The U.S. Department of Energy has cleared the way for construction of a high-voltage electric transmission line in Washington and Greene counties and through wide corridors in the northeastern and southwestern United States.

The DOE announced yesterday that it was affirming its October decision to designate 52 of Pennsylvania's 67 counties and broad swaths of seven other northeastern states as part of a national interest electric transmission corridor, or NIETC. It also reaffirmed a southwestern corridor in southern California and Arizona.

Authorized by a 2005 federal energy law, such corridor designations make it easier to build power lines in those areas by giving the federal government the power to approve such projects over the objections of local and state officials.

The DOE ruling denied 71 requests for a rehearing from citizens groups and state agencies, including the Pennsylvania Public Utility Commission and the state Department of Environmental Protection, saying the challenges were "without merit."

Allegheny Power's plan to construct 37 miles of a 240-mile, 500-kilovolt power line through Washington and Greene counties must still get PUC approval, but the DOE decision announced yesterday provides a "backstop" should the state commission balk.

Doug Colafella, a spokesman for Allegheny Power, said the transmission line to carry power from southwestern Pennsylvania through West Virginia into northern Virginia is needed to prevent electric supply problems that studies show could occur by 2011.

"The DOE decision underscores the importance and need for enhanced transmission in this country. Our transmission system is not keeping pace with demand," he said.

Pennsylvania's PUC will hold hearings on the project during the last week of this month in Pittsburgh. Public hearings are taking place this week in Virginia, and a decision by the Public Service Commission of West Virginia is due May 2.

Mr. Colafella said the company is committed to working through the state agencies and commissions to get approval for the project. That might be tough in Pennsylvania, where the PUC, the DEP and Gov. Ed Rendell have opposed the corridor designations and the transmission line.

"We're disappointed with the DOE ruling. This transmission line is only going to depreciate property values and offer no real benefit to Pennsylvania citizens," said Neil Weaver, a DEP spokesman, adding that the department is reviewing the decision and weighing an appeal.

Greene County Commissioners Chairwoman Pam Snyder said the power line project adds a health risk to a county already living with pollution from dirty coal-fired power plants.

"It's a sorry day when our federal government takes the word of the power company over the interests of its citizens and allows something like this to be shoved down our throats," she said. "We will continue to hope and fight."

Denise DiNunzio, a spokeswoman for the state Public Utility Commission, declined comment, saying the commission had not yet reviewed the 48-page decision.