L.A. Aqueduct Centennial 2013

The LA Aqueduct: U.S. Top Ten Public Works Project

Top Ten United States Public Works Projects of the 20th Century

The Los Angeles Aqueduct

By Fred Barker, LADWP


The City of Los Angeles is today the second largest city in the United States, and a thriving center of highly varied human activity. It is the film and television capitol of the world. Los Angeles has more ethnic diversity than any other city in the world. The very existence of the city, and its economic and social vitality, depend on the reliability and availability of natural resources. The Southern California coastal plain averages less than 15 inches of rain annually, and 85% of the water for the city must be imported.  In the early 1900’s, the city was just beginning a phenomenal period of growth, and also began experiencing its first water shortages. If only local supplies of water were to be relied on, the growth of the region would be halted and its economic potential would never be reached.

The citizens of Los Angeles had come to trust their water system superintendent, William Mulholland, over the years that he had served them. His realization that more water would be necessary if the vitality of his adopted city was to be assured led him to imagine solutions that lay far beyond the city limits. He and others were surveying the mountains, valleys and rivers for hundreds of miles.Mulholland One river in particular, the Owens River in Inyo County, held promise. It was fed by snow melting in the Eastern Sierra Nevada mountains, was of a very high quality and its flow was dependable. The Owens Valley was remote and sparsely settled, and although it was over 230 miles distant from Los Angeles, the elevation was over 3,500 feet.  Mulholland made repeated trips to the Owens Valley to determine the feasibility of constructing an aqueduct to supplement the water supply in Los Angeles. He became firmly convinced of two things: that Los Angeles had to find a new source of water and that it would be possible to build an aqueduct to bring the Owens River to Los Angeles.

It would hard to imagine the United States, let alone California, existing today without the City of Los Angeles or the metropolitan area than stretches from Ventura County to San Diego. The Los Angeles Aqueduct led directly to the growth of Los Angeles from a city of 102,000 people covering 44 square miles in 1900 to 577,000 people and 364 square miles in 1920.  The designed flow of the aqueduct, 313 million gallons per day, had exactly the effect that was intentioned.  People and industry could move to Los Angeles and be assured of a constant supply of clean, clear water. The aircraft and motion picture industries, drawn by sunshine to Los Angeles in the early 1900’s, flourished also because the city had acquired a source of water.  This new source made Los Angeles independent of the local river, which is today little more than a concrete flood control channel.  Agriculture, which initially flourished in the San Fernando Valley portion of the city under the irrigation provided by the aqueduct, later gave way to housing, schools and industry. LAstreet Los Angeles, thanks to the growth spurt made possible by the aqueduct, extended itself to San Pedro and constructed a world class port, today one of the largest on the Pacific Coast.

In 1905 the citizens set about making the aqueduct project a reality. Looking back from the vantage point of the year 2000, the project succeeded beyond anyone’s wildest imagination or hope. The decision to build the aqueduct and the challenges overcome by the public agency that was charged with the work still stand as extraordinary achievements. That the Board of Public Service Commissioners of the City of Los Angeles was able to construct a 233-mile long aqueduct within the 5 years and $23,000,000 (1905 dollars) promised remains a truly wondrous feat.  The benefits of the aqueduct, already stretching nearly 87 years, will continue long into the future.


Designing and building the aqueduct, as difficult as that was, may have been the easiest part of the whole project.  Obtaining the funding, water rights and necessary permits to export the water from the Owens Valley to Los Angeles were crucial and had to be accomplished before any detailed design work or construction began.  These tasks involved multiple layers of local, state and federal bureaucracy.   It took several years before the groundwork was laid and actual work could begin.

