Lower Monumental Lock and Dam was authorized by the River and Harbor Act of 1945. The project includes a dam, a powerhouse, navigation lock, two fish ladders, a juvenile fish facility (JFF), and associated facilities. It provides navigation, hydroelectric generation, recreation, and irrigation. The dam, located on the Snake River, is 3,791 feet long, with an effective height of about 100 feet. It is a concrete gravity-type dam, with earthfill abutment embankments.
Lake West, the project’s reservoir, offers a variety of recreation opportunities such as fishing, swimming, picnicking, boating, hunting, hiking and camping.