The state Department of Administration, which is responsible for the property, delivered the eviction notice to protesters Tuesday afternoon.
The state hopes the advanced warning and other measures will help avert the kind of confrontation that has plagued other Occupy encampments across the county.
"We're hopeful that they are as respectful of the process as we have been to them," said Jon Hanian, spokesman for the governor. "We'll cross that bridge when we come to it."
For protesters, news that the days of living in tents and makeshift shelters in downtown Boise are numbered provoked gloom and irritation.
"I'm pretty aggravated with the state. I think it's wrong they passed the bill," said Chris Sullivan, a 27-year-old Boise resident.
Sullivan and other members were still weighing options, considering whether to take a stand and risk going to jail. Several said that the protests would continue in a new location.
"Just because we're being asked to leave this spot, the fight's not over," Sullivan said.
Albert Garcia, who has camped at the site since December, said he intends to leave the grounds peacefully. But he doesn't believe leaving the state grounds means an end to the protest movement in Boise.
"If we don't continue, then what was this for?" Garcia said.
Teresa Luna, spokeswoman for the Department of Administration, said she hopes the state's efforts to reach out and communicate with protesters in advance will lead to a clean and seamless breakdown of the encampment.
The bill signed by Otter ensures that property left at the camp will be stored by the state for 90 days.