Nelson Creek is tributary to the upper Yakima River at river mile 193 on the Hundley property about 5 miles west of Cle Elum, WA in Kittitas County. A perched, undersized culvert (24” plastic pipe) at the confluence constitutes a fish passage barrier into important tributary rearing habitat in Nelson Creek. This project will cure the fish passage barrier into Nelson Creek by removing the old perched culvert and installing an 11 foot span horizontal ellipse culvert, with an 8 foot rise, to support a forest road. The new culvert will be partly filled with cobbles, gravel and sand to form a semi-natural stream channel connecting the Yakima River with upstream habitat in Nelson Creek. The larger drainage structure will substantially improve flood flow conveyance, passage of wood and debris, and natural bedload transport. The passage design is a combination of the WDFW “Stream Simulation Design” (2003) and Paul Tappel’s determinations of a semi stable streambed design- easily passable for all fish species and lifestages. Upstream of the new culvert and its semi-natural streambed will be a new 20 foot long transitional roughened channel to minimize head cut into the natural Nelson Creek streambed. The sponsor has collaborated with Yakama Nation Fisheries and Yakima Tributary Access and Habitat Program to create tributary habitat access and refuge from the regulated hydrograph of the Yakima River that runs contrary to the biological needs of salmon, steelhead, and bull trout.