A lawyer arguing before the Maryland Board of Education charged today that the Montgomery County school board has created a "moat effect" by segregating minority children at Blair High and other county schools south of the Beltway.

The accusation came as the normally obscure nine-member state board began considering whether to uphold the recommendation of its hearing examiner and for the first time reverse a school closing approved by a county board. After hearing appeals from representatives of a dozen affected schools two months ago, examiner Mitchell J. Cooper found that the Montgomery board had violated its own commitment to integrated education by voting to change Blair's boundaries and to close Rosemary Hills Elementary School.

The lawyer who accused the county board of creating a "moat," Peter J. Nickles, representing Blair, Rosemary Hills and Eastern Intermediate schools, argued in favor of a boundary plan, proposed by county Superintendent Edward Andrews and rejected by the county board, that would have reduced Blair's 58.6 percent minority population.

"The board acted not only in a way that had discriminatory impact, but also with the intent to discriminate . . . ," said Nickles. He also protested a board decision to ignore Andrews' request to "feed" Blair with students from three predominantly white schools north of the Beltway.

E. Stephen Derby, a lawyer specializing in integration cases who was hired by the county board, countered that it was misleading to say Blair had too many minority students. He said its 34.7 percent black, 10.3 percent Asian, and 12.5 percent Hispanic population represented a sound ethnic mix.

"Well, what do you consider a minority?" asked state board member Mary Elizabeth Ellis, a retired principal from Wicomico County. "For reporting purposes you are required to count all these as minorities."

Questions posed throughout the day-long hearing by members of the state board, which includes two blacks and one Asian, gave the impression that they seemed inclined to back the examiner's recommendations.

One of the more avid state board questioners was Verna M. Fletcher, a former Montgomery board president. In answer to one of her questions, Derby said it costs $218,000 to operate Rosemary Hills and $171,000 to operate Rollingwood, the school the board chose to keep open at the expense of Rosemary Hills, which has become a symbol of integration efforts in Montgomery.

State board member Frederick K. Schoenbrodt, a Howard County financial consultant, questioned whether the local board should have considered per-pupil expenditures instead of operating costs in closing Rosemary Hills.

Fletcher also asked whether Rosemary Hills pupils, who will be transferred to several different schools, will receive better educations at their new schools. Derby responded that the students will be in "a more desirable elementary school structure," by remaining in the same building from kindergarten through sixth grade. This year, Rosemary Hills housed children from Head Start through the second grade, with grades three to six attending Chevy Chase Elementary.

Arguing to save Rosemary Hills, lawyer William Skinner said the closure will mean that its minority children will have to "be bused for all of their elementary school years. Only 10 white children will have to be bused."

Derby responded that closing Rosemary Hills will improve racial balance at nearby schools by dispersing its minority students.

"Although you may screen one school, the solution involves all of the schools in the county," Derby said, adding that the overall effect of the Montgomery board's decisions was to sustain high quality education and racial balance. "The burden is on the appellants to show that these decisions were arbitrary and illegal, not whether there could have been other plans that might have worked as well or better," he said.

Not all of the appeals heard today involved challenges to the examiner's decisions. Cooper had agreed with the Montgomery board's decision to close Francis Scott Key Junior High. Lawyer Robert Cohen, representing some Key-area parents, said its closing resulted in placing a "disproportionate burden" on minorities.

But Judith Bresler, another lawyer representing the county board, said, "you cannot isolate the impact on one community, on one part of one decision. Your focus needs to be broader than that." She said Key was closed because of low enrollment and to end a "split articulation pattern" that sent its students to three high schools.

Unlike the stridency that characterized last fall's local hearings, today's session was a quiet one. Only a handful of parents showed up at the state's education headquarters, along with Superintendent Andrews, Board President Eleanor Zappone and Vice President Suzanne Peyser.

The state board's decision, expected by July 20, is likely to play a role in the upcoming school board election in Montgomery, either by vindicating the current board or providing fuel for its opponents.