With fewer than 60 days remaining before its Superfund cleanup money runs out and congressional efforts to renew the law moving at a snail's pace, the Environmental Protection Agency is preparing to shut down most of the program.

EPA Administrator Lee M. Thomas, calling the situation "a real dilemma," told reporters yesterday that a shutdown might affect as many as 100 toxic dumps where cleanup work is in progress or scheduled to begin soon.

If cleanup contracts are delayed at those sites, he said, the agency thinks that it could save enough money to handle unforeseen emergencies elsewhere and maintain some enforcement activity.

Superfund is largely financed by a tax on chemical feedstocks, but authority to collect that tax expires Sept. 30. According to Thomas, the agency has about $125 million left of the $1.6 billion fund, enough to run a skeletal Superfund program for three to nine months.

Neither the House nor the Senate has passed legislation to renew Superfund, although the Senate version, which would expand the program to $7.5 billion over five years, has been ready for the floor since late June. In the House, a $10 billion version has been approved by one committee but faces hurdles in at least two others.

As the law's expiration nears, some lawmakers have begun floating proposals for short-term extensions. Some House leaders have suggested maintaining the program at its current level for one year, and an enforcement-only program is being weighed in the Senate.

In letters last week to key members of Congress, Thomas wrote that he has problems with both proposals. "I am gravely concerned about the future of the Superfund program," he said, warning that stop-gap funding or a short-term renewal would "cripple" cleanup activities.

Thomas said yesterday that 15 Superfund cleanups were near completion and dozens of others were in progress. "You just can't pull the plug without losing a lot of that momentum," he said.