Montgomery County School Superintendent Harry Pitt released a $564-million plan yesterday to build, expand and refurbish schools during the next six years, trying to keep pace with a growth spurt expected to increase school enrollment by 26 percent.

The projects would cost $121 million next year and, by 1996, would add 15 schools in Montgomery, which currently has more buildings than any other Maryland school system.

Pitt's plan, similar to last year's, makes little concession to the county's softening economic climate or to recent taxpayers' complaints. "We don't have any choice," the superintendent said. "The problem is, we are going to have all these kids."

Today, county voters will decide on four measures to limit taxes and spending. If they pass, the ballot questions could have a pronounced effect on education, the biggest item in the county's budget.

One measure would prohibit the county from paying for projects that are theoretically a state responsibility. It is unclear how the measure would be interpreted if it passes, but education officials said it could have drastic effects on school construction. "We'd be dead in the water if that passes," Pitt said. "I don't know what we'd do."

Currently, Montgomery absorbs 83 percent of the expense of building and repairing schools. The state is supposed to pay for half, but has never provided the money.

The superintendent's plan is intended to furnish enough classrooms as the school system continues unprecedented expansion for several years. Enrollment is projected to grow from 91,000 in the early 1980s to 103,700 this fall and to 131,000 by 1996, according to school system figures.

The influx is the result of trends during the mid- and late-1980s that have made Montgomery the state's largest jurisdiction, according to preliminary estimates from the 1990 U.S. Census. Births increased in Montgomery's older, southern neighborhoods, while a building boom transformed northern communities such as Germantown and those along Route 29.

The superintendent's proposal is the opening round in a perennial debate over where schools should be built and which ones are in greatest need of repair. The Board of Education gives its request to the county executive by the end of November. He then advises the County Council, which must decide on a final version of the proposal in May.

Pitt's proposal includes two elementary schools and a middle school that are scheduled to open next fall. It also includes two new middle schools that were not envisioned in previous six-year plans.

Under the plan, 33 classrooms would be added to Montgomery Blair High School in Silver Spring, which already is the school system's biggest building. The school, which has Montgomery's only high school magnet program, is becoming crowded as population increases in the county's southern communities.

Through the 1997 fiscal year, Pitt is requesting $215 million for building and expanding schools, $170 million for renovations and $179 million to repair roofs, remove asbestos and buy computers and telecommunications equipment.

His plan asks the state to chip in $85 million next year. But state officials tentatively have said they plan to allot Montgomery $5.2 million, according to Ann Briggs, the school system's director of facilities and capital projects.

For the current year, the County Council curtailed several major road projects, while giving the school system most of the construction funds that it sought.

According to county Budget Director Robert Kendal, who opposes the tax limit initiatives on the ballot, they could hurt school construction because the county uses some operating funds for such purposes.

Pitt called his proposal "about as tight as I could make it . . . . Certainly, you could make cuts, but if you wait, it is going to cost you more, not less." His spokesman, Brian J. Porter, added: "County residents don't expect to have their kids taught in hallways."