Upper Snake




Text modified from Abell et al. 2000. Freshwater Ecoregions of North America: A Conservation Assessment. Island Press, Washington, DC, USA. Additional text provided by Jennifer Hales.


United States

Major Habitat Type

Temperate upland rivers

Drainages flowing into

The Snake River is the largest tributary of the Columbia River, although prior to the Pleistocene it may have drained the Mohave Basin, Sacramento-San Joaquin system and Klamath River (McPhail & Lindsey 1986).

Main rivers to other water bodies

In addition to the Snake River, major freshwater habitats include Jackson Lake and other lakes of Grand Teton National Park.



This ecoregion is defined by the Snake River above the 30,000-60,000 year-old Shoshone Falls, which serve as a total barrier to the upstream movement of fish (McPhail & Lindsey 1986). The ecoregion boundary lies about 50 km downstream of the falls in order to include the Wood River, a tributary to the Snake. The ecoregion is predominantly restricted to the southeastern part of Idaho, but also extends into eastern Wyoming, northeastern Nevada, and the extreme northwestern corner of Utah.


Originating near the Continental Divide, the upper Snake River follows a course through a rugged landscape of mountain ranges, canyons and plains.

Terrestrial habitats

Shrub-steppe is the dominant vegetation type throughout much of the ecoregion, including sagebrush (Artemisia spp.), wheatgrasses (Agropyron spp.) and Idaho fescue (Festuca idahoensis) (Franklin and Dyrness 1988). In the eastern edge of the ecoregion coniferous forest is the dominant vegetation type at higher elevations (Ricketts et al. 2000).

Description of endemic fishes

The Wood River contains the endemic Wood River sculpin (Cottus leiopomus), and in the Snake River between the Wood River and Shoshone Falls lives the endemic Shoshone sculpin (C. greenei) (McPhail & Lindsey 1986).

Other noteworthy fishes

The Snake River sucker (Chasmistes muriei) is known from a single specimen collected from the Snake River below Jackson Lake, Wyoming, and is apparently extinct (McPhail & Lindsey 1986).

Justification for delineation

Ecoregion boundaries are taken from Abell et al. (2000) and are based on subregions defined by Maxwell et al. (1995).


  • McPhail, J. D. and Lindsey, C. C. (1986). "Zoogeography of the freshwater fishes of Cascadia (the Columbia system and rivers north to the Stikine)" C. H. Hocutt and E. O. Wiley (Ed.) The zoogeography of North American freshwater fishes ( pp. 615-637 ) New York: John Wiley & Sons.
  • Frest, T. J.;Johannes, E. J. (1995). "Interior Columbia Basin mollusk species of special concern" Seattle, WA: Deixis.
  • Franklin, J. F. (1988). "Pacific Northwest forests" M. G. Barbour and W. D. Billings (Ed.) North American terrestrial vegetation. ( pp. 103-130 ) Cambridge: Cambridge University Press.
  • Ricketts, T. H.,E. Dinerstein,D.M Olson;C.J. Loucks (1999). "Terrestrial ecoregions of North America: A conservation assessment" Washington, D.C.: World Wildlife Fund.
  • Abell, R.,Olson, D.,Dinerstein, E.,Hurley, P. T.,Diggs, J. T.,Eichbaum, W.,Walters, S.,Wettengel, W.,Allnutt, T.,Loucks, C. J.;Hedao, P. (2000). "Freshwater ecoregions of North America" Washington, D.C.: Island Press.
  • Maxwell, J. R., Edwards, C. J., Jensen, M. E., et al. (1995) \A hierarchical framework of aquatic ecological units in North America (Nearctic Zone)\ St. Paul, MN. North Central Forest Experiment Station, USDA Forest Service.
  • Clark, G. M., T.R. Maret, M.G. Rupert, M.A. Maupin, W.H. Low and D.S. Ott (1998). "Water Quality in the Upper Snake River Basin, 1992-1995"
  • Franklin, J. F. and C.T. Dyrness (1988). "Natural vegetation of Oregon and Washington" Corvallis, OR: Oregon State University Press.