Status after 5 Years of Survival Compliance Testing in the Federal Columbia River Power System (FCRPS)

Abstract

Survival studies of juvenile Pacific salmon Oncorhynchus spp. implanted with acoustic tags have been conducted at hydroelectric dams within the Federal Columbia River Power System in the Columbia and Snake rivers between 2010 and 2014 to assess compliance with the dam passage survival standards stipulated in the 2008 Biological Opinion. For juvenile yearling Chinook Salmon O. tshawytscha and steelhead O. mykiss that migrate downstream in the spring, dam passage survival (defined as survival from the upstream dam face to the tailrace mixing zone) must be ≥ 96%, and for subyearling Chinook Salmon that migrate downstream in summer, dam passage survival must be ≥ 93%. Precision requirement stipulates a standard error ≤ 1.5% (i.e., a 95% confidence interval of ± 3%). A total of 29 compliance tests have been conducted at six of eight main-stem dams in the Federal Columbia River Power System, using over 109,000 acoustic-tagged salmonid smolts. Of these 29 compliance studies, 23 met the survival standards and 26 met the precision requirements. Of the six dams evaluated to date, individual survival estimates range from 0.9597 to 0.9868 for yearling Chinook Salmon, from 0.9534 to 0.9952 for steelhead, and from 0.9076 to 0.9789 for subyearling Chinook Salmon. Averages across the six dams exceed the survival standards for all three migrant populations.

Received November 9, 2015; accepted February 16, 2016 Published online June 27, 2016

Acknowledgments

This research was supported by the U.S. Army Corps of Engineers, Portland District, under an interagency agreement with the U.S. Department of Energy, Contract DE-AC05-76RL01830, and the U.S. Army Corps of Engineers, Walla Walla District, Contract W912EF-08-D-004. We would also like to acknowledge the many dedicated scientists at the Pacific Northwest National Laboratory, the Pacific States Marine Fisheries Commission, the Army Corps of Engineers, and the University of Washington who made these studies possible.