LOS ANGELES – Peering out over the edge of the Sepulveda Dam Spillway, on most given days, less than a foot of standing water can be seen in the basin below.
Off in the distance, cars pass over a bridge along Burbank Boulevard, a frequently traveled thoroughfare to the 405 Freeway toward San Diego.
During a large rain event, the entire area, including Burbank Boulevard, could be under water, explained John DeSimone, dam tender, Operations Division, U.S. Army Corps of Engineers Los Angeles District, to a group of about a dozen University of California, Los Angeles engineering students touring the dam April 25.
It’s hard to imagine on a sunny day like today, that water can rush through this area from the Santa Susana Mountains, causing an emergency situation, he said. But it happens. And it happened in the 1990s.
“It may not be raining here,” he said, “but if it’s raining in the hills, water comes up superfast and fills up our basin.”
On that particular day more than 20 years ago, the water elevation rose so quickly, he said, people clung to trees and had to be rescued by helicopter. He credits a savvy dam tender, who recognized the dire situation, for saving the lives of a lot of people.
That’s why dam tenders are the “eyes” and “ears” for the Corps, DeSimone said.
Built in 1941, the purpose of Sepulveda Dam is to collect flood runoff from the uncontrolled drainage areas upstream, store it temporarily and release it into the Los Angeles River at a rate that does not exceed the downstream channel capacity, which is about 17,000 cubic feet per second.
The top of the dam is more than 15,000 feet in length with an elevation of about 725 feet, said Reuben Sasaki, hydraulic engineer with the Corps’ Hydrology and Hydraulics Branch, Engineering Division.
“The largest event here on record was about 705 feet (in 1980), so if you look about 20 feet below you, that’s how much water was behind this reservoir,” he told the students. “I’m not sure which way you guys came in, but if you came in through the west side, you saw a golf course and other recreation parks. Those could be under water, especially in a large (rain) event.”
DeSimone and Sasaki, along with several other Corps’ employees explained the dam’s operations, hydrology and design to the students, as well as took them on an outside and inside tour of the spillway.
During large rain events, Sasaki said, the Corps’ Reservoir Operations Center and the dam tenders monitor the inflow levels and activate the spillway to protect lives and properties downstream.
“If this wasn’t here, and we had a (large rain) event, you would see a lot of damage downstream,” Sasaki said. “This dam mitigates, controls and reduces flood risk.”
What is unique about the dam is it has eight outlet passages, of which, only four have gates, said Amanda Walsh, a hydraulic engineer with the Corps’ Reservoir Regulation Section, Hydrology and Hydraulics Branch, Engineering Division. Because the other four passages don’t have gates, she said, Sepulveda Dam can’t "shut off" flow to the Los Angeles River.
“The main purpose for Reservoir Regulation is we try to minimize downstream damage for as long as we can, until we start having a spillway flow,” she said. “Even with eight gates open, that bridge (on Burbank Boulevard) can be underwater.”
Throughout the tour, the students were given opportunities to ask questions.
Kerri Scholte, a third-year civil engineering student at UCLA, said she benefitted from learning about the importance of operator roles, stemming from civil engineering, and how monitoring and reporting procedures are implemented to ensure public safety before, during and after storm events.
“This was a great introduction to the U.S. Army Corps of Engineers,” she said. “I'd be interested to know what a design job would look like and to see some visual context for other sites the Corps oversees in Los Angeles.”
In addition to the tour, students were given information about jobs with the Corps, including various positions, like engineers, biologists, geologists and project managers to support staff positions and many more.
ABOUT SEPULVEDA DAM
Sepulveda Dam is a single purpose flood control project constructed and operated by the U.S. Army Corps of Engineers Los Angeles District. Construction of the project was completed Dec. 30, 1941. The project is located on the Los Angeles River at the junction of the San Diego 405 and Ventura 101 freeways. It is the western-most dam out of the Corps of Engineers’ inventory in the Los Angeles County Drainage Area flood control system.