North Fork Smith River Dam

North Fork Smith River (NFSR) Dam is a 93-foot-high zoned earth fill dam providing recreational opportunities and irrigation water in central Montana. The 70-year-old high-hazard dam was experiencing significant deterioration of the spillway and outlet, inadequate spillway capacity, and uncontrolled foundation seepage.

DOWL performed a detailed feasibility study that included field investigations, hazard evaluation, flood hydrology, and development of rehabilitation alternatives. The feasibility study also included an environmental review of the impacts associated with the alternatives and an economic analysis of funding alternatives. The selected solution involved constructing a new labyrinth crest to enhance the spillway capacity; excavation of an unlined rock channel for the enlarged spillway; utilizing the rock excavation as a stabilizing toe berm over the new toe drain system; and repair of the outlet conduit.