Los Angeles Aqueduct

The aqueduct project began in 1905 when the voters of Los Angeles approved a US$1.5 million 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 US$24.5 million to fund construction.[13][14]

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.[15][16][17][18] In 1913, the City of Los Angeles completed construction of the first Los Angeles Aqueduct.

The aqueduct as originally constructed consisted of six storage reservoirs and 215 mi (346 km) of conduit. Beginning 3.5 mi (5.6 km) north of Blackrock (Inyo county), the aqueduct diverts the Owens River into an unlined canal to begin its 233 mi (375 km) journey south to the Lower San Fernando Reservoir.[19] This reservoir was later renamed the Lower Van Norman Reservoir.

The original project consisted of 24 mi (39 km) of open unlined canal, 37 mi (60 km) of lined open canal, 97 mi (156 km) of covered concrete conduit, 43 mi (69 km) of concrete tunnels, 12.00 mi (19.31 km) steel siphons, 120 mi (190 km) of railroad track, two hydroelectric plants, three cement plants, 170 mi (270 km) of power lines, 240 mi (390 km) of telephone line, 500 mi (800 km) of roads[20] and was later expanded with the construction of the Mono Extension and the Second Los Angeles Aqueduct.[21]

The aqueduct uses gravity alone to move the water and also uses the water to generate electricity, which makes it cost-efficient to operate.[22]

Typical construction view of lined canal and covered concrete conduit.

The construction of the Los Angeles Aqueduct effectively eliminated the Owens Valley as a viable farming community and eventually devastated the Owens Lake ecosystem.[23] 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 Railroad), 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.[23] 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,[24][25] 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.[26] 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.[27]

A picture of the St. Francis Dam, one year prior to its collapse.

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.[10] 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 100-foot high (30 m) 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.

From 1940 to 1970, water exports through the Mono Extension averaged 57,067 acre-feet (70 million cubic meters) per year and peaked at 135,000 acre⋅ft (167 million m³) in 1974. Export licenses granted by the State Water Resources Control Board (SWRCB) in 1974 increased exports to 167,000 acre⋅ft (206 million m³) per year.[29] These export levels severely impacted the region's fish habitat, lake level, and air quality, which led to a series of lawsuits.[12] The results of the litigation culminated with a SWRCB decision to restore fishery protection (stream) flows to specified minimums, and raise Mono Lake to 6,391 feet (1,948 m) above sea level. The agreement limited further exports from the Mono Basin to 10,000 acre⋅ft (12.3 million m³) per year.[31]

The 137-mile-long (220 km) aqueduct was designed to flow 290 cu ft/s (8,200 L/s) and begins at the Merritt Diversion Structure at the junction of the North and South Haiwee Reservoirs,[4] south of Owens Lake, and runs roughly parallel to the first aqueduct. Water flows entirely by gravity from an elevation of 3,760 feet (1,150 m) at the Haiwee Reservoir through two power drops to an elevation of 1,200 ft (370 m) at the Upper Van Norman Reservoir.[32]

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 115 miles (185 km) 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.[33]

The San Francisquito Tunnels (which include the Elizabeth Tunnel) have a flow capacity of 1,000 cu ft/s (28,000 L/s)[33] 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.

An updated version of the concrete box construction used on the second aqueduct.

The last segment of pipe, known as the Saugus Pipeline,[34] 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 24 in (610 mm) sidewalls to both sides of the canal and the raising of overcrossings. This work increased the capacity of the lined canal from 710 cu ft/s (20,000 L/s) to 900 cu ft/s (25,000 L/s) cfs.[35]

The increased flows provided by the second aqueduct lasted only from 1971 through 1988.[36] 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.[29] 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.[37][38]