America’s tallest dam’s “imminent failure” leads to evacuation of 180,000 people
More than 180,000 people have been asked to evacuate the area downstream of the Oroville Dam in California, after officials warned of an “imminent failure” as a result of a hole in the crumbling structure.
At 770 feet, Oroville is the tallest dam in the United States. Residents of eight cities in the dam’s vicinity were told to evacuate shortly before 5 p.m. local time on Sunday.
Lake Oroville was inundated by unusual amounts of rainfall as a result of three atmospheric river storms — a type of storm associated with major flooding events — in the area during January and February. Once Lake Oroville reached capacity, officials from California’s Department of Water Resources began utilizing the dam’s spillway — a structure that provides the controlled release of water.
Cracks began to appear around the spillway last week, according to the declaration of emergency from Gov. Jerry Brown’s office. On Saturday, officials began relying on the backup auxiliary spillway, which had never been used since the dam’s construction in 1968, but soon determined that that structure was also at risk of failing.
— Joe Bobosky (@FITorion) February 12, 2017
“Officials now anticipate a failure of the auxiliary spillway within 60 minutes,” The National Weather Service said in a warning on Sunday afternoon, urging residents to evacuate in a northward direction toward the town of Chico. “This is not a drill. This is not a drill. I repeat, this is not a drill.”
— Nick Merianos (@NickMerianos) February 13, 2017
A failure of the dam could send a 30-foot wall of water cascading into the surrounding towns along the Feather River Basin, causing potentially devastating flash flooding.
Crews from California’s Department of Water Resources have since plugged the large hole in the dam with rocks as they work to fix the problem, which stopped the water spilling out. On Sunday night they began the controlled release of 100,000 cubic feet per second of water in an effort to lower water levels in the lake.
“It’s clear the circumstances are complex and rapidly changing,” said Gov. Brown, assuring residents that the state was deploying “all necessary personnel and resources to deal with this very serious situation.”
But California officials may have ignored warning signs that the dam was at risk of failure a long time ago. Three local environmental groups filed a motion with the Federal Energy Regulatory Commission in 2005 urging federal officials to reinforce the Oroville dam’s emergency spillway with concrete, the Mercury News reported. In the motion, plaintiffs charged that the dam did not meet modern safety standards and would not hold up in the event of extreme rain or flooding.
Meanwhile, Sikh temples, churches, and schools in the Sacramento area have opened their doors to all evacuated people, offering food and shelter.