Yakima River
| Yakima River | |
State Route 10 winds past the Yakima River near the town of Thorp.
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| Country | United States |
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| State | Washington |
| Tributaries | |
| - left | Cle Elum River, Teanaway River |
| - right | Naches River |
| Cities | Cle Elum, Ellensburg, Yakima, Sunnyside, Richland |
| Source | Keechelus Lake |
| - location | Kittitas County, Washington |
| - elevation | 2,520 ft (768 m) |
| - coordinates | 47°19′20″N 121°20′21″W / 47.32222°N 121.33917°W |
| Mouth | Columbia River |
| - location | Richland, Benton County, Washington |
| - elevation | 344 ft (105 m) |
| - coordinates | 46°15′10″N 119°13′51″W / 46.25278°N 119.23083°WCoordinates: 46°15′10″N 119°13′51″W / 46.25278°N 119.23083°W |
| Length | 214 mi (344 km) |
| Basin | 6,150 sq mi (15,928 km2) |
| Discharge | for Kiona, RM 30 |
| - average | 3,493 cu ft/s (99 m3/s) |
| - max | 59,400 cu ft/s (1,682 m3/s) |
| - min | 225 cu ft/s (6 m3/s) |
 Map of the Yakima River watershed
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The Yakima River is a tributary of the Columbia River in south central and eastern Washington state, named for the indigenous Yakama people. The length of the river from headwaters to mouth is 214 miles (344 km), with an average drop of 9.85 feet per mile (1.866 m/km). It is the longest river entirely in Washington state.
The river rises in the Cascade Range at an elevation of 2,449 feet (746 m) at Keechelus Dam on Keechelus Lake near Snoqualmie Pass, near Easton. The river flows through that town, skirts Ellensburg, passes the city of Yakima, and continues southeast to Richland, where it flows into the Columbia River at an elevation of 340 feet (100 m).
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.
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Wikipedia