THERE IS NEW and good reason to believe that one of Washington's most misused but potentially grand areas--the Maine Avenue waterfront in Southwest--is about to come alive in a dramatic and logical way. In what could be a perfect match of this capital's international flavor with 17 acres of prime publicly owned property, a group of federal, local and private planners has come up with a solid proposal for a U.S. International Cultural and Trade Center--with practical benefits for all parties.

The project, conceived and developed by the Federal City Council, a nonprofit coalition of civic leaders that promotes local development, would be located south of the Southwest Freeway, between 7th and 10th streets. The idea is to create something a little different, combining many attractions of other trade centers or urban complexes, with special local and international uses, including 1) an exposition area for presentations by any and all countries represented here; 2) a trade center, for commercial, cultural, agricultural and labor interests of foreign governments, as well as a one-stop center for travelers to obtain passports and other necessary travel documents; 3) an educational center, with facilities for foreign language instruction, cultural studies and student-exchange programs; and 4) an international bazaar, featuring products and foods from around the world.

Plans call for development through a quasi-public corporation authorized by Congress to issue bonds. Federal agencies that have been paying rent elsewhere would pay rent instead for a 20-to-25-year bond period and then would own the facilities. The more than 700 neighborhood and local people who have been briefed this year have been "basically supportive," the planners report, and embassies and international organizations have been enthusiastic about locating their commercial interests in a central, consolidated area.

So far, support for this project has been remarkably strong, from the administration and its executive agencies to city hall and local organizations. As Carlos C. Campbell, assistant secretary of commerce for economic development, observed, "This was an environment waiting to be captured." And it was a good catch.