OROVILLE, Calif.  — Water levels dropped Monday at California’s Lake Oroville, stopping water from spilling over a massive dam’s potentially hazardous emergency spillway after authorities ordered the evacuation of nearly 200,000 people from towns lying below the lake.

California Department of Water Resources officials are waiting for the light of dawn to inspect an erosion scar on the spillway at the Oroville Dam, the nation’s largest.

The evacuations for people living below the lake were ordered Sunday after authorities warned that failure of the emergency spillway could send a 30-foot wall of water into the communities.

The lake that also serves as a reservoir has swelled significantly in recent weeks because California has been hit by a series of storms that have dumped rain and snow across the state, particularly in northern California where the lake lies about 150 miles northeast of San Francisco.

The threat appeared to ease somewhat Monday, which officials saying water flows into the lake stood at about 45,000 cubic feet per second with outflows at 100,000 cubic feet per second.

Lake Oroville is one of California’s largest man-made lakes and had water levels so high on Saturday that its emergency spillway was used for the first time since it was built nearly 50 years ago.

Sunday afternoon’s evacuation order came after engineers spotted a hole on the concrete lip of the secondary spillway for the 770-foot-tall Oroville Dam and told authorities that it could fail within the hour.

The sudden evacuation panicked residents, who scrambled to get their belongings into cars and then grew angry as they sat in bumper-to-bumper traffic hours after the evacuation order was given.

Kaysi and Greg Levias packed everything they could into their car from their Yuba City apartment and piled everything they were leaving behind as high as possible before leaving the city they

“We’ve never been through this before,” said Kaysi Levias. “We have two boys and our dog. All the stuff we could fit in the trunk — clothes and blankets.”moved to just three weeks ago.

Raj Gill, managing a Shell station where anxious motorists got gas and snacks, said his boss told him to close the station and flee himself. But he stayed open to feed a steady line of customers.

“You can’t even move,” he said. “I’m trying to get out of here too. I’m worried about the flooding. I’ve seen the pictures — that’s a lot of water.”

A Red Cross spokeswoman said more than 500 people showed up at an evacuation center in Chico, California.