OROVILLE, Calif. — A huge Northern California reservoir, held in place by a massive dam, has always been central to the life of the towns around it.

Now the lake that has brought them holiday fireworks and salmon festivals could bring disaster.

Nearly 200,000 people, who evacuated Sunday over fears that a damaged spillway at Lake Oroville could fail and unleash a wall of water, have to stay away indefinitely while officials race to repair it before more rains arrive Thursday.

Evacuees felt strange on Monday to see their beloved lake associated with urgent voices on the national news.

“Never in our lives did we think anything like this would have happened,” said Brannan Ramirez, who has lived in Oroville, a town of about 16,000 people, for about five years.

The gold-rush town in the Sierra Nevada foothills some 70 miles northeast of Sacramento is nestled near the foot of the dam, which at 770 feet is the nation’s largest. Houses and churches are perched on tree-lined streets near the Feather River. Old, ornate Victorian homes sit alongside smaller bungalows.

“Everybody knows to go there for the Fourth of July,” evacuee Crystal Roberts-Lynch said of the lake. “Then there’s festivals wrapped around the salmon run.” The mother of three, who has lived in Oroville for 10 years, was staying at a Red Cross evacuation center in Chico.

Local businesses, including one that sells supplies for gold-panning, dominate a downtown area that spans several blocks. A wide range of chain stores sit a short distance away along the main highway.

“The lake brings in an enormous part of the economy for the town. It definitely is a people-catcher,” said Brannan Ramirez, who has lived in Oroville for about five years. “We get people from all over the country.”

Cities and towns further down the Feather River also are in danger.

Yuba City, population 65,000, is the biggest city evacuated. The city has the largest dried-fruit processing plant in the world and one of the largest populations of Sikhs outside of India.

The region is largely rural and its politics dominated by rice growers and other agricultural interests, including orchard operators. The region is dogged by the high unemployment rates endemic to farming communities. There are large pockets of poverty and swaths of sparsely populated forests, popular with anglers, campers and backpackers.