Lake McDonald ~ Glacier National Park: from the colored shores to the towering mountains along the continental divide. The color of the rocks of Lake McDonald are determined by the amount of iron within the rock and its exposure to oxygen. The lake was created from glacial activity; it is fed from McDonald Creek on the north end of the lake, and exits via McDonald Creek at the southern end before going the Middle Fork of the Flathead River. We recently spent over a week in and around Glacier National Park. To experience all of the majestic beauty that Glacier National Park has to offer, it would take a lifetime of exploration.