BUTTE, Mont. (AP) — NorthWestern Energy has asked several government agencies to stop analyzing the potential impact of a proposed $1 billion power line that would run from southwestern Montana to southeastern Idaho, saying they don't believe the work is making any progress.

Company officials are frustrated after spending $14 million for government studies over four years and being no closer to building the 430-mile Mountain States Transmission Intertie, or MSTI.

"We've called a timeout," Northwestern spokeswoman Claudia Rapkoch told The Montana Standard (http://bit.ly/Smyo1q ) for a story published Wednesday. "It's really because of a lack of cooperation with multiple federal agencies. We've been going along for years encountering delay after delay and getting no closer."

Rapkoch stressed that the timeout didn't mean the project was dead.

However, in recent filings with the Securities and Exchange Commission, the company said it was evaluating whether it should continue with the project due to market uncertainty and environmental concerns. It has spent more than $23 million so far and officials have said that amount may have to be written off.

The latest roadblock came when the Bureau of Land Management in Idaho ordered NorthWestern to propose three alternatives through southeastern Idaho that avoid core sage grouse habitat, Rapkoch said.

The requirement could add another 160 miles to the line and cause further delays.

NorthWestern is reimbursing government agencies for the time its employees spend studying the large private project.

"We are funding these agencies and we're not getting a real sense of when this might get completed," Rapkoch said. So the utility told the agencies "to stop until such time as we can sit down, get a plan together and get a reasonable assurance of a time frame. (These studies) just can't continue in perpetuity."

Idaho BLM spokeswoman Heather Feeney said she sympathized with NorthWestern's concerns, but if the BLM doesn't do a thorough study, its decision might not hold up to a court challenge.

NorthWestern has also told the Montana/Dakota BLM and the Montana Department of Environmental Quality to stop work on the project.

Montana DEQ director Richard Opper said the agency's employees have done a lot of analysis, but he understands NorthWestern's decision.

NorthWestern officials filed a major facility-citing application with the Montana DEQ in July 2008 for the proposed 500 kilovolt transmission line to run from a new substation just south of Townsend to one north of Jerome, Idaho, to give new power projects in Montana, including wind projects, a way to reach markets in the West.

The company initially projected the line could be operational by mid-2013. However, the latest timeframe has pushed construction back to 2018 at the earliest.

NorthWestern had initially planned to market primarily wind power to California, but that state may limit the use of out-of-state resources to meet its renewable energy standards, NorthWestern said in its quarterly report filed last month.

NorthWestern had still been seeking customers for the power line.

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Information from: The Montana Standard, http://www.mtstandard.com