ANCHORAGE(CN) - A giant copper and gold mine proposed for Alaska ' s Bristol Bay watershed could devastate thousands of acres of wetlands and the world ' s largest wild salmon run, the Environmental Protection Agency says in a final assessment. Bristol Bay is the large, wildlife - rich bay north of the Aleutian Islands archipelago. The scientificstudy, released Wednesday, concluded that the Pebble Mine project would demolish up to 94 miles of streams, including salmon spawning habitat; destroy more than 5,000 acres of wetlands and lakes; harm the traditional salmon - based culture of 25 federally recognized tribes; and threaten the bay ' s $480 million salmon industry, the National Resources Defense Council said in a statement. " This is a scientific indictment of the Pebble Mine - or any other large - scale mining in the Bristol Bay watershed, " said Joel Reynolds, western director of the NRDC. " The assessment documents what we ' ve feared for years - Pebble Mine would destroy the world - class wild salmon fishery, cost jobs and endanger the communities and wildlife that depend on it. " Bristol Bay, the easternmost arm of the Bering Sea, is 250 miles long and 180 miles wide at its mouth. Several rivers flow into it, including the Nushagak and Kvichak, which are rich in mineral resources, including copper and gold. The bay attracts sport and subsistence fishers and hunters, wildlife viewers and general tourism. Bristol Bay is home to 190 species of birds, more than 40 species of land mammals and 35 species of fish, including sockeye, Chinook and pink salmon. The bay ' s famous salmon fishery produces around 46 percent of the sockeye salmon consumed throughout the world; commercial harvests average 27.5 million fish a year. Its salmon industry provides jobs to 14,000 workers and supports the traditional subsistence lifestyle of more than 4,000 Native Americans, for whom salmon is the " foundation for their language, spirituality, and social structure, " according to the EPA. Backed by Northern Dynasty Minerals, the proposed mine would be dug at the headwaters of the Bristol Bay salmon fishery at the Pebble deposit, which is rich in copper, gold and molybdenum, according to anEPA fact sheet. The area could produce 11 billion metric tons of ore, which would make it the largest North American mine of its kind. But due to the low-grade nature of the mineral deposits, mining would be economically viable only if conducted on a large scale, according to the EPA's Web page about Bristol Bay. In addition to the mine, the project would include a wastewater treatment plant, a transportation corridor to Cook Inlet across 55 salmon-supporting streams, miles of pipeline, and a tailings dam, according to the EPA fact sheet. To assess the risks and environmental impact of large-scale mining on the salmon fishery and the surrounding ecosystem, the EPA undertook a comprehensive scientific assessment of the Bristol Bay watershed. After spending three years on the study, the agency submitted it for two rounds of peer review by independent scientists, as well as two public comment periods. By using realistic mining scenarios based on Northern Dynasty's preliminary plans as well as data from experts in the mining industry, the EPA concluded that the Pebble mine would threaten Bristol Bay's fish populations and the surrounding streams and jeopardize its lucrative salmon industry. Among other things, the report found that a large-scale mine would alter up to 33 miles of salmon-supporting streams and create up to 10 billion tons of mine waste that would need to be stored at the region's headwaters. Failure at the wastewater treatment plant could harm fish in 48 to 60 miles of streams; culvert failures in the transportation corridor could contaminate salmon spawning areas with runoff and chemicals; and a pipeline failure could "release toxic copper concentrate or diesel fuel into salmon supporting streams or wetlands," the Bristol Bay fact sheet states.