Cimarron River (Arkansas River tributary)  The Cimarron River () extends across New Mexico, Oklahoma, Colorado, and Kansas. The headwaters flow from Johnson Mesa west of Folsom in northeastern New Mexico. Much of the river's length lies in Oklahoma, where it either borders or passes through eleven counties. There are no major cities along its route. The river enters the Oklahoma Panhandle near Kenton, Oklahoma, crosses the southeastern corner of Colorado into Kansas, reenters the Oklahoma Panhandle, reenters Kansas, and finally returns to Oklahoma where it joins the Arkansas River at Keystone Reservoir west of Tulsa, Oklahoma, its only impoundment. The Cimarron drains a basin that encompasses about . The river's present name comes from the early Spanish name, "Río de los Carneros Cimarrón", which is usually translated as River of the Wild Sheep (literally, "River of the Feral Rams"). Early American explorers also called it the Red Fork of the Arkansas because of water's red color. Early explorers and mapmakers called it by several other names, including Grand Saline, Jefferson (in John Melish's 1820 U.S. map), Red Fork, Salt Fork, and Salt River. In northeastern New Mexico and in western Oklahoma, the river is known as the Dry Cimarron River. This is by contrast to a wetter Cimarron River flowing further west through New Mexico. The Dry Cimarron is not completely dry, but sometimes its water entirely disappears under the sand in the river bed. The Dry Cimarron Scenic Byway follows the river from Folsom to the Oklahoma border. In Oklahoma the river flows along the southern edges of Black Mesa, the state's highest point. As it first crosses the Kansas border, the river flows through the Cimarron National Grassland. The Cimarron's water quality is rated as poor because the river flows through natural mineral deposits, salt plains, and saline springs, where it dissolves large amounts of minerals. It also collects quantities of red soil, which it carries to its terminus. Before the Keystone Dam was built, this silt was sufficient to discolor the Arkansas River downstream. The first Europeans to see the Cimarron River were apparently Spanish conquistadores led by Francisco Vásquez de Coronado in 1541. The Spanish seem to have done little to exploit the area. The Osage tribe claimed most of the territory west of the confluence of the Cimarron and the Arkansas.