1, Figure B-53). Most of these modifications were composed of mooring buoys (32), pilings (19), stairs (15), groins (14), and docks (14). The rock jetty built in the upper bay to create the historic log pond represents an unnatural tidal constriction in upper Blakely Harbor (Figure B-54). As well, a total of 8 outfalls were recorded along MA-6 shorelines.
Limiting Factors
The average normalized CF score within MA-6 was -0.33, the highest (best) MA score on Bainbridge Island (Table A-2, Figure B-10, Figure B-13). MA-6 had no particularly low (poor) scores relative to other MAs, but rather, had among the best scores in seven of the nine metric categories: wave energy, natural shade, sediment supply, substrate type, depth/slope, pollution, and hydrology (Table A-3, Figure B-16). High (good) wave-energy scores were influenced primarily by the relatively low rate of shoreline armoring (22%) and low rate of armor encroachment (17%) into the intertidal zone. Natural shade scores were low (poor) despite a fairly average total percentage (29%) of total shoreline with overhanging riparian vegetation. Much of this can be attributed to the prevalence of spit/backshore geomorphic class reaches (7 of 16 reaches), where natural shade is not considered an issue because these habitats often are exposed, lack overhanging riparian vegetation, or are composed of low dune vegetation. As well, a number of other reaches in the Blakely Harbor MA also had riparian cover exceeding 90%.
Sediment supply scores were high (good) primarily because of the combination of low shoreline armoring rates combined with the lack of feeder bluffs and backshore sediment sources. However, groins (14) were a somewhat conspicuous feature along this stretch of shoreline with alongshore sediment transport and scarce-to-moderate sediment abundance, which lowered (worsened) sediment supply scores. High (good) substrate-type scores were influenced by low rates of shoreline armoring in this MA, as well as the relatively low density of point modifications (6.5/1000 ft shoreline). Low armoring and armoring encroachment rates also contributed to high (good) scores in the depth/slope metric, despite two reaches with a likely history of dredging activity. Pollution scores were high in MA-6 because of a lack of recreational shellfish closures or warnings, marinas and fish farms. Relatively low %TIA in the marine riparian zone and outfall densities along the shoreline in some reaches further influenced high (good) pollution metric scores. Finally, hydrology scores were also relatively high (good), despite the influence of an artificial tidal constriction in reach 3116, because of low %TIA scores (19%) within the marine riparian zone, low rates of armoring encroachment into the intertidal zone, and relatively low outfall densities.
Opportunities
Three of the least-impacted, low-bank reaches on Bainbridge Island are located in Blakely Harbor (MA-6), including Reaches 3112, 3113, and 3114 (Figure B-60, Appendix C). In all cases, the marine riparian zone of these reaches is composed of fairly intact forest, with no linear modifications and few point modifications present along the shoreline.
At an MA level, the most obvious opportunities for improving scoring would be to enhance processes and functions at reaches with particularly high scores (Figure B-14). This effort may include targeting removal or modification of encroaching armoring structures or groin structures, and modifying/removing the rock jetty that constricts tidal exchange to back-bay habitats in Reach 3115 (Figure B-60).
The EF scores were low (poor) in MA-6 relative to the rest of Bainbridge Island despite high CF scores (Table A-4, Figure B-11, Appendix D). This difference may be attributed to the relatively small documented area of surf-smelt spawning habitat, limited extent of eelgrass in the bay, as well as the lack of geoduck resources found therein (Figures B-57, B-58, and B-59). However, cutthroat trout, and coho salmon are also documented to spawn in two streams, Macs Dam Creek (WRIA 15.0331) and WRIA 15.0332, and efforts should be made to preserve spawning access and functions of juvenile rearing areas, both in-stream and in nearby shoreline habitats (Haring 2000). Blakely Harbor also provides additional support as a non-natal rearing area to juvenile salmon, including chinook and pink salmon; these functions were not quantified in the index.
