The expected battle over President Reagan's environmental budget cuts broke into the open yesterday at the Senate Environment and Public Works Committee, where party-line defeats led to a walkout by two Democratic senators.

Despite warnings from environmental activists that the cuts are an effort to reverse the environmental gains of the last decade, the committee accepted several controversial measures, including the gutting of the Council on Environmental Quality and virtual elimination of noise-control programs, as it fashioned its required estimate of environmental spending in the year ahead.

Proposals accepted by the committee yesterday, before the departure of the two Democrats left it without a quorum, include:

A 20 percent reduction in funds to run the so-called Superfund to clean up toxic waste dumps and spills. The panel went along with a $50 million cut in former president Carter's proposed $250 million, although several environmental groups have warned that the popular program will be drastically slowed in dealing with dangerous dumps.

A $65.6 million cutback -- 14 percent -- for the fish and wildlife unit of the Interior Department, largely in laboratory and hatchery construction and in research funding on endangered species. Environmental groups have noted that several international studies recently cited loss of genetic variety as a major world problem.

A 25 percent cutback in the Environmental Protection Agency's program to develop pollution-control technology, on grounds that private industry will do more of that work in the future. "Just as much as they were doing in the 1950s," snorted one Senate subcommittee staff member. But the committee only rearranged EPA's operating budget proposal of $1.2 billion without adding to it.

A chop of 72 percent in the budget of the Council on Environmental Quality, set up in 1970 to advise the White House on ecological problems and to coordinate agency responses. The council was left with only $1.04 million, and "is lucky to be alive," said committee Chairman Robert T. Stafford (R-Vt.).

The committee even went Reagan one better in slicing noice-control aid to states, paring the president's proposed $2.2 million to $1 million. Carter had proposed $13 million, but the new administration says the problem and its cure are local, not federal, matters. The committee agreed, promising legislation to permit state laws for noise control.

In a rare addition to the president's budget, the committee restored $2.4 billion to sewerage construction grants, which were $3.7 billion in Carter's budget and were zeroed out of Reagan's on grounds mismanagement. But the committee made the grants conditional on the passage of reforms, as Reagan had asked.

The walkout came after ranking minority member Jennings Randolph (D-W.Va.) was defeated in two party-line votes. He failed, 6 to 7, to restore to the gutted Economic Development Administration a third of its lost funding, then was defeated, 6 to 8, in trying to save the Appalachian Regional Commission. He and Sen. Lloyd Bentsen (D-Tex.) then got up and left, forcing the committee to adjourn for lack of a quorum.

"They had other things to do. It was lunchtime," said a Randolph aide, but he added, "The senator was very disappointed in that vote."

The votes taken by the committee yesterday are not binding, but as the first step in the budget-writing procedure they are a clear indicator of the sentiment of the committee, at least at this stage.

Environmentalists point to several other major funding shifts in the Reagan budget as further proof of their worries:

The $600 million Land and Water Conservation Fund, which buys the nation's parks, is zeroed out. But Congress already has authorized the purchase of $1 billion worth of parks at some future date. "They've drawn the lines on the map and made these commitments," said the Sierra Club's John McComb. "There's powerful political resistance to this cut."

The Office of Surface Mining lost $66.6 million, or 27 percent of its budget, which will mean elimination of many field inspectors and a weakening of the enforcement program that keeps strip miners in line, according to OSM workers.

Solar and conservation programs, including the $125 million Solar and Conservation Bank, were "virtually destroyed," McComb said, although solar investment tax credits were retained. The nuclear energy program, on the other hand, was increased to $4.3 billion, including $460 million for fusion energy research and $27 million for research on the damaged Three Mile Island nuclear power plant core.

Meanwhile, Wilderness Society conservation director Charles Clusen said actions yesterday by Interior Secretary James Watt to spur development in Alaska were another example of "this administration's gung-ho development at the expense of environmental protection."

Watt halted work on wilderness surveys in Alaska, dropped as "inappropriate" the ongoing talks with Canada on a treaty over migrating caribou herds, affirmed the right of Alaskans to shoot wolves from airplanes, and directed that oil and gas studies in the Arctic National Wildlife Refuge be handled by the U.S. Geological Survey rather than the Fish and Wildlife Service. Geological Survey is regarded as more development-oriented.

Watt also called for expediting oil and gas leasing in Alaska, an action he has taken nationwide. "They're cutting the funding for the research on the environmental impact statements in order to do that," said the Sierra Club's McComb, "and they run a real risk they'll get hauled up short in court, not necessarily by environmentalists but by fishermen, land owners and a lot of other people."