Engineers begin high-pressure testing of Inland Empire dam

A dam that’s designed to protect people from catastrophic floods is getting its first major test this week. On Tuesday, engineers began sending millions of gallons of water rushing from Seven Oaks Dam near Highland.

The 10-year-old dam is releasing about 3,600 cubic feet of water per second, or about 26,000 gallons, enough to fill up a large backyard swimming pool with a maximum depth of around five feet or so. The release is part of a week of high-pressure tests to see just how the dam might perform during an actual flood emergency.

It’s a trickle compared to the volume of water crews will release at the peak of testing later this week. Engineers will nearly double the usual output to about 45,000 gallons per second.

“The water is going down the Santa Ana River all the way down into Prado Dam," said Rene Vermeeren, chief of hydrology for the Los Angeles office of the US Army Corps of Engineers. "And depending on what happens at Prado Dam it may go out into the ocean.”

The high-pressure tests will gauge just how well, or how poorly, the dam might perform during a real flood emergency.

"What we’re trying to ensure is that the design we used will function," said Vermeeren. "We’ve got instrumentation in the tunnel and we’ve got testing crews monitoring all the instrumentation to make sure the readings they get is normal for this dam.”

The last time engineers tested the floodgates at Seven Oaks, the torrent of water caused sections of the dam complex to crumble. That was four years ago.

Engineers have since made close to $2 million in improvements and repairs to the dam. Drought delayed further testing until this winter.

Inland water agencies plan to divert and capture this week’s runoff and use it to replenish local supplies.

Those who live near the Santa Ana River are warned to stay away from its banks during this week’s tests.