BOISE, Idaho — Federal officials have released their latest analysis on proposed routes for two high-voltage transmission lines in southwestern Idaho intended to modernize the Pacific Northwest’s energy grid.

The 183-page draft environmental assessment released by the U.S. Bureau of Land Management late last week covers two segments of the Gateway West project proposed by Idaho Power and Rocky Mountain Power.

The 1,000-mile (1,600-kilometer) Gateway West project is one side of a giant triangle of transmission lines that Rocky Mountain Power says are necessary to meet future demands in the region and improve reliability.

“We are happy with the results of the assessment,” David Eskelsen, Rocky Mountain Power spokesman, said Tuesday. “And of course we are hopeful we will get the right of way granted sometime next spring.”

Heather Feeney, a BLM spokeswoman, said the agency expects to release a decision then. The agency is taking public comments through Dec. 4.

The segment going through Idaho would deliver power from southern Wyoming to points west, potentially tapping into Wyoming’s wind energy. Federal officials have already approved the rest of the Gateway West project, but no work has started.

The BLM has been working on the Gateway West portion since 2008, trying to thread the transmission lines through a mixture of private, state and public lands that include key habitat for imperiled sage grouse.

The Morley Nelson Snake River Birds of Prey National Conservation Area, which experts say has the greatest concentration of nesting raptors in North America, has been a sticking point throughout the environmental review process.

In January, the BLM approved routes for the two 500-kilovolt transmission lines that mostly avoided the conservation area, with less than 10 miles of transmission lines.

Idaho Gov. C.L. “Butch” Otter asked Interior Secretary Ryan Zinke to direct the BLM to reconsider and use more public land.

But then legislation by Idaho Republican U.S. Rep. Mike Simpson signed into law in May by President Donald Trump ended that plan. The legislation mandated segments and altered the national conservation area, removing some land to make way for the transmission lines while adding land to the conservation area elsewhere.

The new plan has about 300 miles of transmission lines crossing over what used to be designated national conservation area.

The Conservation Lands Foundation, which endeavors to protect national conservation areas, worked with Simpson on the legislation. Danielle Murray, spokeswoman for the group, said the bill was a win for conservation areas.

First, it increased the overall size of the Idaho conservation area by 3.5 square miles (9 square kilometers) with what Murray described as key raptor habitat.

Second, it avoided allowing a federal agency to build power lines through a national conservation area without approval from Congress. “We thought that was a dangerous precedent,” Murray said.

For Idaho, the legislation eliminated some transmission line segments. So the BLM in its latest analysis is trying to connect remaining portions of the transmission lines with the congressionally mandated segments.

If the companies receive the right of way in the spring, they will have to conduct archaeological surveys. Feeney said the proposed rights of way are wide enough that the lines could bend around specific sites.

The companies say there is currently no timeline for construction.

“The companies will continue evaluating the timing of next steps in the project to best meet our customer and system needs,” said Stephanie McCurdy, spokeswoman for Idaho Power.