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The Hollywood Reservoir in Los Angeles

Nestled in the Hollywood Hills since 1924, the Hollywood Reservoir is a little-known but critical part of Los Angeles’ water infrastructure with a fascinating history. As I walked the 3.3-mile path around its banks, I gained an appreciation for how this man-made lake has served Southern California’s water needs for nearly a century.

The idea for the Hollywood Reservoir came after the famous Mulholland-planned dam for the Los Angeles Aqueduct was completed in 1923, bringing vital water south from the Owens Valley. The City realized the growth of Los Angeles would tax even this new water source. They identified a need for storage reservoirs built closer to the end users.

Construction Begins

In 1924, under the direction of Water Department chief engineer William Mulholland, work began on damming part of the Hollywood Creek near its junction with the Los Angeles River. (This reminds me of the great movie called Chinatown, starring Jack Nicholson.) This rocky canyon in the foothills between Mt. Lee and Mt. Bell was chosen as an ideal reservoir location.

The Hollywood Reservoir in Los Angeles 1
An artist rendering of what it must have looked like during construction, as it’s 183 feet deep.

Hauling equipment up the steep slopes was no easy feat in the 1920s. But men and machines managed to erect the tall concrete Weid Canyon Dam as well as smaller earth-filled dams on nearby canyons. The dam foundations were anchored to bedrock as much as 50 feet below the surface to ensure stability.

By November 1925, the dam was complete and the reservoir basin started filling. It ultimately cost $4.5 million to build – over $70 million in today’s dollars. The reservoir’s original holding capacity was 2.5 billion gallons, supplying much-needed storage to even out Los Angeles’ seasonal water flows.

Growth Demands More Water

By the late 1920s, it became clear more reservoirs were needed to keep pace with LA’s booming population. In 1928, Mulholland supervised plans for an extension to the Hollywood Reservoir’s dam, raising it to increase capacity by another 790 million gallons.

Tragically, this same year brought the failure of Mulholland’s St. Francis Dam in Santa Clarita. The resulting flood killed over 450 people and ended his career. Work continued, however, on the Hollywood Reservoir dam upgrade and it was successfully raised in 1930 to increase water storage for the still growing metropolis.

The Hollywood Reservoir in Los Angeles 2
The St. Francis Dam collapse in Santa Clarita was a major tragedy that took 450 lives.

The maximum capacity of the Hollywood Reservoir grew to be 4.36 billion gallons spread over 138 acres. Its water is fed by rainwater, underground aquifers, and LA Aqueduct flows. Along with the smaller Lake Hollywood reservoir in the next canyon over, it provides a gravity-fed backup water supply for Los Angeles.

The compound is secured from public access since it remains a working municipal infrastructure component. Its water feeds into supply pipes running to the neighborhoods and cities to the south. However, the public can enjoy walking and jogging along the 3.3-mile service road encircling its perimeter.

Recent Upgrades

By 2002, concerns arose about the vulnerability of the aging dam to seismic damage. A $60 million retrofit was undertaken over the next six years, completed in 2008. The work improved anchors into bedrock and added steel reinforcements. Now deemed able to withstand a major earthquake, it leaves the Hollywood Reservoir safe to continue serving LA’s water needs for decades more.

Walking the path around the Hollywood Reservoir today, you’d never imagine the bustling metropolis nearby. Its calm waters reflect the surrounding greenery and mountains as waterfowl drift silently across the surface. The only hints of its greater purpose are the water system control towers and warning signs prohibiting public access along its steep banks lined with chain link fences.

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The reservoir is a beautiful part of Los Angeles that many residents have been missing out on.

But despite its protected status, this scenic reservoir still invites you to stroll its perimeter and contemplate its critical role in Los Angeles’ historical growth. Its rugged terrain once funneled torrents of storm runoff straight to the sea. Now safely contained behind engineering marvels, the Hollywood Reservoir’s billions of gallons stand ready to quench the thirst of one of the world’s largest cities in any season or drought.

Media Fanfare at the Start

When plans for the Hollywood Reservoir were announced in the early 1920s, the project received much media attention as a vital expansion of Los Angeles’ water infrastructure. Headlines hailed it as bringing “New Storage for City Water Supply” and a “Huge Project Will Supply Added Water Here.”

