Abstract Submission: Natural Waters, LLC working for the Washington State Department of Transportation (WSDOT), assisted in assessing the effects of the removal of the Elwha River dams (Glines Canyon and Elwha) on the existing and newly constructed US 101 Elwha River bridges. Both dams had influences on the Elwha River reach from above Glines Canyon Dam, through the US 101 crossings and downstream to the Strait of Juan de Fuca. The effects to-date along with the estimated effects to occur in the future, were used to assess the vulnerability of the existing US 101 bridge and aid in the design of the newly constructed bridge. To assess the existing and newly constructed US 101 Elwha River Bridge crossings, several hydraulic analyses were performed utilizing SRH-2D, a two-dimensional, depth-averaged hydraulic model developed by the U.S. Bureau of Reclamation. The SRH-2D model allowed for a detailed understanding of the hydraulics through the existing and newly constructed bridge crossings. This presentation will provide a summary of the analyses conducted and visualization tools used to assess and communicate the vulnerability of the existing bridge and design the new bridge in a river system which has had two large dam removal projects. It will also provide a summary of considerations practitioners should assess when dams are being removed with critical infrastructure located nearby.
