Umtanum Ridge Water Gap, National Natural Landmark in Yakima Canyon, Washington, United States

Umtanum Ridge Water Gap is a natural water passage where the Yakima River cuts through steep basalt cliffs in central Washington. The canyon reveals layers of ancient rock formations that tell the story of how flowing water shaped the landscape over millions of years.

The Yakima River cut this gap through the rising Manastash and Umtanum ridges of the Yakima Fold Belt, near the western edge of the Columbia River Plateau. The river already flowed south over relatively flat Columbia River basalt; as north–south compression folded the layers into east–west anticlines, it kept its course and cut down through them. The gap was designated a National Natural Landmark in 1980.

Geologists and researchers frequently visit this site to study the complex folding patterns and geological processes visible in the rock formations.

Washington State Route 821 follows the Yakima River through the canyon between Ellensburg and Yakima, with pullouts along the way for viewing the basalt walls. Interstate 82 crosses the area on large bridges nearby and carries most traffic. The Umtanum Ridge crest rises to 983 meters within 1 km of the river, which lies at about 470 meters there.

The river maintained its original course while the surrounding ridge was pushed upward by geological forces, creating a rare natural example of water's power overcoming rock deformation. This phenomenon reveals how flowing water stays its path even as the land beneath shifts and rises around it.