Colonial Glacier lies in Washington’s North Cascades National Park, just northwest of Neve Peak, and flows generally north from about 6,800 feet down to 6,000 feet. In recent decades it has shrunk substantially, following the same trend seen in many North Cascades glaciers. Between 1950 and 2006, it is estimated to have retreated by more than 300 meters, and a new proglacial lake formed within the former terminal moraine left by the ice. This loss is part of a wider regional pattern that matters beyond the mountain landscape because shrinking glaciers reduce summertime meltwater runoff that helps support hydroelectric power generation.