How long is the river that contains Colter Falls?
Colter Falls: Colter Falls, also Coulter Falls, (4.3m) waterfall, nearly 0.5 mi in width, part of the Great Falls of the Missouri, on the Missouri River in north-central Montana. Missouri River:  Rising in the Rocky Mountains of western Montana, the Missouri flows east and south for 2341 mi before entering the Mississippi River north of St. Louis, Missouri.
2341 mi