Arkansas River

The Arkansas River is a major tributary of the Mississippi River. It generally flows to the east and southeast as it traverses the U.S. states of Colorado, Kansas, Oklahoma, and Arkansas. The river's source basin lies in Colorado, specifically the Arkansas River Valley. The headwaters derive from the snowpack in the Sawatch and Mosquito mountain ranges. It flows east into Kansas and finally through Oklahoma and Arkansas, where it meets the Mississippi River.
At, it is the sixth-longest river in the United States, the second-longest tributary in the Mississippi–Missouri system, and the 47th longest river in the world. Its origin is in the Rocky Mountains in Lake County, Colorado, near Leadville. In 1859, placer gold discovered in the Leadville area brought thousands seeking to strike it rich, but the easily recovered placer gold was quickly exhausted. The Arkansas River's mouth is at Napoleon, Arkansas, and its drainage basin covers nearly. Its volume is much smaller than the Missouri and Ohio rivers, with a mean discharge of about.
The Arkansas from its headwaters to the 100th meridian west formed part of the U.S.–Mexico border from the Adams–Onís Treaty until the Texas Annexation or Treaty of Guadalupe Hidalgo.

Pronunciations

The river is pronounced in Kansas, and in the other three states that it crosses.

Physical geography

Course changes

The path of the Arkansas River has changed over time. Sediments from the river found in a palaeochannel next to Nolan, a site in the Tensas Basin, show that part of the river's meander belt flowed through that area up to 3200 BCE. While it was previously thought that this relict channel was active at the same time as another relict of the Mississippi River's meander belt, it has been shown that this channel of the Arkansas was inactive approximately 400 years before the Mississippi channel was active.

Hydrography

The Arkansas has three distinct sections in its long path through central North America. At its headwaters beginning near Leadville, Colorado, the Arkansas runs as a steep fast-flowing mountain river through the Rockies in its narrow valley, dropping in. This section supports extensive whitewater rafting, including The Numbers, Brown's Canyon, and the Royal Gorge.
At Cañon City, Colorado, the Arkansas River valley widens and flattens markedly. Just west of Pueblo, Colorado, the river enters the Great Plains. Through the rest of Colorado, Kansas, and much of Oklahoma, it is a typical Great Plains riverway, with wide, shallow banks subject to seasonal flooding and periods of dwindling flow. Tributaries include the Cimarron and the Salt Fork Arkansas rivers.
In eastern Oklahoma, the river begins to widen further into a more contained consistent channel. To maintain more reliable flow rates, a series of dams and large reservoir lakes have been built on the Arkansas and its intersecting tributaries, including the Canadian, Verdigris, Neosho, Illinois, and Poteau rivers. These locks and dams enable the river to be navigable by barges and large river craft downriver of Muskogee, Oklahoma, where the McClellan-Kerr Arkansas River Navigation System joins the Verdigris River.
Into western Arkansas, the river path works between the encroaching Boston and Ouachita mountains, including many isolated, flat-topped mesas, buttes, or monadnocks such as Mount Nebo, Petit Jean Mountain, and Mount Magazine, the highest point in the state. The river valley expands as it encounters much flatter land beginning just west of Little Rock, Arkansas. It continues eastward across the plains and forests of eastern Arkansas until it flows into the Mississippi River near Napoleon, Arkansas.
Water flow in the Arkansas River has dropped from approximately average from 1944–1963 to average from 1984–2003, largely because of the pumping of groundwater for irrigation in eastern Colorado and western Kansas.
Important cities along the Arkansas River include Canon City, Pueblo, La Junta, and Lamar, Colorado; Garden City, Dodge City, Hutchinson, and Wichita, Kansas; Tulsa, Oklahoma; and Fort Smith and Little Rock, Arkansas.
The May 2002 I-40 bridge disaster took place on I-40's crossing of Kerr Reservoir on the Arkansas River near Webbers Falls, Oklahoma.

Table of primary tributaries

Waterway	Orientation	Length	Mouth coordinates	Mouth altitude	Mouth location	Source coordinates	Source location
East Fork Arkansas River	left				Leadville, Colorado		Lake County, Colorado
Lake Creek	right				Lake County, Colorado		Chaffee County, Colorado
Chalk Creek	right				Chaffee County, Colorado		Gunnison County, Colorado
South Arkansas River	right				Chaffee County, Colorado		Chaffee County, Colorado
Hardscrabble Creek	right				Fremont County, Colorado		Custer County, Colorado
Fountain Creek	left				Pueblo, Colorado		El Paso County, Colorado
Saint Charles River	right				Custer County, Colorado		Pueblo County, Colorado
Chico Creek	left				Pueblo County, Colorado		El Paso County, Colorado
Huerfano River	right				Pueblo County, Colorado		Huerfano County, Colorado
Apishapa River	right				Olney Springs, Colorado		Huerfano County, Colorado
Horse Creek	left				Otero County, Colorado		El Paso County, Colorado
Purgatoire River	right				Bent County, Colorado		Las Animas County, Colorado
Two Butte Creek	right				Prowers County, Colorado		Las Animas County, Colorado
Bear Creek	right				Kearny County, Kansas		Baca County, Colorado
Pawnee River	left				Larned, Kansas		Gray County, Kansas
Rattlesnake Creek	right				Stafford County, Kansas		Ford County, Kansas
Cow Creek	left				Hutchinson, Kansas		Barton County, Kansas
Little Arkansas River	left				Sedgwick County, Kansas		Rice County, Kansas
Ninnescah River	right				Sumner County, Kansas		Sedgwick County, Kansas
Walnut River	left				Cowley County, Kansas		Butler County, Kansas
Grouse Creek	left				Cowley County, Kansas		Butler County, Kansas
Salt Fork Arkansas River	right				Kay County, Oklahoma		Comanche County, Kansas
Cimarron River	right				Pawnee County, Oklahoma		Cimarron County, Oklahoma
Neosho River	left				Muskogee County, Oklahoma		Morris County, Kansas
Verdigris River	left				Muskogee County, Oklahoma		Madison, Kansas
Canadian River	right				Haskell County, Oklahoma		Las Animas County, Colorado
Illinois River	left				Sequoyah County, Oklahoma		Pope County, Arkansas
Poteau River	right				Le Flore County, Oklahoma		Izard County, Arkansas
Mulberry River	left				Franklin County, Arkansas		Newton County, Arkansas
Big Piney Creek	left				Pope County, Arkansas		Newton County, Arkansas
Fourche La Fave River	right				Bigelow, Arkansas		Scott County, Arkansas
Bayou Meto	left				Arkansas County, Arkansas		Faulkner County, Arkansas

Allocation problems

Since 1902, Kansas has claimed that Colorado takes too much of the river's water; it has filed numerous lawsuits over this issue in the U.S. Supreme Court that continue to this day, generally under the name of Kansas v. Colorado. The problems over the possession and use of Arkansas River water by Colorado and Kansas led to the creation of an interstate compact or agreement between the two states. While Congress approved the Arkansas River Compact in 1949, the compact did not stop further disputes by the two states over water rights to the river.
The Kansas–Oklahoma Arkansas River Basin Compact was created in 1965 to promote mutual consideration and equity over water use in the basin shared by those states. The Kansas–Oklahoma Arkansas River Commission was established, charged with administering the compact and reducing pollution. The compact was approved and implemented by both states in 1970 and has been in force since then.