Roaring Fork River is a tributary of the Colorado River, approximately 70 miles (110 km) long, in west central Colorado in the United States. The river drains a populated and economically vital area of the Colorado Western Slope called the Roaring Fork Valley or Roaring Fork Watershed, which includes the resort city of Aspen and the resorts of Aspen/Snowmass. The Roaring Fork is a swift, deep, powerful river with very clear water. It is navigable by small craft throughout most of its length to its confluence with the Colorado. The mean annual flow is 1,206 cu ft/s (34.2 m3/s).