Corps installing fish passage smolt flumes at Chittenden Locks in Ballard

Published April 14, 2015

SEATTLE – The Army Corps of Engineers, which operates the Hiram M. Chittenden Locks, is installing four smolt flumes in spillway gates four and five. Work begins April 14 and continues for several days.

As part of an overall project to improve fish passage, the flumes are installed each spring in the two spillway gates to help provide juvenile salmon and steelhead – smolt – safe passage through the Locks and into Puget Sound. The flumes have significantly reduced harm and eased passage for smolt through the Locks to Puget Sound.

On the end of the flumes are electronic passive integrated transponder, or PIT, tag readers that identify previously tagged fish. This system helps scientists understand smolt survival and migration through Lake Washington and the Locks.

Fish passage at the Locks is key to salmon survival in the Lake Washington watershed because the Locks are the only route for fish to the Puget Sound. 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 were injured or killed. Other salmon had a difficult time getting over the spillway near the fish ladder.

“We’re constantly examining ways to improve salmon survival in and around the Locks,” said Seattle District Fish Biologist Scott Pozarycki. “A number of improvements have been made over the years in coordination with our many partner agencies including the City of Seattle, King County, Muckle­shoot Indian Tribe, Washington State Department of Fish and Wildlife, U.S. Fish and Wildlife Service, and National Marine Fisheries Service.”

For current information about activities at the Locks, visit the Locks’ Web site at or follow the Locks on Facebook and Twitter: and

Bill Dowell

Release no. 15-008