Monticello Dam is a concrete arch dam located in Napa County, California. It was constructed in 1953 by the United States Bureau of Reclamation and is situated on Putah Creek, a tributary of the Sacramento River. Monticello Dam Morning Glory Spillway is one of the largest drain holes in the world.
Lake Berryessa is the largest lake in Napa County, California. It is located in the Vaca Mountains, east of the city of Napa. Lake Berryessa is a reservoir formed by the Monticello Dam, which is located at the southeastern end of the lake. The lake has a surface area of about 20,700 acres (8,400 hectares) when full.