President Reagan took final action yesterday on several bills approved at the end of the 98th Congress, signing legislation expanding the Environmental Protection Agency's authority to regulate disposal of hazardous waste and bringing thousands of small businesses under the law for the first time.

At the same time yesterday, the president vetoed legislation reauthorizing the Equal Access to Justice Act, which permitted the award of attorneys' fees to individuals or businesses that are wrongly sued by the federal government or that successfully challenged certain federal regulations.

Reagan approved 10 other bills, ranging from the largest authorization ever for the CIA and other intelligence agencies to a measure providing merit pay increases for federal employes.

In vetoing the Equal Access to Justice Act, Reagan said he took the step even though he is "firmly committed to the policies" of the law, which expired Sept. 30. He said he will make the permanent and retroactive reauthorization of the act a top priority in the 99th Congress.

Reagan he believes that the government should pay the expenses of parties who can prove in court that they have been wronged by federal agencies. But he said Congress went too far in expanding the law not only to include official government litigation, but also to allow courts to look at an agency's justification for bringing a case.

"This would result in needless and wasteful litigation over what is supposed to be a subsidiary issue, the award of attorneys' fees, and would further burden the courts, which would have to hear the claims in each case not once but twice," Reagan said.

In a separate memo to agency heads, Reagan said any claims lodged under the law should be kept on file pending review once Congress has acted again on the legislation.

Here are some of the measures approved yesterday:

* Merit Pay: After waging a crusade to reward teachers for excellence, Reagan signed legislation to enrich merit-pay awards to deserving federal employes.

The bill provides for an annual performance appraisal process, special monetary awards for excellence and assurances that senior executives will not be barred by pay ceilings from receiving bonuses or awards.

It also provides greater job security to senior government workers in case of layoffs and moves toward extending a system of incentives and rewards throughout the bureaucracy to make performance "the central feature of the government's personnel system," Reagan said.

In a statement issued in Santa Barbara, Calif., where he is on vacation, Reagan said the bill "responds to criticisms of the present system and strengthens and improves merit pay in a meaningful way. These changes will ensure that we recognize our very best performers with meaningful financial rewards" to make performance the central feature of the government's personnel system.

* CIA Funds: In signing the largest authorization ever for the Central Intelligence Agency and other intelligence agencies, Reagan insisted on the need to maintain pressure on Nicaragua and made it clear that he plans to ask the 99th Congress to renew covert aid to anti-Sandinista rebels.

The intelligence authorization bill provides billions of dollars for a range of secret activities carried out by the intelligence community, but its precise amount is classified. It did not contain $28 million that Reagan requested for the anti-Sandinista Nicaragua "contras." Congress provided $24 million in aid to the rebels last year, but refused Reagan's request for additional support.

"The necessity of U.S. support for this program is beyond question," Reagan said. "I am signing this act with every expectation that shortly after the next Congress convenes, it will provide adequate support for programs to assist the development of democracy in Central America."

* Computer Chips: This legislation, long sought by the semiconductor-chip industry to combat growing unauthorized duplication, creates a new form of intellectual property protection for chips used in products ranging from computers and sophisticated weapons systems to kitchen products and video games.

Chip manufacturers have complained that pirated versions of their designs have discouraged investment in new ventures. Reagan said the 10 years of design protection offered by the new law should encourage development of new technologies.

* Hazardous Waste: The bill, a package of amendments to the Resource Conservation and Recovery Act, gives the Environmental Protection Agency new authority over municipal landfills and underground storage tanks and establishes a new set of standards for landfills that handle hazardous waste.

In other action, Reagan signed a $104.7 billion fiscal 1985 authorization for the departments of Labor, Health and Human Services, and Education, a bill increasing Medicare reimbursement for hospice home care and a bill extending protection of federal patent laws.