A former City Engineer and Mayor of Los Angeles, Fred Eaton, was the first to realize that the Owens River could be a feasible source of water for the city.  An Owens Valley rancher in the 1890’s, he had purchased land and options on land with water rights in the valley in the years leading up to 1905, when Los Angeles and Mulholland began to look outside the city for more water.  As a private individual he would have had to compete with the U.S. Bureau of Reclamation for water rights, whereas the city would be aided by the federal government.  With this in mind, he presented his plan to  Mulholland and offered to sell his contracts and options to the city.  Mulholland, after making his own survey of the Owens Valley and the proposed aqueduct route, concluded that an aqueduct from the Owens Valley to Los Angeles was a solution to the impending water shortage.  Next the Board of Water Commissioners was told of the project. After they had conducted their own investigation, in concert with leading members of the Chamber of Commerce, the plan was made public.  On September 7, 1905 the voters of Los Angeles approved, by a vote of 10,787 to 755, $1.5 million dollars worth of bonds for the purpose of buying lands and options and inaugurating work.

In 1906 the city hired three of the most eminent hydraulic engineers in the country to examine and report on the proposed project and design.  They found it feasible, and remarked: “We find the project admirable in conception and outline and full of promise for the continued prosperity of the City of Los Angeles.”

In 1907, the question of issuing $23,000,000 worth of construction bonds was submitted to a vote of the people by the City Council.  After a campaign of education by civic and commercial bodies and the press, the voters gave their approval by a ten to one ratio.  Jurisdiction for the project was placed under the control of the Board of Public Works, which in turn worked very closely with the Board of Water Commissioners.  An advisory committee was jointly appointed by the two Boards to oversee details and organize the working force.

In obtaining rights of way over federal land and control of surplus water in the Owens Valley, the city was aided by federal officials such as the Director of the Geological Survey Charles D. Walcott, the Chief Engineer of the Reclamation Service Fredrick H. Newell, Chief Forester Gifford Pinchot and U.S. Senator Frank P. Flint.  President Roosevelt was asked to assist in the passage of federal legislation confirming the city’s right to use public lands for canals, reservoirs and power plants in Inyo, Kern and Los Angeles counties.  President Roosevelt also, by executive order, withdrew from public filing all federal lands along the proposed aqueduct route.  The governing principle at that time was the “greatest good for the greatest number.”

In the fall of 1907 the vast amount of preparatory work was begun.  The design called for 52 miles of tunnels, much of it through hard rock.  Engineers felt that completing the 5-mile long Elizabeth Tunnel would control the completion of the aqueduct as a whole so work started on it in the fall of 1907.  Construction on the rest of the aqueduct dates from October 1, 1908.  Before work on the rest of the aqueduct could start, a great deal of infrastructure had to be built.  Roads, trails, power plants, water supply, telephone and telegraph lines, cement plants and camps to house the workers had to be constructed over 150 miles of waterless desert.  Fifty-seven camps in all were needed during the 5 years.  An extension of the Southern Pacific Railroad was built to transport material between Mojave and the Owens Valley.

The working conditions in the Mojave Desert and Owens Valley were severe.  The work force had to adapt to extreme heat in the summer and freezing cold in the winter.  Workers were drawn by the promise of a long, good paying job from such ethnic groups as Greeks, Bulgarians, Serbs, Montenegrans, Swiss and Mexican.  Pay was $2.25 per day.  Food, shelter and medical care were provided.  A health care plan was introduced in an era before compensation benefits were common.  For $1 per month workers making $40 per month or more had their medical needs taken care of.  (Others paid $0.50 per month.) Although the work was hazardous, the fatality rate for the Los Angeles aqueduct was only about one-tenth that of the New York Aqueduct, which was under construction at the same time.  At its peak, the work force numbered about 3900.

Construction of the aqueduct required blasting and drilling 142 tunnels that ultimately totaled over 43 miles in length.  A world record for hard rock tunneling was set in the driving of the Elizabeth Tunnel: 604 feet in one month.   Original estimates for completing that tunnel were beaten by 20 months because the Board of Public Works established a bonus of 40 cents per man for each foot tunneled in excess of the schedule.  The bonus increased wages by about 30% but saved the City 10-15% overall as well as releasing equipment to be used elsewhere.  More than 6 million pounds of the highest quality blasting powder (used in the interest of safety) were used during construction of the aqueduct.  Once the aqueduct was completed, the workers were hired onto other major public works projects in such places as New York, Spain and Argentina.

