ANCHORAGE — A federal study that reviewed the science behind large-scale mining in Bristol Bay and could affect permitting for the proposed Pebble Mine is going to get more scrutiny, officials said Friday.

The Environmental Protection Agency released the peer review of its draft watershed assessment, which included some panelists’ concerns, including lack of clarity in the document’s objective, missing data and incomplete information.

“The purpose of the report is unclear, which makes it difficult to assess,” wrote panelist Gordon H. Reeves, with the U.S. Department of Agriculture’s Pacific Northwest Research Station.

Because the mine owners have not yet submitted a plan, the assessment looked at the impacts of the kind of mining needed to successfully develop a large deposit, not an in-depth assessment of any specific project.

Pebble Mine is proposed at the headwaters of the world’s largest salmon fishery.

“The report focused on the potential impact of a hypothetical mine on salmon and salmon habitat in two watersheds in Bristol Bay, AK. However, it is not clear whether the analysis was intended to be a case study of the potential impacts of a hypothetical mine under the various scenarios presented or whether the intent was to develop a framework for assessing mining scenarios,” Reeves wrote.

Pebble spokesman Mike Heatwole said it appears the EPA reviewers agree with some of the company’s key points, mainly “that the report itself is pretty flawed in using a hypothetical mining scenario and just relying on impacts without having a concrete plan in front of them that takes into full consideration mitigation and how a modern mine would meet the permitting and review process.”

The agency said it will address all concerns raised by the panel, first with a revised draft. Besides clarifying the objective, the EPA says other revisions will include using more conceptual models to better show how mining activities could impact Bristol Bay fisheries and making clearer the mining scenario used in the study.

The EPA will then bring in a group of experts from outside the agency to review the revised draft, spokeswoman Alisa Johnson said. The final document will include the experts’ review, the agency’s responses to comments from the panel, and about 230,000 comments from the public.

There is no timeframe for release of the final report, which could affect permitting decisions for the proposed Pebble Mine, a massive copper-and-gold prospect in the Bristol Bay region, about 200 miles southwest of Anchorage.

Pebble says the prospect is one of the largest of its kind in the world. Mine supporters say it would bring jobs to economically depressed rural Alaska, but opponents fear it could disrupt, if not destroy, a way of life for Alaska Natives living a subsistence lifestyle.