California Congressman John Garamendi painted a grim picture of how catastrophic the failure of the Oroville Dam's emergency spillway could have been Monday.
Months of heavy rain created a 200 foot-long gash in the Oroville Dam's main spillway last week.
The state water resources department said crews using helicopters would drop rocks to fill a huge gouge, and authorities were releasing water to lower the lake's level after weeks of heavy rains in the drought-plagued state.
Engineers were continuing to assess damage to the emergency spillway that official feared would collapse, triggering the massive evacuation affecting nearly 200,000 residents in Butte and Yuba counties.
The dam, whose structure remains sound, is almost full following a wave of winter storms that brought relief to the state after four years of devastating drought. "There is still a lot of unknowns", said Kony Honea, sheriff of Butte County where Lake Oroville is located. But its spillways - which drain Lake Oroville and aren't part of the main dam structure - are both damaged. Repairing the damaged infrastructure of the dam and its spillways is going to be a massive undertaking, speculated to cost between $100 million and $200 million!
The helicopters, along with two airplanes, will also be available today for search and rescue near the Oroville Dam, California National Guard Adjunct General David Baldwin said at a news conference Sunday.
Those flows could overwhelm the Feather River and other downstream waterways and levees and flood towns in three counties.
Officials are also releasing water from the dam in a bid to reduce the water levels as much as possible ahead of rainfall.
But the evacuation order remained in force, leaving relieved residents now dreading possibly the drive home through the bumper-to-bumper snarls they had negotiated on their way out.
Reportedly, large population residing in areas being evacuated is that of Indian origin Americans.
The main spillway, bottom, and an auxiliary spillway, upper, of the Oroville Dam at Lake Oroville in Oroville, Calif.
California and local officials are rushing to fix the spillways at Lake Oroville and lower the water level by as much as 50 feet ahead of rain forecast for later this week.
Residents of Oroville, which has a population of 16,000, are being ordered to head north north towards Chico.
Residents listen at the Bangor Community Hall as they get the news that the evacuation order has been lifted.
It stands at 230m high, besting the famous Hoover Dam by over 12m.