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.
Major Habitat Type
Temperate upland rivers
Drainages flowing into
The Ouachita River joins the Red River shortly before it drains into the Mississippi.
Main rivers to other water bodies
Primary rivers include the middle portion of the Red River in the southwestern part of the ecoregion, and the Ouachita River in the northeastern part. Smaller rivers within these drainages include the Little Missouri, Saline, Bartholomew, Kiamichi and Little rivers.
This ecoregion covers southeastern Oklahoma, northeastern Texas, southern Arkansas, and northwestern Louisiana, and is largely defined by the Red River and the Ouachita River drainages. The Ouachita Highlands ecoregion is separated from the Ozark Highland ecoregion  by the Arkansas River. Like the Ozark Highlands, this ecoregion is distinguished by its relative biogeographic isolation.
The Ouachita Mountains lie south of the Ozark Plateau and together form the U.S. Interior Highlands. The area is characterized by east-west trending ridges and valleys, and share affinities with the Blue Ridge province, which was formed at the same time. Elevations range between 150 to 790 m, with Magazine Mountain rising 839 m (Robison 1986).
The ecoregion is a source area for several larger streams and is an area of high-gradient and spring-fed springs, and can almost be considered an island surrounded by the Great Plains, coastal plains, and prairie.
The ecoregion is characterized by oak-hickory-pine forests, which are some of the best developed in the United States. Dominant species include white oak (Q. alba), red oak (Quercus rubra), blackjack oak (Quercus marilandica), hickory (Carya texana), shortleaf yellow pine (Pinus echinata), and loblolly pine (Pinus taeda) (Ricketts et al. 1999).
Description of endemic fishes
The ecoregion contains a number of endemic species, including two madtoms (Noturus lachneri and N. taylori) and a darter (Etheostoma pallididorsum) that occur in the headwaters of the Ouachita, and a darter (Percina pantherina), which is endemic to the Little River. Other species that are primarily found in the Ouachita Mountains and Red and Ouachita drainages include the peppered shiner (Notropis perpallidus), rocky shiner (N. suttkusi), and Ouachita shiner (Lythrurus snelsoni) (Cross et al. 1986).
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- Foti, T. L. and S.M. Glenn (1991). "The Ouachita Mountain landscape at the time of settlement" D. Henderson and L.D. Hedrick (Ed.) Restoration of old growth forests in the Interior Highlands of Arkansas and Oklahoma ( pp. 49-66 ) Morrilton, AR: Ouachita National Forest/Winrock International Institute for Agricultural Development.
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