Inner Harbor Navigation Canal (IHNC) Lock Replacement

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Official Project Name
Mississippi River, Baton Rouge to the Gulf of Mexico Mississippi River-Gulf Outlet, Louisiana, New Industrial Canal Lock and Connecting Channels Project.  It is commonly referred to as the IHNC (Inner Harbor Navigation Canal) Lock Replacement Study.

The IHNC Lock is located in the Industrial Canal which runs through a highly urbanized area within the New Orleans city limits. It joins Lake Pontchartrain to the north with the Mississippi River to the south. The canal also connects the eastern segment of the Gulf Intracoastal Waterway (GIWW) with the Mississippi River.

The existing IHNC navigation lock (640 feet long by 75 feet wide by 31.5 feet deep) is not efficient. The average transit time for a tow using the existing IHNC navigation lock is more than 16 hours. The processing time for a tow entering and exiting the lock is nearly 44 minutes on average; meaning the delay for a tow just to enter the existing lock is more than 15 hours. This delay is a result of the existing lock’s limited capacity relative to prevailing levels of traffic and the size of tows navigating the GIWW and Mississippi River that utilize the lock. Furthermore, since the existing IHNC navigation lock was constructed in 1923, operation and maintenance costs have increased due to the increasing frequency of maintenance events that result in additional delays, in addition to delays caused by the limited capacity of the existing navigation lock, or a complete closure of the lock to waterborne traffic.  The overarching purpose, goals, and objectives of the project are to improve efficiency and reliable passage of waterborne traffic locking through the IHNC, by reducing transit times of waterborne traffic locking through the IHNC with a new replacement lock capable of handling today’s waterborne commerce needs.

In 2006, the United States District Court, Eastern District of Louisiana enjoined the Corps from continuing with the project until the Corps prepared a supplemental Environmental Impact Statement (SEIS) further evaluating potential impacts of hurricanes and flooding on the project, and impacts from Hurricane Katrina in particular.  The Court based the injunction upon its finding that the 1997 EIS "failed to take a 'hard look' at the environmental impacts and consequences of dredging and disposing of the canal's contaminated sediment" as required by the NEPA.  The Court also criticized the EIS for failing to "adequately address the risks of flooding and hurricanes in general", and stated further analysis was required of "the reasonable dredging and disposal alternatives that the Corps had recently adopted for maintenance dredging of the same waters," post-Katrina.

In 2009, the Corps completed a final SEIS and a Record of Decision (ROD) in response to the 2006 injunction. The ROD recommended a float-in-place lock construction plan, hydraulic dredging, and disposing of dredged material unsuitable for open water discharge in a confined disposal facility, and for material determined to be suitable for freshwater disposal, in the Mississippi River.

In 2011, the United States District Court, Eastern District of Louisiana, enjoined the Corps from continuing with the lock replacement until the Corps complied with the NEPA and the CWA. The Court found the SEIS failed to sufficiently and properly consider the impact of the closure of the MR-GO to deep-draft traffic upon the IHNC project, particularly the draft of vessels that would use the lock, and how this depth may affect dredging and disposal alternatives.

A SEIS is being prepared in response to the 2011 enjoinment.  A General Reevaluation Report (GRR) is being prepared to reanalyze previously completed studies, using current planning criteria and policies, which is required due to changed conditions and/or assumptions. The results may affirm the previously selected plan; reformulate and modify it, as appropriate; or find that no plan is currently justified.  The SEIS and GRR are being combined as a single integrated document.

Replacement of the IHNC Lock was authorized in Public Law 455, Chapter 112, 84th Congress, 2nd Session, approved March 29, 1956.  Subsequent to the 1956 legislation, the project was modified by Section 844 of the Water Resources Development Acts (WRDA) of 1986 (established cost sharing requirements) and was amended by Section 326 of the WRDA of 1996 (authorizing the Community Impact Mitigation Plan).