We fly upstream, following the Nushagak River toward its source, passing braided stretches where it is joined by the Wood, Iowithla, and Kokwok. Far to the right, the west end of Iliamna Lake, Alaska's largest, comes into view. Aside from a few scattered villages and the plane's fleeting shadow, no human signs are visible. No dams, no deforestation, no highways, housing divisions, or power plants. That this place is mostly undeveloped helps explain why it is home to the world's largest sockeye salmon runs and one of North America's largest chinook, or king, salmon runs, to say nothing of the trophy rainbow trout and grayling and other species that flourish here.
We near our destination, the locus of the toughest dilemma this uncommonly pristine and biologically productive region has ever faced. "Here it is," Halford says, "the spot where streams drain in three directions." From this hilly expanse north of Iliamna Lake, the Chulitna River flows east into Lake Clark, heart of the Lake Clark National Park and Preserve. The South and North Forks of the Koktuli River meander northwest into the Mulchatna River, which feeds the Nushagak, and Upper Talarik Creek tumbles south into Iliamna Lake, which empties into the Kvichak River, which, like the Nushagak, eventually reaches Bristol Bay. Every summer, during a period lasting a few weeks, 30 to 40 million adult sockeye return to the bay. Driven by an ancient and unforgiving imperative, they swim against the shallow currents of these rivers up to their headwaters to spawn and die so that their kind may endure.
But salmon are not the only outstanding feature of this Alaska wilderness. Where the uppermost reaches of three streams originate, a geologic anomaly has been found—an ore body that may hold the world's largest deposit of gold and one of the largest of copper. Two companies, Northern Dynasty, of British Columbia, and Anglo American, a giant multinational based in England, have teamed up as the Pebble Partnership to evaluate the potential for an open-pit mine—possibly up to two miles wide and 1,700 feet deep—and an underground mine of similar scale. The prospect alarms many, especially those who depend on or value the salmon above all else. They fear that the Pebble mine would destroy the fishery, largely by contaminating the water. The Pebble partners argue that extractive industry and wildlife can coexist and that the mine would bring much needed economic benefits. Framing this as "mine versus salmon," however, overlooks the project's larger potential effect: It could stimulate industrial growth on a scale that would permanently transform the Bristol Bay region.