Indicator: Shoreline Armoring
Data and Data Discussion provided by
King County DNRP
Sustainability Snapshot:
The amount of shoreline armoring can be used as a general indicator of the condition of marine shorelines. When armoring is present, the health of habitats decline in the nearshore area (the water, shoreline and adjacent upland areas). These habitats are an important feeding, nesting and resting ground for many fish, animals and plants, including young salmon that feed along the shore after journeying down rivers into the Sound. Much of King County's mainland shoreline has been armored in contrast to the relatively natural shorelines along Vashon-Maury Islands.
Sustainability Trend:
There are increasing levels of riprap and sea walls being installed on Puget Sound shorelines. Conclusions from a baseline survey for shoreline armoring in 2005 show that many beach-feeding sediment sources have been locked up behind armoring.
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Percent of armored marine shoreline in King County. Shoreline armoring can take the form of a bulkhead, sea wall, riprap, or any other built impediment to naturally advancing tidewaters.
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The amount of shoreline that has been armored can be used as a general indicator of the condition of marine shorelines. Our weighting system applies 50 percent towards unincorporated/Vashon Island armoring and 50 percent toward incorporated area shoreline armoring.
Conclusions from a baseline survey for shoreline armoring in 2005 show that many beach-feeding sediment sources have been locked up behind armoring. Much of King County's mainland shoreline has been armored Ñ in stark contrast to the relatively natural shorelines along Vashon-Maury Islands.
The Central Puget Sound Basin is one of the most heavily urbanized areas within Puget Sound, and King County's armored marine shoreline is indicative of this.
When armoring is present, the health of habitats decline in the nearshore area (the water, shoreline and adjacent upland areas). The nearshore area is an important feeding, nesting and resting ground for many fish and wildlife species, including young salmon as they migrate from the stream of their birth to marine rearing areas.
The Central Puget Sound Basin is one of the most heavily urbanized areas within Puget Sound, and King County's armored marine shoreline is indicative of this.
Influencing factors: Property owners build bulkheads to protect their homes and businesses from erosion.
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Data source: The data source for this indicator comes from the King County WLRD Science, Monitoring and Data Management Section.
Collection frequency: This is the first time comprehensive data
has been available to develop this environmental indicator. Now that a
baseline has been established, follow up surveys every 5 years will
provide useful analysis in the future.
Methods for analysis: Aerial photography and limited ground
truthing was used to conduct this survey. The aerial photography
collection was conducted in 2005.
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