Water and Power Associates Informing the Public about Critical Water and Energy Issues facing Los Angeles and California

Once the Los Angeles Aqueduct was completed in 1913, it made possible more than just bringing water to the city. The force of the water as it dropped thousands of feet on its gravity-fed journey created an opportunity to generate electricity.

On March 18, 1917, the San Francisquito Power Plant No. 1 went into service, delivering electricity to Los Angeles over a newly built 115 kV transmission line. The 200 kilowatts from its first generator were the city’s first commercial kilowatts produced by the new Los Angeles Bureau of Power and Light. Units 2 and 3 followed later that spring.

When it opened, Power Plant No. 1 supplied more than 70 percent of the city’s electrical needs. It is still operating today, providing a small but steady share of power to Los Angeles.

Historical Background

In 1909, the Bureau of Los Angeles Aqueduct Power was created to design and build hydroelectric plants along the new aqueduct. When Los Angeles acquired water rights in the Owens Valley, it also secured power sites along the way.

Ezra F. Scattergood, the Bureau’s first chief electrical engineer, led the effort to harness hydroelectric power and became the counterpart to William Mulholland, who oversaw the water system. Together they built the foundation for what would become the Los Angeles Department of Water and Power.

Power Plants on the Aqueduct

The aqueduct system was extensively developed to take advantage of the drop in elevation as water descends from the High Sierras to Los Angeles. Up to 14 hydroelectric power plants were built along the Los Angeles Aqueduct. In 1908, the Division Creek Power Plant in Owens Valley became the first hydro-electric power plant to be constructed. It, along with the Cottonwood Power Plant, were built for the purpose of constructing the aqueduct. This was the first time electric energy had been used in such a construction project.

Historical Notes

This diagram shows the route of the Los Angeles Aqueduct, where water flows entirely by gravity from 3,760 feet at Haiwee Reservoir down to 1,200 feet at Upper Van Norman Reservoir in the San Fernando Valley.

The first two—Division Creek and Cottonwood—were constructed in 1908 in the Owens Valley to provide electricity for the aqueduct’s own construction work. This marked the first time electric energy was used on such a large engineering project.

Historical Notes

Work on Power Plant No. 1 began about 1911. The project required tunnels, penstocks, concrete work, and heavy machinery never before used on such a scale in the canyon.

Historical Notes

The outlet tunnels that carried water to the turbines were lined with reinforced concrete to handle the tremendous pressure from the aqueduct above.

Historical Notes

Trucks hauled the massive steel pipe sections—each up to eight feet in diameter—that formed the penstocks delivering water to the powerhouse below.

(ca. 1916)* - Mulholland and Commissioner Del Valle in 80-Inch Pipe

Historical Notes

William Mulholland and Commissioner Del Valle inspect an 80-inch pipe section during construction. Their combined leadership linked Los Angeles’s water and power systems from the very beginning.

Historical Notes

Crews assemble penstock sections on the steep hillside above the powerhouse. A rail car at left transported both workers and materials up the incline.

Historical Notes

Construction workers pause for a group portrait in front of the newly assembled penstocks that would soon channel water to the Pelton turbines below.

Historical Notes

The Pelton wheel used at Power Plant No. 1 extracted energy from the jet of high-velocity water striking its buckets. This impulse design produced much greater efficiency than older water-wheel systems.

Historical Notes

A worker stands inside the large stator ring that would hold one of the plant’s main generators. The generator converted the turbine’s mechanical energy into electric power.

Historical Notes

The massive rotor flywheel, shown here before installation, was part of the generator assembly that helped regulate speed and maintain steady electrical output.

Historical Notes

Workers install the Pelton wheels that would spin as pressurized water from the penstocks struck their cups, driving the generators to produce electricity for Los Angeles.

Historical Notes

This early interior view shows the turbine-generator units shortly after completion. These machines provided dependable power to the growing city for decades.

Historical Notes

On March 18, 1917 the San Francisquito Power Plant No. 1, Unit 1 was placed in service and energy was delivered to Los Angeles over a newly constructed 115 kV transmission line. The 200 kilowatts generated by Unit 1 were the first commercial kilowatts generated by the Los Angeles Bureau of Power and Light (Click HERE to see more in Early Power Transmission).

Subsequently on April 28 and April 16, 1917, Units 2 and 3 respectively were placed in operation.

The LA Bureau of Power and Light now had a source of low cost electricity and more than enough power to meet the City's needs.  It would sell its excess San Francisquito generated power to Pasadena over two newly constructed 34 kV lines between the two cities. By 1917, World War I had forced the price of fuel oil to rise making the new lower cost hydroelectric power extremely desirable.

Historical Notes

A quarter-mile-long, 16-foot-diameter pipe carried water from Power Plant No. 1 to Power Plant No. 2 downstream, allowing the same water to generate power twice before continuing toward the city.

(1928)* - Power Plant No. 2 prior to the St. Francis Dam failure on March 12, 1928.

Historical Notes

This station is about 1.3 miles downstream from where the St. Francis Dam stood. The building is 60 feet tall, but was destroyed by a wall of water that was 120 feet high. This photo was taken shortly before the St. Francis Dam failed.^

Historical Notes

Power Plant No. 2 was completely destroyed by the flood that swept through the canyon after the St. Francis Dam failed on March 12, 1928. You can clearly see how the hillside in the background has been stripped of all vegetation by the water, which came over the top of the hill upstream of the powerhouse.

Historical Notes

Power Plant No. 2 was completely restored and back in service by November 1928, just 8 short months after the original plant was destroyed in the St. Francis Dam Disaster.

From the LADWP Historic Archive

Although it wasn’t the first City power plant, it’s the oldest in operation and began service even before transmission lines crossed mountains and desert to deliver its power to Los Angeles.

Located south of Olancha and north of Haiwee Reservoir, the power plant was designed by DWP power pioneer Carl A. Heinze to tap the energy of rushing Cottonwood Creek which is diverted to a flume four miles up Cottonwood Canyon in the Sierras. From the flume, water is carried to a forebay behind the plant and then sent through penstocks to the turbines under a 1,200-foot head. Only a few yards form the plant’s tailrace, the water flows directly into the Aqueduct.^

From the LADWP Historic Archive

Power from Cottonwood’s first generator and a second 900-kilowatt unit placed into service October 13, 1909, first traveled over temporary transmission lines to power the Aqueduct dredging operations and later to power equipment at the Monolith cement plant near Mojave which produced millions of tons of cement for miles of the Aqueduct’s concrete-lined conduit and canal sections.^

From the LADWP Historic Archive

In April 1908, in the shadow of the towering snow-clad High Sierra, the Division Creek Power Plant No. 1, Los Angeles’ first municipal power plant, was placed in operation.

The powerhouse was a small frame building with a tiny 120-kilowatt generator. It harnessed the flow of a small creek tumbling down from the High Sierra, producing hydroelectric power for construction work on the new Los Angeles Owens River Aqueduct which was just getting started at the time. It was the first known use of electricity for a construction project of this kind.^

Historical Notes

The Owens River Gorge is a natural canyon carved by the river as it passed through the volcanic tablelands at the northern end of the Owens Valley. This landform, a giant, sloping volcanic scab, was formed on top of the existing valley floor 760,000 years ago by the eruption of the nearby Long Valley Caldera. DWP built three hydropower plants in the gorge, to take advantage of the 2,300 foot drop between Crowley Lake and the Owens River Valley. Between the plants, river water is diverted into pipelines in order to increase the velocity of the water flow, thereby increasing power.^^

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