Major Rivers of Wyoming
Large rivers in Wyoming are few and far between, but they are integral to the state’s agricultural, industrial, and rural communities. Most Wyomingites live within close proximity of a major river. These major rivers are primarily driven by seasonal snowmelt and peak in late May and early June. The wide deviation in stream flow season to season makes storage a key component of water use. A detailed map of Wyoming’s rivers and streams is available from the WSGS (MS-91).
5 Largest Rivers in Wyoming, by average annual flow
The Snake River is the largest river in Wyoming but is used very little due to much of its path being through national parks and forests. It begins on the edge of the Absaroka Range and gains water along the way from several large tributaries, primarily the Lewis River, Buffalo Fork, Gros Ventre River, and the Hoback River. Near the border at Palisades Reservoir the Snake River picks up two additional large tributaries, the Greys River, and the Salt River.
The Wind/Bighorn River is the second largest river in Wyoming, and is heavily used for agriculture and municipal use. This river is unique as it has two different names and passes through two large separate basins. The Wind River begins high in the mountains near the intersection of the Washakie Range, Wind River Range, and the Wind River Basin. Many small tributaries feed into the Wind River from the east side of the Wind River Range and the South side of the Washakie and Owl Creek Mountains. As the river leaves the Wind River Basin through Boysen Reservoir and emerges from Wind River Canyon it becomes the Bighorn River. The Bighorn River drains a considerable area including the Bighorn Mountains, and the Absaroka Range. The Nowood River and Greybull River are large tributaries to the Bighorn River along with the Shoshone River which at times has as much water as the Bighorn River itself. The river exits the state into Bighorn Lake reservoir.
The Yellowstone River (3rd largest) originates from the Absaroka Range and fills Yellowstone Lake. After leaving the Lake and going down two large waterfalls the river merges with the Lamar River and Gardner River. The Yellowstone River goes almost totally unused in Wyoming as it is entirely within the national park and national forest. As the river crosses Montana it converges with several major rivers from Wyoming (Clarks Fork, Bighorn, Tongue, and Powder) and is comparable to the Missouri River at their confluence.
The Green River has the 4th largest average flow of Wyoming rivers. The Green River comes from the heart of the Wind River Range and flows south through the middle of the Green River Basin. From the east out of the Wind River Mountains, the Green River gains the New Fork River and Big Sandy River. From the west out of the Wyoming Range, it gains Cottonwood Creek, Piney Creek, and Labarge Creek. From the south in the Uinta Mountains the Black’s Fork meets the Green River at Flaming Gorge Reservoir where it leaves the state into Utah.
The North Platte River originates from the Park Range (Sierra Madre in WY) and the Medicine Bow Mountains in Colorado. Where it crosses the border into Wyoming its flow accounts for about 30% of the river’s total flow. The upper North Platte has several tributaries from the Medicine Bow Mountains and the Sierra Madre Mountains, most notably the Encampment River, Brush Creek, and Douglas Creek. The river passes north through several reservoirs picking up the Medicine Bow River and the Sweetwater River. As the river turns east then southeast it gains water from many small creeks from the northern Laramie Range before it leaves Wyoming into Nebraska where it meets the South Platte River from Colorado.
Other Notable Wyoming Rivers
- The Tongue and Powder Rivers drain large areas of the eastern Bighorn Mountains and Powder River Basin and flow into Montana.
- The Belle Fourche and Cheyenne Rivers drain large areas of the Powder River Basin and Flow into South Dakota.
- The Little Snake River drains the west side of the Sierra Madre Mountains into Colorado.
- The Bear River drains the northern Uinta Mountains into Utah and Idaho.
- The Madison and Gallatin Rivers form 2 of the 3 headwaters for the Missouri River out of northwest Wyoming into Montana.
USGS Water Data http://waterdata.usgs.gov/nwis
National Water Information System, Wyoming Web Interface, Surface Water Data