About 9 million years ago , the Yakima River flowed south from near Vantage to the Tri-Cities , and then turned west straight for the ocean through Badger Canyon west of Kennewick . Badger Canyon was once a waterway of the Yakima River , this pre-existing channel led the Yakima River to make tribute to the Columbia River at the current location of the city of Kennewick . Beginning nearly 15,000 years ago the Columbia Plateau was transformed by the successive Missoula glacial outburst floods . Much of the flood water made way down the Columbia river Channel where a ' choke-point ' known as Wallula Gap caused the restriction of flow . Floodwaters began ponding near the Tri-Cities resulting in the back-flooding of the Columbia 's tributary valleys . Badger Canyon was an entry point for back-flooding of the Yakima Valley , successive floods left behind thick deposits of sediments in Badger Canyon and the Valley beyond . These flood deposits which were deposited in large quantities in short amounts of time changed the ground elevation within badger canyon causing the Yakima River to re-route north of Red Mountain and enter the Columbia River by present-day Richland
Missoula glacial outburst floods
Missoula Floods
Yakima River