The San Miguel River is a tributary of the Dolores River, approximately 90 mi (145 km) long in southwestern Colorado in the United States. It rises in the San Juan Mountains southeast of Telluride and flows northwest, along the southern slope of the Uncompahgre Plateau, past the towns of Placerville and Nucla and joins the Dolores in western Montrose County approximately 15 mi (24 km) east of the state line with Utah. The San Miguel is more or less free flowing; however, diversion dams dot the river and alter flows. The San Miguel varies in gradient, from extremely steep in its upper reaches (forming a shallow, rocky, unnavigable stream) to more mellow in the lower sections (30-50 feet per mile of drop, which offers the whitewater boater a variety of runs all within the class II+--III range). All told, the San Miguel drops over 7000' from an alpine ecosystem to the desert.
