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The Problem
The National Marine Fisheries Services Biological Opinion on the Columbia River salmon listed under the Endangered Species Act sets guidelines for salmon recovery. Many of the guidelines address salmon passage issues at hydroelectric dams operated by the U.S. Army Corps of Engineers (COE), because fish passing via turbines do not survive as well as those going over the spillways. To meet these guidelines, the COE has undertaken a series of studies to evaluate and improve downstream passage conditions of juvenile salmonids. This project is designed to evaluate the effectiveness of using 24-hour spill at the dam to pass juvenile salmonids via routes other than the turbines versus the use of 12-hour (night) spill. The current Biological Opinion mandates a 12-hour spill program, but requests that fish passage during 24-hour spill be investigated. Objectives The objective of this project is to quantify juvenile fish passage via the turbines, spillway, and juvenile bypass system during 12-h and 24-h spill and determine statistically if any differences exist. This is accomplished by determining 1) the proportion of fish passing each route and 2) comparing residence times in the forebay during each treatment. Methodology This project is based on detections of radio-tagged fish as they approach and pass the dam. Yearling and subyearling chinook salmon (Oncorhynchus tshawytscha) and juvenile steelhead (O. mykiss) are gastrically tagged and released for study. The radio-tagged fish are detected at the dam using aerial and underwater antennas connected to automated telemetry receiving systems. The overall fish passage efficiency (the proportion of fish passing via all non-turbine routes, FPE), spill passage efficiency (the proportion of fish passing via the spillway, SPE) and spill passage effectiveness (the spill passage efficiency divided by the
Highlights and Key Findings Studies of passage of radio-tagged juvenile salmonids during 12-h and 24-h spill treatments at John Day Dam were conducted in 1999, 2000 and 2002. No work was conducted in 2001 due to drought conditions. The FPE estimates of spring migrants were similar at each spill treatment in each year studied (Table 1). The FPE of subyearling chinook salmon was significantly higher during the 24-h treatment than during the 12-h treatment in 2000, but no differences were evident in 2002 (Table 1; note the different treatment conditions between years). Results from 2002 indicated statistically greater FPE of yearling chinook salmon during the 12-h treatment, but no other statistically significant differences in FPE. Data from 1999 and 2001 indicated several important results. The day spill treatment tested did not significantly alter FPE of spring migrants, but resulted in increased spill passage with concomitant reductions in guidance into the juvenile bypass system. In addition, the day spill treatment was efficient at passing juvenile chinook salmon and to a lesser extent, but not hatchery steelhead. Both FPE and SPE of subyearling chinook salmon were significantly higher during the 24-h treatment than during the 12-h treatment (2000 data). In 2002 the 24-h treatment level was 30% spill rather than 30% day and 53% night spill and wild steelhead were used for the first time. Results from this study indicated the FPE of the yearling chinook salmon was significantly greater during the 12-h treatment and that the wild steelhead passage measures were more similar to those of yearling chinook salmon than hatchery steelhead during similar treatments (the 12-h treatments were most similar between years).
Where Are We Headed In 2003 Spill treatments for 2003 are proposed as refinements of either 12-h or 24-h spill during the spring (depending on previous results) and a repeat of 12-h vs. 24-h spill during the summer (due to unplanned spill during 2002 tests). Project Contact John Beeman Email: john_beeman@usgs.gov Publications | ||||
