Upper Crystal Springs Reservoir is part of the Crystal Springs Reservoir system located in San Mateo County, California. The reservoir sits atop the San Andreas Rift Zone and was formed in 1877 when an earthen dam was constructed to submerge Laguna Creek. Highway 92 now crosses the causeway between Upper and Lower Crystal Springs Reservoirs.

Paddling is not permitted on Upper Crystal Springs Reservoir. The entire Crystal Springs Reservoir system is a protected water source for San Francisco and surrounding areas, and public access to the water is prohibited. While there are trails that offer views of the reservoir, direct water access is not allowed due to water quality protection measures.

The Crystal Springs Regional Trail runs along the eastern edge of the reservoir, providing scenic views for hikers, cyclists, and equestrians. The trail is over 15 miles long and divided into three segments. The Upper Crystal Springs Reservoir can be viewed from the southernmost Crystal Springs segment, which is unpaved and open only to hikers and horseback riders.

Wildlife viewing opportunities are abundant in the protected watershed lands surrounding the reservoir. Bald eagles have nested near the reservoir since 2012, the first recorded nesting in San Mateo County in almost 100 years. The area also provides habitat for rare and endangered plant species.

Historically, the reservoir covers the former site of Laguna Grande, a natural lake where the Portolà Expedition camped in 1769. The surrounding lands were once inhabited by Ohlone people before European contact.

While paddling is not permitted, the Crystal Springs Reservoir system plays a vital role in the region's water supply. Some of the water comes from local precipitation, but most is piped in from Hetch Hetchy Reservoir in Yosemite National Park and other watersheds. The reservoirs serve as an emergency backup water supply for the San Francisco Peninsula.