Tri-State Steelheaders completed design and constuction of passage improvements at four channel spanning weirs (sills) within the flood control channel on Mill Creek in Walla Walla. The project also developed conceptual designs to achieve fish passage over the remaining 259 sills on Mill Creek. These structures were identified as barriers in the Mill Creek Barrier Assessment completed in 2009. The Mill Creek flood control channel creates water quality problems and presents a series of complex fish passage barriers. It includes a diversion dam, storage reservoir, and a 6.7 mile long flood control channel, which includes 263 sills within three miles. ESA listed steelhead and bull trout, and reintroduced spring Chinook utilize the flood control channel during migrations. Returning adults encounter flow-dependent passage problems associated with channel spanning weirs, light attraction barriers (in the underground sections), and a lack of resting water in the concrete channel section, among other problems. 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 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.