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 spillway operates when there is excess water in the reservoir; in 2017 after heavy rains it started flowing, for the first time since 2006.

The discovery of gold in the foothills of the Sierra Nevada brought an influx of people to the Central Valley.

In 1907, a few cities in the Bay Area were interested enough to hire three engineers, including Arthur Powell Davis and George Washington Goethals.

Putah Creek was the town's life source, it provided them with close access to water for both crop and livestock raising.

[9] This abandonment was chronicled by the photographers Dorothea Lange and Pirkle Jones in their work Death of a Valley, published in Aperture magazine in 1960.

[citation needed] The creation of Monticello Dam and Lake Berryessa were not intended for public and recreational use.

The lake was initially fenced off but interest from the public increased and many people still managed to access the water in the first two years.

When the contracts ended, all the recreational facilities and mobile homes were forced to move from federal property.

The new reclamation has yet to seriously start any new development on recreational activities at the lake though a new multi-purpose trail is to be in the future.

[18] The Bureau of Reclamation held an open bid period in 2015 to businesses for developmental opportunities at Lake Berryessa.

Based on rules against exclusive occupancy of federal recreation lands, about 1,300 long-term resident trailers were removed from the resorts when the 50-year concession contracts expired.

In the following years, public usage of the lake dwindled due to government delays in formulating a future plan.

One of the larger islands contained a small plane landing area but it was closed in the early 1970s in response to a safety report issued by the Federal Aviation Administration (FAA).

Fish species at Lake Berryessa include; largemouth bass (Micropterus salmoides), smallmouth bass (Micropterus dolomeiu), spotted bass, channel catfish (Ictalurus punctatus), bullhead catfish (Ictalurus dolomeiu), white catfish (Ameiurus catus), carp (Cyprinus carpio), Sacramento pikeminnow (Ptychocheilus grandis), crappie, bluegill (Lepomis macrochirus), rainbow trout (Onchorhynchus mykiss), brown and brook trout, Kokanee, and also Chinook salmon (Onchorhynchus tschawytscha).

[27] Besides the Sacramento pikeminnow, Lake Berryessa also has the golden shiner and threadfin shad which are usually baitfish to the other species of fish.

The California Office of Environmental Health Hazard Assessment (OEHHA) has issued a safe eating advisory for any fish caught in Lake Berryessa due to elevated levels of mercury.

Mercury levels at Lake Berryessa are on the rise and there are no fish that OEHHA recommend to eat more than three times a week.

The Northern California Coastal Wild Heritage Wilderness Act of 2006 set aside the former study area of 6,350 acres (25.7 km2) located 1.8 miles (2.9 km) past Pope Creek bridge on the Pope Creek arm of Lake Berryessa.

Hiking can be difficult as more than half of the wilderness area consists of Sargent's cypress, which covers 3,000 acres (12 km2) and is relatively pure genetically.

It is the second most widely distributed cypress in California, and was named for Charles Sprague Sargent (1841–1927), the founder and director of Harvard University's Arnold Arboretum and author of the 14-volume Silva of North America.

[32] Notable plants in the area include sergeant cypress, white alder, leather oak, Jepson's navarretia, and Bridge's brodiaea.

The east side of the lake has a 2,000-acre (8.1 km2) Wildlife Management Area managed by the California Department of Fish and Game that protects wildlife habitats for such species as mountain lion, black-tailed deer, western rattlesnake, raccoon, skunk, osprey, turkey, rabbit and golden eagle.

On the evening of September 27, Pacific Union College students Bryan Hartnell and Cecelia Shepard were picnicking at Lake Berryessa on a small island connected by a sand spit to Twin Oak Ridge.

A man approached them wearing a black executioner's-type hood with clip-on sunglasses over the eye-holes and a bib-like device on his chest that had a white 3 by 3 inches (76 by 76 mm) cross-circle symbol on it.

Hartnell initially believed it to be a weird robbery, but the man drew a knife and stabbed them both repeatedly.

The killer then hiked 500 yards (460 m) back up to Knoxville Road, drew a cross-circle symbol on Hartnell's car door with a black felt-tip pen, and wrote beneath it: "Vallejo/12-20-68/7-4-69/Sept 27–69–6:30/by knife", the location and dates of the killer's first two crimes, and the date and time of the crime he had just committed.

At 7:40 p.m. (19:40), the killer called the Napa County Sheriff's office from a pay telephone to report this latest crime.

After hearing their screams for help, a man and his son who were fishing in a nearby cove discovered the victims and summoned help by contacting park rangers.

Napa County Sheriff Detective Ken Narlow, who was assigned to the case from the outset, worked on solving the crime until his retirement from the department in 1987.