Fish Passage Flumes Installed at Chittenden Locks in Ballard

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The U.S. Army Corps of Engineers, Seattle District, which operates the Locks, is reinstalling the four flumes in spillway gates 4 and 5 this week to help juvenile salmon and steelhead move through the project quickly and safely.

Visitors to the Hiram M. Chittenden Locks in Ballard can now see the smolt passage flumes on the Locks spillway again. The U.S. Army Corps of Engineers, Seattle District, which operates the Locks, is reinstalling the four flumes in spillway gates 4 and 5 this week to help juvenile salmon and steelhead move through the project quickly and safely.

The flumes provide a safe, water-efficient way for the fish to get through the Locks and into Puget Sound. The flumes have significantly reduced the harm and eased passage for juvenile salmon through the Locks to Puget Sound.

On the end of the slides are electronic PIT— passive integrated transponder— tag readers that can count fish that have been tagged to assist in our understanding of how fish pass through the Locks. The PIT-tag system in the slides provides information about survival and migration timing for juvenile salmon.

Studies in the 1990s showed that young salmon passing through the Locks from Lake Washington to Puget Sound had a difficult journey. Salmon were pulled into the filling culverts for the large locks, where some are injured or killed. Other salmon had a difficult time getting over the spillway near the fish ladder.

Fish passage at the Locks is key to salmon survival in the Lake Washington watershed, with every salmon and steelhead in Lake Washington going in and out through this route. Because of its importance, local, state and federal agencies, local governments and the Muckleshoot Tribe joined together to improve fish passage at the Locks.

The flumes are part of an overall project to improve fish passage, including:

  • seasonal installation of smolt passage slides in two spillway gates to help smolts safely out to sea
  • controlled large lock fills to reduce the force that pulls smolts into the filling culverts
  • measures to prevent adult salmon access to the diffuser well

These studies have been a cooperative effort among the U.S. Fish and Wildlife, Washington State Department of Fish and Wildlife, Muckleshoot Indian Tribe, City of Seattle, King County and Water Resource Inventory Area 8, and Seattle District, U.S. Army Corps of Engineers.

For current information about activities at the Locks, visit the Corps of Engineers Web site at http://www.nws.usace.army.mil and select “Dams and Locks” then “Lake Washington Ship Canal” from the left column.

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Andrea Takash

Public Affairs
U.S. Army Corps of Engineers
206-764-3750
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