Corps reinstalling fish passage smolt flumes at Chittenden Locks in Ballard

Published April 14, 2014

SEATTLE – The Army Corps of Engineers, which operates the Hiram M. Chittenden Locks, is reinstalling four smolt flumes in spillway gates four and five. Work begins April 21 and continues for several days.   

As part of an overall project to improve fish passage, the flumes are reinstalled 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 (PIT) tag readers that count fish that have been tagged to assist in our understanding of how fish pass through the Locks. This system provides in­formation about smolt survival and migration.

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. 

Because of the importance of fish passage at the Locks to the Lake Washington watershed, there have been ongoing cooperative improvement efforts among the U.S. Fish and Wildlife Service, National Marine Fisheries Service, Washington State Department of Fish and Wildlife, Muckle­shoot Indian Tribe, City of Seattle, King County and Water Resource Inventory Area 8, and the Seattle District of the U.S. Army Corps of Engineers.

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

Steve Cosgrove

Release no. 14-017