Glacier National Park, Montana. 10-mile long Lake McDonald lies at the western edge of Montana's Lewis Range in Glacier National Park. Predawn-illuminated clouds reflect in the calm waters of this largest of Glacier Park’s many lakes. Along with the other large lakes within Glacier National Park, Lake McDonald was created during the Pleistocene epoch when large valley glaciers gouged out deep basins at the base of the mountains. Going-to-the-Sun Road parallels Lake McDonald’s east shore before climbing 3,500 feet to the 6,646-foot summit of Logan Pass.