The Notebook on Politics column "Heavyweight Fight for Reservoir Site" {District Weekly, Dec. 13} discussed the proposed development of a site at the McMillan Reservoir in terms of competing developers and neighborhood opposition to the loss of open space. But it is only fair for Washingtonians to know what else is at stake in this last-minute land deal contemplated by Mayor Marion Barry's office.

What has been missing from this debate so far is recognition that any development of the 25-acre McMillan Reservoir site in Ward 5 should be considered in the context of our city's heritage. This special place is not only one of the last undeveloped parklands in the middle of the city but a significant historic landmark as well.

Designed by premier landscape architect Frederick Law Olmsted Jr., McMillan Reservoir is an integral part of the renowned "McMillan Plan" for the nation's capital. Its ivy-covered towers and cavernous underground vaults, although often mistaken for Civil War fortifications, were actually part of an elaborate 19th century water-purification system for the capital city. Later, before security concerns during World War II closed the park, it was a favorite gathering spot for Washingtonians.

Now this unique piece of history is hidden behind a 12-foot chain-link fence, which shuts out the public instead of enhancing the "quality of life" that is vanishing in our urban environment.

This is not an esoteric concern. Three years ago, the president's Advisory Council on Historic Preservation concluded that McMillan Reservoir was eligible for listing on the National Register of Historic Places. This significance recently was confirmed by the District's own preservation consultants. Yet key decisions have already been made to go ahead and choose a developer for the site -- so far without ensuring that development plans take into account the reservoir's historic character.

Clearly, the District's rush to close the deal during the last days of this administration will place Mayor-elect Sharon Pratt Dixon in a difficult position when she assumes office in January. The National Trust for Historic Preservation and the D.C. Preservation League already have brought suit to achieve compliance with applicable historic preservation laws. In addition to inheriting an unnecessary lawsuit, the Dixon administration will have to defend the Barry administration's intensive commercial development proposal before a skeptical D.C. Historic Preservation Review Board and the D.C. Council.

Since McMillan Reservoir is much more than just another lucrative development project, the question has to be "what's the rush"?

J. Jackson Walter is president of the National Trust for Historic Preservation.