In response to the Great Depression and drought conditions in California during the early 20th century, the United States Congress passed the 1935 Rivers and Harbors Act, which authorized the Central Valley Project (CVP) – a system of dams and canals to provide a stable supply of irrigation water to California's Central Valley.

[4] Six years later, however, the U.S. Bureau of Reclamation (USBR), which was responsible for the construction and operations of most CVP facilities, revived the division, which comprised a system of four dams and two tunnels to capture and store the flow of the Trinity and transport it to the Sacramento River, generating a net surplus of hydroelectric power along the way.

[4] Rock placement began on the main structure as early as 1957, but it was not until 1959 when an 11,000 ft (3,400 m) conveyor belt was incorporated, allowing much faster transport of fill to the dam site.

[6] As the reservoir filled, it submerged the pioneer towns of Trinity Center, Stringtown and Minersville as well as parts of a historic Northern California stagecoach route.

The plant generates an average of 358.97 million kilowatt hours (kWh) and has a low capacity factor, which means it operates mainly on a peaking basis.

In addition, the dam blocks the Trinity River's annual floods and sediment loads, leading to degradation in the gravel bars that are vital for salmon habitat.

[5] In 1992, Congress passed the Central Valley Project Improvement Act, which established a minimum annual release of 340,000 acre-feet (420,000 dam3) into the lower Trinity River.

The lake has been developed with boat ramps and marinas, most of which are concentrated in the Stuart Fork arm in the southwest and around the resort town of Trinity Center near the north end of the reservoir.