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CITY OF DES MOINES SHORELINE MASTER PROGRAM

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Des Moines Shoreline Inventory and Characterization<br />

Mapped critical fish and wildlife habitats are shown on Figure 14. Critical fish and wildlife<br />

habitats in the City’s shoreline jurisdiction are characterized throughout the following sections<br />

describing the nearshore biological characterization.<br />

Marine Riparian Zones<br />

Marine riparian vegetation is defined as vegetation overhanging the intertidal zone (KCDNR,<br />

2001). Marine riparian zones function by protecting water quality; providing wildlife habitat;<br />

regulating microclimate; providing shade, nutrient and sources of food; stabilizing banks; and<br />

providing large woody debris (Anchor Environmental and People for Puget Sound, 2002).<br />

Marine riparian zones were examined through limited field reconnaissance and review of 2001<br />

oblique aerial photos (Ecology, 2001). The existing marina, residential and commercial<br />

development, and shoreline armoring have impacted the marine riparian zones of all the city<br />

shoreline segments. Marine riparian zones within the City’s shoreline jurisdiction are typically<br />

associated with the high, steep bluff areas of segments C, D, and E where development is less<br />

desirable. The longest contiguous stretch of intact marine riparian vegetation is found in<br />

Segment C, between S. 240th Street and Saltwater State Park (Segment D). Marine riparian<br />

zones are absent from all of segments A, B, F, and G due to shoreline armoring including<br />

concrete and wooden bulkheads, rip-rap seawalls, marinas, and boat ramps (WDNR, 2001)<br />

(Table A-3, Appendix A).<br />

Banks and Bluffs<br />

Banks and bluffs are part of the marine riparian zone and are generally the primary source of<br />

sediment to adjacent beaches (Downing, 1983), provide habitat to bluff-dwelling animals,<br />

rooting area for riparian vegetation, and a source of groundwater seepage to marine waters<br />

(KCDNR, 2001). Shoreline development and armoring, vegetation clearing, over-water<br />

structures, dredging, and changes in hydrology, among others, adversely impact the natural<br />

functions of bluffs.<br />

The ShoreZone Inventory (WDNR, 2001) maps high, steep bluffs capped by till in Segments C<br />

and D and moderate height, inclined bluffs capped by till in Segment E (Table A-4, Appendix<br />

A).<br />

Beaches and Backshore<br />

Beaches are generally steeper than tidal flats and are often comprised of boulder, cobble, sand<br />

and silt areas that form a great majority of Puget Sound’s shoreline (KCDNR, 2001). Backshore<br />

areas are immediately landward of beaches and are zones inundated by storm-driven tides.<br />

Beaches provide habitat for numerous organisms, including cutthroat trout, piscivorous birds<br />

(grebes, herons, and mergansers), and shorebirds (Dethier, 1990 in KCDNR, 2001). A typical<br />

profile of an undisturbed shoreline in Central Puget Sound would include an upper backshore or<br />

storm berm area that collects logs, algae, and other debris during storms (KCDNR, 2001). The<br />

intertidal portion of the beach is typically relatively steep and composed of a mixture of cobbles<br />

and gravel in a sand matrix (KCDNR, 2001). Sediment abundance throughout the shoreline<br />

segments is characterized as a mixture of “moderate” to “abundant” (Table A-1, Appendix A).<br />

Sediment stability within the shoreline segments is identified as both accretional and stable<br />

March 2005 Page 31

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