WASHINGTON – The U.S. Department of Justice’s announcement this week that it intends to continue with prosecutions of polluting power companies is meeting with cautious applause from environmental groups who long have claimed that prevailing winds carry smokestack pollution from the Midwest and dump it on Maine and other Northeastern states.

Those lawsuits first were filed by the Clinton administration beginning in 1999 and joined with earlier complaints waged by nine Northeastern states, including all six from New England.

The lawsuits accuse power companies in Midwest and Southern states of failing to modernize pollution controls after expanding more than 50 aging coal-fired facilities. The plaintiffs claim the practice blatantly violates a provision of the 1970 Clean Air Act, known as “New Source Review,” which calls for strict adherence to reducing air pollution whenever major plant modifications are made.

Last May, the Bush administration called upon the Department of Justice to review the merits of those lawsuits. The administration also called for several of its officials to propose revisions to the NSR in a sweeping effort to revamp the nation’s energy policies.

On Tuesday, Attorney General John Ashcroft released a report finding that the lawsuits were justified. “The department takes seriously its obligation to enforce the laws protecting our nation’s environment,” Ashcroft said.

Ashcroft’s announcement is a “temporary victory” in fighting pollution wafting over the state of Maine, according to Sue Jones, air quality project director for the Natural Resources Council of Maine in Augusta.

What will be more important, however, is what happens when the administration announces revised NSR guidelines, something expected to take place in the next few weeks. Jones and many state officials involved in the lawsuits anticipate those changes will result in a weakening of the law.

“It could be the biggest rollback of the Clean Air Act over the past 25 years,” Jones said. “We’re not just talking about power plants, we’re talking about paper and pulp mills and oil refineries. We expect a major tidal wave.”

White House spokesman Ken Macias said no final decision has been made on changes to the NSR, but added last week that the administration is determined to strengthen “the nation’s energy security as well as protect the environment.”

Still, environmental groups expect the administration will side with power companies. They also expressed concern over the Environmental Protection Agency’s announcement this week that it will delay enforcing a requirement that would force scores of coal-burning power plants to cut back on smog-causing pollution that travels in prevailing winds from the Midwest and Ohio Valley to the Northeast.

EPA Administrator Christie Whitman, who at one time pushed for stronger clean-air rules while serving as New Jersey governor, said the postponement of the deadline from May 2003 to May 2004 was necessary because of court challenges on two competing rules with separate deadlines. In a letter to Congress, she said the merging of deadlines would avoid confusion and leave states to determine the best course of compliance. “EPA strongly supports addressing ozone transport [problems] through state action,” Whitman wrote.

Conrad Schneider, with the Boston-based Clean Air Task Force, views Whitman’s announcement as “outrageous.”

“What she did is reward the laggards and punish the leaders,” Schneider said. “Power plants that already spent the money to comply by 2003 are punished and the foot draggers get more time.”

Both of Maine’s Republican senators, Olympia Snowe and Susan Collins, repeatedly have pressured the administration to refrain from weakening clean air rules.

On Friday, Collins renewed her effort by joining other Northeast senators in sending a letter to the White House, saying proposed rollbacks would allow power plants and other industrial facilities to avoid installing needed pollution controls.

“It is the responsibility of the federal government to enforce the law for the good of all Americans against the interests of a few,” Collins said.

After traveling hundreds of miles on prevailing winds, pollutants from Midwest power plants have been found to return to earth as acid rain. Power plant pollution also has been found to create smog and trigger respiratory diseases.

If the 51 power plants now being sued had installed the proper pollution controls, an estimated 4,300 to 7,000 premature deaths caused by respiratory and cardiac problems could be prevented each year, according to the environmental group Clean Air Task Force.

Maine is not a plaintiff in the lawsuits against the Midwest power plants, but Maine Attorney General Steven Rowe has joined the fight against weakening NSR along with eight other Northeastern states – New Hampshire, Vermont, Massachusetts, Rhode Island, Connecticut, New York, New Jersey and Maryland.

Several state officials involved in the fight view Ashcroft’s decision with tepid support. The lawsuits would never have been waged if they were not based on legitimate complaints, they said.