THE ENVIRONMENTAL Protection Agency, says its chief of staff, John Daniel, in today's Letters, is doing its job better than ever. He and Administrator Anne Gorsuch claim that budget cuts have hit only the agency's "flab" without weakening its commitment to environmental protection. We see a different picture.

It strains credulity that any agency is so over- staffed and red tape-ridden that cuts of 39 percent in the space of two years--as proposed by Mrs. Gorsuch --could be accomplished without cutting into actual programs. In fact EPA has a reputation as one of the tighter and more efficient agencies in Washington. In testimony and written reports to Congress, Mrs. Gorsuch maintains that budget cuts of this magnitude are possible under her leadership for three reasons: greater efficiency, more delegation of programs to the states and the fact that much research and standard- setting work has been completed.

If that were true it would reflect an astounding administrative achievement. Unfortunately, it isn't. In a report released this week comparing Mrs. Gorsuch's claims to Congress with her budget report to OMB, Sen. Patrick Leahy (D-Vt.) found 70 instances where cuts explained to Congress as reflecting efficiency, delegation or completion were explained to OMB as a "reduction in effort"--either reducing a program, slowing it down or eliminating it entirely. Mrs. Gorsuch, the senator concluded, had been "less than candid" about her intent.

The agency's enforcement efforts have been another sore point with environmentalists and members of Congress. A credible enforcement program is vital to any agency, because without one, voluntary compliance begins to evaporate. Mr. Daniel says the agency has only stopped filing duplicate cases already brought by states. But in 1980, the Justice Department filed 51 cases against violators of hazardous waste disposal requirements. One of these duplicated a state action. In the 10 months since Mrs. Gorsuch arrived at EPA, not one hazardous waste case has been filed. There have been similar drops in enforcement of other laws.

This dramatic change has had the predictable effect: those the agency regulates no longer worry very much about being prosecuted for violating the law. For example, Mr. Daniel refers to the notifications sent to more than 1,000 potential violators of the hazardous waste rules. Yet in testimony last week, EPA's enforcement chief reported that the agency had received just 14 responses to its letters, and only seven of these indicated a willingness to begin talks with the agency. Some enforcement. Some clout.