Lake Valley Main is a privately owned dam located in Placer, California, in the city of Washington. Built in 1889 for hydroelectric purposes, this earth dam stands at a height of 75 feet and spans a length of 1035 feet. With a storage capacity of 7964 acre-feet and a normal storage of 7700 acre-feet, the dam holds back the waters of the North Fork American River, covering a surface area of 298 acres and serving a drainage area of 4.5 square miles.

Managed by the Federal Energy Regulatory Commission, Lake Valley Main is deemed to have a high hazard potential, with a maximum discharge capacity of 5200 cubic feet per second. While the dam lacks a spillway, its inspection, enforcement, and regulatory oversight are carried out by both state and federal agencies. Despite its age, the dam remains in operational condition, with the last inspection conducted in September 2020. With its historical significance and vital role in hydroelectric power generation, Lake Valley Main stands as a testament to the importance of sustainable water resource management in the face of climate change challenges.