Four Horns Dam Modification

Owner: Blackfeet Nation, Bureau of Indian Affairs
Location: Blackfeet Nation,  Browning, Montana
Project Summary: Project consists of constructing a new 6-mile-long access road to the project site including excavation, embankment and gravel surfacing. Excavation of existing earthen dam embankment, demolition of existing outlet works conduit and slide gates. Cofferdam construction to protect multiple work sites & diversion of 200 CFS of reservoir inflow around project, dewatering the work areas. Installation of new 60-inch and 84-inch inlet and outlet steel conduits, concrete encasement of new conduits, new cast-in-place concrete inlet structure, outlet structure and gate tower, new slide gates and operators, placing and compacting zoned earth materials for new dam construction, furnishing and placing riprap, furnishing and placing new drainage system for the dam, furnishing and constructing a new MSE wall, demolition of existing concrete spillway, baffled drop structure and check structure and constructing new cast-in-place labyrinth spillway with automatic siphons, new check structure and new baffled drop structure, final grading and reclamation of areas disturbed during construction.