OMG! This dam is about to collapse

New Delhi: More than 100,000 people fled their homes in northern California Sunday as an emergency spillway next to America's tallest dam threatened to collapse and unleash what authorities called a catastrophic amount of water along the Feather River. 

While the evacuation took place, emergency repairs were performed on the spillway at the 770-foot Oroville Dam, with helicopters dropping rock-filled containers, the San Francisco Chronicle reports. The cities of Oroville, Yuba City, and Marysville were among those under mandatory evacuation orders. Saturday, when a hole developed in the main spillway, was the first time the emergency spillway was used since the dam was completed in 1968.

Damage to a spillway on California's Oroville Dam  which prompted an urgent call for residents downstream to evacuate to higher ground may not be as bad as previously thought, the Butte County sheriff said Sunday.

Still, the evacuation orders for cities and counties near Lake Oroville remain in effect.

"I would rather be safe than sorry. I would rather have people move out of the area hopefully to safety," Sheriff Kony Honea said.

Around 3 p.m. local time (6 p.m. ET), authorities learned that the dam's emergency spillway which has been in use since the primary spillway was recently damaged had a hole in it and was eroding, the sheriff said.

A spillway controls the flow of water from the lake or river being dammed to the area downstream. It also ensures, during times of high water levels, that the water does not rush over the top of the dam or damage the dam.

It's possible that crisis could be averted, however, because the California Department of Water Resources told Honea that the erosion "was not advancing as rapidly as they thought." (Agencies)