Bridge Hunter indicates that 1977 is when the swing span was replaced by the lift span for navigational purposes. But a source indicates that it was added in 1955 to accommodate the barge traffic made possible by the building of the McNary Dam.
A BNSF bridge over the Columbia River also has swing and lift spans.
|C Hanchey Flickr via Bridge Hunter, License: Creative Commons Attribution-NonCommercial (CC BY-NC)
Burbank-Kennewick Railroad Bridge (Kennewick, Washington)
Historic 1924 Burbank-Kennewick Railroad Bridge over the Columbia River between Kennewick, Benton County and Walla Walla County, Washington. The bridge is owned by the Union Pacific Railroad. The bridge has a vertical lift span for navigation with five Parker through truss approach spans (including an old swing span).
|thebbz Photo via Bridge Hunter, Photo taken by Derrek Stewart,
License: Creative Commons Attribution-Share-Alike (CC BY-SA)
A time-lapse video of the lift span going down