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Historical Notes

The Mulholland Dam is a concrete-arched gravity dam constructed between August 1923 and December 1924.  Built under the supervision of William Mulholland, chief engineer for the City's Bureau of Water Works and Supply (later DWP), the dam’s sole purpose was creating a new water reservoir for the City of Los Angeles.

Historical Notes

The reservoir formed behind the dam was called the Hollywood Reservoir (later Lake Hollywood) and would hold up to 2.5 billion gallons of water from the Owens River Aqueduct System (LA Aqueduct) and from the groundwater of the San Fernando Valley.

Historical Notes

In the early 1920s, developers began opening virgin tracts of land for construction all around Los Angeles. To help sell these new developments, real estate agents coined fancy names like Bryn Mawr, Outpost Estates and Whitley Heights, while also constructing large signs spelling out their names with individual letters in white and red.*^*

Click HERE to see more in Early Views of Hollywood.

LADWP Historic Archives

"Tuesday, the 17th of March, 1925, in addition to being St. Patrick’s Day, was also a red-letter day in the annals of the Department of Public Service. To those who were fortunate enough to be the recipients of an invitation to be present at the dedication of that monumental structure in Weid Canyon, the Mulholland Dam, the day will be forever memorable as signalizing the erection of another symbolic milestone to mark the progress of this incomparable city of Los Angeles.

Mulholland Dam, enshrining forever in imperishable stone the name and the fame of its designer and builder, Chief Engineer William Mulholland, not only ranks as one of the great engineering accomplishments of its kind in the United States, but it also stands unique in that it is located squarely in the midst of a thickly populated metropolitan area.

Because of this fact and of its standing at an elevation overlooking and dominating the entire Hollywood section and the downtown Los Angeles district, two major considerations overshadowed everything else in its design and construction – the factors of safety and beauty.

With the inflexible determination that no Johnstown Disaster should ever overwhelm the City of the Angels, the form of the Dam was, for greater safety, thrust forward upstream against the pressure to come, arching in a vast curve like a colossal bow in order to transmit the approaching future strains as a lateral stress to the wide and ample shoulders of the unyielding walls of the canyon which it spans. So great is the resultant strength engendered by this construction and so vast the margin of safety occasioned thereby that no pressure that can in the course of nature be brought to bear against it can ever overstrain or overcome the resistant qualities of Mulholland Dam. Indeed, it has been reliably calculated that if Lake Hollywood, which it impounds, were filled with molten lead instead of water, the Dam would still stand. This becomes all the more impressive when it is recalled that, bulk for bulk, lead is 11.4 times heavier than water, the weight of a cubic foot of lead being 710 pounds as against 62 ½ pounds for a like volume of water.

And then because not only of its commanding position, dominating the city and the cynosure of all eyes for miles around in its enframing background of circling hills, but also because “a thing of beauty is a job forever,” it was determined to make Mulholland Dam sightly and beautiful, as well as solidly and safely utilitarian. How well, this determination was carried out and the vision realized all who have seen the superb structure can abundantly testify.

Constructed of solid concrete, 200 feet in span and 160 feet in thickness at its base, bedded upon the everlasting rock, the white walls of Mulholland Dam tower upward 200 feet into the air between the precipitous hillsides of Weid Canyon to a thickness of 16 feet and a span of 975 feet at its crest, culminating in a roadway flanked on either side by four foot balustraded sidewalks, thus proving a twenty-four-foot viaduct over the entire structure.

Beginning construction in August 1923, the dam proper was completed on December 24, 1924, just in time to figure as the most elaborate, graceful and costly Christmas token for the municipal stocking, ever tendered to the city of Los Angeles. in all a total of 172,800 cubic feet of concrete were poured, at a cost to the city of $1,250,000, in round figures, being at the rate of slightly more than $6 per cubic yard, as against $10 to $12 per cubic yard, the average cost of similar concrete structures elsewhere.

Filled to it full height, Mulholland Dam is capable of impounding 2,500,000,000 gallons of water, a supply sufficient to cover 8,000 acres of land to a depth of one foot. Primarily, the purpose of this vast flood is to furnish gravity pressure for Hollywood and the northwest and the foothill section of the city, all of which will be supplied by direct connection. As one link in a chain of fifteen storage and distribution units, Mulholland Dam and Lake Hollywood will from now on constitute one of the most vital portions of the entire water supply system of Los Angeles.

While the Aqueduct is also available, the present source of supply is from a battery of sixteen wells, drilled and drilling, tapping the enormous accumulations of water seeping form the excess of surface irrigation into the deep and almost bottomless gravels of the San Fernando Valley. Lake Hollywood is now being filled through nine miles of 36-inch pipe from eight completed wells, the level standing at 120 feet on the day of the dedication, or considerably less than one-half the rated capacity of the reservoir."

Historical Notes

Coincidence?  Dedication ceremonies were held on St. Patrick’s Day, Tuesday, March 17, 1925.  And, of course, William Mullholland was Irish (born in Belfast, Ireland, on September 11, 1855).

Historical Notes

The ornamental bear heads on the spandrel walls are emblematic of the California native wildlife.^

Historical Notes

Similar to the “Hollywoodland” sign, the "Bryn Mawr" sign was put up to advertise a new housing development below and around the Mulholland Dam (completed Dec. 1924) in the Hollywood Hills (Click HERE to see more).

Historical Notes

The Mulholland Dam was reinforced with tons of earth on the downstream side as a precaution after the similar St. Francis Dam burst in 1928. Later studies confirmed that the St. Francis disaster was not caused by a faulty design.

Click HERE to see more in St. Francis Dam Disaster.

Historical Notes

At the upper end of the reservoir is Hollywood Knolls Pumping Plant which serves the higher areas with water. Eventually, it will pump water to Hollywoodland and nearby sections. Water will be pumped from this plant to tanks above 1,100 feet elevation. This plant is in additon to the Hollywod Reservoir Pumping Plant located at the base of the dam.*

Historical Notes

Due to more stringent safety and water quality regulations, both the dam and reservoir are no longer being utilized as they were when they were originally built. Two of the world’s largest underground tanks now store treated water, with new pipelines linking the tanks to the distribution system. 

Historical Notes

TIn 1989, the Mulholland Dam and Lake Hollywood Reservoir were designated LA Historic-Cultural Monument No. 421 (Click HERE to see complete listing).

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