The existing Route 9/125 Bridge over the Androscoggin River at Durham/Lisbon Falls was recently replaced. The bridge is located approximately 1200’ downstream of the Worumbo Dam and spans the narrowest segment of the river. The bridge is founded on rock at both abutments and at the piers on rock islands. A channel that carries flow from the dam tailrace is located below the eastern opening between the abutment and the first pier. The bridge has two piers and two abutments. Northstar provided hydrologic, hydraulic and scour evaluations associated with the design of a replacement bridge with the final alignment residing upstream of the existing bridge.