Groups fighting the Pebble gold and copper prospect on Friday swiftly condemned a new federal report summarizing public concerns about the project after a three-month comment period, asserting that the report glosses over key issues.
Supporters of the project shot back, saying the U.S. Army Corps of Engineers has undertaken painstaking efforts to gather information before it prepares an environmental review of potential development scenarios.
The Corps released the report on Friday.
Deantha Crockett, executive director of Alaska Miners Association, said the Corps has shown its willingness to listen, allowing a 90-day period to take public input on the Southwest Alaska project, instead of the original 30.
"We're happy we're seeing progress (on the project)," she said.
But conservation group Salmon State said the comment period was extended only after pressure from leaders like Sen. Lisa Murkowski, who told the Corps one month was not long enough for such a big project.
"Today's report is a preview of how Alaskans should expect the remainder of the permitting process for the Pebble Mine to be managed by the federal government," said Tim Bristol, director of Salmon State. "Their first major action on permitting was rushed, ignored the voices of Alaskans and overlooked countless problems with Pebble's application."
If built, the giant open-pit mine would be located about 200 miles southwest of Anchorage, straddling salmon-producing headwaters of the giant Bristol Bay fishery.
Plans submitted by developer Pebble Limited Partnership call for extracting 1.3 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 reaching 600 feet.
The tailings dam, for storing finely ground waste material and wastewater, attracted the most attention during the public comment period, the Corps said. The agency received 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 Corps said it received 175,000 submissions during the comment period from April to June. Most were form letters, with 3,653 unique submissions. The agency also received five petitions with about 300,000 signatures it did not verify.
The report confirms the Corps' transparent, thorough efforts to gather information for an environmental review, said Mike Heatwole, a spokesman with Pebble.
As part of the process, the agency has posted more than 50 "Requests for Information" it has made to Pebble, available on the agency's website, Heatwole said.
"Lots of material will continue to be compiled and released there," he said.
United Tribes of Bristol Bay said some villagers asked for consideration of potential downstream impacts to commercial fisheries. But those concerns weren't mentioned in the fishery or socioeconomic sections of the report, the group said.
Alannah Hurley, with United Tribes, said the substantive part of the report is far less thorough than the 152-page summary issued in 2013 for the smaller Donlin Gold project near the Kuskokwim River.