Another significant challenge overcome were the construction of reinforced concrete and riveted steel  inverted siphons, used to cross the deeper and wider canyons.  Most notable of these is Jawbone Siphon, which is 8,095 feet in length and has a maximum steel plate thickness of 1-1/8 inch.  The maximum head on the pipe is 850 feet and the largest diameter is 10 feet.  The steel in the siphon weighs 3,216 tons.  The longest siphon along the aqueduct crosses the Antelope Valley.  It is 21,767 feet in length with a maximum head of 200 feet.  A total of 23 siphons, 11.4 miles in length, were constructed.   Steel siphons were used where ever the head exceeded 75 feet.   Most of the siphons are supported above ground on piers.  Studies were conducted to determine optimal spacing of piers to minimize costs.  It was found that ten-foot diameter ¼-inch thick pipe could be supported on piers spaced at 24 feet.   Engineers were also interested in minimizing the weight of steel required for the siphons, by both tapering the diameter and varying the thickness of the pipe, given the pressure head to be consumed.  E. A. Bayley, locating engineer on the project, developed a graphical solution to this problem which allowed the saving of over 298 tons of steel for the Jawbone siphon versus a constant diameter pipe.

In order to make sure the steel pipe would go together correctly when it arrived, successful bidders had to submit detailed drawings showing how the angles, transitions between different diameters and joint types, etc. would fit.  All dimensions and coincidence of rivet holes were checked by assembling before shipment.  All the steel for the aqueduct was bought, rolled and punched in foundries on the East Coast and was shipped by rail to California.  The steel was moved over the last miles usually by 52-mule teams.   The largest pipe section moved weighed 52,000 pounds, was 37 feet long and used in the Jawbone Siphon.   A bonus system for the riveting crews was also established, saving about 25% of estimated riveting costs.

Six reservoirs were built as part of the aqueduct project.  The largest, Haiwee Reservoir, has a capacity of 63,800 acre-feet, which represents a 75 day storage for the aqueduct flowing at full capacity.  The detention time of the water in the reservoir serves to enhance and maintain its quality.  Other reservoirs were built to provide additional storage and to help regulate flow to the power plants that were built near Los Angeles and to the city itself.

After 11 months of work, the rate of construction was such that the aqueduct would be completed a year early, in 1912, had there not been delays in providing funds.  The sale of bonds could not keep up with the pace of construction, and in the summer of 1910 a temporary shut-down of the work was necessary.  The work force dropped from near 4,000 to less than 1,000.  Having to re-establish the work force and the idle time of equipment was estimated to have cost at least $250,000.

Among the innovations that the aqueduct’s builders took advantage of was the use of “caterpillar” tractors to haul materials to difficult work sites.  When new, the just-invented tractors were more efficient than animal teams.  Unfortunately the tractors were eventually abandoned in favor of teams because of the high cost of making repairs to the tractors’ engines.  Materials were also moved up the steeper mountainsides by aerial trams.  Costs of hauling materials were carefully tracked and evaluated to make sure every available economy was taken advantage of.  William Mulholland was well known for wanting to stay within the allotted budget and not spend any more money than was necessary to build the aqueduct.

Another innovation was the use of concrete made from a mixture of Portland cement and ground tufa.  Although this kind of concrete takes longer to cure and has lower early strength than 100% Portland cement concrete, over time it develops higher ultimate strength.  Used in sheltered conditions such as tunnel lining and sub-surface conduits, it proved to be an economical choice.  A barrel of 50/50 Portland cement and ground tufa was $1 cheaper than pure Portland cement.  Over 1 million barrels of cement were used to produce over 1,500,000 cubic yards of concrete in building the aqueduct.  The majority of the cement used in construction came from the Monolith mill, which was built and operated by the city, another innovative feature of the aqueduct.

The northernmost portion of the aqueduct consists of about 61 miles of open canals, both lined and unlined.  These canals were excavated using floating electric-powered shovels.  Water could be let in to the canal gradually as it was dug.  This method had never been used before.  The electric power was generated at a number of small hydroelectric plants, built on streams that fed the Owens River and later the aqueduct.  Most (all?) of these plants are still in use today.

