Los Angeles Aqueduct. The Los Angeles Aqueduct system, comprising the Los Angeles Aqueduct (Owens Valley aqueduct) and the Second Los Angeles Aqueduct, is a water conveyance system, built and operated by the Los Angeles Department of Water and Power. The Owens Valley aqueduct was designed and built by the city's water department, at the time named The Bureau of Los Angeles Aqueduct, under the supervision of the department's Chief Engineer William Mulholland. The system delivers water from the Owens River in the eastern Sierra Nevada mountains to Los Angeles.

The aqueduct's construction was controversial from the start, as water diversions to Los Angeles eliminated the Owens Valley as a viable farming community. Clauses in the city's charter originally stated that the city could not sell or provide surplus water to any area outside the city, forcing adjacent communities to annex themselves into Los Angeles.

The aqueduct's infrastructure also included the completion of the St. Francis Dam in 1926 to provide storage in case of disruption to the system. The dam's collapse two years later killed at least 431 people, halted the rapid pace of annexation, and eventually led to the formation of the Metropolitan Water District of Southern California to build and operate the Colorado River Aqueduct to bring water from the Colorado River to Los Angeles County.

The continued operation of the Los Angeles Aqueduct has led to public debate, legislation, and court battles over its environmental impacts on Mono Lake and other ecosystems.

First Los Angeles Aqueduct

Construction
The aqueduct project began in 1905 when the voters of Los Angeles approved a  bond for the 'purchase of lands and water and the inauguration of work on the aqueduct'. On June 12, 1907, a second bond was passed with a budget of  to fund construction.

Construction began in 1908 and was divided into eleven divisions. The city acquired three limestone quarries, two tufa quarries and it constructed and operated a cement plant in Monolith, California, which could produce 1,200 barrels of Portland cement per day. Regrinding mills were also built and operated by the city at the tufa quarries. To move 14 million ton-miles of freight, the city contracted with Southern Pacific to build a 118 mile long rail system from the Monolith mills to Olancha.

The number of men who were on the payroll the first year was 2,629 and this number peaked at 6,060 in May 1909. In 1910, employment dropped to 1,150 due to financial reasons but rebounded later in the year. In 1911 and 1912, employment ranged from 2,800 to 3,800 workers. The number of laborers working on the aqueduct at its peak was 3,900. In 1913, the City of Los Angeles completed construction of the first Los Angeles Aqueduct.

Route
The aqueduct as originally constructed consisted of six storage reservoirs and  of conduit. Beginning  north of Blackrock (Inyo County), the aqueduct diverts the Owens River into an unlined canal to begin its  journey south to the Lower San Fernando Reservoir. This reservoir was later renamed the Lower Van Norman Reservoir.

The original project consisted of  of open unlined canal,  of lined open canal,  of covered concrete conduit,  of concrete tunnels,  steel siphons,  of railroad track, two hydroelectric plants, three cement plants,  of power lines,  of telephone line,  of roads and was later expanded with the construction of the Mono Extension and the Second Los Angeles Aqueduct.

The aqueduct uses gravity alone to move the water and also uses the water to generate electricity, which makes it cost-efficient to operate.

Reactions by impacted communities

The construction of the Los Angeles Aqueduct effectively eliminated the Owens Valley as a viable farming community and eventually devastated the Owens Lake ecosystem. A group labeled the "San Fernando Syndicate" – including Fred Eaton, Mulholland, Harrison Otis (the publisher of The Los Angeles Times), Henry Huntington (an executive of the Pacific Electric Railway), and other wealthy individuals – were a group of investors who bought land in the San Fernando Valley allegedly based on inside knowledge that the Los Angeles aqueduct would soon irrigate it and encourage development. Although there is disagreement over the actions of the "syndicate" as to whether they were a "diabolical" cabal or only a group that united the Los Angeles business community behind supporting the aqueduct, Eaton, Mulholland and others connected with the project have long been accused of using deceptive tactics and underhanded methods to obtain water rights and block the Bureau of Reclamation from building water infrastructure for the residents in Owens Valley, and creating a false sense of urgency around the completion of the aqueduct for Los Angeles residents.
By the 1920s, the aggressive pursuit of water rights and the diversion of the Owens River precipitated the outbreak of violence known as the California water wars. Farmers in Owens Valley, following a series of unmet deadlines from LADWP, attacked infrastructure, dynamiting the aqueduct numerous times, and opened sluice gates to divert the flow of water back into Owens Lake. The lake has never been refilled, and is now maintained with a minimum level of surface water to prevent the introduction of dangerous, toxic lake-floor dust into the local community.

