By James J. Anderson
Abstract
The National Marine Fisheries Service (NMFS) 2000 Biological Opinion for the operation of the Federal Columbia River Power system defined adequate water quality, quantity, and velocity as essential features of the critical habitat of the juvenile salmon migratory corridor. To meet these features NMFS established a series of Reasonable and Prudent Actions (Actions 14-39) related to water management. Of particular significance RPA 14 calls for seasonal flow targets at Snake and Columbia River dams and RPA 27 restricts water depletions in the basin until the recovery is achieved (NMFS 2000). These RPAs are based on a controversial "flow/survival" hypothesis, established more than two decades ago, which states that more flow would benefit juvenile salmon during their migration, with more flow being provided by augmentation from reservoir releases or fewer water withdrawals (Anderson 2001). In 2003, hypotheses on the factors affecting smolt survival have undergone significant revision and review. These include updates of the data and new analyses by National Oceanographic and Atmospheric Administration (NOAA) (Williams et al. 2002), the Columbia Basin Fish and Wildlife Authority (CBFWA) (FPC 2003; Petrosky et al. 2003), and Columbia Basin Research of the University of Washington (CBR) (Anderson 2003a, b). In addition, reviews were conducted for the Northwest Power and Conservation Council (NPCC) (Giorgi et al. 2002; ISAB 2002), and a review requested by Washington State is being conducted by the National Research Council (NRC). Although these new analyses and reviews examine essentially the same information, they treat the information differently, and reach conclusions that are similar in some aspects but radically different in terms of the effect of flow changes on smolt survival. This white paper discusses these analyses and demonstrates that the information now exists to resolve the issue of the impacts of flow augmentation and water withdrawals on smolt survival.