Portal Forebay Main is a privately owned hydroelectric dam located in Fresno, California. Completed in 1956, this Earth-type dam stands at a height of 65 feet and has a length of 795 feet, with a maximum storage capacity of 390 acre-feet. The dam serves the primary purpose of generating hydroelectric power, utilizing the flow of Camp 61 Creek to produce energy.

Managed by the Federal Energy Regulatory Commission, Portal Forebay Main has a low hazard potential and is inspected every two years to ensure its safety and structural integrity. The dam features an uncontrolled spillway with a width of 100 feet, and its risk assessment is determined to be moderate. Despite its age, the dam's condition assessment is not available, and there are no specific risk management measures outlined for the site.

Located in the picturesque surroundings of Mono Hot Springs, Portal Forebay Main is a key player in California's water resource infrastructure. Its historical significance and ongoing role in hydroelectric power generation make it a noteworthy site for water resource and climate enthusiasts to explore and study.