1996 Tumalt Creek debris flows and debris avalanches in the Columbia River Gorge east of Portland, Oregon

Several canyons along the southern side of the Columbia River about 35 miles east of Portland, Oregon produced debris flows on February 7th and 8th, 1996. Two types of flow occurred in the channel of Tumalt Creek. The earlier flow was more rapid and destructive, carrying boulders up to three meters in diameter with very little mud, and while it left boulder levees on the banks of the channels, the channels themselves were left clean. This flow may be appropriately described as a debris avalanche. The later flow was slower and more gentle, behaving more like a typical muddy debris flow, leaving deposits of muddy debris within the channel as well as in boulder levees along its length.