Lake Berryessa

Lake Berryessa

Lake Berryessa is the largest lake in Napa County. The lake is a human-made reservoir made from the damming of Putah Creek via the Monticello Dam. The main purpose of the lake is to provide fresh water and hydro power to the North Bay section of the San Francisco Bay Area. The name Berryessa comes from the European settlers to the Berryessa Valley, Jose Jesus and Sexto Berrelleza (Berreyesa in English). 

Geography Of Lake Berryessa

Lake Berryessa
Aerial view of Lake Berryessa.

At its full capacity, the lake has a surface area of roughly 80 square kilometers. Its dimensions are approximately 25 kilometers by 5 kilometers, with 265 kilometers of shoreline. The lake is fed by the headwaters from Putah Creek watershed, though Capell Creek, Pope Creek, and Eticuera Creek are all tributaries which also flow into the lake. These creeks are mainly a factor in the wet season, when precipitation levels are higher, whereas they dry out in the hot summer months. 

Lake Berryessa is also a  monomictic lake meaning the water inside the lake circulates or turns over once a year - in this case usually in the fall when the warmer water on the surface begins to cool and is the same temperature as the rest of the lake, therefore making it easier for the entire supply of water in the lake to circulate.

The Hole In Lake Berryessa

Lake Berryessa Hole
The drainage hole in Lake Berryessa.

The lake is also unique due to the large hole in the middle of it. This curious-looking phenomenon has the appearance of an infinity-pool style black hole in the center of the lake. The hole serves as a spillway with a pipe that helps to drain excess water, much like a drain hole in a bathtub, which only has waterflow when the water level in the lake is high enough. The drain measures 22 meters across, and drops for roughly 61 meters. To date, there is only one known casualty of someone who accidently got swept up in the drainage hole. 


Though the lake is synthetic, there is a rich forest which surrounds the area, and provides a home to a variety of wild animals. Common species of plant life in the region include white alder, sergeant cypress, leather oak, Jepson's navarretia, and Bridge's brodiaea. Sergeant cypress is especially common in the Cedar Roughs Wilderness, which sits beside the Lake Berryessa Recreational Area. 

Lake Berryessa wildlife
Geese along the shores of Lake Berryessa.

Aside from native plants, there are many species of native animals which live in and around the lake. Within the lake, there are a number of fish species, many of which are fished for recreation. Species include both large and smallmouth bass, as well as spotted bass, channel catfish, bullhead catfish, white catfish, carp, Sacramento pikeminnow, crappie, bluegill, rainbow and brook trout, threadfin shad, golden shiner, and Chinook salmon. Not all of these species are naturally found here, and many species have been artificially introduced to the lake. Aside from fish, animals in the region include western rattlesnakes, osprey, turkey and golden eagles, racoons, black-tailed deer and mountain lions. 

Visiting Lake Berryessa

Aside from its practical uses, Lake Berryessa is also a popular recreational destination. Activities in the area include boating (including kayaking and canoeing), jet and water skiing, swimming, fishing, cycling and motorbiking, hiking, pickincking, and bird watching. Various marinas and nearby resorts offer accommodations for such activities.

Lake Berryessa is both a practical source of freshwater to drier states, but also a useful source of hydro power for much of the area. On top of this, the area generates income from visitors who wish to experience the wilderness and beauty of Lake Berryessa, or swim and boat in its fine waters.


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