Jackson Lake in Grand Teton National Park is a natural moraine-dammed mountain lake shaped by glacial action, later adapted into a reservoir by Jackson Lake Dam. Fed chiefly by the Snake River, it lies between the Teton Range and Yellowstone Plateau and ranks among the largest high-altitude lakes in the United States. Its upper waters are used for Idaho irrigation through the Minidoka Project under rights predating the park, giving it both scenic and practical importance. The lake also supports cold-water fish species, boating, fishing, lodges, and marinas on the east shore, while the west shore remains more primitive.