Individual Reaches Within MA-6 (Figure B-60, Appendix C, Appendix D)
Reach 3105
CF Rating = Low Impact, Normalized score = -0.15
Most impacted CF metric: physical disturbance
Least impacted CF metric: wave energy, natural shade, artificial shade, sediment supply, substrate type, pollution, hydrology
Geomorphic class: Rocky Shore; Shoreline length: 2700 ft
Sediment source: Don't Know; Wave exposure: semi-protected
Overhanging vegetation: 0%; Riparian zone land use: 9.5% TIA, 14.8% forested
Total shoreline armoring: 1.2%; Total encroaching: 0%
Total point modifications: 1; Density: 0.4/1000 ft; most common is groins, with 0.4/1000 ft
Other: fronts golf course
EF Score: 14
Reach 3106
CF Rating = Low/Moderate Impact; Normalized score = -0.4
Most impacted CF metric: physical disturbance
Least impacted CF metric: natural shade, hydrology
Geomorphic class: Spit/Barrier/Backshore; Shoreline length: 352 ft
Sediment source: Don't Know; Wave exposure: semi-protected
Overhanging vegetation: 0%; Riparian zone land use: 28.4% TIA, 10.6% forested
Total shoreline armoring: 24.6%; Total encroaching: 0%
Total point modifications: 10; Density: 28.4/1000 ft; most common is buoys, with 17.1/1000 ft
Other:
EF Score: 10
Reach 3107
CF Rating = Low/Moderate Impact, Normalized score = -0.222
Most impacted CF metric: natural shade
Least impacted CF metric: hydrology, physical disturbance
Geomorphic class: Low Bank; Shoreline length: 2358 ft
Sediment source: Alongshore; Wave exposure: semi-protected
Overhanging vegetation: 17.3%; Riparian zone land use: 20.7% TIA, 65.7% forested
Total shoreline armoring: 14.2%; Total encroaching: 14.2%
Total point modifications: 1; Density: 0.4/1000 ft; most common is buoys, with 0.4/1000 ft
Other: some clearing of vegetation for road
EF Score: 18
Reach 3108
CF Rating = Low/Moderate Impact ; Normalized score = -0.333
Most impacted CF metrics: wave energy, depth/slope
Least impacted CF metric: artificial shade, physical disturbance
Geomorphic class: Low Bank; Shoreline length: 1402 ft
Sediment source: Alongshore; Wave exposure: semi-protected
Overhanging vegetation: 43.6%; Riparian zone land use: 9% TIA, 85.5% forested
Total shoreline armoring: 51.5%; Total encroaching: 45.7%
Total point modifications: 2; Density: 1.4/1000 ft; most common is outfalls, with 1.4/1000 ft
Other: some clearing of vegetation for road
EF Score: 16
Reach 3109
CF Rating = Moderate Impact ; Normalized score = -0.422
Most impacted CF metric: wave energy
Least impacted CF metric: artificial shade
Geomorphic class: Low Bank; Shoreline length: 522 ft
Sediment source: Alongshore; Wave exposure: semi-protected
Overhanging vegetation: 20.7%; Riparian zone land use: 14.2% TIA, 50.3% forested
Total shoreline armoring: 63.1%; Total encroaching: 59%
Total point modifications: 7; Density: 13.4/1000 ft; most common is groins, with 7.7/1000 ft
Other:
EF Score: 14
Reach 3110
CF Rating = Moderate/High Impact ; Normalized score = -0.675
Most impacted CF metrics: wave energy, substrate type
Least impacted CF metric: natural shade
Geomorphic class: Spit/Barrier/Backshore; Shoreline length: 1522 ft
Sediment source: Alongshore; Wave exposure: semi-protected
Overhanging vegetation: 0%; Riparian zone land use: 16.4% TIA, 41.4% forested
Total shoreline armoring: 87.5%; Total encroaching: 63%
Total point modifications: 33; Density: 21.7/1000 ft; most common is stairs, with 4.6/1000 ft
Other:
EF Score: 16
Reach 3111
CF Rating = Low/Moderate Impact ; Normalized score = -0.325
Most impacted CF metric: wave energy
Least impacted CF metric: natural shade, hydrology
Geomorphic class: Spit/Barrier/Backshore; Shoreline length: 394 ft
Sediment source: Alongshore; Wave exposure: protected
Overhanging vegetation: 24.4%; Riparian zone land use: 13.7% TIA, 51.5% forested
Total shoreline armoring: 55.3%; Total encroaching: 0%
Total point modifications: 1; Density: 2.5/1000 ft; most common is floating docks, with 2.5/1000 ft
Other:
EF Score: 14
Reach 3112
CF Rating = No Impact Normalized score = 0
Most impacted CF metrics:
Least impacted CF metric: wave energy, natural shade, artificial shade, sediment supply, substrate type, depth/slope, pollution, hydrology, physical disturbance
Geomorphic class: Low Bank; Shoreline length: 373 ft
Sediment source: Foreshore; Wave exposure: protected
Overhanging vegetation: 100.1%; Riparian zone land use: 2.8% TIA, 92.9% forested
Total shoreline armoring: 0%; Total encroaching: 0%
Total point modifications: 1; Density: 2.7/1000 ft; most common is outfalls, with 2.7/1000 ft
Other:
