BOWING TO the insular acrimony generated by a few county overseers hungry for commercial gains, Sen. Harry F. Byrd Jr. (I-Va.) has decided he'll definitely block a House-passed bill that would preserve historically valuable land around the Manassas National Battlefield Park. His excuse - which has nothing to do with either Virginia's heritage or the national interest in saving this land from development - is that a "cooling-off period seems in order." But that's because a hot-headed majority of the supervisors in Prince William County are refusing to consider any reasonable compromise. Sen. Byrd's response, then, is to leave plenty of time to bring in the tourist traps, industrial complexes or whatever else the supervisors are willing to wreck the land with.

It isn't as if this issue just landed on Sen. Byrd's desk, either. The bill, sponsored by Democratic Rep. Herbert E. Harris (who, like the senator, happens to represent Virginians), has been passed by the House twice. In the last Congress, Sen. William L. Scott (R-Va.) blocked it (by proxy, from somewhere on a junket) in the closing hours of the session. While no one ever expected Mr. Scott either to explain or get over his obstructions, supporters of historic preservation, including two or three of the county supervisors, did hope that Sen. Byrd might do something. But there's no evidence that he's ever sought to come up with any compromise - or that he even cares about protecting the acreage. This land, by the way, includes an area around Stone Bridge over Bull Run, where a Confederate general named Jackson acquired the nickname "Stonewall" as well as the site of other action in the second Battle of Manassas.

At least Sen. Byrd's own "stonewalling" has drawn a response from Sen. James G. Abourezk (D-S.D.), chairman of the Parks and Recreation subcommittee. Mr. Abourezk says he'll try to find enough votes to push the bill through the full Energy and Natural Resources Committee.As he noted: "This is not a state issue. This is a national park. There are always factions of local people who oppose a park. You have to deal with that." Tha won't be easy. The Senate isn't usually comfortable about taking an action within a state over the opposition of the state's senators.But this is an instance in which self-serving senatorial courtesy ought to give way to the need for action, now - before the land is irretrievably ruined by narrow interests.