Old River Control Auxiliary Structure

Old River Control Auxiliary Structure
Name	Old River Control Auxiliary Structure
Location	Avoyelles Parish, Louisiana, Concordia Parish, Louisiana
Type	Flood control structure
Owner	United States Army Corps of Engineers
Opened	1963
Materials	Concrete, steel

Old River Control Auxiliary Structure The Old River Control Auxiliary Structure is a component of the larger Old River Control Structure complex on the Old River near the confluence of the Mississippi River and the Red River in southeastern United States. It functions as an engineered supplement to the principal Old River Control Structure and the Low Sill Structure, forming part of the system that preserves the course of the Mississippi River channel to protect navigation, agriculture, and urban centers such as New Orleans, Louisiana and Baton Rouge, Louisiana. The auxiliary structure has been central to federal waterway policy administered by the United States Army Corps of Engineers and is tied to regional flood response coordinated with agencies like the Federal Emergency Management Agency.

Overview

The auxiliary structure sits in a complex network that includes the Morganza Spillway, the Bonnet Carré Spillway, and the Old River Control Complex near Lake Providence, Louisiana and Natchez, Mississippi. It assists in regulating flow between the Mississippi and the Atchafalaya River to maintain a roughly 70/30 split of discharge as defined by interagency agreements among the United States Army Corps of Engineers, the United States Geological Survey, and the U.S. Fish and Wildlife Service. The structure interacts with navigation interests represented by the American Waterways Operators and river commerce stakeholders in port cities like New Orleans, Baton Rouge, and Port of South Louisiana.

History and construction

The need for the auxiliary structure grew from historic channel changes recorded during events such as the Great Mississippi Flood of 1927 and the Mississippi River flood of 1973. Early federal responses trace to the Rivers and Harbors Act of 1930 and the Flood Control Act of 1936, which empowered the United States Army Corps of Engineers and influenced construction programs under administrators including Chief of Engineers Glen E. Edgerton and later generals. Major construction phases in the 1950s and 1960s involved contractors under oversight by the New Orleans District, United States Army Corps of Engineers and coordination with state authorities like the Louisiana Department of Transportation and Development. The structure opened in the early 1960s, contemporaneous with other projects such as the Bonnet Carré Spillway expansions and the completion of the Mississippi River and Tributaries Project.

Design and engineering

Engineered with reinforced concrete piers, steel gates, and movable stoplogs, the facility complements the hydraulic design principles applied across works like the Bonnet Carré Spillway and the Morganza Floodway. Hydrologists from the United States Geological Survey and engineers from the United States Army Corps of Engineers modeled discharge scenarios incorporating data from gauging stations at Red River Landing and Tarbert Landing. The auxiliary structure's components resemble movable features used in the Low Sill Structure and are designed to withstand stresses outlined in standards from bodies such as the American Society of Civil Engineers and the Hydraulic Institute. Construction methods referenced technologies applied on projects like the Erie Canal rehabilitation and borrow practices used in the Atchafalaya Basin restoration.

Operational role and management

Operational control rests with the United States Army Corps of Engineers, New Orleans District under policies coordinated with the Mississippi River Commission and federal directives from the U.S. Army Corps of Engineers Headquarters. The auxiliary structure plays a management role during high-water events similar to operations at the Morganza Spillway and the activation protocols of the Bonnet Carré Spillway, with contingency planning involving the Federal Emergency Management Agency and Louisiana state agencies including the Governor of Louisiana's office. River pilots and organizations such as the New Orleans-Baton Rouge Steamship Pilots Association rely on maintained channel stability supported by the auxiliary works to ensure safe passage for vessels in the Lower Mississippi River.

Environmental and flood control impacts

Ecological assessments by the U.S. Fish and Wildlife Service and studies from universities such as Louisiana State University and Tulane University have examined impacts on the Atchafalaya Basin and the Mississippi River Delta. The auxiliary structure influences sediment transport processes also studied in the context of the Coastal Wetlands Planning, Protection and Restoration Act and the Louisiana Coastal Master Plan. Environmental groups including The Nature Conservancy and Audubon Louisiana have entered discourse about trade-offs between flood risk reduction for urban centers like New Orleans and habitat changes affecting species managed by the National Oceanic and Atmospheric Administration and the U.S. Fish and Wildlife Service.

Incidents and modifications

The auxiliary facility has been subject to operational stress during significant flood years such as the Mississippi River floods of 1973 and the Great Mississippi Flood of 1993. Emergency responses involved federal coordination with the Federal Emergency Management Agency and the activation of spillways like Morganza and Bonnet Carré. Subsequent modifications incorporated lessons from investigations by the National Research Council and retrofit projects overseen by the United States Army Corps of Engineers to enhance resilience against scenarios evaluated by the Interagency Committee on Water Resources and scientific studies from the U.S. Geological Survey.

Cultural and legal significance

Legally and politically, the control system including the auxiliary structure has been central to decisions by the United States Congress, contested in hearings involving the House Committee on Transportation and Infrastructure and the Senate Committee on Environment and Public Works. Court cases and policy debates have invoked statutes such as the Rivers and Harbors Act provisions and the Federal Water Pollution Control Act Amendments. The complex figures in cultural references to the Mississippi in works by authors like Mark Twain and historians of the Antebellum South, and it features in regional planning discussions involving entities such as the Port of New Orleans and Louisiana Department of Wildlife and Fisheries.

Category:Flood control structures in the United States Category:Buildings and structures in Louisiana