METRO OFFICIALS and union members are in grim agreement that a wildcat strike on Washington's buses and subways could erupt on July 1, depending on how much employes are paid while a new contract is being arbitrated. At issue is an unacceptably expensive cost-of-living clause in the contract that has covered nearly 5,000 drivers, mechanics and other employees. They have been receiving quarterly increases equal to the full rise of the Consumer Price Index. This meant that the last payment was at an 18 percent annual rate. It also means that another payment in July under this formula would cost Metro $7.6 million in the first four months. Understandably, Metro's board and General Manager Richard S. Page are seeking to clip this rate of increases; the budget for the 12 months starting July 1 assumes a 6 percent increase.

Clearly some lid on the cost-of-living payments is necessary, or else bus and subway service -- and jobs -- will have to be eliminated. Just as clearly, any employees who stage a strike of their own, in defiance of their union and collective bargaining procedures, should be dealt with severely. But Metro officials want to skip the July payment -- even though an arbitrator ruled two years ago that the contract meant what it said when it stated that provisions "shall remain undisturbed" and that Metro had to pay whether or not the whole contract was settled.

Metro officials discount that decision, arguing that the difference this time is that they would put the full amount of the increase in escrow and pay whatever turns out to be due whenever an arbitration on a new contract is completed -- which wouldn't be until fall at the earliest. But regardless of whether the same arbitrator permits such a move, a unilateral withholding of the scheduled increases would be an unnecessary provocation. It could lead to job actions similar to the eight-day stoppage that took place here two summers ago.

If the next contract includes a recision of the July payment, Metro Could make necessary adjustments in paychecks. But right now, the full time and attention of Metro's board and labor negotiators should be directed toward an essential and reasonable adjustment of the outlandishly costly pay provision now in force.