Columbia Glaciated




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

Most of the major rivers rise to the west of the Continental Divide and flow westward across the areas of uplift toward the Pacific Ocean (McPhail & Lindsey 1986).

Main rivers to other water bodies

Among tributaries to the Columbia are the Yakima, Okanagan, Spokane, and the Kootenai rivers.



This ecoregion marks the glaciated portion, or upper third, of the Columbia River basin (McPhail and Lindsey 1986). It includes most of eastern Washington, the northern portion of Idaho, the northwestern corner of Montana, and southeastern British Columbia.


The ecoregion is mountainous, with elevations ranging from 100 to over 3000 m. This part of the Columbia River basin was glaciated, forming valleys filled with glaciofluvial and morainal sediments (ESWG 1995). Folded sedimentary and volcanic strata and metamorphic rocks of Palaeozoic and Mesozoic age also characterize the landscape (Ricketts et al. 1999).

Freshwater habitats

The ecoregion is heavily forested, with cold, high-gradient streams and several lakes, primarily in British Columbia (McPhail and Lindsey 1986).

Terrestrial habitats

The dominant vegetation type within this ecoregion is coniferous forest, including hemlocks (Tsuga spp.), Pacific yew (Taxus brevifolia), larch (Larix spp.), Engelmann spruce (Picea engelmannii), and alpine fir (Abies lasiocarpa) (Peet 1988). The ecoregion also contains mountain meadows, foothill grasslands, and riparian woodlands (Ricketts et al. 1999). The southwestern portion of the ecoregion is characterized by grasslands and shrub-steppe, dominated by sagebrush (Artemisia spp.), bluebunch wheatgrass (Agropyron spicatoin), and Idaho fescue (Festuca idahoensi) (Ricketts et al. 1999).

Description of endemic fishes

There are no true endemic fish to this ecoregion.

Ecological phenomena

Historically, the Columbia Glaciated ecoregion supported substantial runs of sockeye salmon (Oncorhynchus nerka), Chinook salmon (O. tshawytscha), cutthroat trout (O. clarkii), and rainbow trout (O. mykiss) (McPhail and 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).


  • 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.
  • Eswg (1995) \A national ecological framework for Canada\ Ottawa/Hull, Ontario, Canada. Agriculture and Agri-food Canada, Research Branch, Centre for Land and Biological Resources Research; and Environment Canada, State of the Environment Directorate, Ecozone Analysis Branch..
  • 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.
  • 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.
  • Peet, R. K. (1988). "Forests of the Rocky Mountains" M. G. Barbour and W. D. Billings (Ed.) North American Terrestrial Vegetation ( pp. 63-102 ) Cambridge, UK: Cambridge University Press.