dollars). It was originally planned as one of several flood control dams inside Big Tujunga Canyon and was thus referred to as Big Tujunga Dam No. 1 until the larger Hansen Dam was completed in 1940 at the mouth of the canyon, eliminating the need for the other dams. During the Los Angeles flood of 1938, the dam was able to stop a huge debris flow of boulders and uprooted trees, sparing much of Sunland, Tujunga and Glendale from destruction. In 1976, the dam was recognized as in danger of failure from earthquakes (the San Andreas Fault runs nearby) and the reservoir's level was temporarily restricted to about 25% of capacity. In 2008 the Los Angeles County Flood Control District began a project to rehabilitate the aging structure. Approximately of concrete was added to the dam, transforming it from a thin-arch to a thick-arch design. A new spillway was built and the original one was expanded, increasing the floodwater capacity from to more than . In addition, a valve was installed at the dam base to pass low flows for habitat conservation. The seismic retrofit project was completed in July 2011 at a cost of $100 million. See also List of lakes in California List of dams and reservoirs in California References External links Los Angeles County Department of Public Works dams Arch dams Los Angeles River San Gabriel Mountains Angeles National Forest Dams completed in 1931 Historic American Engineering Record in California 1931 establishments in California