Formal notices were posted at the encampment near the stadium of the Los Angeles Angels team.
Deputies will give tent-dwellers reasonable time to move, and Orange County will provide transportation to area shelters and storage for personal belongings, said Carrie Braun, a spokeswoman for the county sheriff's department.
The encampment is a 2-mile (3.2 kilometer) stretch of tents and tarps surrounded by trash on a dusty patch of land near a bike trail where cyclists zoom by. It sprang up in recent years on the trail along the Santa Ana River.
"The goal is to get people out of there and restore it to a flood control channel," Braun said.
The Associated Press has reported over the last few months on an unprecedented homeless crisis on the West Coast, where tens of thousands of people are sleeping on the streets from Seattle to San Diego. The problem is caused in part by soaring housing costs, rock-bottom vacancy rates and a roaring economy. A drug addiction crisis and need for mental health services are also factors.
Homeless advocates said Orange County's decision will simply shuffle people elsewhere due to a lack of available housing and drive the homeless to sleep in parks and on sidewalks.
Neighbors of the riverbed have been urging officials to shut down the encampment and restore the trail for biking and jogging.
Braun said the area will be entirely closed for up to three months. Once it reopens, she said deputies will regularly patrol the area to prevent overnight camping.
Bruce Bishop, 58, said he's not sure yet where he will go and wishes they would not shut down the camp where he's lived for two years since getting evicted from his home. But he doesn't entirely blame the county either.
"This is an eyesore for everybody. It's an eyesore for us," he said.
Orange County last summer hired a nonprofit group to provide case management services to those living in the encampment, then home to roughly 400 people. Since then, officials have said they eventually planned to close it down.
Bishop said he's speaking with the nonprofit about his options and may be able to move back in with his girlfriend. He said he won't go to a homeless shelter because there are too many rules about coming and going.
"That's jail," he said.
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