It was late on election night in Albuquerque, and a weary and ebullient Jeff Bingaman was declaring victory in one of the Democratic Party's most important upsets: the defeat of Republican Sen. Harrison H. Schmitt.

Bingaman told a cheering crowd that he was off to Washington to face "the real problems with the environment, the economy and Social Security."

The environment?

It was not an issue that that was mentioned to pollsters by many voters as they exited voting booths around the country Tuesday. But environmentalists, along with other traditionally Democratic constituencies, appear to have strengthened their hand in the 98th Congress.

More than two-thirds of about 80 candidates supported by five young environmental political action committees (PACs) were elected Tuesday. Many of those men and women scarcely mentioned the Clean Air Act, the Clean Water Act, the Wilderness Protection Act or other key environmental measures as they stumped their districts.

But they have committed themselves to support the measures and make a stand against the Reagan administration's environmental policies in the coming Congress, according to leaders of the environmental PACs.

"The noise level from the economic issue was so high it overshadowed the importance of the environment compared to other social issues," said one House strategist on environmental issues. "But when it shakes down, the impact is going to be pretty clear."

Election '82 leaves eight vacancies on the House Energy and Commerce Committee, which must vote on the administration's proposals to relax key sections of the Clean Air Act.

House strategists predict that Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.) will strengthen the panel's environmentalist coalition with his new appointments. Only one of the missing, Toby Moffett (D-Conn.), was considered a strong environmentalist.

On the Senate Environment and Public Works Committee, which sent a stringent Clean Air Act to the floor this year over administration objections, the leading advocates of pollution control were reelected.

Two of them, Chairman Robert T. Stafford (R-Vt.) and John H. Chafee (R-R.I.), won narrowly. Environmentalists plowed money and volunteers into both races.

On the House Interior Committee, two of seven Republicans targeted by the League of Conservation Voters as "clones" of Interior Secretary James G. Watt, Reps. Bill Hendon (N.C.) and David Michael Staton (W.Va.), were upset by advocates of wilderness protection.

Meanwhile, Reps. Phillip Burton (D-Calif.) and James Weaver (D-Ore.) won reelection with heavy infusions of money and volunteers from the environmental PACs.

"What you're seeing is a grass-roots movement that can deliver more volunteers than any other group except labor," said Marion Edey, director of the League of Conservation Voters. "We saved our key senators and we sent a more generalized message to Reagan that we don't want these laws tampered with."

Aides to the president said the administration will analyze the "green vote" carefully.

"We know we've got a problem," one high official said, adding that he questioned whether the environmental vote had swung many races in an election overshadowed by concerns over unemployment.

In races in the East, such as Stafford's and Chafee's, where air pollution and toxic wastes are pressing concerns, environmentalist support was believed essential.

In New Mexico, environmentalists played a major role in staffing the strapped Bingaman campaign, supplying 770 volunteers who walked targeted precincts, placed 10,000 calls on the Bingaman telephone bank and stuffed 22,000 envelopes that were sent to people on environmentalist mailing lists.

However, environmentalists had several major failures in races where they used considerable resources: Moffett's challenge to Sen. Lowell P. Weicker Jr. (R-Conn.), California Gov. Edmund G. (Jerry) Brown Jr.'s abortive Senate bid, and other races in the West, including Democratic challenges to Sen. Orrin G. Hatch (R-Utah), Sen. Malcolm Wallop (R-Wyo.), Rep. Manuel Lujan Jr. (R-N.M.) and Rep. Denny Smith (R-Ore.).

Environmental activists noted that some of those Republicans portrayed themselves as wilderness advocates, distancing themselves from the administration on the issue. But Republican officials said this had little significance.

On the contrary, aides to Watt said they took the GOP victories in the West, particularly the defeat of Brown, an outspoken Watt foe, as a pat on the back.

"We see nothing that in any way would be interpreted as a repudiation of what we're doing," said Watt's aide, Douglas Baldwin. "On the contrary, full speed ahead."