Niobrara River

Niobrara River
River
Niobrara River at the Nebraska Highway 7 crossing
Country	United States
States	Wyoming, Nebraska
Source	near Manville
- elevation	5,500 ft (1,676 m)
Mouth	Missouri River
- elevation	1,220 ft (372 m)
Length	568 mi (914 km)
Basin	11,580 sq mi (29,992 km2)
Discharge	for Verdel, NE
- average	1,718 cu ft/s (49 m3/s)
- max	39,100 cu ft/s (1,107 m3/s)
- min	102 cu ft/s (3 m3/s)
Map of the Niobrara River (light blue)

The Niobrara River (/ˌnaɪ.əˈbrærə/; from the Ponca Ní Ubthátha khe pronounced [nĩꜜ ubɫᶞaꜜɫᶞa kʰe], meaning "water spread-out horizontal-the") is a tributary of the Missouri River, approximately 568 miles (914 km) long, running through the U.S. states of Wyoming and Nebraska. The river drains one of the most arid sections of the Great Plains, and has a low flow for a river of its length. The Niobrara's watershed includes a small south-central section of South Dakota as well as the northern tier of Nebraska and a tiny area of eastern Wyoming.

The river rises in the High Plains of Wyoming, in southern Niobrara County. The Niobrara flows east as an intermittent stream past Lusk and southeast into northwestern Nebraska. It then flows southeast across the Pine Ridge country of Sioux County, then east through Agate Fossil Beds National Monument, past Marsland, and through Box Butte Reservoir. The stream flows east across northern Nebraska, near the northern edge of the Sandhills and past Valentine. It is joined by the Snake River about 13 miles (21 km) southwest of Valentine. In north-central Nebraska it is joined by the Keya Paha River approximately 6 miles (10 km) west of Butte. The river joins the Missouri northwest of Niobrara in northern Knox County. Its total drainage basin is about 11,580 square miles (30,000 km²).