Mulholland Dam facts for kids
Quick facts for kids Mulholland Dam |
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A view of Hollywood Reservoir and the back side of the Mulholland Dam
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| Location | Hollywood Hills, Los Angeles, California |
| Coordinates | 34°07′4.8″N 118°19′51.8″W / 34.118000°N 118.331056°W |
| 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) |
| Maximum water depth | 183 ft (56 m) |
| Designated: | 1989 |
| Reference #: | 421 |
The Mulholland Dam is a large dam located in the Hollywood Hills area of Los Angeles, California. It was built by the Los Angeles Department of Water and Power (LADWP).
This dam creates the Hollywood Reservoir. This reservoir can hold a lot of water, about 7,900 acre-feet, and it can be as deep as 183 feet. The water in the reservoir comes from different aqueducts and also from a creek called Weid Canyon.
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The Story of Mulholland Dam
The Mulholland Dam has had a few names over the years. It was first known as the Weid Canyon Dam. Then it was called the Hollywood Dam. Finally, it was named the Mulholland Dam. This last name honors William Mulholland. He was a very important engineer. At the time, he was the General Manager and Chief Engineer of the Bureau of Water Works and Supply. This group later became the LADWP.
William Mulholland was key to building the Los Angeles Aqueduct. He also helped create much of the city's water system. This included many early dams and reservoirs. The area where the dam stands was first called Holly Canyon. Later, it became Weid Canyon. This name came from Ivar Weid, who lived there after the Civil War. A street in Hollywood, Ivar Avenue, is also named after him.
Building the Dam
Engineers first looked at this area for a reservoir in 1912. They surveyed it again in 1922. That's when they started designing a dam made of stone. Construction of the Mulholland Dam began in August 1923. It was finished in December 1924.
When it was completed, the Mulholland Dam was special. It was the first concrete, curved gravity dam built by the Bureau of Water Works and Supply.
Focusing on Dam Safety
Another dam, the St. Francis Dam, was also designed by the same group. It was very similar in size and shape to the Mulholland Dam. However, in March 1928, the St. Francis Dam broke apart. This terrible event caused a huge flood in the Santa Clara River Valley. More than 430 people lost their lives.
After this disaster, William Mulholland ordered the Hollywood Reservoir to be lowered. This was a safety step. It also helped calm public fears about another dam breaking.
Because of the St. Francis Dam failure, California created new dam safety rules. In 1929, the Department of Public Works gained power to check all non-federal dams. This included dams over 25 feet tall or those holding more than 50 acre-feet of water. The new laws also allowed the state to hire experts. They could also oversee how dams were maintained and operated.
Soon after the St. Francis Dam broke, a group of engineers and geologists looked at the Mulholland Dam. In 1930, the State of California also formed a panel to review the dam. The City of Los Angeles also created its own review board.
These groups found that the dam needed more support against water pressure. This was important to prevent it from becoming unstable. While the state's panel didn't suggest big changes, all groups agreed on the need for better support.
Making the Dam Stronger
In 1931, another group looked at whether to stop using the Mulholland Dam. An expert report on the dam's foundation also came out. These reports showed some design issues in both the Mulholland and St. Francis Dams.
The final decision was to keep the Hollywood Reservoir at a lower level. Its capacity would be no more than 4,000 acre-feet. Today, it usually holds about 2,800 acre-feet. To make the dam much stronger, a huge amount of earth was added to its downstream side. This was about 330,000 cubic yards of soil.
Adding this earth helped the dam resist water pressure and earthquake forces. It also helped hide the dam from public view. This work was done between 1933 and 1934. After that, the LADWP planted many trees and plants on the new earth. This helped screen the dam even more. Recent studies confirm that the Mulholland Dam now meets state safety rules.
