President Reagan has decided to name Denver attorney and former state legislator Anne M. Gorsuch to head the Environmental Protection Agency. The announcement is expected within the next few days.

A corporate attorney for Mountain Bell Telephone Co. since 1975, Gorsuch is a native of Casper, Wyo., and reportedly was recommended for the EPA job by another Denver attorney, Interior Secretary James Watt. With her nomination, the government's top two environmental posts will be in the hands of conservative Colorado lawyers.

Gorsuch, 38, is known to Colorado environmentalists largely from her controversial work last summer chairing a state legislative committee on a possible measure to control toxic wastes. She opposed any state role and was instrumental in killing the proposal.

In a telephone interview yesterday, Gorsuch said she thought state involvement would mean eventual federal intervention in the state budget. "It would be the worst of both possible worlds," she said. "If they [EPA] are going to dictate every comma, crossing every T and dotting the I's, they should be responsible for the law's administration."

She added, however, that she supports the Superfund concept for federal funding of abandoned toxic dump and spill cleanup and is concerned only with strengthening technical bases for action.

Gorsuch called herself a conservative Republican, dedicated to carrying out President Reagan's program for regulatory reform if she should receive the EPA nomination. She served on Reagan's transition advisory committee on intergovernmental relations. "Whether you contact my friends or my enemies, they'll tell you two things: I'm intelligent, and I'm capable of making hard decisions," she said.

EPA, she added is "the one spot where I think the most can be done to effect real change in the way we conduct business, without making any sacrifice to the objectives of the agency: clean air and water."

The Clean Air Act reauthorization this year will be her main early interest, she said, adding she "absolutely" thinks cost-benefit analysis should apply to standards for pollution emissions. The causes and cures of acid rain are "largely speculation" now, she said, and cannot be linked for sure to power plant smokestacks. But she noted that one third of western utility construction costs now are for stack scrubbers, " and they never trigger. There isn't enough sulfur in western coal to turn them on. Is that rational?"

Gorsuch has her critics in Denver. "She's hard-working and conscientious, but she's not particularly sympathetic to environmental concerns," said Reed Kelley, legislative representative for the Colorado Open Space Council.

In 1976 and 1977, Gorsuch's first two years in the House, she earned 33 and 8 points respectively on the council's annual 100-point environmental consciousness rating of state legislators, Kelley said. He added, however, that she had sponsored automobile inspection and maintenance legislation aimed at controlling Denver's air pollution and had earned a "good" rating of 72 last year.

Gorsuch said she had offered that bill but disagreed with the basic idea of requiring auto emissions controls to be regularly inspected. "I don't believe there are any adequate data to show that it works," she said.

Gorsuch decided not to run for a third term last year, saying she wanted to spend more time with her husband David, an attorney whose firm usually represents mining companies, and their three children. The couple has since filed for divorce. But there was some question as to whether she could have been reelected from her heavily Jewish, middle-income east Denver district, partly because of controversy over legislation specifying minimum jail sentences for convicted criminals, according to Colorado political insiders.

She also was opposed by some women's groups for her energetic role, in killing the largely ceremonial State Commission on Women. "She did that almost single-handedly. She's very tough," one state politician said.

Gorsuch laughed when asked if those factors affected her decision not to run. "It takes more than that to scare me off," she said. She did not want to add the strains of a six-month campaign from her pending divorce, she said, and also felt that Republican domination of the legislature was secure without her very difficult district.

Gorsuch graduated from the University of Colorado at 19 and finished law school there in 1964, traveling afterward to India where she taught English and studied the penal system as a Fulbright scholar.

After working as a lawyer for the First National Bank of Denver, she became assistant district attorney in a Denver suburban county and then was named deputy district attorney in Denver in 1972. She was a hearing officer in 1974 and 1975 for the state real estate commission before joining Mountain Bell.

There she initially handled land acquistion and easements, dealing with city and county governments. She then moved into equipment leasing and finally to antitrust research and labor relations, handling grievance cases. In the House, she served on the Judiciary, Finance and Appropriations committees and was named outstanding freshman legislator in 1976.

Sen. Gary Hart (D-Colo.) said he was pleased that another Coloradan was expected to be named to the new administration. But he added, "It is unclear what Mrs. Gorsuch's views are on the Clean Air Act and other important issues facing EPA, and those views will be directly related to the support or opposition she receives for confirmation."

A third Coloradan, former state House speaker Robert Burford, a cattle rancher and a close associate of Gorsuch's, also will be coming to Washington as head of Interior's Bureau of Land Management.