PICO RIVERA - A flood control dam in Pico Rivera could fail in a huge flood, endangering 500,000 people between Whittier and Seal Beach, it was reported today.
The Whittier Daily News says the three-mile-long dam, an earthen structure that straddles the San Gabriel River and Rio Hondo, could fail in a 100-year storm, according to the U.S. Army Corps of Engineers.
The dam does not currently hold any water, but is a standby facility in case intense rain hits the San Gabriel Valley or the mountains above Azusa. Its twin outlets flow through concrete channels through southeast Los Angeles and northwest Orange counties to the ocean at Seal Beach, including cities like Pico Rivera, Downey, Bellflower and Cerritos.
Water agencies had hoped to build a small, shallow lake at the Whittier Narrows Recreation Area to replenish underground aquifers with storm water runoff that otherwise flows out to sea. They are studying if a 3.4-foot-deep lake would endanger the extensive downstream suburban development.
But Virginia Tech engineering professor James Michael Duncan has told the Corps of Engineers that the earthen and rock dam is not structurally sound.
When a Whittier Daily News reporter asked the engineer what was wrong with the dam, the consultant replied "it's not my job to explain it to the general public.''
The dam was remodeled in 2000 to provide a bigger spillway into Rio Honda, to allow potential floodwaters a path out other than overtopping the 3-mile-long dam.