[2] Since 1915, the six-unit powerhouse on the left side of the dam has occupied a significant portion of the 87-foot (27 m) high waterfall.

On the right side of the dam is a concrete-arch spillway structure, that when functioning, releases water over the remains of the waterfall.

The center part of the dam consists of a dike that extends from the falls' base to Ryan Island (separating the tailrace from the main river, which it meets a few hundred yards downstream).

This segment of the dam contains the outlet works, a water jet that bursts out and cascades over the waterfall.

The dam was constructed on top of a 10-foot (3.0 m) cascade that Lewis and Clark observed to lie just upstream of Grand Fall.