Evaluating Cumulative Ecosystem Response to Restoration Projects in the Lower Columbia River and Estuary, 2009

Abstract

Final Annual Report, 2009 iii Executive SummaryThis is the sixth annual report of a 7-year project (2004 through 2010) to evaluate the cumulative effects of habitat restoration actions in the lower Columbia River and estuary (LCRE). The project, called the Cumulative Effects Study, is being conducted for the U.S. Army Corps of Engineers Portland District (USACE) by the Marine Sciences Laboratory of the Pacific Northwest National Laboratory (PNNL), the Pt. Adams Biological Field Station of the National Marine Fisheries Service (NMFS), the Columbia River Estuary Study Taskforce (CREST), and the University of Washington.The goal of the Cumulative Effects Study is to develop a methodology for evaluating the cumulative effects of multiple habitat restoration projects intended to benefit ecosystems supporting juvenile salmonids in the 235-km-long LCRE. Literature review in 2004 revealed no existing methods for such an evaluation and suggested that cumulative effects could be additive or synergistic. From 2005 through 2009, annual field research involved intensive, comparative studies paired by habitat type (tidal swamp versus marsh), trajectory (restoration versus reference site), and restoration action (tide-gate replacement vs. culvert replacement vs. dike breach).During 2009, the specific objectives for the Cumulative Effects Study were as follows:1. Support the cumulative effects assessment at pilot and estuary-wide scales through field work to document selected higher-order metrics, develop a time series, and expand the spatial and temporal diversity of sites for cumulative effects analysis, as follows:a. At Crims Island, Kandoll Farm, and Vera Slough restoration and reference sites, sample all core metrics.b. At selected historical breach and created sites, sample hydrology, morphology, vegetation, and fish abundance.c. Perform an intensive material-exchange study at the Kandoll Farm culvert over 48-hr periods during a spring-and a neap-tide series.2. Test estuary-wide the cumulative effects methodology developed in previous years, including geographic information system (GIS) assessments of wetted area, discrete hydrodynamic modeling, and meta-analyses of effectiveness data.The 2009 results may be summarized as follows:• Fish and Hydrography• -Large numbers of juvenile chum salmon were sampled in the tidal channels at the Kandoll Farm restoration site, implying the sampling covered the main outmigration. Juvenile Chinook salmon were present in the trap-net samples in low numbers, as in previous years. Coho salmon sampling included fry, subyearling, and yearling fishes. Marked fish from the Grays hatchery were captured at the Kandoll Farm.Vegetation-Elevation -Elevations are higher at the restoration site than at the reference sites at both Kandoll Farm and Vera Slough. At Crims Island, the elevations are the same between restoration and reference sites. As a corollary, accretions rates are higher at restoration sites than at reference sites. All tidal wetlands examined in this study exist within a 3-m vert...