Contra Costa Canal, Aqueduct system in Contra Costa County, California

The Contra Costa Canal is a 47-mile (76 km) aqueduct that begins at Rock Slough in the Sacramento-San Joaquin Delta and runs to Martinez. Built from 1937 to 1948, it is a fenced, earthen channel with concrete sides, about 18 feet wide and 6–8 feet deep in places, carrying water at up to 12 mph.

The canal grew from a 1930s initiative to develop water resources for the region, beginning construction as part of a broader water management scheme. Progress on the project stretched through the 1940s as wartime material scarcity slowed completion.

The canal's right of way carries the Contra Costa Canal Trail, a paved route for bikers, runners, pedestrians and equestrians that links schools, shops and public transport. Pittsburg held a three-day celebration when canal water arrived in 1940, and residents credited the new supply with better water quality than their local reserves.

Public trails run alongside the waterway, offering routes for walking and cycling through the region. These paths are generally easy to access and good for daytime outings.

The Contra Loma Reservoir, a 2,000 acre-foot basin in Antioch, was built as an emergency supply for the canal. Los Vaqueros Reservoir, approved by voters in 1988, stores water from the canal to improve water quality. Both are off-stream or emergency facilities that most visitors never see.