California's Lake Oroville remained on on the verge of flooding Monday after heavy rains eroded an emergency spillway used to prevent floods.
At least 188,000 people were evacuated after a leak was spotted in the spillway on Sunday. Engineers said Sunday afternoon the spillway could fail within the hour.
While the dam itself is sound, the spillway eroded under heavy rain, creating a 200-foot-long, 30-foot-deep hole that continues to grow. Engineers don't know what caused the cave-in.
WATCH | Here's an overhead look at the spillway from the California Highway Patrol.
Here's another look.
You can't even move. I'm trying to get out of here too. I'm worried about the flooding...that's a lot of water.
In the meantime, locals from Yuba, Sutter and Butte counties attempting to evacuate have been caught in gridlocked traffic.
Butte County Sheriff Kory Honea said he had no choice but to order an evacuation, adding, "I didn't have the luxury of waiting," the Record Searchlight reported.
Erosion was first reported days ago.
Kevin Lawson, California Fire incident commander, said the spillway was no joke.
"When you start to erode the ground, the dirt and everything else starts to roll off the hill," Lawson said. "Essentially, what we're looking at is approximately a 30-foot wall of water."
Lawson said if the lake's water level can drop 50 feet, the situation will be much calmer. But no repairs have been done on the spillway since it's too dangerous to reach the area.
The Associated Press contributed to this report.