BEVERLY - Grant PUD officials said Wednesday they expect 99 percent of juvenile fish to safely pass through the newly built Priest Rapids fish bypass.

A fish bypass allows yearlings to pass downstream, but uses large amounts of water that could otherwise be transferred into power generation.

The old fish bypass at Priest Rapids Dam used 110,000 cubic feet per second, while the new one uses 27,000 cfs. The bypass cost the utility $28 million, but will pay for itself within seven years with the increased potential in power generation, according to the utility.

Beginning this week, Grant PUD will begin transporting and releasing 3,400 tagged juvenile steelhead and yearling Chinook salmon about 38 miles above Wanapum Dam via helicopter as the utility begins studies on juvenile fish passage.

The studies evaluating the survival and behavior of juveniles moving through the new fish bypass are part of a 2008 agreement with the National Oceanic and Atmospheric Administration.

The results will inform Grant PUD and other agencies about the impacts of the lowered river condition on juvenile fish. The results will also show the utility route-specific behavior and survival rates of juvenile fish as they pass through Priest Rapids.

Adult fish passage at Wanapum

The utility said that as of last week, 31 adult Chinook salmon and 270 adult steelhead were counted exiting the modified fish ladders at Wanapum Dam.

Grant PUD continues to trap fish at Priest Rapids and truck them past Wanapum while experts evaluate the effectiveness of the newly modified fish ladders. As of April 27, the utility said they have transported 74 Chinook salmon and 27 steelhead around the lowered Wanapum Dam reservoir.

The reservoir will remain lowered until after the July 4 holiday, according to the utility.