Every so often in this city of political accommodation and compromise, the irresistible force still meets the immovable object, with predictably entertaining results.

Such a case is a-building now. The Office of Management and Budget is on a collision course with a powerful western senator, and the Reagan administration's philosophical dedication to user fees is hanging in the balance.

The senator is James A. McClure (R-Idaho), chairman of the Senate Appropriations subcommittee that oversees Interior's budget, who on several recent occasions has proven not to be bashful about seeking help for corporate constituents.

The issue is who should pay for the often costly environmental studies required when a private interest seeks a right-of-way over federal lands -- when, for example, a utility wants to construct a power line.

In the past, Interior's position has been that the applicant pays.

The department was forced to rethink that position two years ago when a group of utilities won a federal appellate court decision tossing out the cost-recovery rules as inconsistent with federal law requiring the department to consider the "reasonableness" of the costs.

Enter the irresistible force. Last fall, the OMB approved a new set of rules, but only after a good deal of back and forth with Interior aimed at restoring the government's advantage. Environmental impact statements can run into the hundreds of thousands of dollars, and OMB wanted the bottom-line federal responsibility carefully defined. "We cleared it because they changed it to minimize the cost to the government," an OMB official said.

Six months later, the rules have yet to be proposed. That's where the immovable object comes in. McClure wants to minimize costs to the companies instead.

Dissatisfied with the regulations as approved by OMB, McClure inserted language in the appropriations committee report last year prohibiting Interior from issuing the rules. The language was eventually dropped, but the message was clear enough.

"Sen. McClure believed the regulations were too onerous on western users," one Interior official said.

McClure did not return a call seeking elaboration, but other sources suggested that the senator was moved by the plight of a company called Energy Transportation Systems Inc. (ETSI), formed by a consortium of energy firms eight years ago to construct a 1,300-mile coal-slurry pipeline from the Powder River Basin in Wyoming to Gulf ports in Texas. ETSI, which included such heavyweights as Bechtel Corp., Texas Eastern Transmission Co. and the Kansas-Nebraska Natural Gas Corp., would have gotten its rights-of-way if the pipeline had not fizzled first.

The plan foundered in the face of a weak coal market and a flurry of lawsuits from railroad interests and downstream states.

By that time, however, ETSI had shelled out nearly $4 million for environmental studies, and now it wants the money back. The case is pending in the U.S. Claims Court, along with an assortment of cases from western utilities seeking lesser refunds.

Interior's ultimate decision on the regulations is expected to have significant impact on those cases, as well as on who pays for what in the future. ETSI attorney David Hayes said the company believes it is entitled to reimbursement under the appellate court decision, which held that Interior had to consider the public benefit of the studies as well as the private benefit.

According to an Interior spokesman, the contretemps is headed for the desk of Interior Secretary Donald Hodel, who has of late spent a considerable chunk of his time plumping for increases in national park fees, the prices of duck stamps and the like as a way to shift more of the government's costs to those who benefit from its services.