EF Score: 19
Reach 3113
CF Rating = No Impact, Normalized score = 0
Most impacted CF metrics:
Least impacted CF metric: wave energy, natural shade, artificial shade, sediment supply, substrate type, depth/slope, pollution, hydrology, physical disturbance
Geomorphic class: Low Bank; Shoreline length: 331 ft
Sediment source: Foreshore; Wave exposure: protected
Overhanging vegetation: 98.4%; Riparian zone land use: 2.8% TIA, 96.5% forested
Total shoreline armoring: 0%; Total encroaching: 0%
Total point modifications: 0Other:
EF Score: 22
Reach 3114
CF Rating = Low Impact, Normalized score = -0.089
Most impacted CF metric: artificial shade
Least impacted CF metric: wave energy, sediment supply, substrate type, depth/slope, pollution, hydrology
Geomorphic class: Low Bank; Shoreline length: 1291 ft
Sediment source: Foreshore; Wave exposure: protected
Overhanging vegetation: 70.4%; Riparian zone land use: 10% TIA, 88.5% forested
Total shoreline armoring: 0%; Total encroaching: 0%
Total point modifications: 3; Density: 2.3/1000 ft; most common is outfalls, with 0.8/1000 ft
Other:
EF Score: 27
Reach 3115
CF Rating = Low/Moderate Impact ; Normalized score = -0.3
Most impacted CF metric: hydrology
Least impacted CF metric: wave energy, physical disturbance
Geomorphic class: Marsh/Lagoon; Shoreline length: 3018 ft
Sediment source: Foreshore; Wave exposure: very protected
Overhanging vegetation: 48.3%; Riparian zone land use: 17.6% TIA, 77% forested
Total shoreline armoring: 16.1%; Total encroaching: 16.1%
Total point modifications: 4; Density: 1.3/1000 ft; most common is pilings, with 0.7/1000 ft
Other: tidal constriction present
EF Score: 20
Reach 3116
CF Rating = Low/Moderate Impact ; Normalized score = -0.375
Most impacted CF metric: depth/slope
Least impacted CF metric: natural shade
Geomorphic class: Spit/Barrier/Backshore; Shoreline length: 2032 ft
Sediment source: Alongshore; Wave exposure: protected
Overhanging vegetation: 5.5%; Riparian zone land use: 37.3% TIA, 53.4% forested
Total shoreline armoring: 4.3%; Total encroaching: 4.3%
Total point modifications: 13; Density: 6.4/1000 ft; most common is pilings, with 3/1000 ft
Other: dredged regions present
EF Score: 17
Reach 3117
CF Rating = Moderate Impact ; Normalized score = -0.475
Most impacted CF metric: depth/slope
Least impacted CF metric: natural shade
Geomorphic class: Spit/Barrier/Backshore; Shoreline length: 1477 ft
Sediment source: Alongshore; Wave exposure: protected
Overhanging vegetation: 18.9%; Riparian zone land use: 46.7% TIA, 45.2% forested
Total shoreline armoring: 13.4%; Total encroaching: 5.6%
Total point modifications: 20; Density: 13.5/1000 ft; most common is buoys, with 3.4/1000 ft
Other: dredged regions present
EF Score: 17
Reach 3118
CF Rating = Moderate Impact ; Normalized score = -0.425
Most impacted CF metrics: wave energy, artificial shade, substrate type, depth/slope
Least impacted CF metric: natural shade
Geomorphic class: Spit/Barrier/Backshore; Shoreline length: 543 ft
Sediment source: Foreshore; Wave exposure: protected
Overhanging vegetation: 18%; Riparian zone land use: 26.3% TIA, 72.9% forested
Total shoreline armoring: 56.8%; Total encroaching: 56.8%
Total point modifications: 6; Density: 11.1/1000 ft; most common is floating docks, with 3.7/1000 ft
Other:
EF Score: 16
Reach 3119
CF Rating = Moderate Impact ; Normalized score = -0.475
Most impacted CF metric: substrate type
Least impacted CF metric: natural shade
Geomorphic class: Spit/Barrier/Backshore; Shoreline length: 1098 ft
Sediment source: Alongshore; Wave exposure: protected
Overhanging vegetation: 15.7%; Riparian zone land use: 44.6% TIA, 49.1% forested
Total shoreline armoring: 36.3%; Total encroaching: 27.5%
Total point modifications: 29; Density: 26.4/1000 ft; most common is buoys, with 6.4/1000 ft
Other:
EF Score: 17
Reach 3120
CF Rating = Low Impact, Normalized score = -0.05
Most impacted CF metric: artificial shade
Least impacted CF metric: wave energy, natural shade, sediment supply, substrate type, depth/slope, pollution, hydrology, physical disturbance
Geomorphic class: Rocky Shore; Shoreline length: 932 ft
Sediment source: Alongshore, with feeder bluff activity; Wave exposure: semi-protected
Overhanging vegetation: 97.9%; Riparian zone land use: 0.6% TIA, 96.2% forested
Total shoreline armoring: 0%; Total encroaching: 0%
Total point modifications: 1; Density: 1.1/1000 ft; most common is buoys, with 1.1/1000 ft
Other: good home setbacks
EF Score: 24
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