The U.S. Environmental Protection Agency warns that the proposed large-scale Pebble Mine development in the hills above Alaska’s Bristol Bay could cause devastating habitat loss for the world’s largest sockeye salmon fishery. In a draft report, EPA officials calculate that proposals to mine the region — which include an open-pit mine producing 2 billion to 6.5 billion metric tons of copper, gold, and molybdenum ore — could destroy up to 87 miles of streams and nearly seven square miles of wetlands. The EPA also said large-scale mining could make the region vulnerable to catastrophic accidents — including the possible release of acid, metals, and other waste from the mine sites — that could potentially destroy more than 30 miles of salmon-bearing streams leading into Bristol Bay, which hosts runs of roughly 30 million salmon annually. “We conclude that, at a minimum, mining at this scale would cause the loss of spawning and rearing habitat for multiple species of anadromous and resident fish,” the draft assessment states. Even before its release, the 339-page assessment was denounced by critics, including some in Congress who question the EPA’s authority to regulate the mine proposal.