The U.S. Environmental Protection Agency (EPA) is proposing a restriction on mine waste disposal and mining at the Pebble Mine in Bristol Bay, Alaska.

The EPA is proposing to restrict all discharge of dredged or fill material related to mining the Pebble deposit that could result in the loss of streams, wetlands, lakes and ponds and alter stream flow, according to a news release. The restriction on large-scale mining there would protect the Bristol Bay watershed that supports one of the world’s most productive salmon fisheries, the agency said.

The agency is seeking public comment, plans to hold public meetings and meet with area tribes for formal consultation. Northern Dynasty Minerals and the Pebble Ltd. Partnership back the development of the mine, which would be one of the largest open pit copper mines in the world.

“The science is clear that mining the Pebble deposit would cause irreversible damage to one of the world’s last intact salmon ecosystems,” said Dennis McLerran, regional administrator for EPA Region 10. “Simply put, this will be a uniquely large mine in a uniquely important place.”

According to information provided by Northern Dynasty, mining the Pebble deposit likely would result in mine waste that would fill a major football stadium up to 3,900 times; create mine tailings impoundments that would cover about 19 square miles; and created a mine pit nearly as deep as the Grand Canyon.

The move was applauded by a group of Alaska Native leaders, commercial fishermen, investors, jewelers and conservation organizations, according to a news release from the Washington-based non-profit organization, Earthworks.

“As a jeweler whose business depends on precious metals, and therefore mining, we have nevertheless long opposed the development of new mines that threaten areas of high ecological and cultural value,” said Michael Kowalski, chairman and CEO, Tiffany & Co.