The tallest dam in the US now faces the risk of collapse after its once-strong basement was weakened by heavy rainfall. As a result, thousands have been asked to evacuate from their northern California home to evade any catastrophic occurrences.
Officials report that the Oroville Dam’s emergency spillway may collapse at any given moment thus prompting them to ask people residing in the flood risk areas to leave immediately, reports CNN.
After years of severe drought, California skipped from the enraging drought to dangerous rain and snow. The two have collectively contributed to an increase in the reservoir’s water levels.
This is the first time in about 50-year history that the dam has been exposed to an emergency situation.
The California Department of Water Resources first called for an evacuation around 4:40 p.m. Sunday, just four hours after holding a news conference during which they said they didn’t anticipate such problems.
They said that it was releasing as much as 2,830 cubic metres of water/sec in attempts to drain the lake.
Via a social media statement, the sheriff in charge of the Lake Oroville Dam area said that residents have to evacuate as this is an order and not a drill.
Engineers had begun working on the draining work on Thursday after which they noticed a huge chunk of concrete had been washed off the spillway.
They had initially predicted that it would collapse within an hour but the imminent risk subsided and officials made efforts to reduce the reservoir’s level.
According to Sheriff Kory Honea, they chose to stay safe rather than be sorry later on.
Honea added that they are making efforts to see the crisis is averted while they also relocate people to safety in the event of a worst-case scenario. Some of the methods they are using to shore up the spillway include the use of “drop rocks into the crevice.”
Water district officials have in the past maintained that US’s highest dam is structurally stable and doesn’t face any risk of collapsing.
But the National Weather Service in Sacramento seemed to disagree has it advised that the dam can collapse at any given moment.
The agency stated that dam operators came across a “hazardous situation is developing with the Oroville Dam auxiliary spillway.” It continued to explain that erosion had intensified and this could hugely contribute to the structure’s collapse.
“The concern is that erosion at the head of the auxiliary spillway threatens to undermine the concrete weir and allow large, uncontrolled releases of water from Lake Oroville,” said a release from the water department. “Those potential flows could exceed the capacity of downstream channels.”
The Oroville’s 16,000 occupants are now headed to the north. Officials have also advised any other involved city to follow suit.