Evaluate the Restoration Potential of Snake River Fall Chinook Salmon Spawning Habitat
Statement of Work and Budget FY2007

The goal of this study is to identify hydrosystem operational conditions that could expand and restore spawning populations the Snake River stock of fall Chinook salmon. This project addresses NOAA's 2000 FCRPS BiOp RPA 155, and contributes to the ESA commitments made by BPA and the FCRPS Action Agencies under NOAA's revised 2004 BiOp.  This project is identified in the Crosswalk of Draft UPA (August 2004, page 30) as the project that is implementing RPA 155.  The objectives of this project are consistent with and are integral components for implementing the 2005-2007 Final Implementation Plan for the FCRPS Updated Proposed Action (May 2005).  This project is specifically identified in the Implementation Plan (page 41, Table 22) as one of the hydrosystem RM&E projects that the Action Agencies will implement in the 2005-2007 timeframe to address their UPA commitments.  Continuation of this project helps reduce critical hydrosystem uncertainties and provides status monitoring for restoring Snake River fall Chinook salmon spawning habitat.

This project was approved for FY2004 funding on October 2, 2003, with a contract start date of December 15, 2003.  The project scope included one reference site (Wanapum Dam tailrace in the Columbia River) and two study sites (tailraces of Ice Harbor and Lower Granite dams) in the lower Snake River.  During FY2004 we collected physical habitat data (bathymetry, substrate, channel morphology) at the reference site, spanning 10 river kilometers and 2000+ fall Chinook salmon redds.  Also during FY2004 we completed hydrodynamic modeling for a wide range of flow regimes at the reference site.  During FY2005 we collected physical habitat data (bathymetry, substrate, channel morphology) at the lower Snake River study sites, covering 30 river kilometers. Also during FY2005 we completed additional hydrodynamic modeling at the reference site, and initiated modeling at the lower Snake River study sites.  Hydrodynamic modeling at the lower Snake River study sites was hampered by the lack of high resolution and high quality bathymetry data.  The lack of bathymetry data forced us to refocus our FY2005 efforts more on bathymetry data collection and processing and less on hydrodynamic modeling.  In late-FY2005 we completed the initial hydrodynamic modeling for a wide range of flow regimes at both of the study sites in the lower Snake River.  Work in FY2006 focusesd on collecting additional physical habitat data at the study sites, completing the hydrodynamic modeling, and completing the analyses necessary for determing the presence and extent of similar characteristics at the reference site and study sites.  The FY06 final report will summarize results describing the quantity of potential fall Chinook salmon spawning habitat in the Ice Harbor and Lower Granite tailraces.

The research to be conducted under this proposal will evaluate the restoration potential of mainstem habitats for fall Chinook salmon.  The studies will address two research questions: “Are there sections not currently used by spawning fall Chinook salmon within the impounded lower Snake River that possess the physical characteristics for potentially suitable fall Chinook spawning habitat?” and “Can hydrosystem operations affecting these sections be adjusted such that the sections closely resemble the physical characteristics of current fall Chinook spawning areas in similar physical settings?” We propose to focus our efforts at study sites downstream from each of the four lower Snake River dams (Ice Harbor, Lower Monumental, Little Goose, Lower Granite).  The research will be carried out in two phases at each site.  The first phase involves estimating the quantity of potential fall Chinook salmon spawning habitat, while the second phase involves evaluating the quality of the potential habitat.  These two phases are necessary for accurate estimates of future habitat use, because, as previously described, estimates of just habitat quantity tend to overestimate habitat use.  Unrealistic fall Chinook salmon production goals for the lower Snake River may be developed in the absence of accurate estimates of both habitat quantity and quality. Years 1 (FY07) and 2 (FY08) of the study will focus on data collection, analysis and summary.  This includes evaluating the quality of potential habitat at the Ice Harbor and Lower Granite study sites, and quantity of potential habitat at the Lower Monumental and Little Goose study sites. Years 2 (FY08) and 3 (FY09) of the study will focus on modeling alternative flow scenarios and evaluating habitat quality at the Lower Monumental and Little Goose study sites, culminating in a report on recommended restoration options.  This report will include a study plan for 2 years of monitoring and evaluation of the physical characteristics resulting from altered flow regimes, should such recommendations be implemented.

The study sites will be evaluated under existing structural configurations at the dams (i.e., without partial removal of a dam structure), and alternative operational scenarios (e.g., varying forebay/tailwater elevations). The areas to be studied represent tailwater habitat (i.e., riverine segments extending from a dam downstream to the backwater influence from the next dam downstream).  We will use a reference site, indicative of current fall Chinook salmon spawning areas in tailwater habitat, against which to compare the physical characteristics of each study site.  The reference site for tailwater habitats will be the section extending downstream from the Wanapum Dam tailrace on the Columbia River.  Escapement estimates for each of the last five years indicate more than 9000 adult fall Chinook salmon returned to this area, accounting for more than 2100 redds within a 5 km section of river (Grant Co. PUD, personal communications; McMichael et al. 2003).