This project will implement final designs (15-1324) for fish passage improvements in a 5,000 foot long reach of the concrete-lined Mill Creek flood control channel. The implementation-project reach connects with a passage project completed in 2011 (Mill Creek Flume Transitions, 09-1587). Flood control measures on Mill Creek include a concrete channel that extends over two miles through Walla Walla. The Mill Creek Barrier Assessment (06-2203) completed in 2009 identified and described barriers for ESA listed steelhead and bull trout, and for reintroduced spring chinook. Returning adults encounter flow dependent depth and velocity barriers, and a lack of resting opportunities. Juvenile fish encounter low spring flows, and high water temperatures in late spring. Often by mid-May adults and juveniles become trapped in the flood control channel where they experience lethal temperatures. Many of these passage issues are considered as imminent threats in the Snake River Salmon Recovery Plan. Mill Creek, upstream of the flood control project, is a critical and under-utilized area for spawning and rearing of ESA listed species, and provides for an important recovery opportunity for those listed fish, as well as good habitat for other native fish and reintroduction efforts for spring chinook.