A Canadian-Japanese venture is considering building a copper mine upstream from the Alaska Chilkat Bald Eagle Preserve, where as many as 3,000 of the majestic birds — the highest concentration in the world — sometimes congregate.

Environmentalists fear a mine could leak toxins into the Chilkat River, kill the fish that draw eagles to the pristine, mountainous region every year and ruin a national treasure. The eagles congregate on the river because thermal springs keep it ice free for longer periods than most waterways in The Last Frontier, allowing the eagles, as well as bears and other animals, to feast on fish into the late fall before the river freezes over.

"It's the wrong mine in the wrong place," said Guy Archibald, mining and clean water program manager at the nonprofit Southeast Alaska Conservation Council. "It's directly above one of the most productive salmon rivers in southeast Alaska. This is a looming train-wreck."

A representative of the mining company, Vancouver-based Constantine Metal Resources, said environmentalists were exaggerating the threat posed by the mine.

"It's not 1901 anymore," said Darwin Green, vice president of exploration at Constantine, adding that prospectors are only exploring whether they can dig copper, zinc, gold, and silver from an area between the preserve and the Canadian border.

"We've gotten increasingly stringent regulations," Green said. "Mining water standards in Alaska are more stringent than drinking water standards."

'This is not jobs versus greens. This is about jobs versus jobs.'

The mine has been in the planning stages for decades, but it appears the company is now moving closer to extraction. Three years ago, Dowa Metals & Mining of Japan invested $22 million in exchange for a 49 percent share of the project. Based on an estimate last year in North of 60 Mining News, the copper in the area alone is worth around $540 million at current prices — though Green said that number doesn't account for the costs of processing the metal or the $200-$300 million price tag of constructing the mine.

The company has applied to the US Bureau of Land Management to build a road into the area and expand drilling to figure out where exactly the copper is located. Currently, the company airlifts equipment to the proposed mining site using a helicopter.

Conditions in the remote, rugged area have raised the stakes for both pro- and anti-mine forces in the debate.

The ground in the area is especially high in sulfides as well as other metals that become poisonous when they dissolve in water, said Archibald. "You or I could eat a copper penny and be alright," he said. "But if we drank a cup of dissolved copper, we'd be rushed to the emergency room."

High levels of sulfides aren't present in all copper mines, he said. But this one is loaded with them. Mining uses water to separate copper and other metals from rock. This proposed mine would be on a mountain overlooking a tributary of the Chilkat. While miners would recycle the water and safeguard against it pouring into the river, undoubtedly some would find its way into the ecosystem, he said.

"You are going to have large waste rock piles," he said. "All the rainwater that comes in contact with these sources has to be contained and has to be treated."

But the mine is also in a perfect spot for business. It's near a highway that runs north to Whitehorse and, closer by, south to a deepwater port in the town of Haines, a center of the region that's home to 2,500 residents.

Haines Mayor Janice Hill, who supports the mine, said that while Haines has a strong fishing and tourism industry, young people leave because they can't find good-paying jobs there.

"When I was a kid, there were three active saw mills running," Hill said. "I see this as an opportunity to make things better. Some of us choose to have a little more trust in the fact that these people really want to do it the right way, and I believe they do. None of us want to do anything that is going to damage the environment."

But Gershon Cohen, a biologist and environmental activist who lives in Haines, said Hill was misrepresenting the question before the public. If the mine pollutes the river and ends the salmon runs, the eagles won't stay and one of the town's biggest tourist draws will disappear, he said.

"The mine and the mine supporters are trying to paint this as this classic battle between people who want jobs and people who want to protect the environment," Cohen said. "In fact, nothing could be further from the truth. This is not jobs versus greens. This is about jobs versus jobs."

The rest of the country should be involved in the debate too, if only because of a national interest in bald eagles, Cohen said. "You can have 50 bald eagles sitting in a cottonwood tree just hanging out and waiting to go down to the river," he said.

Cohen and the Tlingit Native Americans living near Haines have filed a petition with the Alaskan government to give the Chilkat River special protections due to its "exceptional recreational or ecological significance," a designation that could stymie Constantine's plans. That petition is pending.

The mayor believed Hill and other mine critics were entitled to their opinions, but she thought they were overreacting.

"I think there is a certain amount of truth to what they're saying," said Hill. "I just think it gets embellished, and they don't take into consideration all of the monitoring and all of the regulations and all of the people keeping an eye on things. Of course a disaster could happen. I could walk out of my office and get hit by a car. I'm not going to not go outside."

Follow John Dyer on Twitter: @johnjdyerjr

Image via Flickr