Rocky Reach is nationally recognized for efforts to protect the environment. A first-of-its-kind juvenile fish bypass system was completed in 2003 to help young salmon and steelhead on their way to the ocean. A major powerhouse upgrade started in 1995 includes new turbines that are more fish friendly. Improvements to turbines and generators are also designed to improve efficiency and reliability.
The Chelan County Public Utilities Department, beginning in 1985, began laboratory studies and tests to determine exactly how to best allow fish to pass the Rocky Reach Dam. The result was an innovative surface screen and bypass system, unlike deeper water systems employed previously.
Excerpt from the
Chelan County P.U.D. website:
Bypass system background
Starting in 1985, the PUD developed laboratory models and tested prototype fish bypass systems for intercepting and moving juvenile fish around Rocky Reach as they travel downriver to the ocean. Screens were designed to steer young salmon and steelhead away from the turbines and into a bypass channel. None of the prototype screening systems tested achieved the results experienced at other Columbia River hydro projects. So a new approach was taken in 1995 -- a surface bypass and collection system that appeals to the young fish's natural instinct to migrate downriver near the surface, following the water flow. This differs from conventional turbine intake screens, which require fish to dive into the turbine intakes before they are intercepted by the screens. Also, after the prototype surface collector was added in 1995, the fish guidance effectiveness improved for the screen systems left in two units to enhance interim protection. Because of the improvement in the screens' performance, they have been incorporated into the final design of the fish bypass system.
Sonar studies determined that fish generally travel in the upper 60 feet of the river. The prototype was designed to use natural and turbine-induced surface currents in the upper 60 feet of the flow to give fish an alternative to diving into the turbine intakes -- entering the bypass system instead. Attractive features of this concept include the minimal volume of flow that's lost, minimizing power losses, as well as the relatively low installation cost.
Flows through the bypass pipe were occasionally diverted to an evaluation facility, where the juvenile fish were examined to identify species and condition. A 24-hour videotaping system counted the number of fish using the bypass system.
To measure the collector's effectiveness in moving fish, a few of the young salmon and steelhead were implanted with electronic tags and released upstream of the hydro project during the spring and summer testing period. The movements of other test fish outfitted with acoustic tags were monitored as they moved through the forebay to determine how they reacted to the surface collector. These studies allowed biologists to view 3-dimensional movement of fish in the forebay as they approached the fish bypass system and dam. This technique was used for this reason first at Rocky Reach.
The prototype surface collection system was modified each year, based upon test results from the previous year. Increased flows into and through the collector, plus improvements to the diversion screen/gatewell collection system in certain units, provided very encouraging study results in 1997. A second entrance was added to the surface collector in 1998, but results in attracting fish were not as good as anticipated. So in 1999, the second entrance to the surface collector was modified to allow biologists to vary the entrance width from a minimum of 22 feet to a maximum of 44 feet. This allowed biologists to analyze how water flows affected, and which water flows were better at attracting fish.
By 2000 and 2001, the District, in coordination with the fisheries agencies and native American Tribes determined that the configuration of the fish bypass system had been tested satisfactorily and that installation of a permanent system was warranted.
After final testing, the permanent bypass system was installed in 7 months between fall 2002 and the beginning of the 2003 migration of juvenile salmon in April towards the ocean. Each day from April 1 through August 31 during bypass operations, the flow in the bypass pipe is temporarily diverted for short periods to an evaluation facility, where the juvenile fish are counted and examined to identify species and condition.
The District has conducted nine additional years of project passage and survival studies following permanent construction, confirming its efficiency and that survival of young fish using the bypass system is nearly 100 percent.