One of the thousands of documents that the Reagan administration is refusing to turn over to the House of Representatives is sitting in a safe in Room 2323 of the Rayburn House Office Building.

It has been there since April, nine months before the administration provoked an unprecedented constitutional confrontation with Congress to keep the document, and others like it, from the House.

At the time, it was delivered without fanfare to a House Energy and Commerce subcommittee that wanted it for an investigation of a hazardous waste dump in Santa Fe Springs, Calif.

Another of the disputed documents, a memo on the liability of mining companies for cleaning up poisons that leak from their pits, was published, in part, in a chemical industry newsletter last spring.

These are exceptions among the piles of subpoenaed Environmental Protection Agency documents being withheld from the House under orders from President Reagan. Congress knows virtually nothing about the contents of the others, except that Reagan considers them too "sensitive" for members of Congress to see.

But the past availability of these and other documents has fueled suspicions in Congress over the administration's reasons for withholding them now under the powerful claim of executive privilege, a presidential prerogative that has unnerved Congress since George Washington first invoked it in 1792 during a House probe of Gen. Arthur St. Clair's aborted campaign against the Indians.

For the first time in history, the full House has resorted to charging a Cabinet-level official -- EPA Administrator Anne M. Gorsuch -- with contempt of Congress in an attempt to obtain the papers it wants. The House vote was a lopsided 259 to 105, with 55 Republicans joining 204 Democrats to lodge the charge.

A review of EPA's inventory of withheld documents shows certain records now being kept from Congress were once available to a House committee; the staff of one committee was allowed to read more than 100 pages of documents now off-limits to its members; about 100 employes of engineering, consulting and secretarial firms have had access to several dozen disputed papers; one of the records was described by an EPA official as "of limited sensitivity," and other agencies have provided Congress with records deemed equally sensitive.

The records pertain to potential EPA lawsuits against companies responsible for 160 of the nation's most dangerous hazardous waste dumps.

House leaders have said they need the records to determine whether EPA is seeking high enough fines from the polluters or letting them "buy out" of damage suits too cheaply.

One of the disputed documents on the inventory is a memo from an EPA attorney about a controversial legal settlement with Inmont Corp., a paint manufacturer, over its liability for cleaning up an abandoned hazardous dump in Santa Fe Springs, Calif.

Now classified as too "enforcement-sensitive" to release to Congress, the memo was delivered upon request last spring to a House Energy and Commerce panel for use in an April 2 hearing.

House leaders have expressed special interest in the Inmont file because a former assistant to Gorsuch admitted at the April 2 hearing that he had disclosed inside information to Inmont while EPA's lawyers were negotiating a settlement with the firm.

Thornton Field, now an EPA enforcement official, testified that he divulged to Inmont that EPA was willing to settle with the company for $700,000, $150,000 less than the agency's negotiating team was pushing for at the time. Inmont eventually made a $700,000 settlement offer and EPA accepted it, according to a transcript of the hearing.

House leaders have cited this exchange as reason for suspecting that the enforcement files contain embarrassing evidence of "sweetheart deals" with polluters, such as drafts of proposed settlements and communiques between the agency and liable companies.

EPA officials deny these allegations, but acknowledge that they have tightened secrecy policy on hazardous waste documents since the Inmont hearing.

Until then, they said, congressional requests for information were handled within the agency. Now, Gorsuch said in a recent interview, all "enforcement-sensitive" documents subpoenaed by Congress must be reviewed by attorneys and policymakers at EPA, the Justice Department and the White House before they are released. It is this "triple screen," she said, that held back the documents now in dispute.

Before the screen was erected, however, three staff members of the House Energy and Commerce Committee were allowed to review 139 pages of enforcement records now on the forbidden list, officials said. Attorneys for EPA and Justice were present, and an EPA lawyer described at least one of the documents as "of limited sensitivity," according to two sources familiar with the Oct. 14 session.

The screen has so far snagged 74 documents out of an estimated 780,000 pages covered by the House subpoena, but several EPA officials speculate that the list will eventually number in the thousands.

The preliminary inventory includes a memo on EPA's litigation strategy against firms that dumped waste at the infamous Love Canal in New York, a legal memo on settling the Chem-Dyne dump case in Ohio, strategy papers naming firms that may be sued for cleanup costs, lists of potential witnesses against illegal dumpers, lists of possible defendants, strengths and weaknesses in the government's cases, proposed financial settlements with firms and more.

Gorsuch said she fears that certain companies could use this information to thwart EPA lawsuits, while others might declare bankruptcy upon learning that EPA plans to sue them. However, asked at a recent hearing whether EPA's enforcement efforts had suffered after the Energy panel obtained the disputed Inmont memo, Gorsuch answered, "To my knowledge, there has been no harm created."

Rep. Elliott H. Levitas (D-Ga.), chairman of the Public Works panel that issued the subpoena, said the records on the inventory are "exactly the documents we need to ensure that the law is being carried out." A memo detailing weaknesses in the government's case against a polluter could show Congress how to tighten its hazardous waste laws, he said.

Other agencies apparently have delivered similar documents to Congress without resistance. The Energy Department, for example, recently turned over what it termed highly sensitive enforcement records to the House, detailing weaknesses in certain cases being brought by the agency, on a promise that the records would be kept confidential.

Another purpose of the "triple screen," administration officials said, is to avoid embarrassing gaffes. For example, earlier this year EPA asserted executive privilege to keep secret a letter to defendants in the case of the Stringfellow dump near Riverside, Calif.

The letter, inviting all the firms to a negotiating session at a Los Angeles hotel, was originally among those that Reagan described as "sensitive documents found in open law enforcement files whose release would impair my solemn responsibility to enforce the law."

EPA officials later delivered the letter to Congress with profuse apologies, but the incident became fodder nonetheless for administration critics such as Rep. Mike Synar (D-Okla.), who described it on the House floor as evidence of a "patently ludicrous" secrecy policy.

Citing the switched signals and inconsistencies in the handling of the EPA files, House Republicans and Democrats have accused the administration of attempting a "sweeping" and "arrogant" extension of the secrecy privilege. They stressed that presidents have invoked executive privilege fewer than 70 times to withhold information from Congress, most often for records relating to national security, diplomacy and Oval Office discussions.

Nonetheless, the administration has stood firmly behind its right to hold back the EPA files. Referring to the tightened secrecy rules, Gorsuch said, "The fact that we may have erred in the past does not obviously prevent the president from asserting executive privilege at any time."

Justice has announced it does not plan to prosecute Gorsuch. One high department official recently accused the House of "looking for a political fight rather than looking for information."

Acting on behalf of the executive branch, Justice filed suit in federal court here asking a judge to nullify the contempt citation and to rule that the House subpoena was unconstitutional, in part because it intrudes on the power of the executive to withhold documents from Congress.

As the basis for the executive privilege claim, Justice quoted the Supreme Court ruling in the landmark case over President Nixon's Watergate tape recordings: "The executive has the privilege to ensure the confidentiality of its law enforcement files and its deliberative process."