Monticello Dam is a dam

Dam

A dam is a barrier that impounds water or underground streams. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions. Hydropower and pumped-storage hydroelectricity are...

 in Napa County, California

Napa County, California

Napa County is a county located north of the San Francisco Bay Area in the U.S. state of California. It is coterminous with the Napa, California, Metropolitan Statistical Area. As of 2010 the population is 136,484. The county seat is Napa....

, United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 constructed between 1953 and 1957. It is a medium concrete-arch dam

Arch dam

An arch dam is a type of dam that is curved and commonly built with concrete. The arch dam is a structure that is designed to curve upstream so that the force of the water against it, known as hydrostatic pressure, presses against the arch, compressing and strengthening the structure as it pushes...

 with a structural height of 304 ft (93 m) and a crest length of 1023 ft (311.8 m). It contains 326,000 cubic yards (249,000 m³) of concrete. The dam impounded Putah Creek

Putah Creek

Putah Creek is a major stream in Northern California, a tributary of the Yolo Bypass. The creek has its headwaters in the Mayacamas Mountains, a part of the Coast Range...

 to cover the former town of Monticello

Monticello, California

Monticello was a town in Napa County, California. The site of the settlement is completely covered by Lake Berryessa.-History:Monticello was a town erected within Rancho Las Putas, a Mexican land grant of given in 1843 by Governor Manuel Micheltorena to José de Jesús Berelleza and Sexto "Sisto"...

 and flood Berryessa Valley to create Lake Berryessa

Lake Berryessa

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....

, then the second-largest man-made lake in California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

. The capacity of the reservoir is 1602000 acre.ft. Water from the reservoir primarily supplies agriculture in surrounding areas. The dam is noted for its classic, uncontrolled morning-glory type spillway

Spillway

A spillway is a structure used to provide the controlled release of flows from a dam or levee into a downstream area, typically being the river that was dammed. In the UK they may be known as overflow channels. Spillways release floods so that the water does not overtop and damage or even destroy...

. The diameter at the lip is 72 ft (21.9 m). Locally, the spillway is also known as 'The Glory Hole'.

The Monticello Dam Powerplant was built at the dam in 1983 and has three generators. The electrical power is sent mostly to the North Bay

North Bay (San Francisco Bay Area)

The North Bay is a subregion of the San Francisco Bay Area, in California, United States. The largest city is Santa Rosa. It is by far the least populous and least urbanized part of the Bay Area...

 area of San Francisco.