Hurricane Gloria apparently reactivated a former "Superfund" toxic-waste site, one of only six to be declared "clean" by the Environmental Protection Agency, releasing thousands of gallons of oily wastes down the Susquehanna River toward the Chesapeake Bay.

The Butler Tunnel near Pittston, Pa., an abandoned mine shaft that had been used for years as an illegal repository for oil and chemical wastes, has discharged an estimated 100,000 gallons of chemical wastes into the Susquehanna, state and federal officials said yesterday.

Officials said the tunnel began leaking the oily wastes Friday night, probably as a result of heavy rains from the passing hurricane. Abandoned mines in the area frequently are connected to the surface by hundreds of old "bore holes" that serve as sewer and storm drains, and the Butler Tunnel was designed to drain water from those mine workings into the Susquehanna.

State authorities, who have set up a command post near the site, said the tunnel is still leaking. Pennsylvania Department of Environmental Resources spokesman Mark Carmen said emergency crews have erected two booms near the site and that the wastes are not thought to pose an immediate health threat.

But the incident is certain to add to the heated debate over renewing the Superfund cleanup law, which went into limbo at midnight when its taxing authority expired. Among the key issues facing lawmakers are whether containment of toxic wastes should be considered an adequate cleanup under Superfund, and how to deal with the lingering liability for cleanup activities that fail.

EPA officials removed the Butler Tunnel from the Superfund cleanup list in 1982, saying that emergency action to contain a 1979 leak had halted seepage and that the tunnel no longer posed a threat to human health or the environment.

Janet A. Luffy, a spokeswoman for the EPA's regional office in Philadelphia, said the agency spent more than nine months cleaning up after the 1979 spill, which sent more than 160,000 gallons of oily goo into the river. For two years after that, the EPA maintained an electronic monitoring system at the mouth of the tunnel.

The monitor came off when the site was declared clean, and the state took responsibility for inspections of the site, she said.

The first alert to the new leak, however, came from residents, who complained to local officials of an oily smell from the river.

Luffy said federal officials were using emergency funds under the Clean Water Act to deal with the new leak, although the site may still qualify for emergency work under Superfund.

Meanwhile, the battle over the toxic cleanup law continues in Congress. The Senate passed a Superfund bill last week, but the House is not expected to act on its version until mid-October.

The EPA, anticipating that Congress would not complete work on Superfund by today, already has put dozens of cleanup projects on hold to conserve money for emergency work.

Congressional aides said yesterday that a 45-day extension of the law may be offered on the House floor today, but its chances are uncertain. Key supporters of the leading House bill, including Energy and Commerce Committee Chairman John D. Dingell (D-Mich.), oppose an extension on the grounds that will take pressure off Congress to renew the law.