For nearly 15 years, a group of citizens in Potomac has waged an all-out war with the U.S. Postal Service.

The residents--more at ease with disputes over hunting rights and the encroachment of commercial zoning in their once-rural neighborhood--have spent days and months battling over building sites and plans the service has proposed for a new facility in the area.

They have become caught up in the minutiae of parking spaces, traffic patterns, lock boxes, package pick-ups, and undelivered letters. They have collected maps and statistics and held meetings and written letters and called congressmen. They have even called the Postmaster General.

Now the war is almost over, and to the chagrin of the crusaders in Zip code 20854, the Postal Service appears to have won.

"It's the classical 800-pound gorilla that can do anything it likes, and does," says Marcia Airis, zoning chairman of the West Montgomery County Citizens Association, who has visited 20 post offices during her career as a civic activist.

"It's an incredible sequence of administrative looseness and sloppiness and misinterpretation," says Potomac resident Bob Gibson who, like many in his neighborhood, favors a split postal facility that would divide mail sorting and customer services into two small offices in the area.

"The issue is the power of the Post Office in a local community," says Allan S. Cohen, president of the community group.

The source of debate between the citizens group and postal officials is a planned $2.6 million, 16,000-square-foot Potomac Post Office, which is to have 100 parking spaces, 35 postal jeeps and 1,000 lock boxes--all on a 2.9-acre site (that is part flood plain) at the busiest intersection in Potomac village. The Zip code zone is the largest in Montgomery County and the Postal Service says it needs a much-expanded facility to serve it. While upgraded service is needed, both sides acknowledge, the dispute is over how to provide it.

The Maryland-National Capital Park and Planning Commission last year deemed the ground, known as the Moran site, unacceptable. But the Postal Service (which says the Potomac Chamber of Commerce backs its action) is negotiating to buy the land anyway, reportedly for $800,000, to replace and expand its sole facility in Potomac, a small post office in the Potomac Village mall.

"The Post Office doesn't have to finagle their way," says planning board chairman Norman Christheller. "They just have to ignore us. The stated federal policy is for the Postal Service to try to adhere to local land use planning facilities. It is their policy to hear our recommendations. Beyond that we can do nothing."

It isn't the first conflict between the Postal Service and its customers here over building plans: In Frederick, Md., the Postal Service angered residents when it proposed to stop services at its main downtown office, and in Fairfax and Prince George's counties, there have been on-going debates over the placement of large-scale postal facilities such as the one proposed for Potomac.

Last June the local planning board told postal officials that a new facility built on the Moran site would cause an automatic expansion of the Potomac village commercial area, create more congestion at the intersection of Falls and River roads, pose environmental threats to the now-clean Rock Run stream, which runs into the Potomac, and be inconvenient to the residential center of the Zip code area, which lies further north and east of Potomac Village.

"We spent six months working with the the postal staff to find other sites," Christeller said. "They submitted three sites to us, including Moran. We told them one of those, Srour site was acceptable. The Srour site is less than a mile from the Moran site, but not on a busy intersection. We didn't repeat all that we had said before about the Moran site, but obviously the land hasn't changed and the community hasn't either."

Despite the objections by local citizens and the local planning board, the Postal Service recently began negotiations for the Moran site after the Maryland-National Capital Planning Commission, the body of highest authority in this case, decided not to reject the site flat out. At a meeting earlier this year, the commission merely said another site would be preferable.

"The basis for our selection was that the other site was not in a commercial area and use of that site would be less efficient and less convenient to serve the needs of the business area," said James McDougald, manager of the D.C.-Maryland Postal Service District. "We would have needed some continued form of service in the village." McDougald added that engineers have studied the site and that "there would be no significant environmental impact."

Some citizens say the Postal Service is retaliating against Potomac because residents tried a few years ago to prevent construction of a postal training center in the community.

"I've got the feeling that the Post Office has gotten to the point where they just think Potomac would never be satisfied, and they're going to do it whether we like it or not," said citizens' group president Cohen.

"The fact that you can have a unanimous turn-down by a local board and then this outcome suggests a bankrupcty in the process," says Gibson. "The Post Office has the best of two worlds. They are a quasi-corporate entity. They are sovereign in getting around zoning restrictions, and at the same time they are not held accountable by Congress. That is the fundamental part of our problem."