The corridors cover large swaths of undeveloped and wilderness land in Arizona, California and mid-Atlantic states. The federal agency dropped Clark County as transmission corridor of national interest, but a state regulator said Nevada officials are watching challenges to the corridor designations with interest.

Environmental groups asked the DOE to reconsider its decision, but DOE has not set a deadline for responding to those requests, said Ann Atwood, staff attorney for the Center for Biological Diversity in Tucson, Ariz.

Attorneys for environmentalists fear that transmission line projects will proceed in the Southwest corridor before DOE responds to the requests.

The center, however, did not ask for DOE reconsideration. The center on Thursday signed a letter advising the government of plans to file a lawsuit alleging DOE violations of the Endangered Species Act.

A list of 95 endangered species could be affected to the national transmission corridor designations, according to the center. They include the Arroyo Southwest toad, California tiger salamander, giant gartersnake and numerous plants.

"While it doesn't directly affect Nevada, we're interested and we'll be tracking how that plays out," Public Utilities Commissioner Rebecca Wagner said.

Lydia Ball, Nevada representative for the Sierra Club, compared the DOE's response to its dealing with foes of the Yucca Mountain nuclear waste depository. In both cases, DOE has tried to frustrate public participation, which is key to government in the United States, she said.

Contact reporter John G. Edwards at jedwards@reviewjournal.com or (702) 383-0420.