The Trump administration on Wednesday unveiled the first-ever draft environmental review of the controversial Pebble gold and copper project.

The report is a key step in the regulatory process and will lead to a 90-day public comment period for the Southwest Alaska mine that has been in the works for more than a decade, the U.S. Army Corps said Wednesday.

The agency is expected to release a final environmental report and make a final decision in 2020 to help determine how development should proceed at the giant prospect in the Bristol Bay region. Other state and federal agencies must also weigh in before mining can begin, and the Environmental Protection Agency still holds the option to essentially veto the project, Corps officials said.

The 1,400-page report, including hundreds more pages in supporting documents, is broken down into several chapters and is available at the federal agency’s Pebble Project website, pebbleprojecteis.com.

If built, the open-pit mine would be about 200 miles southwest of Anchorage, straddling salmon-producing headwaters of the valuable Bristol Bay fishery.

Plans submitted by developer Pebble Limited Partnership call for extracting 1.4 billion tons of ore and 200 million tons of waste rock over 20 years. They include a 188-mile natural gas pipeline crossing Cook Inlet, construction of a port in the Inlet, and a tailings dam with an embankment 600 feet high.

The dam, for storing finely ground waste material and wastewater, attracted the most attention during the last round of public comments about what the Corps should consider in its draft environmental report. The agency heard a range of concerns, including on the impacts of a dangerous dam failure like those that have occurred elsewhere, such as at British Columbia’s Mount Polley mine in 2014.

The draft review analyzes the impact of various development scenarios, including no development. The first alternative listed would accept Pebble’s proposed development plan.

One option proposes reducing the length of access roads and altering construction plans for the tailings storage facility. Another would eliminate a ferry crossing at Iliamna Lake that would transport materials.

A tribal group on Wednesday immediately slammed the "woefully inadequate” report, saying it ignores major impacts to fish and people from the region. The draft review shows the process is rigged for Pebble, said Alannah Hurley, United Tribes of Bristol Bay executive director.

“The Army Corps’ review ignores the very real concerns about the changes and devastation Pebble would bring to our region, and is clearly the result a rushed process that has ignored local voices and ignores the existing science in the Bristol Bay Watershed Assessment that shows how devastating this project would be in Bristol Bay,” Hurley said.

Hurley said the report’s flaws include underestimating the risk of a tailings dam failure and a lack of analysis of the collective impacts of spills.

Developer Pebble Limited Partnership said Wednesday it believes the review, a draft environmental impact statement, demonstrates that its proposed plan can be done in an environmentally responsible way.

“Our preliminary review of the DEIS shows no major data gaps or substantive impacts that cannot be appropriately mitigated,” said Tom Collier, chief executive of Pebble Limited. “We see no significant environmental challenges that would preclude the project from getting a permit and this shows Alaska stakeholders that there is a clear path forward for this project that could potentially generate significant economic activity, tax revenue and thousands of jobs.”

The public comment period is expected to begin March 1 after the report is published in the Federal Register, said John Budnik, a spokesman with the Army Corps in Alaska.

“The intent is to give people time to digest it, read the document, think about their comments and provide the feedback we’re looking for,” Budnik said.

Pebble applied with the Corps for the construction-related permit in 2017 to discharge fill material into U.S. waters. The company proposed a scaled-back project from an earlier version, saying it would not build major mine facilities in the Upper Talarik drainage. It says it won’t use cyanide to extract gold.

“We have stated that the project must co-exist with the important salmon fishery in the region and we believe we will not harm the fish and water resources in Bristol Bay," Collier said. “Now we have a science-based, objective assessment of the project that affirms our work.”

Pebble has said the project could create up to 2,000 Alaskan jobs, $1 billion in state revenue, and $21 million annually to the region’s Lake and Peninsula Borough.

Opponents of Pebble on Wednesday said it’s not worth the loss of the commercial salmon fishery they say is valued at more than $1.5 billion annually. They say Pebble wants a foot in the door with its smaller proposal, but plans to launch new efforts in coming years to mine the full, and much larger, mineral deposit.

Collier has said such a step will require a new public regulatory process and additional scrutiny from federal agencies before it can be approved.

The federal government’s fast-tracked schedule is driven by Pebble’s financial and political agenda, said Alexus Kwachka, with Commercial Fishermen for Bristol Bay. He said Pebble would devastate the fishery, ending his livelihood.

“The Pebble mine is a direct and proven threat to more than 14,000 fishermen who depend on Bristol Bay’s salmon for our jobs,” Kwachka said. “That’s why Bristol Bay’s fishermen ask that the Army Corps uphold the original purpose and intent of our federal laws and not continue to push this irresponsible mining project forward at the expense of the greatest wild salmon fishery left on earth.”

Shane McCoy, the Corps’ program manager reviewing Pebble’s application, said a final environmental review is expected to be released in February next year.

The Corps may deny a permit, or select a development alternative, he said.

Other required federal approvals must come from the U.S. Coast Guard, for a bridge over the Newhalen River, and the Bureau of Safety and Environmental Enforcement, which must permit the pipeline right-of-way crossing federal waters in Cook Inlet, McCoy said.

The agency permits, if approved, could set the stage for final federal approval in 2020.

The EPA also retains the option to impose the limits on the mine it had proposed in 2014 that were widely considered a “pre-emptive veto” of Pebble. Pebble sued the agency, leading to a settlement in May 2017 that allowed the regulatory process to move ahead.

The EPA, under former administrator Scott Pruitt, said in early 2018 that Pebble’s permit application “must clear a high bar, because EPA believes the risk to Bristol Bay may be unacceptable.”

McCoy said the Corps took pains to consider the wide range of views on the mine’s proposed development.

“We do consider everyone’s position and stance,” he said in an informational meeting with reporters on Wednesday.

Some options, such as smaller mine operations, were dismissed from consideration because they were not economically viable, based on industry standards. Those explanations can be found in Appendix B of the report.

Some options were considered not practicable, taking into account costs, logistics and technology, McCoy said.

McCoy, addressing criticism from Pebble opponents who call the report inadequate, said he hopes people will read it and recommend changes.

“I want everyone to review it,” he said. “If there’s something we missed, please provide those in the comments.”

Public meetings on the report are scheduled to run in nine Alaska communities from March 25 until April 16, including in the Bristol Bay region in Dillingham, Igiugig, Kokhanok, Naknek, Newhalen, New Stuyahok and Nondalton.

The meetings will wrap up in Homer on April 11 and in Anchorage on April 16.

Each of the meetings will have an open-mic format, McCoy said.