In a story yesterday on alterations in transcripts of a House environmental hearing, the House Science and Technology natural resources subcommittee was identified incorrectly as having had possession of the master transcript for a period of time. Sources said it was the investigations and oversight subcommittee that had possession.

A vigorous House ethics committee investigation into who altered transcripts of congressional hearings on the Environmental Protection Agency a year ago in ways that made Republicans look foolish has pitted congressmen and their staff members against each other and filled the halls of House office buildings with unsubstantiated rumors.

While dozens of people had access to the transcripts during their preparation for publication, a number of Capitol Hill sources said the committee's attention has focused for now on an investigator for a House Government Operations subcommittee, Lester O. Brown.

Described by colleagues as a brilliant, intense, partisan Democrat, Brown, 31, had a major role in organizing and running the EPA hearings and the ultimate responsibility for final preparation of the transcripts.

Brown has denied making unauthorized changes in the transcripts and refused further comment. Both Democratic and Republican congressmen and staff aides have said the transcripts spent time in the offices of at least two subcommittees and were never secured from potential tampering by staffers or even casual visitors.

Brown was hired as an investigator of the environment subcommittee by then-Rep. Toby Moffett (D-Conn.) and retained there by Rep. Michael L. Synar (D-Okla.).

In a telephone interview from his house in Connecticut, Moffett said that, from conversations with friends on Capitol Hill, he believes Brown is a major subject of the probe by the House Committee on Standards of Official Conduct. He said Brown has retained a lawyer and was questioned intensively by the staff of the ethics committee.

But Moffett said he does not believe Brown had anything to do with the alterations. "The guy is a very high-class congressional investigator, very thorough, a very tough guy, very aggressive," said Moffett. "I can't picture him doing something like this."

Brown, who has been a congressional staff member for eight years, was the lead investigator for inquiries into Tris-treated children's wear, lead in gasoline, and, most recently, management of the EPA "Superfund" for cleaning up toxic wastes. He is co-author of a book recently published by the Sierra Club, entitled, "Hazardous Waste in America."

Members and the staff of the ethics committee have refused to comment on ongoing investigations. But other congressional sources said it would be premature to conclude anything from the ethics committee's pattern of questioning.

By all accounts, the ethics committee's investigation into who tampered with the transcripts of the acrimonious EPA hearings last July is aggressive and wide-ranging. About 30 people have been questioned informally by the committee's staff, several more than once, and a number have been asked for handwriting samples.

According to sources, the ethics committee is believed to have all the early versions of the transcripts with handwritten changes on them. One source quoted a staff member of the ethics committee as saying, "We are really going to crack this by laying these documents side by side."

The remarks of seven Republicans at the hearings were changed or omitted in 14 instances in ways that made them look foolish or ill-prepared. The fact that the unauthorized changes were made is not disputed by anyone.

The hearing transcript initially was to be prepared in the environment, energy and natural resources subcommittee where Brown is an investigator. The subcommittee's staff sent copies of the transcript to members and witnesses for editing, following normal procedure, and received those changes back, incorporating them into one "master" transcript to be sent to the printer.

But, last autumn, the environment subcommittee asked the Science and Technology natural resources subcommittee--one of five subcommittees that participated in the joint hearings--to handle the submission of the transcript to the printer and subsequent proofing.

The transcript was shipped to the natural resources subcommittee, remained there for six to eight weeks, and eventually was returned to the environment subcommittee for printing. During its peregrinations, the master transcript passed through the hands of a number of staffers and was accessible to dozens more.

It is not known whether the unauthorized changes were inserted early in the document's travels or just before the final manuscript was sent to the printer. But the changes were not discovered during proofreading of the galleys by congressional staff.

According to sources close to the investigation, staff members have accused each other under questioning by the ethics committee, and the probe, like the EPA hearings themselves, has brought to the surface a number of old, passionate rivalries.

"I chaired a lot of hearings," said Moffett, who left Congress to run for the Senate in 1982 and was defeated. "But there was a real strong partisan disagreement in those hearings. I never chaired a hearing that was as nasty as that one."

There had been longstanding tension between Moffett and Republican subcommittee members Judd Gregg (N.H.) and John Patrick Hiler (Ind.). The remarks of both Gregg and Hiler were altered in the transcript.

On Sept. 30, 1980, as Hiler was campaigning for Congress, the Moffett subcommittee had released a report that listed the Hiler family firm, Accurate Castings Inc. of La Porte, Ind., along with 2,100 other firms, as potential sources of pollution to underground water supplies. The report was briefly a source of embarrassment to Hiler in the campaign, but it was revealed later that the firm had been listed mistakenly.

The incident angered Hiler. After being elected to Congress, he sought to join the Moffett subcommittee, in Hiler's words, "to see that what happened to my family's small business and other small businesses would never happen again."

The dispute over who made the changes in the transcripts of last summer's EPA hearings has brought charges from Republicans that Democrats are stonewalling or covering up, and countercharges from Democrats that Republicans are promoting the investigation to divert attention from the the probe into the Reagan campaign's possession of documents from the Carter White House in 1980.

A number of Democratic staff members on Capitol Hill have even suggested that a Republican staffer may have made the changes out of frustration or spite and then tried to pin them on a Democrat. That possibility is reported to be the subject of questions from the ethics committee.

Republicans and Democrats agree on only one thing beyond the fact of the changes: They are puzzled about why any congressional staff member would risk his or her career to make the kind of changes that have been discovered. While the changes do make Republicans members look silly, the published hearing record is far from a widely circulated document, and partisans on both sides say the changes are juvenile, almost pranksterish.

"I doubt that before this controversy, 20 people had read this transcript," said one staffer. "The changes are so stupid, it's just not worth it."

If a staff member is responsible for the changes, the most the ethics committee can do is recommend dismissal. The decision to fire a staff member would be up to the member of Congress who hired him.

The seven Republicans whose remarks were changed have requested that the Justice Department investigate the matter for possible criminal violations. A Justice spokesman said the matter was still under consideration.

In another development in the increasingly bitter, partisan dispute over alleged changes in House documents, Democratic staff members of the Government Operations Committee have provided material they say refutes charges made on the floor by Republicans that the published record of 1980 hearings on sales of silver also were altered.

A line-by-line comparison of the original House reporter's transcript and the published hearing record shows only minor grammatical changes. The Republican charges were based on an apparently inaccurate colloquy printed as part of a Barron's magazine editorial.