House conferees on the water pollution bill are pressing an amendment that could exempt steel companies from clean up deadlines, although steel is now the worst water polluter of any major industry.

Only 46 per cent of the nation's steel plants have met this year's federal clean water requirements, compared to a comphance rate of about 35 per cent for all industry.

But the House conferees say the steel companies whose sales and profits are in decline and which have laid off thousands of workers already this year, do not have the money to comply and still compete against reports.

On the other hand, environmentalists, the Carter administration and Senate opponents of the exemption say it would reward the most recaleitrant polluters and encourage other industries to resist cleaning up.

Steel companies have killed plants and fish in hundreds of rivers across the country by dumping oil, ammonia, eyanide, phenol, lead, zinc and other poisons into the water. The 1972 act required them to install millions of dollars worth of clean-up equipment by last July.

The water pollution exemption is one of several kinds of preferential treatment the steel industry is seeking. It also has pressed in the last several months for various forms of protection from foreign competition, and an assortment of special tax breaks.

The exception, proposed by House conferees chairman Ray Roberts (D-Tex.), would permit the President to exempt any plant from cleanup requirements if he determined it were in the national interest. House conferees said it would mainly benefit steel companies.

When senators objected to a blanket exemption, the House added requirements that any exempted plant show reasonable progress in cleaning up and promise to operate after the exemption expires.

However, most Senate conferees still oppose the new version. "It's a bad idea," said Sen. Gary W. Hart (D-Colo.). "There's no evidence it would alleviate the problems of the steel industry."

Sen. John H. Chafee (R-R.I.) said it would place "incredible pressure on the President and, in an election year, he would ten to go along." Japanese and German steel companies are cleaning up, he added, so American companies should, too.

Charles Warrn, the Environmental Protection Agency's legislative director, said the provision would "encourage people who don't want to obey the law. It's not fair to the companies who have already complied to reward those who have dragged their feet."

The steelworkers union also opposes any relaxation of EPA regulations. "It is necessary for the steel industry to commit ifself to a program of modernizing marginal facilities," legislative director John Shechan wrote House members last week. Pollution "abatement" should be an integral part of modernization."

However, Roberts said, "We've got 30,000 steel workers who will be out of work in January. Some of that is our fault because we're unable to get EPA to provide the [clean-up] guidelines." EPA issued guidelines, but they have been challenged in court by the steel industry.

Rep. Henry J. NOwak (D-N.Y.), said the exemption proposal would allow the President to take economic factors into account. It would give the companies another broader hearing on their problems," he said, bacause EPA is commited to an environmental viewpoint.

William H. Hoffman of the American Iron and Steel Institute said "the Roberts amendment would be beneficial because industry may run into technical problems and may need extension of the dead lines."

The steel exemption is expected to be resolved at conference meetings next week. If it doesn't pass the conference may adop an earlier amendment which would extend the 1977 deadlines until April, 1979, on a case by-case basis for companies that have shown "a good faith effort" to clean up.

That amendment would not apply to the steel industry a Senate staffer said. "They'd have a hard time proving good faith."

But steel plants, especially newer ones, do a lot berrer than others, according to a recent Council on Economic Priorities study. For example a U.S. Steel plant in South Chicago dumps less than a pound of cyaxide per million gallons of waste water a day, whereas a Republic Steel facility in Cleveland dumps 48 pounds per million gallons of water.