5.3 Project Area 39 (River Mile 4.95 to 4.5)
Project Area 39 (PA-39) is located in the channel and along right bank between RM 4.95 to RM 4.5 in the town of Starbuck, Washington. This project area includes the U.S. Army Corps of Engineers (USACE) Starbuck levee along the right bank that extends through the
entire project area.

5.3.1.1 Channel Characterization
The channel in the project area consists mostly of a single-thread, confined channel. In the area immediately upstream of the Kellogg Road Bridge, the channel is wider and has braided channel characteristics with multiple gravel bars and flow paths. This depositional area is likely the result of backwater conditions created by the constriction caused by the bridge and Starbuck levee. In this dynamic area, recent channel migration is evident with recent wood recruitment in the channel. The channel is a single-thread channel downstream of the Kellogg Bridge and flows along the base of the Starbuck levee (right bank). One large pool
(i.e., Starbuck Swimming Hole) is located downstream of the Kellogg Road bridge at the bedrock outcrop located along the left bank at RM 4.6.

5.3.1.2 Floodplain Characterization
There is limited floodplain within the project area and the channel is highly confined due to the alignment of the Starbuck levee. The levee extends along the right bank throughout the entire project area (RM 4.95 to 4.5), limiting channel migration and floodplain development along the right bank. This levee protects the town of Starbuck from high flood waters during peak flows. Along the left bank is a high-cut bank (upstream of Kellogg Road bridge) and a bedrock outcrop (RM 4.6) that limits floodplain connectivity and channel migration along the left bank. Some overbank area exists along the left bank immediately upstream and
downstream of the Kellogg Road Bridge. The riparian zone through the project area is generally in poor to moderate health. Riparian vegetation along the right bank is limited due the presence of the Starbuck levee downstream of the Kellogg Road Bridge. Dominant tree species in the area consists of alder and locust. Recent vegetation removal of trees on the levee face is evident. USACE levee requirements limit the diameter size of vegetation allowed to grow on the face and levee toe. Upstream of
the Kellogg Road Bridge (right bank), vegetation occurs between the levee and active river channel with young to mature alder trees present between the margins of the active channel and the Starbuck levee. Limited to no riparian vegetation is present upstream of the Kellogg Road Bridge crossing on the left bank). Because of the limited riparian zone, channel shading is lacking throughout most of the project area.

5.3.2 Conceptual Project Actions
Recommendations for PA-39 are to setback the Starbuck levee throughout the area, replace the Kellogg Road Bridge with a wider span, and improve pier and abutment placement. Two setback options are potentially feasible throughout the project area. The first option is to setback the Starbuck levee extent along the entire project area (RM 4.95 to RM 4.5). The second option is to setback the levee downstream of the Kellogg Road Bridge where the channel is more confined and lacks complexity. Both options include replacing the Kellogg Road Bridge.