This Giant Lock Complex Could Help Restore Wetlands in the Bayou Region

By Victoria Sagrera, Special Projects Coordinator

To restore Louisiana’s coast, we need a suite of large-scale restoration projects across the coast working together to deliver maximum benefits to reduce land loss, restore ecosystems and maintain healthy and diverse habitat. In our “Restoration Project Highlights” series, we take a deeper look at specific projects from our list of Priority Projects, highlighting why they’re needed and hearing local perspectives on their importance.

Marshes near Cocodrie in the Terrebonne Basin have struggled due to a combination of factors like saltwater intrusion, increased subsidence and sea level rise among others.

At their essence, many canals are artificial waterways constructed to allow boats to come inland. In the Terrebonne Basin, the Houma Navigation Canal (HNC) is important for navigation but also comes with significant threats to wetlands and surrounding communities by allowing increasing amounts of saltwater to work its way through the channel.

The changed hydrology has been one of the factors in the degradation of the basin’s marshes. The Houma Navigation Canal Lock Complex will look to address the increased saltwater and, ultimately, offer a combination of ecological, economic and protection benefits to the Bayou region.

What is the Houma Navigation Canal Lock Complex?

Once constructed, the Houma Navigation Canal Lock Complex will be massive. It will span 110 feet across and stand 800 feet high with gates on either side, directly adjacent to the existing 250-foot-wide Bubba Dove barge floodgate. The two components will be tied together by a braced flood wall across the channel and work in concert to allow larger ships to pass through the canal. 

The HNC Lock Complex would also act as a midpoint, closing one of the few remaining gaps of the Morganza-to-the-Gulf hurricane protection system. That hurricane protection system uses a mix of levees, floodgates and locks to protect 150,000 Terrebonne and Lafourche residents from potentially deadly storm surge. 

A Local’s Take on the Houma Navigation Canal Lock Complex

“The Houma Navigation Canal Lock has always been the anchor for restoring this part of the Bayou Region, providing benefits well beyond the protection afforded through the Morganza to the Gulf system.  We have taken careful consideration to design a complex with far-reaching environmental benefits by distributing freshwater into the basin and keeping salt water at bay, but also making critical accomodations for business and industry to continue to thrive along our working coast.”

Reggie Dupre, Terrebonne Levee & Conservation District

What Progress Has Been Made to Build This Lock Complex?

Since the late 1990s, the canal has allowed severe saltwater intrusion from the Gulf of Mexico, causing flooding and affecting the parish’s drinking water supply as far north as Houma. The lock complex was conceived and designed as part of the 2002 Louisiana Coastal Area Study. 

Progress on the lock complex’s design slowed when Hurricanes Katrina and Rita hit Louisiana’s coast in 2005. The catastrophic effects of these storms on local structures resulted in the changing of design standards in Louisiana to stand up to larger storms.

However, these obstacles were overcome through innovative design and financing solutions as funds from the BP oil spill disaster settlement, Gulf of Mexico Energy Security Act (GOMESA) and Gulf Coast Ecosystem Restoration Council (RESTORE Council) offered additional support to continue project design and begin construction.

When Will This Project be Constructed?

With final plans and specifications scheduled for August of 2020, the first phase of construction is on track to begin later this year. This year-long phase will focus solely on dredging the area. Once complete, the lock complex itself will take two years to be built in the second phase. 

While the lock complex is under construction, work will also start on modifying the adjacent Bubba Dove Floodgate and portions that will connect to the lock complex. The complicated nature of this project contributes to the lengthy completion time, but, ultimately, all three phases are expected to be finished by 2024.

What Does a Future Without Action Look Like?

Future with action assumes all projects in the 2017 Coastal Master Plan are operating.

 

What does a future without action look like?
What does a future with action look like?

Why Is This Important?

This large-scale, multi-dimensional project will help restore the hydrology of thousands of quickly eroding acres of wetlands in the Terrebonne Basin by controlling the flow of freshwater through the canal and limiting saltwater intrusion. The HNC Lock Complex will work in tandem with the Increase Atchafalaya Flow to Terrebonne diversion project to further manage freshwater flow into the basin to maintain and restore wetlands. Ultimately, they will work to nourish wildlife and fisheries habitat as well as address saltwater-induced land loss.

Additionally, the Houma Navigation Canal Lock Complex uniquely allows for safe harbor navigation of marine traffic without simultaneously flooding the canal and nearby communities from storm surge and tides.

This project provides a model for coastal restoration and protection in Louisiana. Successful collaboration among local, state and federal authorities helped advance this large-scale project that can address the complex coastal challenges faced by the Bayou region. 

How Will This Project Benefit Wildlife?

A Purple Gallinule leaps across lily pads. George Sanker/Audubon Photography Awards

Found creeping around our marshes along the Gulf coast, the Purple Gallinule will be one of the many bird species helped by this project. This brightly colored, long-legged bird thrives in wetlands as they tiptoe across floating vegetation in search of food.

Restoring the hydrology of the Terrebonne Basin’s marshes will help maintain a healthy habitat of emergent marsh thick with the weeds and lily pads that these migratory birds love. 

By marrying environmental and ecological benefits, in addition to crucial flood protection, the HNC Lock Complex validates and underscores the meaning behind a “working coast.”