Cutbacks in gasoline allocations to some Washington area school systems have prompted lcoal officials to draft contingency plans to ensure that school buses will keep running through the end of the academic year.

Concern over dwindling supplies is most acute in Montgomery and Prince George's counties, which were informed last week that their gasoline supplies for May will be cut back 10 percent from the amount they received in May 1978.

Gasoline supplies have been cut back 10 percent in Fairfax County and Arlington County and 20 percent in Loudon County in Northern Virginia, but officials indicated they expected to have no problems accommodat the reduction.

District school officials said yesterday that they expect no reduction in gasoline allocations. "I spoke to our supplier last week, and we seem to be in good shape," said Joe Powell of the school transportation office.

Montgomery County schools spokesman Kenneth Muir said yesterday that there was a slight chance "there would not be enough gas to run the buses by the end of the month." However, the Maryland Office of Energy Policy would almost certainly provide Montgomery with backup gasoline supplies if needed, Muir said.

Although school systems have contracts with oil companies to supply them with the gasoline they need, the companies have imposed allocations based on federal guidelines.

Montgomery schools, which used 231,000 gallons of gasoline last May, would only get 208,000 gallons under the allocation it expects from its supplier, Gulf Oil Co. Its projected use is 260,000 gallons, Muir said, which would leave the schools with a 52,000 deficit by the month's end.

At a meeting of Montgomery school officials yesterday, a variety of conservation measures were discussed, including:

Doubling up on maintenance trucks and putting a third of those trucks out of service.

Doubling up on the trips of plumbers, painters and other workmen.

Forbidding school staffers to use pool cars.

Increasing the number of tuneups of buses and cars to improve fuel efficiency.

A more painful option, he noted, would be cutting back students' field trips and athletic trips.

However, such trims would save an estimated 11,000 gallons-not enough to meet the shortfall, so the school district has asked the state energy office for an emergency allocation.

A spokesman there said he thought Montgomery school people were overreacting slightly. "People say 'Me first, I have to be assured of gas," said state energy official Donald Milsten. "We have the capability of dealing with school systems and dealing with their needs."

The extra gasoline comes from the state's set-aside program, which keeps 3 percent of motor fuel coming into the state in reserve for emergencies. This fuel is then allocated on a case-by-case basis. At the moment, Maryland has 5 million galloons, Milsten said, enough gas to keep the entire state rolling for one day.

Virginia has a simlar set-aside program available to its schools, governments, industries and dealers.

Local schools and nonemergency government services now rank third on a complicated three-tiered allocation system devised by the federal govvernment. Defense and agricultural needs carry the top priority, while emergenccy services such as police and fire rank next and face only a fractional reduction of their current needs if supplies become extremely tight.

Schools and governments, industries and businesses have third priority.

In Prince George's County, school officials met yesterday morning to develop short and long-range plans to meet their 10 percent reduction.

"Curtailing field trips, athletic trips are options being considered," spokesman John Aubuchon said. But, he added, Prince George's school system hopes to get aid from the state's emergency set-aside program, and was also asking Gulf to boost its allocation.

Cutbacks have already been in effect in Loudoun County, which got 30 percent less gas last month than in April 1978 and expects a 20 percent cutback this month from its supplier, Cities Service Co.

A county official said that the number of field trips has been cut, athletic teams have been doubling up on travel, and the school district dipped into Virginia's emergency reserve to keep the school buses running.

In other Northern Virginia districts, however, school officials were less concerned about cutbacks. "I have no knowledge of any shortages," said Robert Harper of Alexandria schools.

"Northern Virginia seems to be doing all right," said June Kopald, of the State Energy Office, in Richmond, which is in charge of allocating set-aside gasoline. She said her office would not give any "blanket commitment" but would help schools and governments on an individual should tighten up," she said, "but we will work with them."