By Robert Redford.

A proposed open-pit mine would endanger a pristine Alaskan fishery and destroy jobs. The EPA must prevent it.

Coursing through vast reaches of Alaskan tundra, glacial lakes and emerald forests, six major river systems converge along the rim of the Bering Sea to form the crystalline waters of Bristol Bay, the richest wild salmon grounds in the world.

Yet if three global mining giants get their way, this region — one of the last truly wild places in our country — could be destroyed.

Each year, up to 40 million sockeye salmon make the journey from deep ocean waters into Bristol Bay and, from there, upstream to spawn in the inland shallows of their birth. The salmon provide food for brown bears, bald eagles and wolves. And they’re the centerpiece of sustenance and culture for native peoples who have lived there for thousands of years.

Here, amid this rich web of life, is where Pebble Limited Partnership (Anglo American, Northern Dynasty Minerals and Rio Tinto) want to dig one of the largest open-pit gold and copper mines in the world.

The Obama administration must put a stop to this exploitative and misguided scheme.

The mining companies propose blasting open a massive pit, up to 2 miles wide and more than 1,500 feet deep. To service the mines and get their ore to port, they would slash the landscape with a road and pipeline corridor 104 miles long.

They would bring in industrial equipment to crush, grind and process mineral ore, leaving behind up to 10 billion tons of contaminated waste. That’s 3,000 pounds for every man, woman and child on Earth. Much of that waste would be dumped in a giant containment pond behind earthen dams up to 70 stories high, where it would have to stay put — in an active earthquake zone — forever.

But even without a catastrophic earthquake, the toxic chemicals used in copper processing have an ugly way of finding their way into local water and soil. If that happens in this watershed, we can kiss the wild salmon goodbye.

That’s not just my view. In an April assessment, the Environmental Protection Agency found that this mine could devastate Bristol Bay’s salmon runs, laying waste to as much as 90 miles of streams, vital habitat for wild sockeye, coho and chinook.

Where I live in Utah, we’ve seen firsthand the environmental costs of copper mining, compliments of Rio Tinto. They run the giant Bingham Canyon mine, where open-pit operations like those proposed for Pebble Mine left groundwater contaminated with arsenic and lead across 72 square miles. And, most recently, the mine was forced to temporarily shut down because of a massive landslide inside the giant open pit.

Now they want to do the same for the richest wild salmon fishery in the world? No thanks.

Of course, the mining companies claim that the project will create jobs. Well, not for the people of the region; for them, it would be a job killer. Fishing and hunting bring in $1.5 billion annually and 14,000 jobs. Pebble Mine, the companies say, would employ about 1,000 permanent workers. Even if that’s true, the project puts 14 jobs at risk for each one it creates.

No wonder 80% of Bristol Bay residents don’t want it. Pebble Mine is opposed by a local coalition that has united commercial fishermen with Bristol Bay Native Corp., the largest private landowner in the region, and 10 native communities gathered under the umbrella group Nunamta Aulukestai, or “Caretakers of Our Lands” in the native Yup’ik language.

I’m not against mining, where it can be done responsibly. But Bristol Bay is just too important, environmentally and economically, to be sacrificed for the sake of foreign mining profits.

The public has until the end of May to tell the EPA to stop this mine. President Obama can prevent the economic devastation of Bristol Bay and secure a lasting environmental legacy for his administration by allowing the EPA to use its authority under the Clean Water Act.

The rest of us have our own role to play. Americans everywhere need to raise our voices and speak out in support of the people of Bristol Bay.

Robert Redford, the actor and director, is a trustee for the Natural Resources Defense Council.