"Located on the Columbia plateau in Central Washington, the Yakima is the longest river entirely in Washington state, flowing 214 miles from Keechelus Lake to the Columbia river near West Richland. Millions of years ago, the Yakima was a slow, meandering river flowing through a flat basalt plain. Geologic pressure lifted and folded the basalt over many more millions of years." - Bruce Skotland, The Yakima River Canyon