The Niobrara is a relatively undammed river for most of its 535 miles. The only dam that currently exists on the Scenic River stretch is Cornell Dam. Cornell Dam is located on the Ft. Niobrara National Wildlife Refuge and has a significant historical context for the Niobrara River Valley and the nearby town of Valentine. The dam was built in the early 1900's, but has not been operational since 1984. It now exists as a "run-of-the-river" dam; however it still serves as an impediment to upstream migration of aquatic species. It also continues to alter the hydrology of the upper portion of the Scenic River stretch.