It's one of the most controversial mining projects in the United States, and it's sparked heated debate among Alaskans for more than a decade.

Last week, Gov. Bill Walker urged the U.S. Army Corps of Engineers to suspend a key environmental impact study of the proposed Pebble Mine in the Bristol Bay watershed, home to the world's largest wild salmon fishery. The move would effectively stall the project, which Pebble claims is the largest undeveloped copper deposit in the world. 

In a press release last Saturday, Walker said there were too many unanswered questions for the important review to advance further -- adding that Pebble has not demonstrated to Alaskans that the proposed mine is feasible and realistic and that without a preliminary economic assessment the Corps would be unable to thoroughly vet alternative plans of development.

"I think that the governor's action has a lot more to do with politics than policy," Mike Heatwole, a spokesperson for Pebble Limited Partnership said Sunday. "Because all of the questions, the high bar that the governor has put out there, are exactly the type of issues that should be resolved and looked at and evaluated through the regulatory process."

In a similar appearance last week, the Commissioner of the Alaska Dept. of Natural Resources, Andy Mack, said there's only one way the Walker administration would support the project.

"We wouldn't support the project unless we were absolutely sure that it can be done in a manner that would have zero impacts on the fisheries today," Mack said. "Fifty million fish returned to that district last year. It's a miracle of nature, and it's something worth protecting."

But Heatwole says zero impact isn't possible. 

"Any time you have development, you're going to have an impact," Heatwole said. "But I come back to the criteria that you have for development. So, is your project going to have an impact on water? In our case, we believe the answer is no."

Heatwole says Pebble has invested over $150 million in environmental studies of the area. 

As for the financials on the proposed mine, Heatwole said he couldn't address why a potential investor, First Quantum Minerals, backed away from the project in May. 

"I can't speak to why they backed away, I think that's probably best answered by them," Heatwole said. "But we certainly have the financial resources to continue our summer work and to continue to work through permitting and are confident we'll have another investor for the project soon."

Heatwole notes that the company is exercising its right to pursue permits under the federal permitting process. 

"Pebble is on state of Alaska land open to mineral development. We're merely exercising the rights by which the state has said this land is available for this opportunity," Heatwole said. "There are minerals now that have been discovered under the ground and we've entered into the permitting process and are going through that much like any other project would in the state."

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