The Columbia River was pretty wild in spots when Lewis and Clark traveled on it in 1805 and 1806. Since 1900, there has been a lot of dam development for hydroelectric power and irrigation water. When a dam is built, a lake is formed upriver and places get flooded. The Dalles dam was completed in 1957 and the slackwater from the dam covered up a lot of stuff including Celilo Falls. Another thing it covered up was a lot petroglyphs. Some were salvaged and stored for quite a few years. They are now on display at Temani Pesh-wa in Wishram, Washington.They were pretty neat to see.