Ouachita -Black River
"The Ouachita River ( /ˈwɑːʃɨtɑː/ wah-shi-tah) is a 548-mile-long (882 km) river that runs south and east through the U.S. states of Arkansas and Louisiana, joining the Tensas River to form the Black River near Jonesville, Louisiana. The Ouachita River begins in the Ouachita Mountains near Mena, Arkansas. It flows east into Lake Ouachita, a reservoir created by Blakely Mountain Dam. The North Fork and South Fork of the Ouachita flow into Lake Ouachita to join the main stream. Portions of the river in this region flow through the Ouachita National Forest. From the lake, the Ouachita flows south into Lake Hamilton, a reservoir created by Carpenter Dam, named after Flavius Josephus Carpenter. The city of Hot Springs lies on the north side of Lake Hamilton. Another reservoir, Lake Catherine, impounds the Ouachita just below Lake Hamilton. Below Lake Catherine, the river flows free through most of the rest of Arkansas.
Just below Lake Catherine, the river bends south near Malvern, and collects the Caddo River near Arkadelphia. Downstream, the Little Missouri River joins the Ouachita. After passing the city of Camden, shortly downstream from where dredging for navigational purposes begins, the river collects the waters of Smackover Creek and later the Ouachita’s main tributary, the Saline River. South of the Saline, the Ouachita flows into Lake Jack Lee, a reservoir created by the Ouachita and Black River Project, just north of the Louisiana state line. The Felsenthal National Wildlife Refuge encompasses the Ouachita from the Saline River to Lake Jack Lee’s mouth.
Below Lake Jack Lee, the Ouachita continues south into Louisiana. The river flows generally south through the state, collecting the tributary waters of Bayou Bartholomew, Bayou de Loutre, Bayou d’Arbonne, the Boeuf River, and the Tensas River. The river below the junction of the Tensas is called the Black River 31°16′22″N 91°50′01″W and flows for 41.6 miles (66.9 km) in Catahoula Parish and Concordia Parish until it joins the Red River, which flows into both the Atchafalaya River and the Mississippi River, via the Old River Control Structure.
The Ouachita has five locks and dams along its length, located at Camden, Calion, and Felsenthal, Arkansas, and in Columbia and Jonesville, Louisiana.”
Source - Wikipedia
The Corps has river miles for 343 miles of this river. Only 200 miles left to plot!