Beamer, E., Henderson, R. and Brown, B., 2015. Juvenile Chinook Salmon Utilization of Habitat Associated with the Wiley Slough Restoration Project, 2012 – 2013. Skagit River System Cooperative, La Conner, WA. pp. 51.

Restoration of Skagit River delta habitat was identified as a priority to help recover Skagit Chinook salmon listed as Threatened under the Endangered Species Act. The Wiley Slough Restoration Project was completed in 2009. Fish monitoring was conducted within restored habitat area of the Wiley Slough Restoration Project in 2012 and 2013. The monitoring design primarily consisted of a post-treatment (i.e., after restoration) stratified random design using beach seines to capture fish. The monitoring effort caught over 22,000 fish representing at least 23 fish species, including 7 species of salmon (genus: Oncorhynchus). Unmarked juvenile Chinook salmon dominated the catch of salmon. Unmarked juvenile Chinook salmon density varied within the Wiley Slough Restoration Project by lobe, year, and season, but not habitat type. The Wiley Slough lobe had higher densities of juvenile Chinook salmon than the Teal Slough lobe; higher densities of juvenile Chinook salmon were found in 2013 than in 2012; seasonal use of restored areas by juvenile Chinook salmon began in February, peaked from April through June, then declined afterward. Juvenile Chinook salmon density did not vary by channel and impoundment. In general, juvenile Chinook salmon are using the restored areas of both Wiley and Teal Slough lobes at seasonal density levels consistent with other long term monitoring sites in the Skagit River estuary. An estimated 88,206 (37,326-139,086, 95% CI) and 247,692 (128,973-366,412, 95% CI) unmarked juvenile Chinook salmon used restored habitat of the Wiley Slough Restoration Project in 2012 and 2013, respectively. Based on two years of monitoring the number of juvenile Chinook salmon that used the restored areas of the Wiley Slough Restoration Project: 1) exceeded the updated carrying capacity estimate based on actual restored channel habitat, and 2) exceeded the Skagit Chinook Recovery Plan’s estimated benefit to juvenile Chinook salmon. However, the number of juvenile Chinook salmon that used the restored areas were somewhat less than predicted by the carrying capacity estimate that included all wetted areas (29 hectares of channel and impoundment combined). Sustainable channel conditions are reached after natural hydrologic and sedimentation processes achieve a balance at the site. Sustainable channel area is estimated at 2.03 hectares (0.50-8.25, 95% CI) suggesting total habitat area will be less than the 29 hectares currently present. Thus, actual juvenile Chinook salmon carrying capacity could change within the Wiley Slough Restoration Project based on how channel/impounded areas evolve over time. The issue of restored habitat conditions within recently restored areas using dike setback design and the long term sustainability of that habitat may be an emerging theme for estuary restoration adaptive management. This issue is of particular importance when restoration projects are intended to achieve specific goals, such as recovery of listed Chinook salmon populations. If as-built restoration conditions are not in a sustainable state, then a false sense of restored benefits might be accepted without sufficient monitoring and adaptive management of projects.