This story is part of a special National Geographic News series on global water issues.

Last June, preparations were made in a remote village in Southwestern Alaska for the upcoming commercial sockeye salmon season at one of the largest salmon runs in the world. All along the gravel beach, crew members could be seen mending their patchwork of well-worn green nylon nets, as boat captains prepared their open-hull aluminum skiffs for the highly anticipated sockeye run.

Nushagak Point village in Bristol Bay is ground zero for salmon heading toward their ancestral spawning ground. Each year, Nushagak families join thousands of returning and residential fishermen in Bristol Bay to catch a share of the salmon's annual migration through the bay and up the winding Wood River.

And each year, gossip runs rampant from cabin to cabin, predicting whether the run will be late and if it will be larger than last year. Yet for centuries, the fish have returned, following the ancient route of their ancestors to spawn in the same small streams and rivers.

During 2010, in fact, more than 40 million salmon swam through Bristol Bay, according to the Alaskan Fish and Game Department. It is estimated that more than half of all wild salmon sold in the United States comes from Bristol Bay fisheries.

But as National Geographic magazine reported in its December 2010 issue, the salmon run—and those who fish there—are under threat from another enterprise that is steadily working its way into the region's economy: gold and copper mining. Despite widespread opposition—and although one of the mining company officials has pledged not to continue the project "if we're not wanted"—the plans for a gigantic mining operation show little sign of slowing down.

A little background: Beneath the headwaters of two main tributaries of Bristol Bay lies one of the largest deposits of undeveloped copper and gold in the world. Northern Dynasty of Canada and Anglo American of London jointly own the rights to the area, the site of what is known as the Pebble Mine project. The companies have spent the past six years working to secure permits to begin mining the ore. According to Anglo American, the 187-acre (75-hectare) mining area holds 80.6 billion pounds (36.5 billion kilograms) of copper and 107.4 million ounces (3,044,000 kilograms) of gold.

If given the go-ahead, the companies expect to dig a crater spanning two miles (3.2 miles) wide and thousands of feet deep. According to the Alaska Law Review, three large dams would be required to permanently contain 10 billion tons of hazardous mining waste, known as tailings. Some locals claim tailings dams have a poor safety record, and point out that failures have created water-pollution problems in communities around the world in the past decade. They also worry that Southwest Alaska is in a seismic fault zone, making it vulnerable to earthquakes.

Threat to Indigenous People and Water Quality?

The companies involved have requested permits to siphon nearly 35 billion gallons (132.5 billion liters) of water per year—as much water as the city of San Francisco uses in a year—from tributaries and underground aquifers to operate the mine.

The companies insist that the project would adhere to the standards of the U.S. Environmental Protection Agency. Opponents of the project fear that, over time, the gold and copper tailings will seep into the Bristol Bay watershed, causing reactive copper sediment and other toxins to harm spawning salmon and other animals in the bay.

Kologanek village council member Anuska Wysoki is among those who fervently oppose the project. Year after year she has returned with her two daughters and husband to the remote, wind-swept Nushagak Point beach. Working with her sleeves rolled up, she has a gentle, content smile as she bustles between pots of boiling fish stew and cuts up the rich, glistening red sockeye meat to prepare for salting. Her family is part of generations of native Yupik subsistence and commercial fishing communities that have survived on the salmon run for millennia.

Wysoki believes the Pebble Mine would forever alter the way of life of her people. "Toxic waste will contaminate the fish and they won't come again," she said.

Not only the fish, but also the fate of indigenous Alaskans who depend on them hangs in the balance, she said. Should the salmon run be affected, "everyone will be forced to move to the cities," Wysoki said. "Right now we don't have to because we have salmon."

Nushagak Point fisherman Tom Rollman, Sr. has fished in Bristol Bay for the past 27 years. Asked about the Pebble Mine, he said, "It would be nice if we could do both." But, he added, "any time you tamper with freshwater, salmon do not survive." Rollman reflects the opinion of many in the commercial Bristol Bay fishing community when he says, "I don't think we can take a chance on the greatest salmon resource in the world."

Job Creator or Loser?

Louis Finch has been fishing in Bristol Bay for 20 years. He maintains that, should the Pebble Mine companies keep their promise of hiring locally, it could be a desperately needed boon for communities. Commercial fishing drives the local economy, and Finch isn't the only one who says they would welcome the opportunities presented by Pebble. Finch believes in the EPA's ability to protect the area from adverse environmental effects. "I don't want to see this fishery damaged more than anyone else," he said.

Pebble Mine promises 2,000 jobs for the first phase of the mining operation. That number would later drop to 1,000 long-term jobs over the 30-60 year lifespan of the mine. The companies also tout significant tax revenue for the state of Alaska.

Opponents of the project insist that, while jobs may be created, at least 12,000 jobs related to salmon fishing and processing would slowly be eliminated should the migration be affected. But for most in the tight-knit fishing community, it's about more than just jobs. It's a way of life that ties generations to each other, and to the watershed where they live.

Anglo American CEO Cynthia Carroll told a reporter several years ago that she would not go ahead with the project unless "the majority of the community" is in support of the mine. "I will not go where people don't want us. I just won't," she told Fast Company reporter Melanie Warren. "We've got enough on our plate without having communities against us."

It would seem that Carroll has a decision to make. According to a poll in June 2011 by the research group Craciun, Bristol Bay fishers are united against the project, with 86.2 percent opposing the mine. An earlier survey by Craciun found that 71 percent of the households in the Bristol Bay area opposed the mine, with only 9 percent even somewhat supportive of it; other polls have found the majority of Alaskans say the mine is not worth the risk.

Environmental groups such as the Renewable Resources Coalition are fighting the proposed mining development, and even prominent jewelry companies such as Tiffany's and Helzberg Diamonds have weighed in: They and several other leading jewelry retailers have already promised to boycott the Pebble Mine gold and copper products should the project be built.

Despite the opposition, Anglo American and the other Pebble Mine partners have continued to spend millions of dollars on permits and mineral exploration in the area, as well as an advertising campaign. But they face a new foe: on September 12, the Seattle Times reported that Democratic Senator Maria Cantwell, worried about the impact on salmon fishing in her state of Washington, announced that she would ask the head of the Environmental Protection Agency to consider using the Clean Water Act to stop the proposed Pebble Mine project. (She'll be dueling with Republican Representative Don Young of Alaska, who has already introduced a bill to take away the EPA's authority over the project.)

On September 26, according to Bloomberg Businessweek, Alaska Superior Court Judge Eric Aarseth declared that evidence presented by plaintiffs in the latest lawsuit against Pebble—relating to recent fuel spills and exploratory operations—shows there has not been a significant environmental impact on the area.