Wikipedia sums up the significance of this site very well:
For 15,000 years, native peoples gathered at Wyam to fish and exchange goods. They built wooden platforms out over the water and caught salmon with dipnets and long spears on poles as the fish swam up through the rapids and jumped over the falls. Historically, an estimated fifteen to twenty million salmon passed through the falls every year, making it one of the greatest fishing sites in North America.
Celilo Falls and The Dalles were strategically located at the border between Chinookan and Sahaptian speaking peoples and served as the center of an extensive trading network across the Pacific Plateau. Artifacts from the original village site at Celilo suggest that tribes came from as far away as the Great Plains, Southwestern United States, and Alaska. When the Lewis and Clark expedition passed through the area in 1805, the explorers found a “great emporium…where all the neighboring nations assemble,” and a population density unlike anything they had seen on their journey. Accordingly, historians have likened the Celilo area to the “Wall Street of the West.”
All of this came to an end in 1957 when the final construction of The Dalles Dam flooded the entire area, destroying the falls and rapids, along with 15,000 years of fishing. According to the Government lawyers, none of this was a violation of treaties with the native tribes, although cash awards were made in compensation.
Much of this now feels like ancient history, but yesterday I was working through a series of my father’s slides he’d had scanned and found some gems that he had taken before the dam was completed, quite probably that same year. I’m sure there were lots more, but he purged his slides a few years back (god, I wish he’d talked to me about it) and these are all that remain.