St. Francis Dam failure 

In 1917, The Bureau of Los Angeles Aqueduct sought to build a holding reservoir to regulate flow and provide hydroelectric power and storage in case of disruption to the aqueduct system. The initial site chosen was in Long Valley along the Owens River, but Eaton, who had bought up much of the valley in anticipation of the need for a reservoir, refused to sell the land at the price offered by Los Angeles. Mulholland then made the decision to move the reservoir to San Francisquito Canyon above what is now Santa Clarita, California. The resulting St. Francis Dam was completed in 1926 and created a reservoir capacity of 38,000 acre-feet (47,000,000 m3). On March 12, 1928, the dam catastrophically failed, sending a  wall of water down the canyon, ultimately reaching the Pacific Ocean near Ventura and Oxnard, and killing at least 431 people. The resulting investigation and trial led to the retirement of William Mulholland as the head of the Los Angeles Bureau of Water Works and Supply in 1929. The dam failure is the worst man-made flood disaster in the US in the 20th century and the second largest single-event loss of life in California history after the 1906 San Francisco earthquake.

Mono Basin Extension
In an effort to find more water, the city of Los Angeles reached farther north. In 1930, Los Angeles voters passed a third  bond to buy land in the Mono Basin and fund the Mono Basin extension.  The  extension diverted flows from Rush Creek, Lee Vining Creek, Walker Creek, and Parker Creek that would have flowed into Mono Lake. The construction of the Mono extension consisted of an intake at Lee Vining Creek, the Lee Vining conduit to the Grant Reservoir on Rush Creek, which would have a capacity of , the  Mono Craters Tunnel to the Owens River, and a second reservoir, later named Crowley Lake with a capacity of  in Long Valley at the head of the Owens River Gorge.

Completed in 1940, diversions began in 1941. The Mono Extension has a design capacity of  of flow to the aqueduct. However, the flow was limited to  due to the limited downstream capacity of the Los Angeles Aqueduct. Full appropriation of the water could not be met until the second aqueduct was completed in 1970.

The Mono Extension's impact on Mono Basin and litigation 
From 1940 to 1970, water exports through the Mono Extension averaged  per year and peaked at  in 1974. Export licenses granted by the State Water Resources Control Board (SWRCB) in 1974 increased exports to  per year. These export levels severely impacted the region's fish habitat, lake level, and air quality, which led to a series of lawsuits. The results of the litigation culminated with a SWRCB decision to restore fishery protection (stream) flows to specified minimums, and raise Mono Lake to  above sea level. The agreement limited further exports from the Mono Basin to  or less per year during the transition period.

Second Los Angeles Aqueduct

In 1956, the State Department of Water Resources reported that Los Angeles was exporting only  of water of the  available in the Owens Valley and Mono Basin. Three years later, the State Water Rights Board warned Los Angeles that they could lose rights to the water they were permitted for but not appropriating. Faced with the possible loss of future water supply, Los Angeles began the five-year construction of the aqueduct in 1965 at a cost US$89 million. Once the city received diversion permits, water exports jumped in 1970, adding 110,000 AF that year into the aqueduct system. By 1974, exports climbed to  per year.  Unlike the First Aqueduct which was built entirely by Public Works, the Second Los Angeles Aqueduct was primarily built on contract by various private construction firms including R.A. Wattson Co., Winston Bros., and the Griffith Co. The Los Angeles Department of Water and Power managed the project and performed some finishing construction on the Mojave conduit and Jawbone & Dove Spring pipelines.

Route
The  aqueduct was designed to flow  and begins at the Merritt Diversion Structure at the junction of the North and South Haiwee Reservoirs, south of Owens Lake, and runs roughly parallel to the first aqueduct. Water flows entirely by gravity from an elevation of  at the Haiwee Reservoir through two power drops to an elevation of  at the Upper Van Norman Reservoir.

