Lester Brown, a member of the Democratic staff of the House Government Operations Committee, has resigned after admitting that he made unauthorized alterations in the transcript of a 1982 hearing on environmental issues.

Government Operations Chairman Jack Brooks (D-Tex.), in a brief news release and in letters received by committee members yesterday, said that Brown told him Sept. 1 "that he personally had made unauthorized changes in the record of a hearing conducted last year by [Government Operations'] environment, energy and natural resources subcommittee along with four other House subcommittees."

Brooks did not say whether Brown had admitted making all the changes found in the transcripts, nor whether he made the specific changes about which Republicans have most complained on grounds that they make them look foolish or malicious. Brooks did say, however, that Brown told him he had submitted detailed statements to the House Committee on Standards of Official Conduct.

Brooks also said that committee is continuing its investigation, previously authorized by the House, and will issue a full report on the matter later.

The July, 1982, hearing on the enforcement record of the Environmental Protection Agency in the Reagan administration was an acrimonious, partisan event. Republicans, led by Reps. Robert S. Walker (R-Pa.), John Patrick Hiler (R-Ind.) and Judd Gregg (R-N.H.), were furious later when they discovered that remarks of some Republican members had been altered in ways that made them look foolish or reversed their meaning.

For example, a statement by Walker that he was willing to take part in reasonable hearings came out in the printed version as "I am not willing to take part in reasonable hearings."

Brown, as an aide to former representative Toby Moffett (D-Conn.), then the chairman of the subcommittee, was the staff member primarily responsible for organizing the hearings. He had been a staff investigator for Democrats on various congressional committees for eight years. When Republicans first made an issue of the transcript alterations, Brown denied making alterations.

Brown was unavailable for comment yesterday, but his attorney, Mark Foster, said in an interview that Brown's statement to Brooks did not spell out whether Brown was responsible for all of the transcript changes.

Moreover, Foster said, the statement to Brooks did not specify whether Brown had made the changes that made Republicans look foolish.

Foster declined to discuss whether Brown had made those changes, saying the matter is still under study by the ethics committee, and he could not discuss it.

Asked whether anyone other than Brown had made transcript alterations, Foster said he could not comment. In addition, he said there was "no deal with the Justice Department" under which Brown would be free from any possible prosecution in return for admitting he had made alterations and resigning.

A Justice Department spokesman said he could not comment on whether the department has decided to go ahead with its investigation of the matter, or if so, where the investigation stands. Moffett has said he had no knowledge of any alterations.

"This action clearly identifies the serious nature of the alterations," Gregg said through an aide after receiving Brooks' letter. "There are still many questions that remain unanswered. Was Mr. Brown acting in concert with other staff people at the direction of members? And has this type of alteration occurred in other manuscripts?"

Rep. Mike Synar (D-Okla.), who became chairman of the subcommittee after Moffett left the House to run unsuccessfully for the Senate, said he had advised Brooks that "I felt the resignation" of Brown "should be accepted. Until the ethics committee investigation is completed, it would be inappropriate for me to make any further comments."