Mulholland Dam

Mulholland Dam

A view of Hollywood Reservoir and the back side of the Mulholland Dam
Location 3005 Lake Hollywood Dr., Hollywood Hills, Los Angeles, California
Coordinates 34°07′4.8″N 118°19′51.8″W / 34.118000°N 118.331056°W / 34.118000; -118.331056Coordinates: 34°07′4.8″N 118°19′51.8″W / 34.118000°N 118.331056°W / 34.118000; -118.331056
Construction began 1923
Opening date 1924
Owner(s) Los Angeles Department of Water and Power
Dam and spillways
Width (crest) 16 feet (4.9 m)
Reservoir
Creates Hollywood Reservoir
Total capacity 7,900 acre·ft (9,700,000 m3)
Max. water depth 183 ft (56 m)
Designated 1989
Reference no. 421[1]

The Mulholland Dam is a Los Angeles Department of Water and Power dam located in the Hollywood Hills of Los Angeles, California. Designed with a storage capacity of 7,900 acre·ft (9,700,000 m3) of water at a maximum depth of 183 feet (56 m), the dam forms the Hollywood Reservoir, which collects water from various aqueducts and impounds the creek of Weid Canyon.[2]

History

Originally named Weid Canyon Dam, then Hollywood Dam and, finally, Mulholland Dam in honor of William Mulholland who at the time was the General Manager and Chief Engineer of the Bureau of Water Works and Supply, a predecessor department of what is now known as the Los Angeles Department of Water and Power. Mulholland was responsible for the design and construction of the Los Angeles Aqueduct and much of the city's water system, including many of the early earthen dams and storage reservoirs.

The area was first surveyed for use as a reservoir in 1912. In 1922, the area was again surveyed and designs for a masonry dam began to be made. Construction of the dam began in August 1923 and it was completed during December 1924. Upon its completion, the Mulholland dam became the first concrete, curved gravity dam designed and built by the Bureau of Water Works and Supply.[3]

The St. Francis Dam was also designed and built by the Bureau of Water Works and Supply, and in that its design was an adaptation of the Mulholland Dam, it was nearly identical in size and shape.[4] In March 1928, the dam experienced a catastrophic failure, and the resulting flood devastated the Santa Clara Valley and took the lives of as many as six hundred people.[5] William Mulholland ordered the Hollywood reservoir lowered shortly after the collapse of the St. Francis Dam as a precaution as well as to help ease public fears of a repeat disaster.[6]

Due to the St. Francis Dam disaster, the California legislature created an updated dam safety program and in 1929, the Department of Public Works, under the oversight of the State Engineer was given authority to review all non-federal dams over 25 feet high or which would hold more than 50 acre-feet of water. The new legislation also allowed the State to employ consultants, as they deemed necessary. Additionally, the State was given full authority to supervise the maintenance and operation of all non federal dams.[7]

Soon after the failure of the St. Francis Dam a Committee of Engineers & Geologists to Assess Mulholland Dam was appointed to reviewed the safety of the Mulholland Dam. This was followed in January 1930 by the External Review Panel to evaluate the structure, convened by the State of California. In March 1930 the City of Los Angeles Board of Water & Power Commissioners appointed their own Board of Review for the dam.

Although the state’s panel did not recommend modification of the dam, both panels came to similar conclusions that the fact the dam lacked, what was at the time considered, sufficient uplift relief and which may possibly lead to destabilization and that this was unacceptable. A fourth panel, the Board of Engineers to Evaluate Mulholland Dam, was appointed in 1931 to examine the feasibility of abandoning Mulholland Dam. An external Geological Report of the Suitability of Foundations followed this in late 1931, appointed by the Board of Water & Power Commissioners. These believed design deficiencies, made by the engineering department while planning and which were not only employed in the Mulholland but, thereby the St. Francis Dam as well were brought to light though given little public notice in 1931.

The decision ultimately made was to permanently keep the Hollywood Reservoir drawn down, and keep its capacity to no more than 4,000 acre·ft (4,900,000 m3), the reservoir now is usually maintained at about 2,800 acre·ft (3,500,000 m3), and to place an enormous amount of earth, 330,000 cu yd (250,000 m3), on the dam’s downstream face. This was to be done not only to bolster its resistance against hydraulic uplift and earthquake forces, it also did well in screening it from public view. This work was carried out in 1933-34, after which the LADWP undertook a forceful program of re-vegetation on the new earth, which succeeded in screening the dam from most everyone’s notice. More recent studies have revealed Mulholland Dam to be within the State guidelines for dam safety. [6][8]

The Mulholland Dam was portrayed in the 1974 disaster film Earthquake, where after a large earthquake destroys much of Los Angeles, the dam threatens to collapse and does due to aftershocks.

See also

References

  1. ↑ Los Angeles Department of City Planning (February 28, 2009), Historic - Cultural Monuments (HCM) Listing: City Declared Monuments, City of Los Angeles, retrieved 2000-03-02 Check date values in: |access-date= (help)
  2. ↑ 22nd Annual Report of the Board of Public Service Commissioners
  3. ↑ Rogers, David J. (1995). "A Man, A Dam and A Disaster". The St. Francis Dam Disaster Revisited Nunis Jr., Doyce B. Ed. Historical Society of Southern. p. 23-24. ISBN 0-914421-13-1.
  4. ↑ Rogers 1995, p. 21.
  5. ↑ Pollack, Alan (March–April 2010). "President's Message" (PDF). The Heritage Junction Dispatch. Santa Clara Valley Historical Society.
  6. 1 2 Rogers 1995, p. 85.
  7. ↑ "Statutes and Regulations pertaining to Supervision of Dams and Reservoirs" (PDF). State of California. Retrieved 10-04-2013. Check date values in: |access-date= (help)
  8. ↑ "Earth Guards Dam from Quakes." Popular Science, April 1934

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