The Second Aqueduct was not built as a single contiguous conduit. For design and construction purposes the aqueduct was divided into Northern and Southern sections and the two are connected by the San Francisquito Tunnels, which are part of the First Aqueduct.

The Northern Section carries water starting at the North Haiwee Reservoir through the Haiwee Bypass passing around the South Haiwee Reservoir. The flow then continues  south through a series of pressure pipelines and concrete conduits where it connects with the First Aqueduct at the North Portal of the Elizabeth Tunnel near the Fairmont Reservoir.

The San Francisquito Tunnels (which include the Elizabeth Tunnel) have a flow capacity of   and are large enough to handle the flow of both aqueducts. Once the combined flow reaches the penstocks above Power Plant #2, water is diverted into the Southern Section of the second aqueduct through the Drinkwater Tunnel to the Drinkwater Reservoir.

The last segment of pipe, known as the Saugus Pipeline, carries water south past Bouquet Canyon, Soledad Canyon and Placerita Canyon in the city of Santa Clarita. From there it roughly parallels Sierra Highway before it enters Magazine Canyon near the Terminal structure and Cascades.  Water from the Terminal structure can then flow to either the Cascade or penstock to the Foothill Power Plant and into the Upper Van Norman Reservoir.

In addition to the construction in the Northern and Southern sections, improvements were also made to the lined canal between the Alabama Gates and the North Haiwee Reservoir in the Northern Section that consisted of adding  sidewalls to both sides of the canal and the raising of overcrossings. This work increased the capacity of the lined canal from  to  cfs.

Second aqueduct's impact on the water system

The increased flows provided by the second aqueduct lasted only from 1971 through 1988. In 1974 the environmental consequences of the higher exports were first being recognized in the Mono Basin and Owens Valley. This was followed by a series of court ordered restrictions imposed on water exports, which resulted in Los Angeles losing water. In 2005, the Los Angeles Urban Water Management Report reported that 40–50% of the aqueduct's historical supply is now devoted to ecological resources in Mono and Inyo counties.

Influence on Los Angeles and the county
From 1909 to 1928, the city of Los Angeles grew from  to . This was due largely to the aqueduct, and the city's charter which stated that the City of Los Angeles could not sell or provide surplus water to any area outside the city.
Outlying areas relied on wells and creeks for water and, as they dried up, the people in those areas realized that if they were going to be able to continue irrigating their farms and provide themselves domestic water, they would have to annex themselves to the City of Los Angeles.

Growth was so rapid that it appeared as if the city of Los Angeles would eventually assume the size of the entire county. William Mulholland continued adding capacity to the aqueduct, building the St. Francis Dam that would impound water creating the San Francisquito Reservoir, filed for additional water from the Colorado River, and began sending engineers and miners to clear the heading at the San Jacinto Tunnel that he knew was key to the construction of the Colorado River Aqueduct.

The aqueduct's water provided developers with the resources to quickly develop the San Fernando Valley and Los Angeles through World War II. Mulholland's role in the vision and completion of the aqueduct and the growth of Los Angeles into a large metropolis is recognized with the William Mulholland Memorial Fountain, built in 1940 at Riverside Drive and Los Feliz Boulevard in Los Feliz. Mulholland Drive and Mulholland Dam are both named after him.

Many more cities and unincorporated areas would likely have annexed into the city of Los Angeles if the St. Francis Dam had not collapsed. The catastrophic failure of the St. Francis Dam in 1928 killed an estimated 431 people, flooded parts of Santa Clarita, and devastated much of the Santa Clara River Valley in Ventura County.

The failure of the dam raised the question in a number of people's minds whether the city had engineering competence and capability to manage such a large project as the Colorado River Aqueduct despite the fact that they had built the Los Angeles Aqueduct. After the collapse, the pace of annexation came to a rapid halt when eleven nearby cities including Burbank, Glendale, Pasadena, Beverly Hills, San Marino, Santa Monica, Anaheim, Colton, Santa Ana, and San Bernardino decided to form the Metropolitan Water District with Los Angeles. The city's growth following the formation of the MWD would be limited to 27.65 square miles.

