Oroville report blames design, supervision

SANFRANCISCO— Bad design and construction of the tallest U.S. dam a half-century ago and inadequate state and federal oversight since led to a disastrous spillway collapse, an independent national team of safety experts said Tuesday as they urged tougher safety reviews nationwide.

The experts investigating February’s spillway failures at California’s Oroville Dam say the state probably could have detected the problems that led to the collapse if dam managers had assessed the original construction flaws in the 1960s-era structure in light of modern engineering standards.

Cluestothecrisis“wereallinthe files” of California officials, showing the original flaws in the spillways’ foundation, concrete and drainage, said John France, speaking for the expert panel formed by national dam-safety associations.

At Oroville Dam, “there has never been an evaluation completely that went back thoroughly in the files,” as far as the outside experts could determine, France said.

Erin Mellon, a spokeswoman for California’s Department of

Water Resources, the owner of the 770-foot-high dam, said state officials are committed to applying lessons from Oroville.

“The reconstruction efforts at Oroville will bring the spillway design and construction up to today’s standards to ensure we address the physical causes that led to the February failure,” Mellon said.

Assessing whether similar problems lie in other dams around the country depends partly on whether authorities budget the money for those historical reviews, France said. The average dam in the United States was built more than a half-century ago using now-outdated design standards.

Tuesday’s report cites a series of problems with the Oroville spillway construction, including thin concrete, poorly placed drains and inadequate foundations.