The State of Virginia, in a move that stunned some local officials, is challenging a new regional sewer agreement that would give the District and Montgomery County more sewer taps that they say they desperately need to continue development.

Thomas M. Schwarberg Jr., regional director of the Virginia Water Control Board, said there is "real concern within the state that if the present allocations [at the Blue Plains regional sewer plant] are not maintained, there will be a lot of growth in the area, and suddenly we'll wind up with a lot of flows that can't be treated properly."

"This is the most incredible thing I have heard of in eight years in public office," said Fairfax County Board Chairman John F. Herrity when informed of the state's action. "I am shocked by the lack of notification."

Acting on behalf of the Water Control Board, Assistant Attorney General Frederick S. Fisher filed a request last Monday with the federal Environmental Protection Agency seeking a formal hearing on the sewer allocation.

Mayor Marion Barry yesterday wrote a letter to EPA regional administrator Jack J. Schramm saying Blue Plains' users are in "general agreement" with the new permit and accompanying order that gives the city and other users power to allow more sewer taps.

Barry said the two documents permit the region "to meet its immediate needs, for sewer treatment capacity...and avoid costly moratoriums."

City Administrator Elijah Rogers said "the specter of a moratorium in the city has been listed."

The agreement, which represented a major concession by EPA, in effect permits Blue Lains users to make 5 percent more sewer commitments than they have now in allocations.

Both the District and Montgomery say they have come close to exhausting their allocations through commitments. While many of the commitments have not been used yet by developers, they are still counted against allocations.

When a jurisdiction's allocation is exhausted, then it must impose a moratorium. A moratorium could cripple the city's economic renaissance, officials have said. The same fears have been raised by leaders in Montgomery, which is trying to bring more industry to the county.

Two environmental groups, the Maryland Environmental Coalition and the Citizens' Coordinating Committee on Friendship Heights, also have asked for a hearing before an EPA Administrative law judge.

The EPA must decide whether there is sufficient reason to hold such a hearing and then would consider the judge's decision as a formal recommendation.