Construction of the Swinomish jetty and McGlinn causeway during the 1930s interrupted a significant salmon migratory pathway between the Skagit River and Padilla Bay. We will model sediment transport, mixing of fresh/saltwater in the Swinomish Channel, and migratory rates and pathways of juvenile Chinook salmon following restoration of hydraulic connectivity between the North Fork Skagit River and Swinomish channel. This is a second phase of feasibility analysis of breaching the Swinomish jetty and McGlinn causeway to facilitate Chinook salmon access to important rearing habitat in Padilla Bay. It responds to issues identified in the first phase and evaluates a particular restoration alternative. We also propose 90%-level engineering design. The need for this study was identified in the Skagit Chinook Recovery Plan and the report on the first phase. Second phase tasks include: expand 3-D hydrodynamic model domain into Padilla Bay (aquire data on bathymetry, water salinity, tidal dynamics for Padilla Bay); evaluate Alternative 3 - lowering the jetty over a 60-ft width and >75-ft breach in the causeway; develop salinity probability histograms/rating curves for points along the Swinomish Channel; model sediment transport and sensitivity to restoration alternatives; model fish migration pathways and rates; 90%-level engineering design; data collection for model verification (water salinity and velocity); permitting and reporting.