Dam evacuation could last weeks

OROVILLE, Calif. (NBC News) – The rush to repair crumbling spillways at California’s Oroville dam continues as crews work to beat approaching rain.

Helicopters are being used to drop loads of boulders into the damaged spillways.

Nearly 200,000 people living near the dam have been evacuated.

The evacuation order will remain in place until the next round of rain has passed.

NBC News has learned three environmental groups warned of potential danger back in 2005 that the emergency spillway should be lined in concrete and didn’t meet modern safety standards.

Officials then concluded it was safe and “would perform as designed”.