This massive structure is truly unique—its one-of-a-kind design combines fish collection and water flows for power generation. After years of research, PGE and the Confederated Tribes of Warm Springs have chosen a design that makes Pelton Round Butte an important source of green energy for Oregon. Referred to as a "Selective Water Withdrawal Tower," this structure is designed to draw water both from the surface and from the bottom of Lake Billy Chinook. This accomplishes several things:

• Changes the currents to attract fish into the fish collection facility.
• Lowers the temperature of Lake Billy Chinook, providing healthier conditions for the fish.
• Modifies the temperature of the lower Deschutes River to more closely match what it was before the dams were constructed.
• Improves the water quality both in the reservoirs and in the river.

In addition, 100 percent of all powerhouse flows are screened to protect the fish.

Fish passage issues
The tower consists of three sections and is being constructed on a floating barge at the right side of Round Butte dam. As each section is completed, it will be floated over to the intake site and lowered into place.

• Bottom section – attaches to the existing powerhouse intake and completely screens the powerhouse flows so fish can’t get in
• Pipe – 40-foot diameter steel pipe connects the bottom intake with the top intake, mixing the warmer surface water with the colder bottom water
• Top section – floating fish collection facility with two V-screens that allow for both fish collection and water intake for powerhouse generation

Once the top section is in place, the access bridge will anchor it to the shoreline and provide a means to transport people, materials and equipment to the fish collection facility.

How it works
When the tower is completed, it will draw water both from the warmer surface layer and from the colder bottom layer of Lake Billy Chinook. This will be enough to change the currents in the lake to draw fish toward the tower and into the fish collection facility. The fish are collected in the two V-screens and sorted by size. Larger fish (bull trout and kokanee) are returned to the lake. The smaller fish are further sorted and tagged on an adjacent floating Fish Transfer Facility. The juvenile Chinook salmon and steelhead are then trucked and released downstream to continue their migration to the sea.

Why this design
PGE and the Tribes spent many years researching different options for restoring fish passage above Pelton Round Butte. Of all the proposals they reviewed, this plan was the most effective in attracting fish into the facility and maintaining the current level of power output. It was also the most cost effective design. Other options would have either decreased the power output of the facility, cost more or both.