The Red River flows easterly from the northwest portion of Texas along the border between Texas and Oklahoma through southwestern Arkansas into northwestern Louisiana, then southeasterly to join the Old River and form the Atchafalaya River. John H. Overton Lock and Dam is located in a cutoff canal approximately 74 miles above the Mississippi River and about 31 channel miles above Lindy C. Boggs Lock and Dam (formerly Lock and Dam No. 1). John H. Overton Lock and Dam is the second in a series of Rivers Waterway from the Mississippi River to Shreveport, a distance of 238 miles. The general design of John H. Overton Lock and Dam consists of a 26- by 209-m (84- by 685-ft) navigation lock with an adjacent spillway containing five 18-m (60-ft) wide gate bays and a 9300 ft upstream to about 3124 m (10,250 ft) downstream of the dam to an undistorted scale of 1:100. Since John H. Overton Lock and Dam was to be constructed in an excavated channel bypassing the natural river channel, it was important that the alignment of the channel and the arrangement of the lock and dam be satisfactory for navigation. The model investigation was concerned with evaluation of navigation conditions for proposed lock designs and development of modifications required to ensure satisfactory navigation conditions. The study identified any needed modifications to navigation channel alignment, guard wall lengths, or remedial structures. Results of the investigation revealed that a system of structures was required to eliminate adverse current patterns and establish satisfactory navigation conditions for tows entering and leaving the upper and lower lock approaches.