Auburn Dam - Early History

Early History

In the 1850s, the city of Sacramento was rapidly growing around the confluence of the Sacramento River and its tributary the American River, near the middle of the Central Valley of California. The city's increasing population necessitated the construction of an extensive system of levees on the two rivers to prevent flooding, especially on the American. The flood control works were not enough to keep the rivers within their beds, however; in 1862, the city was inundated so completely that the state government was temporarily moved to San Francisco. In 1956, the U.S. Army Corps of Engineers built the Folsom Dam on the lower American, near the confluence of its North and South Forks, to provide flood control for the Sacramento metropolitan area. However, the Folsom Dam provided inadequate flood storage, and overflowed on several occasions since its construction. In fact, a flood in 1955 filled the Folsom Reservoir to capacity, before the dam was even completed.

Water demand in the Central Valley in the Sacramento area was also growing, mainly for agricultural usage. In 1854, a diversion dam was constructed on the North Fork American River at the site of Auburn Dam, to divert water into a series of ditches that supplied irrigation water for downstream farms. Irrigation with dam and canal systems was favored because severe flow fluctuations in Central Valley rivers created floods in some years and droughts in others. It was in this light that the Auburn Dam was first contrived. As early as the 1950s, plans for a giant dam at the Auburn site were already being considered, in the name of flood control. Several designs, both earthfill and concrete, were considered. Before the dam could be built, however, the Auburn-Foresthill Road, which crossed the river just upstream of the dam site, had to be relocated. Even before the project was authorized, several companies had already taken contracts for the construction of a high bridge to carry the road over the proposed reservoir and preliminary excavations at the dam site.

Auburn Dam was to be a massive flood-control and storage structure on the North Fork of the American River, just upstream from Folsom Reservoir. It would create a reservoir with more than twice the capacity of Folsom, which could help reduce floods on the American. With the introduction of the Central Valley Project in the mid-1930s, came the Auburn-Folsom South Unit, with the purpose to "provide new and supplemental water for irrigation, municipal and industrial use, and to replenish severely depleted ground water in the Folsom South region". In 1965, Congress authorized the Auburn-Folsom South Unit of the Central Valley Project, the primary feature of which was to be Auburn Dam. The targeted completion date was 1973.

As the proposals for the Auburn Dam evolved, the project saw a transformation from a purely flood-control structure to a multipurpose high dam that would serve various purposes including storage, hydroelectricity generation, and recreational activities. One of the first ideas, publicized in the late 1950s, called for a 515-foot (157 m) embankment dam impounding 1,000,000 acre feet (1,200,000 dam³) of water. In 1963, a 690-foot (210 m) earthfill dam holding back 2,500,000 acre feet (3,100,000 dam³) of water was proposed. The pre-construction design was finalized in 1967, for a concrete thin-arch gravity structure over 680 feet (210 m) high. This dam would be 4,200 feet (1,300 m) long, 196 feet (60 m) thick at the base, and equipped with five 150MW generators at its base for a total generating capacity of 700 MW. Two concrete-lined flip bucket spillways would abut both sides of the dam. Construction work for the dam started in late 1968.