The Interior Department memo writer had a handy way with words when it came to sizing up Congress, and now some of the sizees are sizzling about it.

The writer was telling his superiors how legislators could be dealt with last year during a battle over amendments to the federal strip-mine control law.

Sen. S. I. Hayakawa (R.-Calif.) "won't be influenced or care," he wrote. House Speaker Thomas P. (Tip) O'Neill Jr. (D.-Mass.) "will do whatever Udall asks," referring to Rep. Morris K. Udall (D.-Ariz.).

Sen. John Melcher (D.-Mont.) was called "a good friend," and Sen. Howard M. Metzenbaum (D.-Ohio) came off as "our best friend." But Pennsylvania Republican Sens. H. John Heinz III and Richard S. Schwelker were too "mercurial" to be of much help.

Accurate or not, those assessments and other seemingly incriminating tid-bits in memos from Interior's Office of Surface Mining have set off a small tempest on Capitol Hill.

Sen. Mark O. Hatfield (R-Ore.), recipient of a packet of documents from a fired OSM official, has asked the General Accounting Office, the Justice Department and the FBI to take a closer look for possible violations of lobbying laws.

The executive branch is prohibited from lobbying with appropriated money and, generally speaking, executive agencies are permitted only to provide information -- and clearly not to try to swing a congressional vote.

But virtually everyone in government knows and understands that the executive branch lobbies regularly under the guise of "informing," and keeps close track of legislators' foibles.

One memo to the director of OSM acknowledged the sensitivity of the situation. "The issue is urgent enough to justify overlooking some of the usual inhibitions in the interest of stopping this bill," he said.

That, and his reading of other OSM papers, Hatfield said, convinced him that this was "the most blatant" executive branch lobbying he had ever witnessed.

The OSM documents, written mostly by Len Stewart, who was the agency's legislative affairs director, described efforts to sidetrack congressional action on the strip-mine amendments.

A committee staff assistant said that Stewart, who left OSM earlier this year to work in a congressional campaign, "got carried away . . . . but most of this is just smoke and mirrors."

The memos suggest that Stewart was orchestrating a campaign to help environmental organizations bring pressure on Congress to kill the amendments, sought by the coal industry and friendly politicians. The amendments would have eased requirements on operators to reclaim land after they strip coal from it.

Another document was read by Hatfield to mean that OSM was going to award grants for state mineral institutes according to the way the states' legislators voted on the amendments.

OSM Director Walter Heine, at a House Interior subcommittee hearing recently, said that reading was wrong. The memo, he said, alluded to ways of publicizing grants that already had been determined.

The OSM papers and the agency's regulatory actions, the subject of oversight hearings by the Udall subcommittee, have given the industry a kind of opening it never before had in challenging the regulations.

While Stewart was writing his memos last year, the Senate overwhelmingly passed the amendments sponsored by Hatfield and Sen. Wendell H. Ford (D-Ky.).

Interior and major environmental groups were opposing the amendments, and Udall, father of the 1977 law, was objecting to the Senate's apparent retreat from the regulatory statute.

OSM's critics got new help last winter when Heine fired Ronald Drake, a top level aide from Indiana and Georgia who worked in the Carter presidential campaign in 1976.

Drake claimed he was fired because he objected to the arrogance of Washington regulators. OSM said he was fired for obstructionism.

Whatever the case, since his firing, Drake has been quoted widely as saying that Heine and other OSM officials are captives of environmentalists who call the shots on strip-mine control.

The same environmentalists who supported Heine's appointment have been unhappy with him for months, contending that he has been too lenient with the industry and coal-state governors in drawing up regulations.

But before Drake left OSM, he collected documents and turned them over to Hatfield's staff at the Energy and Natural Resources Committee.

Hatfield and coal executives released the documents on the same day Udall's oversight hearings began, although Udall and OSM were not told in advance. OSM critics on the subcommittee took it from there, unloading on Heine and his alleged ties to the environmentalists.

The OSM director said he was unaware of some of Stewart's assertions and that others simply have been misread or misinterpreted by the critics. He also said he would ask Interior's inspector general to investigate the situation.

Louise Dunlap, director of the Environmental Policy Center, and others testified that Stewart's memos had misrepresented what they and he had been doing on the Senate amendments.

"What is tragic," she said, is that Stewart was taking credit for things he didn't do. We organized the lobbying meetings . . . We wrote the letters to the senators -- not Stewart. We were trying to keep Interior informed because we had similar interests in seeing the amendments defeated.

"It is not that the coal industry is being locked out," she said. "It is that, for the first time, citizens are being let in on the process and the industry people are furious that we take advantage of the access."