Sunken Arch Falls

Sunken Arch Falls is the second-to-last major waterfall along Stevens Creek as it makes its descent from its origin glacier on Mount Rainier to its confluence with the Muddy Fork Cowlitz River. The falls are found at the head of a narrow canyon that the creek has carved through the volcanic bedrock in its final step down to the plain of the Cowlitz River. The creek splits around a narrow fin of rock, accelerating down twin chutes, and then plunges 29 feet into the defile with the streams of water crossing over each other mid-fall. At the base of the falls the pounding action of the water has carved a deep pothole with such fervor that the hydraulic action has actually undercut it beneath the surface, forming a natural arch in the bedrock which the water plunges into and flows beneath. When the creek is running at moderate or lower levels, the falls plunge into a pothole but the surface of the stream never surmounts the top of the arch - instead the water flows underneath. During high flow in the spring and early summer, we would expect the arch to be overwhelmed and be totally inundated.