Implications of Enhancing Forage Fish Spawning Habitat in the Absence of Sediment Processes that Maintain Spit Systems
Presentation Abstract
Ediz Hook is one of the most well studied spits anywhere in the Salish Sea. The loss of sediment supply to the spit and the construction of a riprapped road prism to the tip of the spit has caused rapid erosion, necessitating “nourishment” on the outside (north side) of the spit by the US Army Corps of Engineers. The erosion was exacerbated by the installation of dams on the Elwha River, which have been recently removed. As part of this extremely large restoration project, there is a large international monitoring effort examining the impacts to the outside of the spit, which should see significant new sediment from the river over time. Though the outside of the spit has been of intense interest, a much smaller habitat enhancement program has been active since 2003 in improving shoreline conditions of the inside of the spit (on the south side). Here, sediment reduction has been complete. Not only is the sediment supply to the spit at large reduced, but the road prism completely blocks the overwash that supplied the inside of the spit with sediment. This sediment loss has caused rapid erosion of former spit deposits, also endangering the roadway. Although the shoreline is somewhat unusual in that the sediment supply has been eliminated completely by the placement of a riprapped road, the observations made in response to placed sediment and wood provide indications as the effectiveness of various approaches. First, the observations suggest that even in situations where sediment supply has been completely eliminated, nourishment can recreate productive habitat features. Also, it appears that the placement of large amounts of untethered but buried wood does enhance the ability of the beach to retain sediment appropriate for forage fish spawning. Finally, the project also illustrates a project setting where protection of infrastructure (in this case the road) if designed properly can also improve habitat.
Session Title
Session S-02G: Reimagining Shorelines
Conference Track
Shorelines
Conference Name
Salish Sea Ecosystem Conference (2014 : Seattle, Wash.)
Document Type
Event
Start Date
30-4-2014 1:30 PM
End Date
30-4-2014 3:00 PM
Location
Room 6E
Genre/Form
conference proceedings; presentations (communicative events)
Contributing Repository
Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.
Subjects – Topical (LCSH)
Sedimentation and deposition--Salish Sea (B.C. and Wash.); Spits (Geomorphology)--Environmental aspects--Salish Sea (B.C. and Wash.); Restoration ecology--Salish Sea (B.C. and Wash.)
Geographic Coverage
Salish Sea (B.C. and Wash.)
Rights
This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.
Type
Text
Language
English
Format
application/pdf
Implications of Enhancing Forage Fish Spawning Habitat in the Absence of Sediment Processes that Maintain Spit Systems
Room 6E
Ediz Hook is one of the most well studied spits anywhere in the Salish Sea. The loss of sediment supply to the spit and the construction of a riprapped road prism to the tip of the spit has caused rapid erosion, necessitating “nourishment” on the outside (north side) of the spit by the US Army Corps of Engineers. The erosion was exacerbated by the installation of dams on the Elwha River, which have been recently removed. As part of this extremely large restoration project, there is a large international monitoring effort examining the impacts to the outside of the spit, which should see significant new sediment from the river over time. Though the outside of the spit has been of intense interest, a much smaller habitat enhancement program has been active since 2003 in improving shoreline conditions of the inside of the spit (on the south side). Here, sediment reduction has been complete. Not only is the sediment supply to the spit at large reduced, but the road prism completely blocks the overwash that supplied the inside of the spit with sediment. This sediment loss has caused rapid erosion of former spit deposits, also endangering the roadway. Although the shoreline is somewhat unusual in that the sediment supply has been eliminated completely by the placement of a riprapped road, the observations made in response to placed sediment and wood provide indications as the effectiveness of various approaches. First, the observations suggest that even in situations where sediment supply has been completely eliminated, nourishment can recreate productive habitat features. Also, it appears that the placement of large amounts of untethered but buried wood does enhance the ability of the beach to retain sediment appropriate for forage fish spawning. Finally, the project also illustrates a project setting where protection of infrastructure (in this case the road) if designed properly can also improve habitat.
