Old River Control Structure

[3] Beginning in the 15th century, the Mississippi River created a small, westward, oxbow loop, later called Turnbull's Bend, near present-day Angola, Louisiana.

With this increased water flow, the channel of the Atchafalaya River was worn deeper and wider throughout the 1800s and early 1900s.

Some researchers believe the likelihood of this event increases each year, despite manmade artificial control efforts.

[11] If the Mississippi diverts its main channel to the Atchafalaya Basin and the Atchafalaya River, it would develop a new delta south of Morgan City in southern Louisiana, greatly reducing water flow to its present channel through Baton Rouge and New Orleans, with adverse economic effects on both port cities.

Maintenance of the integrity of the Old River Control Structure, the nearby Morganza Spillway, and other levees in the area is essential to prevent such a diversion.

The primary one that regulates routine flow in the waterway is the Low Sill Control Structure.

The ORCAS is used during floods to assist the ORCS and prevent it from being damaged due to high flow rates.

ORCAS was added to reduce pressure on the original floodgates after extensive damage caused by the flood of 1973.

All five structures in the complex carry Louisiana Highway 15, starting at the power plant, then the Overbank Structure, then the Low Sill ORCS, followed by ORCAS, the island created between the rivers, and finally the Old River Lock.

The Old River Control Structure complex. View is to the east-southeast , looking downriver on the Mississippi , with the three dams across channels leading to the Atchafalaya River to the right of the Mississippi. Concordia Parish, Louisiana is in the foreground, on the right, and Wilkinson County, Mississippi , is in the background, across the Mississippi on the left.
Old River low-sill control structure discharging water into the Atchafalaya, May 2011
Formation of the Atchafalaya River and construction of the Old River Control Structure.
diagram of river flows during Project Design Flood
A diagram that depicts river flows associated with Project Design Flood .