The Montgomery County Board of Education early today reinstated a much debated desegregation program at Rosemary Hills Elementary School in Silver Spring that was ended by the previous school board last year after six years of operation.

The action, which came after nearly five hours of often acrimonious debate, was a major victory for civil rights activists who had campaigned for more than a year to get the program reinstated. The previous board tried to close Rosemary Hills, which has a high minority enrollment, and disperse its students to four schools throughout the Chevy Chase and Bethesda areas.

That action was overturned by the State Board of Education, and last night's vote was in response to the state board's demands for a new plan for Rosemary Hills.

The plan approved last night again pairs Rosemary Hills, located in a predominantly minority area, with Chevy Chase Elementary, located in an affluent and white neighborhood. The new plan also brings another school, North Chevy Chase, closed last year by the previous school board, into the arrangement.

Students from all three school areas will attend Rosemary Hills for preschool classes through second grade. Rosemary Hills students will then go to North Chevy Chase, along with students from that school area, for grades three through six. Chevy Chase students will return to their neighborhood school for the final four grades of elementary school.

In an important bow to the communities involved, any student now attending Chevy Chase can remain at that school to finish his or her education.

The bitterness of last night's debate and the reaction from the predominantly white audience highlighted the controversy that has plagued the county's only desegregation program since its inception in 1976 and reflected the problem that board members all along knew they were facing: They could not approve a plan that would please everyone.

Several members of the audience told the board they would withdraw their children from the county schools if they were required to go to school with black students.

Board member James Cronin said he felt sorry for the parents who made those statements and added that he resented being threatened with that sort of action. "I do not want minority children in this county seen as detriments or drawbacks or threats to education," said Cronin.

The Chevy Chase community, he said, must "look within itself for its conscience. This was not the best of years for the Chevy Chase image."

The subsequent vote was 5 to 2, with board members Marian Greenblatt and Suzanne Peyser, the two holdovers from the previous board that voted to close Rosemary Hills, opposing the program's reinstatement.

The majority of the Chevy Chase community had asked the board to continue their school as kindergarten through grade six. They, along with Greenblatt and Peyser, argued that actions taken by the previous board last year increased dramatically the minority percentage at Chevy Chase and that their school was not well integrated. Chevy Chase this year has a minority enrollment of 43 per cent.

The new school board members argued that although Chevy Chase appeared to be integrated, the state Board of Education had demanded that integration efforts had to be shared equally by the community.