page_title: Snake River
section_title: Tributaries
hierarchical_section_title: Snake River / Tributaries
caption_attribution_description: Grande Ronde River
context_page_description: The Snake River is a major river of the greater Pacific Northwest region in the United States. At 1,078 miles long, it is the largest tributary of the Columbia River, in turn the largest North American river that empties into the Pacific Ocean. The Snake River rises in western Wyoming, then flows through the Snake River Plain of southern Idaho, the rugged Hells Canyon on the Oregon–Idaho border and the rolling Palouse Hills of Washington, emptying into the Columbia River at the Tri-Cities, Washington.
  The Snake River drainage basin encompasses parts of six U.S. states and is known for its varied geologic history. The Snake River Plain was created by a volcanic hotspot which now lies underneath the Snake River headwaters in Yellowstone National Park. Gigantic glacial-retreat flooding episodes that occurred during the previous Ice Age carved out canyons, cliffs and waterfalls along the middle and lower Snake River. Two of these catastrophic flooding events, the Missoula Floods and Bonneville Flood, significantly affected the river and its surroundings.
  Prehistoric Native Americans lived along the Snake starting more than 11,000 years ago.
context_section_description: The Salmon River is the second largest tributary.  Although the Salmon has a larger drainage than the Clearwater, the Salmon drains much drier country and therefore has a smaller discharger than the Clearwater, about 8,000,000 acre feet (9.9 km³) annually compared to about 11,000,000 acre feet (14 km³) annually for the Clearwater River.
  The Snake River has over 20 major tributaries, most of which are in the mountainous regions of the basin. The largest by far is the Clearwater River, which drains 9,000 square miles (23,000 km²) in north central Idaho.  Many of the rivers that flow into the Snake River Plain from the north sink into the Snake River Aquifer, but still contribute their water to the river. Aside from rivers, the Snake is fed by many significant springs, many of which arise from the aquifer on the west side of the plain.
caption: The Grande Ronde River meets the Snake near the middle part of Hells Canyon
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