Lake Berryessa is a federal reservoir formed when the Bureau of Reclamation built Monticello Dam in 1957. Monticello Dam is located on Putah Creek where the stream crosses the eastern boundary of Napa County. It regulates flows along the lower reaches of Putah Creek and stores surplus water. The dam is a concrete, medium-thick arch structure with a height of 304 feet above the foundation and a crest length of 1,023 feet.
Morning glory spillway
When water levels rise above 440 feet, water starts flowing down a funnel-like ‘morning glory spillway’ (pictured above) into Putah Creek. Located directly behind the dam, it is a type of drop inlet spillway, and was chosen due to limited space and adequate rock foundation. (Its construction photo also above.)
At the surface, the spillway measures 72 feet across. Water drops about 200 feet straight down a narrowing shaft, measuring 28 feet in diameter at the bottom, where it then turns 90 degrees and flows into Putah Creek, and eventually into the Yolo Bypass.
Monticello Dam Powerplant
Monticello Dam Powerplant was built in 1983. It is at the base of the Monticello Dam, and has 3 generators. It was built under a FERC license and is owned, operated and maintained by Solano Irrigation District.
Lake Berryessa has a storage capacity of 1,602,000 acre-feet. Visit Lake Berryessa's website at: https://www.usbr.gov/mp/ccao/berryessa/index.html.
|National ID Number||CA10170|
|Base Width||100.0 ft|
|Crest Elevation||456.0 ft|
|Structural Height||304.0 ft|
|Hydraulic Height (Normal Operating Depth at Dam)||239.0 ft|
|Crest Length||1023.0 ft|
|Crest Width||12.0 ft|
|Top of Active Conservation Pool (Elevation)||549.0 ft|
|Volume of Dam Construction Materials||326000.0 cu yd|
Hydraulics & Hydrology
|Total Water Storage at Elevation||48400.0 acre-ft at 455.5|
|Outlet Works Capacity at Elevation||2580.0 cfs at 455.5 ft|
|Hydrometeorological Report (HMR)||HMR|
|Drainage Area||566.00 sq mi|