|Location||Napa County, California, U.S.|
|Operator(s)||Bureau of Reclamation|
|Dam and spillways|
|Length||1,023 ft (312 m)|
|Height||304 ft (93 m)|
|Width (base)||100 ft (30 m)|
|Total capacity||1,602,000 acre·ft (1.976×109 m3)|
|Catchment area||566 sq mi (1,470 km2)|
|Surface area||20,700 acres (8,400 ha)|
|Turbines||2 x 5 MW, 1 x 1.5 MW|
|Installed capacity||11.5 MW|
|U.S. Geological Survey Geographic Names Information System: Monticello Dam|
Monticello Dam is a dam in Napa County, California, United States constructed between 1953 and 1957. It is a medium concrete-arch dam with a structural height of 304 ft (93 m) and a crest length of 1,023 ft (312 m). It contains 326,000 cubic yards (249,000 m³) of concrete. The dam impounded Putah Creek to cover the former town of Monticello and flood Berryessa Valley to create Lake Berryessa, then the second-largest man-made lake in California. The capacity of the reservoir is 1,602,000 acre·ft (1.976×109 m3). Water from the reservoir primarily supplies agriculture in surrounding areas. The dam is noted for its classic, uncontrolled morning-glory type spillway. The diameter at the lip is 72 ft (22 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 area of San Francisco. To the south is Putah Creek State Wildlife Area.
Morning Glory Spillway
The dam's spillway is the largest drain in the world. The Glory Hole is 72 feet (22 m) in diameter at lake level and narrows down to about 28 feet (8.5 m) at the exit. At the lake's peak level the spillway can drain 48,400 cubic yards (37,000 m3) per second. Swimming near the glory hole is prohibited. The exit of the spillway is famous in the skateboarding world as a full-pipe.
|Wikimedia Commons has media related to Monticello Dam.|
- "Monticello Dam: Hydraulics & Hydrology". United States Bureau of Reclamation. Retrieved March 24, 2011.
- Antonio Martinez Ron. "The Largest Drain Hole in the World". Retrieved June 29, 2013.
- "Woman Sucked Into Lake Berryessa Spillway". San Francisco Chronicle. March 12, 1997. Retrieved June 29, 2013.