Trinity Dam is an earthfill dam on the Trinity River located about 7 miles (11 km) northeast of Weaverville, California in the United States. The dam was completed in the early 1960s as part of the federal Central Valley Project to provide irrigation water to the arid San Joaquin Valley.Standing 538 ft (164 m) high, Trinity Dam forms Trinity Lake – California's third largest reservoir, with a capacity of more than 2,400,000 acre feet (3,000,000 dam3).