Snake River (United States)

Snake River (United States)
Ansel Adams · Public domain · source
Name	Snake River
Country	United States
States	Wyoming, Idaho, Washington, Oregon
Length	1,078 mi (1,735 km)
Discharge location	Wallula Gap
Source	Big Springs / Yellowstone National Park
Mouth	Columbia River
Basin size	108,000 sq mi

Contents

Snake River (United States) is a major river of the Pacific Northwest, flowing through Wyoming, Idaho, Oregon, and Washington before joining the Columbia River. It is a principal tributary of the Columbia and has played a central role in the exploration of the region by figures such as Lewis and Clark Expedition and John Colter. The river’s course, geology, ecology, and human uses have shaped settlement, transportation, and energy development across the Interior Columbia Basin and the Great Basin margins.

Course and Geography

The Snake River originates in the Rocky Mountains near Yellowstone National Park with headwaters from Big Springs and tributaries draining Teton County and Teton Range. It flows south through the Snake River Plain across Idaho, past Idaho Falls, Pocatello, and Twin Falls, carving features such as Shoshone Falls and the Snake River Canyon. Turning north, it bisects the Hells Canyon area of the Wallowa Mountains and Seven Devils Mountains, forming the border between Idaho and Oregon before flowing west into Washington where it joins the Columbia River at Wallula Gap near Pasco. Major cities along or near its corridor include Boise, Lewiston, and Clarkston. The basin overlaps regions such as the Columbia Plateau and the Palouse and interfaces with federal lands managed by the United States Forest Service, Bureau of Land Management, and National Park Service.

The Snake’s hydrology is influenced by snowmelt from the Yellowstone Plateau and precipitation across the Sawtooth Range and Blue Mountains. Significant tributaries include the Boise River, Weiser River, Payette River, Salmon River, Clearwater River, Grande Ronde River, Palouse River, and the Hells Canyon streams. Flow regimes have been altered by irrigation projects of the Bureau of Reclamation and reservoirs such as Brownlee Reservoir, Hells Canyon Reservoirs, Perrine Bridge vicinity impoundments, Lucky Peak Lake, and Anderson Ranch Reservoir. Seasonal discharge at points like Minidoka Dam and Lower Granite Dam shows spring peaks from snowmelt and reduced late-summer flows due to withdrawals for Columbia Basin Project and agricultural diversions in the Snake River Plain Aquifer region.

The Snake River’s course traverses the Columbia River Basalt Group, the Idaho Batholith, and volcanic terrains related to the Yellowstone hotspot. The Snake River Plain is a product of hot spot volcanism and caldera events associated with Fountain Formation-era eruptions and later rhyolitic flows; cinder cones and shield volcanos dot the plain near Craters of the Moon National Monument and Preserve. Catastrophic floods from the Missoula Floods sculpted the Canyonlands and produced coulees such as the Wallula Gap. Bedrock exposures along the river include granite of the Idaho Batholith and basalt columns of the Columbia River Basalt Group, with tectonic influences from the Basin and Range Province extension and fault systems like the Nephi seismic zone affecting regional uplift and incision.

Riparian corridors along the Snake support habitats for species including Chinook salmon, sockeye salmon, steelhead trout, bull trout, and westslope cutthroat trout, historically sustaining Nez Perce, Shoshone-Bannock, and Coeur d'Alene Tribe fisheries. Terrestrial fauna includes populations of rocky mountain elk, mule deer, bighorn sheep, grizzly bear (historic ranges), and predators such as gray wolf and cougar. Vegetation communities range from sagebrush steppe—dominated by Artemisia tridentata—to riparian cottonwood-willow galleries supporting migratory bird species protected under the Migratory Bird Treaty Act; important avifauna include American white pelican, great blue heron, and bald eagle. Invasive species challenges involve Northern pike, zebra mussel concerns in tributary reservoirs, and whirling disease affecting trout populations, while conservation efforts have involved agencies such as the U.S. Fish and Wildlife Service and tribal co-managers under agreements like the Columbia Basin Fish Accord.

Indigenous peoples—Nez Perce, Shoshone, Bannock, Yakama Nation, and Umatilla Indian Reservation inhabitants—relied on the river for salmon, camas root, and trade networks connecting the Columbia Plateau and Great Plains. European-American exploration included trappers like John Colter and expeditions led by Meriwether Lewis and William Clark, with subsequent settlement during the Oregon Trail and development tied to the California Gold Rush supply routes. Conflicts such as the Nez Perce War and treaties like the Treaty of 1855 reshaped access and rights. Federal projects in the 20th century—championed by figures like Franklin D. Roosevelt and agencies including the U.S. Army Corps of Engineers—transformed water use for irrigation, navigation, and flood control, impacting indigenous treaty fisheries and prompting litigation and settlements such as those involving the Confederated Tribes of the Umatilla Indian Reservation.

The Snake hosts a system of hydroelectric dams built by the U.S. Army Corps of Engineers and the Bonneville Power Administration including Brownlee Dam, Oxbow Dam, Lower Granite Dam, Ice Harbor Dam, Little Goose Dam, and Lower Monumental Dam on the lower river and its tributaries. These projects support navigation improvements for barges to facilities in the Columbia-Snake River System and supply electricity to markets served by the Bonneville Power Administration and utilities such as Idaho Power Company and Avista. Dams have been focal points of policy debate involving the Endangered Species Act, NOAA Fisheries, tribal rights, and proposals for removal tied to restoring anadromous fish runs, as seen in discussions about Elwha River precedents and litigation before the United States District Court for the District of Idaho.

Recreation along the Snake includes whitewater rafting in Hells Canyon, angling for trout and steelhead at locations like Idaho's Silver Creek, birdwatching at Malheur National Wildlife Refuge adjacency areas, and hiking in Sawtooth National Recreation Area and Craters of the Moon National Monument and Preserve. Conservation initiatives involve organizations such as The Nature Conservancy, Idaho Conservation League, and tribal programs with co-management by the Nez Perce Tribe and Shoshone-Bannock Tribes. Protected areas and designations include Hells Canyon National Recreation Area, Sawtooth National Forest, and scenic segments overseen in cooperation with the National Park Service and Bureau of Land Management to balance hydroelectric, agricultural, and biodiversity objectives.

Category:Rivers of Idaho Category:Rivers of Oregon Category:Rivers of Washington (state)