A new study released Thursday projects that thousands of jobs could be supported by a potential copper and gold mine near Alaska’s Bristol Bay, now home to much of the state’s famous sockeye salmon.

An independent study commissioned by the Pebble Limited Partnership, a corporate partnership seeking to develop the so-called Pebble mine, says that the copper, gold and molybdenum mine could support more than 16,000 jobs nationally during a five-year construction period.

As the mine operates for more than 20 years, the report continues, about 14,700 jobs could be supported. With construction and operation combined, the mine could add about $4 billion to the country’s GDP, and at least $1.2 billion in fresh tax revenues, over decades.

“This clearly shows Pebble development could be an important economic driver for Alaska’s future,” said Pebble CEO John Shively, in a statement.

The coveted mineral deposits contain silver and palladium, besides copper and gold. The two companies behind the partnership, Britain’s Anglo American PLC (LON: AAL) and its Canadian partner Northern Dynasty Minerals (NYSEANEX: NAK), have already spent $500 million in the past six years on preparations for permits and paperwork, even as the Environmental Protection Agency appears to view the project with some skepticism.

The deposit’s 5.9 billion tons of mineral deposits are worth up to $55 billion in total, if fully mined over several years, according to the report. Tapping the mine would expand U.S. copper production by 20 percent compared to 2011 levels, with annual production worth about $1.7 billion.

But these touted economic benefits face stiff skepticism and criticism from the area’s fishermen, who brandish their own statistics. The group Commercial Fishermen for Bristol Bay, which opposes a mine, argues that Bristol Bay salmon fishing supports 12,000 jobs, is worth at least $1.5 billion annually, and is home to the world’s most valuable wild salmon fishery.

The group says that developing a proposed Pebble mine will destroy 90 miles of salmon streams and 4800 acres of wetlands, citing an April 2013 draft EPA report.

Katherine Carscallen, a fisherman and organizer with the group, is skeptical of these new job impact figures from the partnership. “I don’t really have faith in that report,” she told International Business Times. “I’m interested to see what the information and plan is behind that report: how large the pit is going to be, and how much toxic trailings they’re going to leave behind.” “Maybe then they can start answering some of the tougher questions on what the impact on my job is going to be,” she continued.

Although the partnership puts out figures when it pleases, Carscallen says, they ignore questions about negative environmental and economic impacts. When convenient, they maintain that it’s “too early to speculate," given that detailed mine development blueprints haven’t yet been released, she said.

That points to one odd aspect of the controversy, which has raged for months. Both the federal government and the mining companies maintain that they’re discussing a “hypothetical” and “conceptual” mine.

That led the U.S. Chamber of Commerce to blast the EPA for “stacking the deck” against a Pebble mine by constructing a poorly performing “hypothetical mine” to criticize in their draft reports, according to a Chamber letter sent on Wednesday.

“The details of the Pebble Partnership Mine have yet to be released. EPA’s decision to choose a poor performing hypothetical mine plan to base their study on is problematic and is stacking the deck against the project before it has even been proposed,” reads the letter from Senior Vice President William Kovacs. “At a minimum, this exercise by EPA prejudices the fair and unbiased consideration of a mine proposal that would actually provide much needed jobs—thousands of them—for America’s economy.”

Kovacs is referring to the EPA’s draft assessment, which charts the broad general impacts of large-scale mining on the region. The draft assessment notes that the local fishing industry was worth $300 million in 2009, and supplied more than 14,000 jobs. In his letter, Kovacs requested that the EPA grant a four-month extension for public input on the report, calling the current process “rushed” and against the EPA’s own protocol.

An EPA spokeswoman said the agency would extend the deadline by 30 days, on the back of many requests.

"This extension is reasonable given the complexity and length of the revised draft assessment," wrote the spokeswoman in an email. "Once the public comment period ends and we receive feedback from the 12 peer reviewers, EPA will proceed with finalizing the assessment in 2013."

These latest developments come after much attention to the topic in the media. Last year PBS Frontline produced an investigative report on the proposed Pebble mine. Yesterday Robert Redford penned an editorial opposing a potential mine.

CEO Shively hinted in his statement that actual development plans could materialize within the year. “While we are still finalizing our initial development plan for Pebble, this starts to give us some context about the project from an economic perspective. … We look forward to sharing our plan with Alaskans later this year,” said Shively in his statement.