THE RECORD of the 99th Congress on Superfund is an embarrassment. The bill extending this program to clean up industrial dumps, lest their contents leach into water supplies, was supposed to be passed by last Sept. 30, when the old enabling act expired. The Senate Environment and Public Works Committee approved its version last March. The Senate didn't pass it until Sept. 26. You might think that was cutting it a little close, but not really: the House didn't pass its version until Dec. 10. All this year the bill has been in conference.

The liveliest moment of the conference thus far was the tricky time in April when the Senate finally sent over an offer accepting several important parts of the House bill. A majority of the House conferees, led by their chairman, John Dingell, rejected that and sent back a counteroffer said to be closer in some respects to the Senate version. Environmental groups accused the House conferees of selling out -- the environmentalists like the House bill better -- and about 100 House members sent a letter of protest to the speaker, urging him to intervene and "assure that the . . . conference committee returns to its traditional and appropriate role of defending the House position." Aides to Mr. Dingell say the critics have it wrong. What matters more is that the conference continues to drag on.

Superfund was set up in 1980, the congressional response to Love Canal. In retrospect it is generally agreed there was too little appreciation for the complexities involved, both technical and legal. The Reagan administration compounded the difficulty by choosing people to run the program who had little enthusiasm for its goals. Only in the last two years has it been put back in serious hands. The environmentalists, still distrustful of the administration and frustrated by the lack of progress, have been pressing Congress in effect to regulate the regulators by reducing their discretion. The affected industries -- those facing taxes or liability for clean-up costs -- have fought back. The bill has become a legislative forest that almost no one can get through.

Everyone wants to clean up toxic wastes, but there are major disagreements about how to do it, how much to spend and who should pay the costs. The administration's main concern continues to be to limit these costs, at least as they redound to the Treasury. Superfund has become a very large program about which the interest groups care a lot but most people and the administration care only mildly. In the absence of some other discipline, the environmentalists and resisting industries can keep each other from prevailing, but neither of them can prevail; that is why Congress is choking on it.

There needs to be a bill; the dumps are a problem that need to be addressed. The administration is not providing the necessary leadership, so it falls to the senior members of Congress involved -- Robert Stafford on the Senate side, Mr. Dingell for the House -- to do it. If they are forceful and fair, they plainly can. They should get on with it.