Lably
Skip to content

Lake Berryessa

Reservoir in California, United States

  • 15 min read
  • 7 chapters

Related on Lably

Through Lake, Reservoir and Hydroelectricity

The reservoir was named after the Berryessa family of California; José Jesús and Sexto "Sisto" Berryessa were granted Rancho Las Putas in 1843.

Geography

The lake is over 20,000 acres (8,100 ha) when full. It is approximately 16 mi (25 km) long and 3.1 mi (5 km) wide. It has approximately 165 mi (265 km) miles of shoreline.

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 pipe has a straight drop of 200 feet (61 m), and the diameter shrinks down to about 28 feet (8.5 m). The spillway has a maximum capacity of 48,000 cfs (1360 m3/s). The spillway operates when there is excess water in the reservoir; in 2017 after heavy rains it started flowing, for the first time since 2006. It started flowing again in 2019 after heavy rains. In 1997 a woman was killed after being pulled inside the spillway.

Geology

The active Green Valley Fault runs parallel to the Lake in the hills to the west.

Climate

The National Weather Service has maintained a cooperative weather station at the lake since November 1, 1957. Records show that the area has hot, mostly dry summers and cool, wet winters. Normal January temperatures are a maximum of 57.4 °F (14.1 °C) and a minimum of 36.4 °F (2.4 °C). Normal July temperatures are a maximum of 94.8 °F (34.9 °C) and a minimum of 56.8 °F (13.8 °C). There is an average of 90.7 days with highs of 90 °F (32 °C) or higher and an average of 24.1 days with lows of 32 °F (0 °C) or lower.

The record high temperature was 115 °F (46 °C) on July 24, 2006. The record low temperature was 13 °F (−11 °C) on December 22, 1990.

The wettest year was 1983 with 56.94 inches (1,446 mm) and the driest year was 1976 with 7.78 inches (198 mm). The most precipitation in one month was 21.33 inches (542 mm) in January 1995. The most precipitation in 24 hours was 5.29 inches (134 mm) on December 31, 2005. Snowfall is very rare, but 0.4 inches (10 mm) fell in January 1974.

Sign in to keep reading

6 more chapters are free with a Lably account.

More in Physical geography