Monticello Dam is a concrete gravity dam located in Napa County, California. Completed in 1957, it was built to create Lake Berryessa, which serves as a water supply and recreational area. The dam stands 304 feet tall and spans 1,400 feet across the Putah Creek. The primary purpose of Monticello Dam is flood control and water storage for agricultural and urban use. It is operated by the U.S. Bureau of Reclamation and plays a crucial role in managing water resources in the region. The dam also features a spillway that allows excess water to be safely released during heavy rainfall.