Mancos River

The Mancos River, formerly also El Rio de San Lazaro, is an 85.4 mi northeast tributary of the San Juan River. It flows from the confluence of West Mancos River and East Mancos River near Mancos, Colorado and joins the San Juan near Four Corners Monument in New Mexico.

The river was named after an incident during which a horse rider hurt his hand while crossing, the word Mancos being derived from Spanish meaning "one-armed".