Dam & Spillway Lake Berryessa, Glory Hole, Napa California
Lake Berryessa is the largest lake in Napa County, California. This reservoir is formed by the Monticello Dam, which provides water and hydroelectricity to the North Bay region of the San Francisco Bay Area.
The lake was named for the first European settlers in the Berryessa Valley, José Jesús and Sexto “Sisto” Berrelleza (a Basque surname, Anglicized to Berreyesa then later respelled Berryessa), who were granted Rancho Las Putas in 1843.
Prior to its inundation, the valley was an agricultural region, whose soils were considered among the finest in the country. The main town in the valley, Monticello, was abandoned in order to construct the reservoir. This abandonment was chronicled by the photographers Dorothea Lange and Pirkle Jones in their book Death of a Valley. Construction of Monticello Dam was begun in 1953, completed in 1958, and the reservoir filled by 1963, creating what at the time was the second-largest reservoir in California after Shasta Lake. The Monticello Dam with Lake Berryessa, Putah Diversion Dam with Lake Solano, and associated water distribution systems and lands are known collectively as the Solano Project, which is distinct from other federal water projects in California such as the Central Valley Project.
The lake has been heavily used for recreational purposes and encompases over 20,000 acres (80 km²) when full. The reservoir is approximately 15.5 miles (25 km) long, but only 3 miles (5 km) wide. It has approximately 165 miles (265 km) of shoreline. It has a seaplane landing area that is open to the public. One of the larger islands supported a small plane landing area, but was closed in the early 1970s after the FAA issued a safety report.
Near the dam on the southeast side of the reservoir is an open bell-mouth spillway, 72 feet (22 m) in diameter, which is known as the Glory Hole, the diamater of the pipe then shrinks down to about 28 ft. The spillway has a maximum capacity of 48,000 cfs.
The lake was the site of one of the infamous Zodiac murders on September 27, 1969.