Sandy River Delta

"I arrived at the enterance of a river which appeared to Scatter over a Sand bar, the bottom of which I could See quite across and did not appear to be 4 Inches deep in any part; I attempted to wade this Stream and to my astonishment found the bottom a quick Sand, and impassable…"

--William Clark November 3, 1805

One can image the haste with which Clark would have beckoned his men to come retrieve him with their dugout canoe. He named the river the Quicksand. Over time, it came to be known simply as the Sandy. Clark found himself sinking not in quicksand, but rather fine sand and silt washed down the river during volcanic activity on Mt. Hood.

During the last two millennia, several periods of eruptive activity have sent swiftly moving mudflows known as lahars rushing down the Sandy River valley as well as other local drainages. The heat from volcanic eruptions rapidly melted ice and snow, sending a slurry of material downstream. Geologists believe that the largest of these events—the Timberline eruptive period between 1400 and 1800 years ago—left a deposit almost 24 feet higher than the present river level. Another smaller eruptive period in the late 1700s left the fine sediments through which the Corps of Discovery slogged in their exploration of the river. Much of the sand and silt has since been washed away, but the Sandy still lives up to its name.

The Forest Service acquired much of the 1,400-acre delta in 1991, and today the area is part of the Columbia River Gorge National Scenic Area. The area is popular with dog walkers, bird watchers, and fisherman. 

Sandy River Delta is also the site of various habitat restoration efforts; one project was led by the Estuary Partnership in 2014, in addition to ongoing revegetation work by volunteers.