Question

How building dams affect the ecology of the region

Answer 1

Both carve through narrow, red sandstone canyons. Eventually, the two rivers become one when the San Miguel merges into the Dolores and the Dolores with the Colorado River in eastern Utah.

But there is one major difference: The Dolores is dammed at McPhee Reservoir near the town of Dolores, while the San Miguel is one of the last free-flowing rivers in the West.