In the North Cascades glaciers contribute 21 billion cubic feet of water every year to streamflow. That is about one-fourth of the total volume of water draining from the North Cascades. Yet, the almost 700 alpine glaciers in the northern Cascade Range are a fraction of the size of their ice age counterparts. Glacial concentrations surround all major peaks. Mt. Baker's slopes support 13 glaciers.
Glaciers are sensitive to changes in temperature and snowfall.
Their constant changes are important climatic indicators. They influence vegetation patterns, move and carve rock, add minerals to the ecosystem, and serve as reservoirs for domestic and hydroelectric water supplies. Glaciers have tremendous effects on the hydrology of streams. The most important effects are related to changes in the supply of runoff from melting and the seasonal storage of water within glaciers. In drought years glacial meltwater is the only thing flowing in some streams.