Yakima and Touchet River Basins Phase II Fish Screen Evaluation, 2006-2007 Annual Report.
- Pacific Northwest National Laboratory
In 2006, Pacific Northwest National Laboratory (PNNL) researchers evaluated 27 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 those National Marine Fisheries (NMFS) criteria for juvenile fish screen design, that promote safe and timely passage of juvenile salmonids. The NMFS criteria against which the sites were evaluated are as follows: (1) a uniform flow distribution over the screen surface to minimize approach velocity; (2) approach velocities less than or equal to 0.4 ft/s protects the smallest salmonids from impingement; (3) sweep velocities that are greater than approach velocities to minimize delay of out-migrating juveniles and minimize sediment deposition near the screens; (4) a bypass flow greater than or equal to the maximum flow velocity vector resultant upstream of the screens to also minimize delay of out-migrating salmonids; (5) a gradual and efficient acceleration of flow from the upstream end of the site into the bypass entrance to minimize delay of out-migrating salmonids; and (6) screen submergence between 65% and 85% for drum screen sites. In addition, the silt and debris accumulation next to the screens should be kept to a minimum to prevent excessive wear on screens, seals and cleaning mechanisms. Evaluations consist of measuring velocities in front of the screens, using an underwater camera to assess the condition and environment in front of the screens, and noting the general condition and operation of the sites. Results of the evaluations in 2006 include the following: (1) Most approach velocities met the NMFS criterion of less than or equal to 0.4 ft/s. Of the sites evaluated, 31% exceeded the criterion at least once. Thirty-three percent of flat-plate screens had problems compared to 25% of drum screens. (2) Woody debris and gravel deposited during high river levels were a problem at several sites. In some cases, it was difficult to determine the bypass pipe was plugged until several weeks had passed. Slow bypass flow caused by both the obstructions and high river levels may have discouraged fish from entering the bypass, but once they were in the bypass, they may have had no safe exit. Perhaps some tool or technique can be devised that would help identify whether slow bypass flow is caused by pipe blockage or by high river levels. (3) 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. (4) Screen and seal materials generally were in good condition. (5) Automated cleaning brushes generally functioned properly; chains and other moving parts were typically well-greased and operative. (6) Washington Department of Fish and Wildlife (WDFW) and U.S. Bureau of Reclamation (USBR) generally operated and maintained fish screen facilities in a way that provided safe passage for juvenile fish. (7) Efforts with WDFW to find optimal louver settings at Naches-Selah were partly successful. The number of spots with excessive approach velocities was decreased, but we were unable to adjust the site to bring all approach values below 0.4 ft/s. (8) In some instances, irrigators responsible for specific maintenance at their sites (e.g., debris removal) did not perform their tasks in a way that provided optimum operation of the fish screen facility. Enforcement personnel proved effective at reminding irrigation districts of their responsibilities to maintain the sites for fish protection as well as irrigation. (9) We recommend placing datasheets providing up-to-date operating criteria and design flows in each site's logbox. The datasheet should include bypass design flows and a table showing depths of water over the weir and corresponding bypass flow. A similar datasheet relating canal gage readings and canal discharge in cubic feet per second would help identify times when the canal is taking more water than it should. This information is available at some of the sites and assists operators in determining if the site is running within the site specific design criteria. (10) Data were collected at Gleed when the protective metal plates were set down to the forebay floor and when they were raised to expose most of the screens. These data were sent to USBR personnel for use in looking for ways to reduce high approach velocities and erratic flow pattern at Gleed. (11) Alternatives to a screen site at Taylor are apparently being considered. A lot of effort was spent in 2005 and 2006 trying to increase water to the site, but it still was unable to operate within NMFS criteria for much of the year and may be a hazard to juvenile salmonids at times.
- Research Organization:
- Bonneville Power Administration (BPA), Portland, OR (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- 26934 REL 1
- OSTI ID:
- 961995
- Report Number(s):
- DOE/BP-00026934-1; R&D Project: 1985-062-00; TRN: US200915%%373
- Country of Publication:
- United States
- Language:
- English
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