Farmers 

In 1905, the city of Los Angeles began the process of acquiring water and land rights in the Owens Valley region in preparation for the construction of the Los Angeles Aqueduct, initially misleading farmers who were under the assumption that the purchases were intended for a local water project. Due to many farmers holding on to a very small portion of the total water in Owens Valley, no singular farmer had the means to influence or divert attention away from the desires of Los Angeles in wanting to acquire water and land rights in the region. Accordingly, farmers formed collective groups to increase their bargaining power, the most notable being the Owens Valley Irrigation District. Nevertheless, the city of Los Angeles bypassed such efforts from the collective farmer groups through engaging in checkerboarding, purchasing and acquiring surrounding land of an opposing farmer and essentially circumvent the need to buy their land altogether. By 1934, the city of Los Angeles had acquired 95% of the agricultural land in the Owens Valley.

Indigenous 
According to archaeologists and anthropologists, the Paiute people, also known as Nüńwa Paya Hūp Ca’á Otūǔ’m (translates to “We are Water Ditch Coyote children"), settled in the Owens Valley region as early as 600 C.E., having long adopted and specialized in a hunting and harvesting economy. 

As a result of mining and agricultural development in California in the mid-19th century following the annexation of the state as well as the subsequent influx of white settlers coming into the region, many Paiute people were relocated to what is now modern-day Porterville, California in 1863. The Paiute people that remained found it difficult to continue harvesting indigenous food sources as the ongoing siphoning of the Owens Valley water by the city of Los Angeles for the aqueduct project dramatically altered the supply of water in the surrounding region. 

In 1937, the United States Federal Government signed into the law the Bankhead-Jones Farm Tenant Act,  commonly known as the Land Exchange Act, which allowed Paiute people to trade 2,914 acres of allotted land to the city of Los Angeles in exchange for 1,392 acres of hospitable lands which became the Bishop, Big Pine, and Lone Pine Reservations located east from the Sierra Nevada Mountains. Nevertheless, the U.S. federal government was unable to secure for the Paiutes water rights from the city of Los Angeles, which insisted that they required a two-third vote from city residents to be able to transfer water. This left the Paiute people without adequate amounts of water to accommodate for their growing population. 

In 1994, the Department of the Interior opened an ongoing investigation looking into the water rights issues between the city of Los Angeles and the Paiute people, led by the Owens Valley Indian Water Commission, a consortium comprising the Bishop, Big Pine, and Lone Pine Reservations.

Owens Valley Ecosystem and Agriculture 
The impact of the Los Angeles Aqueduct Project to the Owens Valley region was immediate and detrimental to future agricultural work of local farmers. In 1923, in an effort to increase the water supply, the city of Los Angeles began purchasing vast parcels of land and commenced the drilling of new wells in the region, significantly lowering the level of groundwater in the Owens Valley, even affecting farmers who “did not sell to the city’s representatives.” By 1970, constant groundwater pumping by the city of Los Angeles had virtually dried up all the major springs in the Owens Valley, impacting the surrounding wetlands, springs, meadows, and marsh habitats.

Ecological Disruption 
The consequent transfer of water out of the Owens Lake and Mono Lake decimated the natural ecology of the region, transforming what was a “lush terrain into desert.”  Furthermore, alkaline sediment from the receding shorelines of both Owens Lake and Mono Lake resulting from increased water usage made their way to areas of human settlement by way of being lifted from dust storms, ultimately increasing the chances of respiratory illnesses and cancer. Some of the first victims to be impacted by these dust storms were Japanese Americans interned at the Manzanar War Relocation facilities during World War II.

Despite the ecological and environmental destruction of both Mono and Owens Lake from the construction of the Los Angeles Aqueduct, the Owens Valley and adjoining Mono Lake remain a sanctuary for many bird species that migrate to this region. The legal notion of a “Public Trust Doctrine” used by community members of Owens Valley has been successful in restoring regions of Mono Lake, Mono Highlands and the Owens Valley impacted by the Los Angeles Aqueduct, evident by the re-watering projects that have spurred revitalization of natural local ecosystems. 

In 1991, the City of Los Angeles signed the Inyo-LA Long Term Water Agreement despite objections from community members and stakeholders. Concessions of the deal included mitigation projects like the Lower Owens River Project that sought to reduce further air contamination and health risks associated with the dust storms as well as future preservation of the ecology of the Owens Valley. 

