Water flowing over emergency spillway at tallest United States dam

Butte County officials said Nelson Avenue is closed at Table Mountain Boulevard due to on going road construction. Heavy rains this week swelled Lake Oroville and keeping water moving over the dam takes pressure off the structure and reduces flooding risks.

Water started flowing over an emergency spillway at the nation's tallest dam, on Lake Oroville, for the first time Saturday after erosion damaged the Northern California dam's main spillway. "Failure of the auxiliary spillway structure will result in an uncontrolled release of flood waters from Lake Oroville".

Residents of Oroville, located about 65 miles north of Sacramento, were ordered to evacuate northward, toward Chico, Calif.

"We're going to continue to flow water down the spillway and lower the lake", See said.

Water flowing over emergency spillway at tallest United States dam

Water cascades over the emergency spillway at Oroville Dam on February 11.

The main spillway can handle water flows up to 250,000 cfs. Officials said they'll assess the damage starting Monday.

The Sacramento Bee quoted California Department of Forestry and Fire Protection spokesperson Mike Smith: "What they're expecting is as much as 30 vertical feet of the top of the spillway could fail and could fail within one to two hours".

A spokesman for the Water Resources Department has said officials estimate the cost of repairing the dam could approach $100 million, but noted the estimate was an early, ballpark figure.

  • Larry Hoffman