Washington Phase II Fish Diversion Screen Evaluations in the Yakima and Touchet River Basins, 2005-2006 Annual Reports.

Abstract

In 2005, Pacific Northwest National Laboratory (PNNL) researchers evaluated 25 Phase II fish screen sites in the Yakima and Touchet river basins. Pacific Northwest National Laboratory performs these evaluations for Bonneville Power Administration (BPA) to determine whether the fish screening devices meet National Marine Fisheries Service (NMFS) criteria to promote safe and timely fish passage. Evaluations consist of measuring velocities in front of the screens, using an underwater camera to look at the condition and environment in front of the screens, and noting the general condition and operation of the sites. Results of the evaluations in 2005 include the following: (1) Most approach velocities met the NMFS criterion of less than or equal to 0.4 fps. Less than 13% of all approach measurements exceeded the criterion, and these occurred at 10 of the sites. Flat-plate screens had more problems than drum screens with high approach velocities. (2) Bypass velocities generally were greater than sweep velocities, but sweep velocities often did not increase toward the bypass. The latter condition could slow migration of fish through the facility. (3) Screen and seal materials generally were in good condition. (4) Automated cleaning brushes generally functioned properly; chains and other moving parts were typicallymore » well-greased and operative. (5) Washington Department of Fish and Wildlife (WDFW) and U.S. Bureau of Reclamation (USBR) generally operate and maintain fish screen facilities in a way that provides safe passage for juvenile fish. (6) In some instances, irrigators responsible for specific maintenance at their sites (e.g., debris removal) are not performing their tasks in a way that provides optimum operation of the fish screen facility. New ways need to be found to encourage them to maintain their facilities properly. (7) We recommend placing datasheets providing up-to-date operating criteria and design flows in each sites logbox. The datasheet should include bypass design flows and a table showing depths of water over the weir and corresponding bypass flow. This information is available at some of the sites but may be outdated. These data are used to determine if the site is running within design criteria. (8) Modifying use of debris control plates at Gleed helped minimize the extreme fluctuations in flow, but approach velocities are still too high. Other ways to reduce the approach velocities need to be tried, possibly including redesign of the site. (9) Alternatives to a screen site at Taylor should be considered. A lot of effort was spent trying to increase water to the site, but it still was unable to operate within NMFS criteria for most of the year and may be a hazard to juvenile salmonids. We conclude that the conditions at most of the Phase II fish screen facilities we evaluated in 2005 would be expected to provide safe passage for juvenile fish. For those sites where conditions are not always optimum for safe fish passage, PNNL researchers will try to coordinate with the WDFW and USBR in 2006 to find solutions to the problems. Some of those problems are consistently high approach velocities at specific sites, including Congdon, Naches-Selah, Union Gap, and Yakima-Tieton. We would like to be able to monitor changes in velocities as soon as operations and maintenance personnel adjust the louvers or porosity boards at these sites. This will give them immediate feedback on the results of their modifications and allow additional adjustments as necessary until the conditions meet NMFS criteria. Pacific Northwest National Laboratory has performed evaluations at many of these sites over the past 8 years, providing information WDFW and USBR personnel can use to perform their operations and maintenance more effectively. Consequently, overall effectiveness of the screens facilities has improved over time.« less