Lower Peak Lake Main, also known as Cascade Lakes, is a privately-owned hydroelectric dam located in Placer County, California. This earth dam stands at a height of 31 feet and was completed in 1860, showcasing its historical significance in water resource management. With a storage capacity of 484 acre-feet and a surface area of 33.3 acres, Lower Peak Lake Main serves as a vital component in the regional water infrastructure, regulating the flow of the South Yuba River tributary.

Managed by the Federal Energy Regulatory Commission, Lower Peak Lake Main is subject to state regulations, permitting, inspection, and enforcement to ensure its structural integrity and operational safety. Despite being classified as a low hazard potential structure, the dam poses a high risk due to its age and lack of detailed condition assessment. In case of emergencies, the dam operators are required to have an Emergency Action Plan in place, although details on its preparation and compliance with guidelines are currently unavailable.

With its picturesque location in Washington, California, Lower Peak Lake Main stands as a testament to the intersection of water resource management and historical engineering achievements. As climate change continues to impact water availability and infrastructure resilience, the importance of maintaining and updating structures like Lower Peak Lake Main becomes increasingly crucial for sustainable water management in the region.