A draft environmental impact statement on the proposed Pebble Mine is over 1,000 pages long, but some say it doesn't go far enough in evaluating the project's potential risks to the environment.

Members of the Bristol Bay Regional Seafood Development Association, which represents commercial fishermen in Bristol Bay, commissioned their own report regarding those concerns at a cost of $83,000.

Lead scientist Cameron Wobus looked specifically at what could happen if the facilities meant to hold waste from the mine, called tailings, were to fail. Wobus said the potentially toxic material would spill onto the land and into the water where salmon spawn.

"Every scenario we looked at with a tailings dam failure would directly impact hundreds of miles of anadromous waters," Wobus said.

The U.S. Army Corps of Engineers statement cites the risk of a large-scale tailings dam failure as very low during the 20-year life of the mine. But Wobus said tailings from the mine will be around a lot longer than that.

"It is important to understand that this tailing dam will be there forever," Wobus said. "It is not a 20-year dam, it is a dam that will be on the landscape forever and Pebble will eventually walk away and leave that thing on the landscape."

Mike Heatwole, a spokesman for the Pebble Partnership behind the mine, said the company has taken into account the things that are likely to contribute to dam failure including climate, earthquakes and the amount of precipitation in the region.

"There seems to be a notion out there that we have not taken all these things into consideration and that's just flatly not the case," he said.

Plans call for Pebble to have two separate tailings storage facilities, specially designed to let water flow underneath them.

Heatwole said the water will be collected and treated before being discharged, provided the state approves the plan. He pointed out that the Corps of Engineers assessed the changes of a major breach as minimal.

"There were potential failure scenarios that were looked at that were outlined in the draft environmental impact statement," he said. "However, the issue of a catastrophic failure, it was viewed that that was not a plausible scenario because of the approach taken to design and operation for the facility."

The Corps of Engineers is accepting public comment on the draft plan through its website until the end of May.

A decision on whether to issue federal permits to Pebble is expected to be released in early 2020. Heatwole said the mine would still need to obtain state operating permits, which could take several more years.

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