Three months after the aqueduct was placed in service one of the inverted siphons suffered a break due to a desert flash flood and collapsed under atmospheric pressure.  At first engineers felt that the pipe would have to be completely taken apart, reformed, re-riveted and reassembled, at a cost of $250,000.  Instead water under pressure was gradually reintroduced into the pipe and it re-rounded itself.  It was the first time this technique had been tried.

The 215.5 miles of constructed aqueduct are made up of a variety of conduit types: open, unlined canals; open concrete-lined canals; buried concrete conduits; lined and unlined tunnels; and reinforced concrete and riveted steel inverted siphons.  Construction materials and methods and the route were all carefully chosen to minimize costs.  The final accounting of the project, published in 1916, showed that the original estimate of $24.6 million was beaten by about $2.865 million.

For a city the size of Los Angeles in 1906-07 to consider borrowing $24.6 million  was a staggering leap of faith and determination.  This amount represented just over 12% of the total assessed valuation of all taxable property within the city. Its total bonded debt before taking on the debt to build the aqueduct amounted to $7 million.  By municipal charter the maximum bonded debt the city could undertake was 15%.  Borrowing for the aqueduct essentially exhausted the city’s legal credit.  Fortunately, the outstanding financial performance of the Water Department, since 1902, when $2 million worth of bonds had been issued and sold, convinced the eastern bond houses that Los Angeles was a good credit risk.  Borrowing the same proportionate amount today would mean a bond issue of just over $23 billion.


In the first decade of the 20th Century, environmental awareness was much different than it is today.  Rivers than ran free to oceans or saline sinks were viewed as wastes of resources.  Anything in the environment that was not put to the maximum use of humans was simply underachieving.  There was no end to the rivers and basins that were being studied for their potential to be harnessed for the benefit of human economic activity.  Los Angeles, with its growing population and its immense potential, deserved the opportunity to fulfill that potential, and it could only do so if a distant and available source of water could be found.

It was in the best interests of Los Angeles, once it had secured the right to  take water from the Owens River, to keep the watershed of the river as pristine and protected as possible.  As the largest landowner in the Owens Valley, the city has continuously taken steps to maintain the quality of the lands under its ownership as well as mitigate the effects of groundwater pumping and other activities in the valley.  Eighty percent of the land owned by the city is leased, and it is the city’s policy that 75% of leased land remain open to the public for recreational uses.  Twenty thousand acres of leased land are irrigated for agriculture, while 240,000 are leased for cattle grazing.

Los Angeles has devoted much time and effort to working with the local communities in the valley to enhance public recreational facilities and access.  Fishing in particular is a recreational activity that Los Angeles has promoted by building hatcheries and consulting with the California Department of Fish and Game to maintain the quality of lakes, creeks and rivers.  Other environmental projects the city supports include agricultural greenbelts, rare plant and endangered species studies, research stations, woodlots, a visitor center, and wildlife habitats.  The Owens Valley today is year-round vacation destination for more than 1 million visitors (?) annually, thanks in part to the stewardship of the city’s Department of Water and Power.

In the 1930’s the aqueduct was extended 105 miles north to the Mono Basin.  The flow of some of the streams that feed Mono Lake was diverted to the aqueduct.  Over time, the level of Mono Lake began to drop, and environmental concerns were raised.  The city reduced the stream diversions, and now the lake level is steadily going back up towards its prior level.

The diversion of the Owens River also affected Owens Lake, which was the alkaline sink into which the river flowed.  The lake had been shrinking since prehistoric times, and by 1929 it was dry.  Today Los Angeles is taking steps to control the alkali dust that occasionally blows off the dry lakebed and causes air pollution in the southern Owens Valley.  Some water will be required to control the dust.  Water conservation measures implemented in Los Angeles over the past 10-15 years have allowed the city to reduce per capita consumption by 20 percent and save over 100,000 acre-feet of water per year (enough water for about 1 million people.)

In the years since Mulholland realized his dream of building the Los Angeles Aqueduct, millions have come to the city.  They have shared his vision of the city as an ideal home.  But the water the aqueduct brought has made it possible for them to stay, to flourish, and to continue to dream of the greatness of the future.

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