In 2001, the Los Angeles Department of Water and Power commenced studies on the environmental impact of dust storms, suggesting proposals in re-watering both Mono Lake and Lake Owens.

In 2006, work commenced on the Lower Owens River Project 15 years after it was signed, helping boost the number of fish in the river, restoring marsh habitats, and promoting recreational activities such as fishing and canoeing by re-watering 62 miles of riverbed.

In 2009, the Los Angeles Department of Water and Power resumed ongoing efforts to a proposed master plan in the preservation of the natural habitat of Lake Owens as part of its Owens Lake Dust Mitigation Program (OLDMP).

Future Water Needs 
Los Angeles faces significant challenges in securing its water supply for the future due to climate change, population growth, and increasing competition for resources. The city's reliance on imported water from the Los Angeles Aqueduct (LAA), the Colorado River Aqueduct, and the California State Water Project is becoming increasingly strained. These sources are threatened by reduced Sierra Nevada snowpack, prolonged droughts, and legal disputes over water rights.

Efforts to address these challenges include transitioning to more sustainable, local sources such as reclaimed water, desalination, and rainwater harvesting. The city is also exploring integrated water management strategies, including groundwater treatment and water reuse. Additionally, demand management measures, such as incentives for water conservation and public awareness campaigns, are being implemented to reduce dependency on imported water. Innovations in water pricing and regulation are expected to play a vital role in managing future demand.

Water Scarcity 
Water scarcity is a growing concern in Los Angeles, driven by factors such as climate change, population growth, and environmental obligations. Reduced Sierra Nevada snowpack and changing precipitation patterns have jeopardized the reliability of the Los Angeles Aqueduct, while prolonged droughts strain access to water from the Colorado River and other sources. 

Los Angeles must also balance its water needs with environmental restoration efforts. Legal requirements mandate water retention in Owens Valley and Mono Lake to address ecological damage caused by aqueduct operations. At the same time, agriculture consumes the majority of water statewide, leading to conflicts between urban and rural water use. Despite these challenges, urban water conservation measures, including rainwater harvesting and improved irrigation practices, offer promising strategies for mitigating scarcity. Increased public awareness of water scarcity's historical and environmental roots has also led to advocacy for more sustainable water management practices, such as preserving the Los Angeles River.

In popular culture
 Saugus High School derives the name of its daily newsletter, The Pipeline, from an exposed portion of the first aqueduct that passes southwest of the school's property.
 San Francisquito Canyon and DWP Power House #1 are featured in Visiting... with Huell Howser Episode 424.

California Historical Landmark – Cascades 
The Cascades, which was completed on November 5, 1913, is located near the intersection of Foothill Boulevard and Balboa Boulevard, four miles northwest of San Fernando. It was designated as a California Historical Landmark on July 28, 1958.

Gallery

See also
 American Water Landmark
 California Aqueduct
 Colorado River Aqueduct
 State Water Project
 Owensmouth

References
Notes

Further reading

External links

 LADWP: official  Los Angeles Aqueduct website
 UCLA: Los Angeles Aqueduct Digital Platform
 Los Angeles Aqueduct Landscape Atlas
 Mono Lake Committee Website
 LADWP: History page on William Mulholland
 Los Angeles Aqueduct Slideshow
 The William Mulholland Memorial Fountain
 Image of workers making repairs on a damaged section of the Los Angeles Aqueduct in No-Name Canyon, Inyo County vicinity, [about 1927].  Los Angeles Times Photographic Archive (Collection 1429). UCLA Library Special Collections, Charles E. Young Research Library, University of California, Los Angeles.
 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
Aqueducts in California
Interbasin transfer
Water in California
Aqueduct
Aqueduct
History of the San Fernando Valley
History of Inyo County, California
History of Mono County, California
Owens Valley
Sierra Nevada (United States)
Transportation buildings and structures in Inyo County, California
Transportation buildings and structures in Kern County, California
Transportation buildings and structures in Los Angeles County, California
Transportation buildings and structures in Mono County, California
Buildings and structures in the San Fernando Valley
Historic American Buildings Survey in California
Historic American Engineering Record in California
Historic Civil Engineering Landmarks
Los Angeles Historic-Cultural Monuments
1913 establishments in California
Hydroelectric power plants in California