Template:SPU 7086

Nearshore Strategies Data Report

Cereghino et al 2012 completed a soundwide analysis to identify and describe beach sites in Puget Sounds as part of a nearshore ecosystem restoration strategy (using remote sensing data c. 2000-2006). The following narrative was developed to support distribution and use of analysis results:

Beach Site 7086 is a 6.03 km long beach system containing 2580 meters of barrier beach (43%) and one creek mouth, one of 121 beach sites located in the San Juan Sub-basin. Based on these attributes it ranks 83 out of 100 in terms of size and complexity among all Puget Sound Beach systems. Over five generations of beach development, 1 percent of beach length now has some indicator of sediment supply degradation, and 10 percent of the nearshore zone has estimated impervious levels higher than 10 percent. Property boundaries now legally segment the shoreline with an average of one property every 69 meters. Based on these metrics, this site ranks 35 out of 100 in terms of estimated degradation among all beach sites in Puget Sound. The PSNERP Strategy Analysis places this site in Degradation Group D6, a group of 44 sites with below average parcel density but still minimal evidence of nearshore development. Based on this grouping we recommend this site for a protection-based strategy, where due to low levels of degradation, a concerted effort based on protection may preserve beach ecosystem processes, thereby maintaining a high level of ecosystem services. The site faces a high risk from jetty development impounding sediment, has no impacts from active shoreline railroad, and faces a slight risk from predicted future population growth.

This site is among 518 littoral cells that contained barrier-type embayments. Historically this system contained 6 barrier-type embayments, with an embayment shoreline of 3.95 km, encompassing 10.7 hectares of tidal wetlands - considering the length of beach this is the equivelent of one embayment every 1 km. This system is one among 89 barrier embayment complexes in the San Juan Sub-basin. Based on these metrics this site ranks 88 out of 100 in terms of size and complexity among all Puget Sound barrier embayment systems. The PSNERP Strategy Analysis placed this site in Potential Group P9, a large group of 69 sites with large embayments and wetlands at a typical density, identified as noteworthy sites for their high potential to provide ecosystem services.

Site 7086 currently has 3 embayment--3 less than under historical conditions. This has been accompanied by a 49 percent loss of wetland area and a 63 percent loss of embayment length, based on comparison to historic maps. 34 percent of the remaining embayment shoreline length has evidence of shoreline modification. Based on these metrics, and the general development status of the drift cell, the PSNERP Strategy Analysis ranked this system 53 out of 100 and placed this site in Degradation Group D6, a small group of 18 barrier embayment systems where there has been moderate to high levels of degradation both in loss of length, development of embayment shorelines, as well as urbanization and loss of sediment supply across the surrounding drift cell. Based on this grouping, the site is recommended for a restoration-based approach, where there may be the opportunity through a combination of protection and restoration efforts to recover the full operation of ecosystem processes thereby recovering ecosystem services that are either degraded or at risk.