Articles touted the imported water from the LA Aqueduct but emphasized the need for more reservoirs so this water could be captured and stored. The 1924 headline “Stone Canyon Flood Water Will Fill Big Reservoir” described how the Hollywood Reservoir would allow storm runoff to be conserved rather than wastefully flowing to the ocean.

Updates continued through construction, with the L.A. Times reporting breathlessly on the progress of completing the dam and the excitement when the basin finally began to fill: “New Hollywood Reservoir Starts to Fill Up.” Even the devastating 1928 failure of Mulholland’s St. Francis Dam was explicitly linked to highlighting why the upgrades underway to raising the Hollywood Dam were important safety improvements.

The Hollywood Reservoir in Los Angeles 4
Visitors are usually very surprised at how beautiful some parts of Los Angeles are.

Once construction finished, accounts of the reservoir’s capacity and key statistics were widely reported. But then it faded into the background – an integrated, reliable cog in LA’s water supply network.

The Water’s Journey to Homes

Rain or LA Aqueduct water flows into the reservoir constantly, but how does it get safely to consumers’ taps? The first step is ensuring contamination doesn’t enter the protected reservoir. Feeder streams and pipes are secured to prevent contact with outside pollutants before even reaching the lake.

From there, the LA Department of Water and Power (DWP) oversees regular testing for over 800 possible contaminants as the water makes its journey to homes and businesses. Nearly every day, water samples are examined at the DWP’s state-certified Water Quality Lab. Any detection outside tight regulatory levels prompts immediate investigation and corrective action.

As water exits the Hollywood Reservoir into underground pipes, chlorine is added to remove pathogens. At various checkpoints, additional testing validates chlorine and pH levels before the water ever reaches consumer plumbing. The DWP also maintains 580 protective covering stations throughout the water system keeping pipes flowing efficiently and safely.

What starts as rainfall and snowmelt from hundreds of miles away ends up flowing reliably from taps across Los Angeles thanks to pioneering civil engineering achievements like the Hollywood Reservoir. Combined with extensive testing and safety controls, this man-made lake has helped Southern California boom by ensuring there’s always enough clean water on tap to allow that growth.

The Hollywood Reservoir in Context

The Hollywood Reservoir’s 4.36 billion gallon capacity may seem large, but how does it compare to other major water storage projects across the arid Southwestern states?

The Southwest faces constant drought and water supply challenges with growing populations. Cities have addressed this through ambitious dam construction projects in recent centuries. When ranking major Southwestern U.S. reservoirs strictly by capacity, the Hollywood Reservoir lands high on the list but is still dwarfed by some larger projects.

The largest reservoir in the region is Lake Mead on the Colorado River, built in the 1930s on the Arizona/Nevada border. Its nearly 30 million acre-foot capacity makes it the largest reservoir in the United States – over 200 times the size of Hollywood Reservoir! It provides vital water storage for much of the Southwest via diversions from the Colorado River. Hoover Dam’s construction was an unprecedented engineering feat that still awes visitors with its immense scale today.

Even major reservoirs in Hollywood’s home state fall significantly above the Hollywood Reservoir’s capacity. Northern California’s Lake Shasta holds over 4.5 million acre-feet, while the iconic Oroville Dam bottles up 3.5 million acre-feet. Closer to Hollywood, Silverwood Lake in San Bernardino County tips the scales at 73 billion gallons or over 200 times the Hollywood Reservoir’s size.

Yet within the regional context of Los Angeles’ own water infrastructure, the Hollywood Reservoir stands out from its peers. The iconic Los Angeles Aqueduct delivered water from farther afield rather than damming local rivers for storage in reservoirs. As the city grew in the early 20th century, the foresight to build storage closer to home set the Hollywood Reservoir apart from LA’s other supplies. Its location minimizes pumping needs and infrastructure demands downstream.

Now integrated as a key component of the Los Angeles water grid, the Hollywood Reservoir might seem diminutive next to epic multi-state water projects like Lake Mead or massive Northern California reservoirs. But its historical role in securing reliable water as LA boomed in the early 1900s can’t be overstated. What it lacks in sheer size, it makes up for in strategic importance in the regional water puzzle sustaining one of America’s largest cities.