Lewiston is a Federal-owned dam located in Trinity, California, along the Trinity River. Built in 1963 by the Bureau of Reclamation, this Earth-type dam stands at a height of 73 feet, with a structural height of 91 feet and a length of 745 feet. It serves a primary purpose of water supply, providing a storage capacity of 14,660 acre-feet and covering a surface area of 750 acres.

With a high hazard potential and a moderate risk assessment rating, Lewiston Dam plays a crucial role in managing water resources in the region. Despite not being state-regulated, the Bureau of Reclamation oversees its operations, inspections, and regulatory aspects. The dam's uncontrolled spillway, with a width of 66 feet, further underscores its importance for flood protection and water management in the area. Overall, Lewiston Dam stands as a significant infrastructure for water resource enthusiasts and climate advocates to monitor and study in Trinity County.