The flood-control spillway at the nation’s tallest dam will be deployed this week for the first time since it was rebuilt after it crumbled during heavy rains two years ago, forcing nearly 200,000 people to evacuate, California officials said Sunday.
Disaster was ultimately averted during the 2017 downpours, but Oroville Dam needed repairs that totaled $1.1 billion.
The Department of Water Resources has “restored full functionality to the Oroville main spillway and is operating the reservoir to ensure public safety of those downstream,” the agency said in a statement.
No more than a relatively gentle 20,000 cubic feet (566 cubic meters) per second will be released down the spillway during expected rains on Tuesday, the statement said. Triple that amount could be released later in the week as more water flows into Lake Oroville.
The state has been hinting for weeks that the spillway could be reused soon as an exceptionally wet winter starts to give way to the spring snowmelt season in the Sierra, according to the Sacramento Bee . The lake level, deliberately kept low during repairs, has risen to about 50 feet (15 meters) from the top.
The dam was releasing water at around 50,000 cubic feet (1,416 cubic meters) per second in February 2017 when a giant crater erupted in the main spillway. Dam operators dialed back water releases to minimize the damage, causing lake levels to rise so high that water spilled over the adjacent emergency spillway several days later for the first time since the dam opened in 1968.
DWR and its contractor, Kiewit, spent the last two years making repairs. A panel of independent investigators blamed the crisis on “long-term systemic failure” dating back to the original design and construction of the two spillways.
The Federal Emergency Management Agency said this month that it was refusing to reimburse California for $306 million of the $1.1 billion repair bill, citing the investigators’ report and blaming the state for years of neglect. DWR officials said they plan to appeal the decision.