Big Creek Hydroelectric Project

California engineer John S. Eastwood was the principal designer of the system, which was initially funded and built by Henry E. Huntington's Pacific Light and Power Company (PL&P).

Today, these facilities include 27 dams, miles of tunnels, and 24 generating units in nine powerhouses with a total installed capacity of more than 1,000 megawatts (MW).

[5] The Big Creek reservoirs also provide irrigation and flood control benefits for the Central Valley, and are popular recreation areas.

However, the project has had various environmental and social impacts, including the disruption of fish and animal migration, and the flooding of historical sites and traditional Native American lands.

The Big Creek Project was the vision of California engineer John S. Eastwood, who first surveyed the upper San Joaquin River system in the late 1880s and mapped potential sites for reservoirs and hydroelectric plants.

However, they lacked the capital to build a storage dam and when a drought hit, the North Fork dried up, leading to the financial failure of that project.

However, investors balked at the massive potential costs of this project (the tunnel required to carry water to the power station would be 20 miles (32 km) long) and by 1901 Eastwood ceased to promote this plan.

[7] Following this, Eastwood began to draw up much grander plans for a hydroelectric system encompassing the entire upper San Joaquin River basin.

[8][9] In 1902 Eastwood took his plans to William G. Kerckhoff, a Southern California businessman who was affiliated with Henry Huntington, a wealthy developer and power magnate from Los Angeles.

[9] Although Huntington was initially skeptical of the feasibility of the project, he was impressed by Eastwood's studies and hired him to PL&P granting him 5,400 shares in return for making a thorough survey and a final plan for the hydroelectric system.

However, construction was postponed for many years because the company's directors thought that the project would generate far more power than was needed at the time and emphasized development of more thermal plants.

[13] By 1905, Eastwood had developed his initial proposal for the system, consisting of a large reservoir and two powerhouses along Big Creek, a major tributary of the San Joaquin.

Huntington placed George Ward in charge of the project and hired the Boston engineering firm Stone & Webster to oversee construction.

The company was forced to compromise and sold the remaining bonds at 85 percent value to a syndicate formed by investment bankers William Salomon & Co.[17] Huntington had to convince farmers in the San Joaquin Valley – including Miller & Lux, run by land barons Henry Miller and Charles Lux, who owned nearly a 1,000,000 acres (400,000 ha) in the valley – that the dams would increase rather than decrease the amount of water available for their use.

The rail line, known as the San Joaquin and Eastern Railroad, would split off from the Southern Pacific main line at El Prado (about 20 miles (32 km) northeast of Fresno) and carve its way 56 miles (90 km) deep into the Sierra Nevada, to the company town of Big Creek.

[19] Winding its way up the San Joaquin River Canyon, the railroad – featuring 1,078 curves, 43 bridges and 255 grades of up to 5.2 percent[20] – was nicknamed the "Slow, Jerky and Expensive".

Work proceeded at a rapid pace because of the tight budget: the project had to start producing electricity so as to pay for itself before the company's funds ran out.

The proposed expansions would involve increasing the capacity of the powerhouses by diverting water from other streams in the upper San Joaquin River system.

Construction of this concrete arch dam was exceedingly difficult due to the narrowness of the canyon and the large flow of the San Joaquin River.

Also completed in 1923 was the conversion of Big Creek's power transmission system from 150kV to 220kV – the highest commercial voltage in the world at the time.

1 and 2 were expanded in preparation for an influx of diverted water from the South Fork San Joaquin River, a stream much larger than Big Creek that descends from the main crest of the Sierra several miles to the east of Huntington Lake.

A huge siphon was built in order to carry the water across the 700-foot (210 m) deep valley of the South Fork to join with the Ward Tunnel.

The combined 154,400-acre-foot (190,400 dam3) capacity of Huntington and Florence Lakes was much smaller than the annual 1,700,000-acre-foot (2,100,000 dam3) runoff of the upper San Joaquin River system.

As a result, a dam was built on Stevenson Creek between 1925 and 1927, forming Shaver Lake, to store excess water from Huntington.

The lake replaced an earlier reservoir built in the valley by the Fresno Flume and Lumber Company to store water for a timber operation.

[21] In early 1958, work began on Mammoth Pool Dam, located on the main San Joaquin River above the confluence of Big Creek.

During times of low demand, the station draws water from Shaver Lake up to a small reservoir, the Balsam Meadows Forebay, located on the top of a nearby mountain.

[21][30] Big Creek consists of multiple closely interconnected projects, operating under seven Federal Energy Regulatory Commission licenses.