 It was named for Billy Chinook, a Native American of the Wasco tribe who traveled alongside American explorers John C. Frémont and Kit Carson in their expeditions of 1843 and 1844.The canyon in which Lake Billy Chinook lies was carved by the three rivers that flow into the lake.The Deschutes Formation into which it is carved began forming about 11 million years ago, as alternating layers of basaltic lava, stream sediment, and volcanic debris flowed into the area from the Cascade Range.