Officials have announced that all those people who evacuated due to a threat from the tallest dam in the United States can now return to their homes.
On Sunday, as many as 1,88,000 people living down river from the Oroville Dam were ordered by the officials to evacuate after a drainage channel was weakened by heavy rain. Officials have revealed that state crews have now reinforced the weakened channel by working round the clock.
People can now move back to their homes and businesses can reopen; however, officials have said that they should be prepared to evacuate again if such an issue crops up again.
Both the primary and backup drainage channels of the dam, known as spillways, were damaged by a buildup of water that resulted from an extraordinarily wet winter in Northern California that followed years of severe drought. The greater danger was posed by the emergency spillway, which was subject to urgent repairs in recent days. Though damaged, the primary spillway was still useable, officials said.
More rain was forecast for as early as Wednesday and through Sunday, according to the National Weather Service, but the state Department of Water Resources said the upcoming storms were unlikely to threaten the emergency spillway.
President Donald Trump declared an emergency in the state thereby authorizing the Federal Emergency Management Agency and the Department of Homeland Security to coordinate disaster relief efforts.
The lifting of the mandatory evacuation improved the mood among evacuees at Silver Dollar Fairgrounds in Chico, where families packed cars and sifted through piles of donated clothing.
According to numbers released by the state, officials used 40 trucks carrying 30 tons of rock per hour to reinforce the eroded area around the emergency spillway while two helicopters dropped rock and other materials into the breach.
Water authorities had been relieving pressure on the dam through the concrete-lined primary spillway last week, but lake levels rose as storm water surged in and engineers moderated its use. Then the rising water topped over the earthen backup spillway, which has a concrete top, for the first time in the dam’s 50-year history over the weekend.
When the emergency spillway showed signs of erosion, engineers feared a 30-foot-high section could fail, leading to the evacuation order on Sunday. Both spillways are next to the dam, which itself is sound, engineers say.