Alamosa River

The Alamosa River is a river in the southern part of the U.S. state of Colorado. It is about 64 mi long, flowing roughly east through the San Luis Valley. Its watershed comprises about 148 sqmi.

The river's name means "shaded with cottonwoods" in Spanish.

The river was affected by the Summitville mine disaster, the worst cyanide spill in United States history.