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Thursday, May 25, 2017

Neighborhood Fixture: Silver Lake’s South Dam helped protect city against “water famine”

SILVER LAKE  —  An open house on Saturday put the spotlight on one of the neighborhood’s most important but often overlooked public works: the South Dam of the Silver Lake Reservoir.

The dam, which was originally built more than a century ago, prevents more than 700 million of gallons of water from flowing down Silver Lake Boulevard. But the towering structure is easy to overlook because the south facing side is a grassy slope — instead of a wall of concrete — that rises over the Silver Lake Recreation Center and dog park. The north side is usually hidden from view by water.

Now that officials want to open the top of the structure as a public walk way, here is some historical information about the original South Dam from stories that appeared in the L.A. Times over the decades:

  • Concerns about a “water famine” before the Owens Aqueduct brought water to the city prompted the construction of the Silver Lake Reservoir and the South Dam in what was called Ivanhoe Canyon.  The new, 767-million-gallon storage basin was several times larger than the adjacent Ivanhoe Reservoir, which was the city’s largest until the new dam and reservoir were completed.
  • Legendary engineer William Mulholland designed the earthen dam, which was strengthened by a three-foot-thick wall of concrete and steel plates.  “While an ordinary earth dam probably would be adequate, the location of the reservoir is such that more than the usual margin of safety is deemed desirable, as a break would cause disaster similar to the Johnstown flood,” said the L.A. Times.

The south side of the dam is covered by a grassy slope

  • The original dam was 56-feet high, 950-feet long and 300-feet wide at its base.  It was built at an estimated cost of $80,000.
  • Instead of having teams of workers dig out and haul dirt to build up the dam, Mulholland set up a trio of high-powered water cannons  to “melt” away layers of dirt. The muddy mix created by the water cannons was then pumped into the interior of the dam as part of the hydraulic-fill method.
  • The South Dam was completed in 1907. An L.A. Times story from Nov. 25 of that same year said that water was expected to start flowing into the reservoir behind the “staunch dam” within a few weeks. “Stupendous” said the headline.
  • The reservoir was taken out of service in 1973 because the dam failed to meet quake standards.  A new dam made of compacted soil was built and dedicated in Sept. 1976.

A spokeswoman with the L.A. Department of Water & Power said the top of the South Dam could be opened to the public by the end of the year “provided that the community is in agreement with the plan.”

The top of the South Dam

Neighborhood Fixture  provides a bit of history and background about buildings and places that catch our attention.  Got info about a neighborhood landmark? Send details [email protected]

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One comment

  1. Sandy Driscoll

    Thanks very much for this fascinating history! I’ve lived in Silver Lake for many years and never heard the entire story.

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