Initial results reveal that modifications to Wanapum and Rock Island dam’s fish ladders following the discovery of a fracture in the Wanapum Dam structure are allowing safe passage to upstream migrating adult salmon and steelhead.

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Initial results reveal that modifications to Wanapum and Rock Island dam’s fish ladders following the discovery of a fracture in the Wanapum Dam structure are allowing safe passage to upstream migrating adult salmon and steelhead.

Direct observation studies demonstrate salmon successfully navigating the modified ladder and passing upstream. Most recent fish counts show 31 spring chinook and 102 steelhead successfully exiting the Wanapum Dam left bank fish ladder. These are the first of an anticipated 15,000 spring chinook expected to make their way up the Columbia River to spawning habitat. 36 miles upstream from Wanapum, three steelhead and eight whitefish have passed Rock Island Dam ladders since official fish counts began this week.

Two additional evaluation techniques will assist in the active monitoring of adult passage in the coming days. These techniques include tagging 250 hatchery-program adult spring chinook salmon at Priest Rapids Dam with a combination of PIT tags and acoustic tags and releasing them below Wanapum Dam. The technology allows biologists to monitor the progress of tagged fish as they advance up the river past Wanapum and Rock Island dams. As additional data confirms effective passage the utility hopes to end the trap-and-haul method currently in place at Priest Rapids Dam.

Utility biologists and engineers are confident that results will continue to affirm that modifications installed at both dams allow for safe and effective fish passage, said Grant County PUD in a statement, adding that both hydroelectric facilities have safely passed fish for more than 50 years and it believes these early results are an indication of what will likely be another successful passage season.

Since the onset of the Wanapum Spillway incident a collaborative group comprised of representatives from The Confederated Tribes of the Colville Reservation, the Yakama Nation, The Confederated Tribes of the Umatilla, The Wanapum Band of Priest Rapids, NOAA Fisheries, WDFW, USFWS, Chelan PUD and Grant PUD have been working to identify innovative ways to safely pass fish. The solutions in place are a result of their efforts.

Image: Wanapum dam, courtesy of Grant County PUD