The House Public Works Committee yesterday voted to kill Maine's $750 million Dickey-Lincoln hydroelectric project.

The 24-to-17 vote was the first time in its history that the committee has agreed to scrap a major water project, after substantial sums have already been spent. Environmentalists, who have for decades fought a losing battle against what they regard as port barrel politics, are hoping it will set a pattern for the future.

The deauthorization, if not reversed, would block future funding for the project, although a House-Senate Conference committee this week voted to appropriate $710,000 for environmental studies on the dam during fiscal 1980.

The project, which is in the advanced planning stage, has already cost the government $10 million.

While the deauthorization move is expected to fail in the Senate Public Works Committee where Sen. Edmund Muskie (D-Maine) supports the project, a vote on the Senate floor this fall could be close. Sen. William Cohen (R-Maine), an opponent, nearly killed the project's appropriation in a floor last week.

In the House, where both Maine members, Republicans Olympia Snowe and David Emery oppose Dickey, deauthorization could easily pass. "Pork-barreling has been popular in Congress for years," Snowe said. "Every member wants federal money, but we have to look at these projects objectively. Dickey is not worthwhile when you consider the small amount of energy it would produce."

The 830 megawatt project would provide an average of 2.5 hours of peaking power daily - increasing New England's electrical capacity by about 1.1 percent.

Rep. James Cleveland (R-N.H.), who led the committee fight against Dickey, said the project's 400 miles of transmission lines would destry thousands of acres of forest land. While Dickey could replace 2.3 billion barrels of oil yearly, burning more wood could save eight million barrels, he added.

However, Public Works Committee Chairman Harold (Biz) Johnson (D-Calif.) said the dam is not too expensive. "We're paying through the nose for energy now," he said. "Anytime you can generate power with a favorable cost-benefit ratio, it beats dealing with foreign countries. Hydro is a very clean way to generate energy."

Dickey-Lincoln, authorized in 1965, is the largest federal water project planned for the Northeast - an area which has traditionally received only the dregs of the pork barrel. An immense dam, 27 stories high and nearly two miles wide, larger than Egypt's Aswan, it would flood the St. John, a popular canoeing and fishing river, and 88,000 acres of timberland on the Canadian border.