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

Assessment of Operational and Structural Factors Influencing Performance of Fish Collectors in Forebays of High‐Head Dams

“…, ; Skalski et al. ). These examples show that forebay collectors can be used to provide efficient downstream passage at high‐head dams.…”

“…Forebay collectors at the Clackamas River dams operate nearly year-round and target all life stages of downstream migrants. This minimizes delay and the factors associated with mortality that commonly occur during out-migration through impounded systems (Keefer et al 2012(Keefer et al , 2013Skalski et al 2016). These examples show that forebay collectors can be used to provide efficient downstream passage at high-head dams.…”

“…Collectively, these efforts led to improved passage survival at Columbia and Snake River dams. Skalski et al (2016) reported that 22 of 29 annual dam passage survival estimates exceeded 95% for yearling Chinook Salmon, juvenile steelhead, and subyearling Chinook Salmon at main-stem Columbia and Snake River dams. Dam passage improved significantly at main-stem run-of-the-river dams in the Columbia River basin, where efforts required many years to complete and were very expensive (Williams 2008).…”

“…; Skalski et al. ). Mean annual river discharge at the projects we examined ranged from 32.1 to 131.4 m 3 /s during 2016 (Table ), which was characterized as a “normal” water year in the Pacific Northwest (USGS ).…”

“…Collectors at these two dams were included in our assessment because their strategy for providing fish passage is similar to the strategy at high-head dams where forebay collectors are operated as the primary option for providing downstream fish passage. These seven sites represent an increasingly popular method of collecting juvenile migratory fishes at such sites in the U.S. Pacific Northwest, and they differ in scale, structure, and operation from well-known main-stem dams on the Columbia and Snake rivers (Evans et al 2008;Adams et al 2014;Skalski et al 2016). Mean annual river discharge at the projects we examined ranged from 32.1 to 131.4 m 3 /s during 2016 (Table 2), which was characterized as a "normal" water year in the Pacific Northwest (USGS 2017).…”