Middle Missouri




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 floodplain rivers and wetlands

Drainages flowing into

This ecoregion drains the middle basins of the Missouri, which is the largest tributary of the Mississippi River (Robison 1986).

Main rivers to other water bodies

In addition to the Missouri River, main rivers include the James River in North and South Dakota; the Platte River in Nebraska, Colorado, and Wyoming; the Niobrara River in Nebraska; and the Republican River in Kansas and Nebraska.



This ecoregion extends from central North Dakota to northwestern Colorado, including eastern South Dakota, a small portion of southwestern Minnesota, western Iowa, northwestern Missouri, virtually all of Nebraska, the northern half of Kansas, and southeastern Wyoming. The ecoregion is defined by the watersheds that constitute the middle portion of the Missouri River.


The ecoregion includes rugged topography of the eastern slopes of the Rockies to the flat relief of the Great Plains, with elevation declining eastward (Robison 1986).

Freshwater habitats

The far northern portion of the Middle Missouri ecoregion was glaciated as recently as 10,000 to 15,000 years ago. The portion that sits on the eastern slope of the Rocky Mountains is semiarid, with limited freshwater habitats other than ephemeral prairie potholes.

Terrestrial habitats

The Middle Missouri is characterized primarily by grasslands of the Central Great Plains and includes tall and short grass prairies. Temperate coniferous forests and Wyoming Basin shrub steppe are dominant vegetation types along the western edge of the ecoregion (Ricketts et al. 1999).

Description of endemic fishes

The Middle Missouri harbors no known endemic fish, mussels, crayfish, or aquatic herpetofauna, though prairie potholes may harbor unknown endemic invertebrate or plant species.

Justification for delineation

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


  • 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.
  • Robison, H. W. (1986). "Zoogeographic implications of the Mississippi River Basin" C. H. Hocutt and E. O. Wiley (Ed.) The zoogeography of North American freshwater fishes ( pp. 267-285 ) New York, New York, USA: Wiley.
  • 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.
  • Cross, F. B., R.L. Mayden and J.D. Stewart (1986). "Fishes in the western Mississippi drainage" C. H. Hocutt and E.O. Wiley (Ed.) The zoogeography of North American freshwater fishes ( pp. 363-412 ) New York, NY: John Wiley & Sons.
  • Köppen, W. (1936). "Das geographische System der Klimate" Köppen W. and R. Geiger (Ed.) Handbuch der. Klimatologie ( (Vol. 1, pp. 1–44 ) Berlin, Germany: Gebrüder Borntröger.