In any other year, the release of water from Lake Oroville would be no big deal.
But a gaping hole erupted in the middle of the lake’s main spillway in February 2017, and on Tuesday — after two years and $1.1 billion worth of repairs — the sound of success was water shooting down it before crashing onto rocks and finally emptying into the Feather River.
The California Department Of Water Resources used the dam’s main spillway for the first time since the 2017 incident, which led to the evacuation of more than 180,000 people in Oroville and downstream.
The occasion drew a crowd. Cars lined the shoulder of East Oroville Dam Boulevard across the river from the spillway. Joan Bosque, a freelance photographer, said that, two years ago, she was hiking next to the spillway when it failed.
She recalled how water shot into the air halfway down the ramp’s bottom section. “I thought it was a kind of prank, or something got lodged,” Bosque said. “And then I kind of sensed something was wrong.”
Joel Ledesma with the California Department of Water Resources says the agency is confident the dam’s new spillway will not suffer the same fate.
“We are prepared,” he said. “We spent the last two years restoring full functionality of the spillway.”
He added that the department will continue to inspect and review other dams and facilities to head off failures akin to Oroville.
The dam spillway’s breach was first noticed on February 7, 2017, when concrete on its top collapsed. As the hole grew wider, DWR officials stopped releasing water and began preparing to use the emergency spillway.
On February 12, officials issued a mandatory evacuation in anticipation that the emergency spillway might fail. More than 180,000 people were eventually evacuated from Butte, Colusa and Sutter counties, which officials have said was the largest evacuation for a non-hurricane event in the country’s history.
As of October 2018, the cost of repairs was $1.1 billion. Erin Mellon with DWR says the department will appeal a Federal Emergency Management Agency decision to pay for just $333 million of the work.
Some minor finishing work remains to be done along the walls of the spillway, according to Mellon.
Correction: A previous version of this story misidentified Erin Mellon. We have corrected the error.