The Environmental Protection Agency's enforcement of air and water pollution laws is hampered by red tape and incompetent legal work, environmentalists charged yesterday.

Moreover, although the EPA just signed a $400 million settlement with U.S. Steel Copr., "the federal government's enforcement program against the steel industry has been a failure," the Natural Resources Defense Council said. Of the nation's 50 steel mills, only one complies with pollution laws passed more than six years ago, it added.

The charges, which echo a General Accounting Ofice report in January, came at a Senate Environment and Public Works subcommittee hearing. The inquiry Chairman Jennings Randolph (D-W.Va.) noted, reflects "a new phase in the history of environmental laws . . . where enforcement is the most important activity."

Defense council attorney Stephen Schroeder testified at the hearing that although EPA announced an aggressive new enforcement policy last year, "the results have not matched predictions." Of 795 major polluters who failed to meet the law's July 1977 deadline to clean up their water pollution, only 114 have been taken to court by EPA, he said.

Other cases, he added, are "bogged down in the enforcement bureaucracy." A recent memorandum requiring cases to be cleared in Washington has resulted in 11 new steps and lengthy delays in processing cases, thus disouraging lawsuits, he said.

Often, Schroeder added, "EPA case preparation has been inadequate . . . [due] to the relative inexperience of EPA regional attorneys."

Another defense council attorney, Frances Dubrowske, criticized the EPA for taking legal action against only half of the steel and coke plants which are violating federal pollution laws. Even when polluters are put on cleanup schedules, she said, "few plants will see an EPA inspector even once a year."

At the same hearing, three steel industry executives called for more "flexibility" in enforcement. "Environmental regulations . . . have had a devastating effect on coke productivity," said George Stinson, chairman of National Steel Corp.

Coke, a product of metallurgical coal, is used in blast furnaces to refine iron ore into steel. EPA has forced the industry to retire polluting ovens used to make coke before new ones are built, thus forcing the industry to import foreign coke, Stinson said.

In 1977, 1.8 million tons of coke were imported. In 1979, 10 million tons are expected to come from abroad with "an increasingly bad effect on the balance of trade," Sen. Randolph said.

Stinson attributed the loss of 5,000 steelworker jobs and 9,500 coal industry jobs to the coke problem.

EPA officials will testify today. Assistant Administrator Marvin Durning contends he has begun "a far more vigorous EPA enforcement effort than in previous years directed against larger, more serious sources of pollution, and involving a great increase in the volume of civil litigation."