Opposition to the Pebble Mine centers around the threat to the Bristol Bay salmon fishery, which is the economic, social and ecological backbone of the region - generating $400 million in annual revenue, employing more than 5,500 FTE people and supporting the subsistence livelihoods of the local communities throughout Bristol Bay.  Athabaskan, Aleut and Yu'pik Eskimo peoples have relied on the salmon runs for subsistence for thousands of year, and salmon is still the primary source of food for these communities, comprising 60-80% of their total subsistence harvest.

The project is vigorously opposed by a diverse set of regional stakeholders, including:

• the Alaska commercial fishing industry (e.g., United Fishermen of Alaska, the Bristol Bay Regional Seafood Development Association, etc.)
• Indigenous people, such as the Alaska Intertribal Council (a consortium of 231 federally recognized tribes in Alaska), the Bristol Bay Native Corporation (representing 8,500 shareholders in the region),and numerous native village corporations.
  
• Sportfishing and tourism businesses, and
  
• Bristol Bay residents (79% of Bristol Bay residents surveyed in 2009).

Athabaskan, Aleut and Yu'pik Eskimo peoples have relied on the Bristol Bay salmon runs for subsistence for thousands of year, and salmon is still the primary source of food for these communities, comprising 60-80% of their total subsistence harvest. The proposed Pebble Project is vigorously opposed by indigenous people in the region, including the Bristol Bay Native Corporation (which represents 8,500 shareholders), Nunamta Aulukestai (an association of nine Native Village corproations), and the Alaska Intertribal Council (a consortium of 231 federally recognized Alaska Tribes). Bristol Bay Tribes are pursuing litigation against the Pebble Project, and Alaska native leaders have met with Anglo American CEO, Cynthia Carroll, to communicate their opposition to the proposed mine, and to urge Anglo American to recognize the rights of indigenous peoples and the irreplaceable value of the fishery, and forego development of the project.

The Pebble Project is located in a Fishery Reserve at the headwaters of the Bristol Bay watershed, which supports the world's largest remaining wild sockeye salmon fishery and generates roughly 30-50% of the world's commercial supply of wild sockeye salmon.  Scientists consider the salmon stocks of Bristol Bay to be globally significant and a top priority for conservation.  Development of  the Pebble Mine is a direct threat to this internationally significant fishery.

Destruction of Salmon Habitat
The footprint of the mine is estimated to cover 15 square miles.  Independent fisheries biologists contracted by the Nature Conservancy to survey salmon streams in the proposed mine area, found salmon habitat throughout the mine area, including directly above the ore deposit. The researchers concluded in a  2009 report that, "Our findings remove any doubt that the construction of a mine will destroy salmon and salmon rearing habitat."

Acid Mine Drainage
Based on current ore estimates of 10.78 billion tons, the mine is projected to generate 10 billion tons of mine waste (tailings) which the company proposes to store behind large earthen dams at the headwaters of Bristol Bay in perpetuity.  Due to the high concentration of sulfides in the Pebble deposit, the majority of rock is "reactive" or acid-generating rock. Acid mine drainage is considered the greatest environmental liability associated with mining. When the ore is excavated, and the sulfides in the rock are exposed to air and water, they react to form sulfuric acid that can increase metals and other pollutants downstream. A 2006 study of hardrock mines found that 93% of mines with the same characteristics as Pebble - high acid generating potential and close proximity to surface and groundwater - resulted in water pollution. This has serious implications for the salmon fishery.  Research shows that miniscule chanages in copper concentrations in the water (as low as 2 - 10 parts per billion (micrograms per liter)) can alter the salmon's ability to migrate.

Dewatering
The company has projected the need for 35 billion gallons (1.1 billion liters) of water per year from salmon streams for mine activities.  A 2007 report has identified this as a serious threat to the salmon fishery.

Over thirty prominent jewelry retailers have signed the Bristol Bay Protection Pledge, supporting permanent protection of the Bristol Bay watershed and committing not to source gold from the proposed Pebble Mine. These companies, which represent over $6 billion in sales and whose livelihood depends on gold mining, recognize that Alaska's Bristol Bay watershed is an ecosystem of national and international significance - supporting the world's largest remaining wild salmon fishery.  The jewelers include U.S. based companies Tiffany & Co., Zales, Helzberg Diamonds, Herff Jones, Ben Bridge, and U.K. based companies Goldsmiths, Mappin & Webb, and Beaverbrooks.