THE PEOPLE who bring you Metro -- a disparate but regionally alert and remarkably cooperative group made up of elected officials from all area governments, state legislators, members of Congress and federal representatives -- came together in harmony last week for their 16th annual renewal-of-fiscal-faith retreat. Though the conferences have never had any legal standing, the agreements forged at these sessions have helped keep alive the miracle of Metro subway financing.

Even as a new set of stations is opening, the subway system continues to roll along a financial brink. It's too late now for anyone to repossess the project, but keeping up with the payments is as difficult as ever for local governments. No longer will the federal government settle for last-minute scrambles to meet local shares of the bill; by agreement with the federal government, the state and local partners have all committed themselves to come up with a "stable and reliable source of revenue" to cover their Metro obligations.

Translated, that means taxes earmarked for Metro. While a single regionwide tax of some sort might seem best, most of this year's conferees recognized the political impossibility of any such arrangement. It would be looked upon less than fondly in Annapolis and Richmond -- where sympathy and dollars will be desperately needed in the next few months. Instead, Maryland, Virginia and the District each will work on a formula for raising the money. The understanding and support of Govs. Harry Hughes and John Dalton are crucial to the efforts, for Metro is an important part of each state's transportation program, to be included along with highway improvements when the state governments consider tax changes.

Meanwhile, there is another piece to the puzzle, in the form of a bill passed by the House and now awaiting action in the Senate to provide federal matching funds. It is not a federal giveaway measure, but a fiscally responsible plan for completing the project and binding the local governments to a solid payment arrangement. It also is supported by the administration as a sensible and moderate measure to complete the one new mass transit system in the country that is on the verge of having a substantial impact on gasoline consumption and air pollution. Enactment of the bill this month, before Congress leaves town for the holidays, is essential to any follow-ups in Maryland and Virginia.