The stream heads in a pair of small lakes and the remaining portions of the Lyall Glacier, and flows down a cascade that is said to be approximately 850 feet (260 m) high.

A steep talus cascade is also found at the foot of the falls.

Rainy Lake's outlet stream eventually flows into the Stehekin River.

The drainage area of Rainy Lake Falls is very small, but its sources allow it to retain water all year long, with best flows from May through August.

This Chelan County, Washington state location article is a stub.