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OCCASIONAL PAPERS

OF THE LOYOLA CENTER FOR ENVIRONMENTAL COMMUNICATION

P.O. Box 199, Loyola University New Orleans, New Orleans, Louisiana 70118 USA

Recommended citation for this article:  Thomas, Robert A.  2024.  A naturalist's drive across the LaBranche Wetlands, Louisiana.  Occas. Pap. Loyola Ctr. Enviro. Comm.  (3: ver. 2.5): 1-33.

A NATURALIST’S DRIVE ACROSS THE LABRANCHE WETLANDS, LOUISIANA

By Robert A. Thomas, Loyola Center for Environmental Communication, Department of Strategic Communication, School of Communication & Design, Loyola University New Orleans, & Louisiana Master Naturalists of Greater New Orleans (rathomas@loyno.edu, 504-865-2107)

Note: All place references are by mile marker points (MM) on I-10. Drive time between the Kenner levee on I-10 and the I-55 exit from I-10: 10 minutes.

Warning: Do not stop along I-10 to make observations outside of your car. Such action may be very dangerous.

The LaBranche Wetlands are the rich marshes you cross on I-10 between I-310 and the Bonnet Carré Spillway (MM 214.4 to 219). They are so named as they are bisected by today’s Bayou LaBranche (with its associated tributary, Bayou Trepagnier), originally known to Native Americas as bayouque. During the 1700s and 1800s, this area was occupied by several owners, notably the LaBranche and Trepagnier plantations. For details of the records of owners, lessors, and lessees, see Pearson et al., 1993:29-38.

View of most of the LaBranche Wetlands, taken from a commercial airplane.

Of interest is how many cars pass this area each day, and only rarely does someone question their ecology or present/past structures. Data shared by the New Orleans Regional Planning Commission for 2022 indicate there are annually 27, 813,000 cars passing the LaBranche Wetlands! Yes, that is “millions.” We don’t have current information about the number of cars passing this area daily, but I was once told a study found that 30,000 people drive between Greater New Orleans and Baton Rouge, meaning those people see these wetlands about twice a day during a five-day work week – this translates to almost 16 million passes by people going to and from work.

Hopefully, this publication will entice them to understand the wetlands they cross.

These mildly brackish wetlands were near and dear to citizens who love fishing, canoeing, and bird and nature watching, and just seeing large stretches of wetlands from a car. Do understand that these wetlands are mostly under private ownership and buildings you see from the interstate are either leasing land or owners of small pieces of property. All you see as you drive by are camps that owners visit for fishing, hunting, and just relaxing, but in some cases a few people may reside on site.

One of the main values of LaBranche Wetlands is that it is one of the largest nursery areas for fisheries along the edge of Lake Pontchartrain. It is a marvelous wetland, but has its own challenges brought on my humans.

It seems that for every convenience we add, there is a tradeoff. This is true of when the I-10 was completed across its present site in December 1971. Its construction was done by setting up the

concrete support standards, then digging a channel between the parallel supports that would become the two spans to allow barges to enter the construction zone to deliver the concrete components of the elevated highway. This was a seemingly practical way to construct the I-10 across water, but in hindsight there was a huge unintended consequence. The barge channel allowed saltwater from the lake to infiltrate the fresher LaBranche Wetlands, thus stimulating loss of freshwater vegetation that formed the wetlands. This disturbed the nursery ground function of the wetlands and soon required the addition and management of various types of weirs in attempts to control the amounts of saltwater entering the core of the wetlands.

Did we learn any lessons from the I-10 mistakes? When the I-310 needed to be built to link with the Hales Boggs Bridge and the west bank in St. Charles Parish, we knew to avoid deep canals to move construction materials. The I-310 was built through a healthy swamp, and introduction of saltwater would have been ecologically devastating. The contractors cut a swath through the cypress trees, installed the support standards, then, from the I-10, they installed the concrete components of the roadway by placing them from the existing highway (so called “end- on” construction). As they moved forward, the interstate was completed behind them. Very effective and allowed the swamp to continue to be healthy.

From cover of Engineering News-Record, 11-4-1991.

https://www.smartsmiles.com/mobile/about_drsmart_engineering.html

Have you ever wondered why I-310 winds through a swamp (where trees had to be removed) when it would have been a much shorter, direct highway if it left I-10 at MM 218.6? The direct crossing of the LaBranche Wetlands at this MM would have been enormously cheaper, the construction time much shorter, and with no loss of cypress trees. The record (Coastal Environments, 1978: 5-42 & 5-43) of decision considerations give rather simple reasons for the path we have today – the Alternate 6/6b. This route would have:

Ahhh, but there is a deep rooted opinion among many naturalists that another situation had an effect on the I-310 placement. There was a federal law that federal construction cannot take place within a mile of a Bald Eagle nest. At the time of construction (planning to construction 1977-1993; the section between US 61 and I-10 was completed on May 7, 1993) Bald Eagles

were still rare and there was an eagle nest at the ecotone of the swamp and the marsh on the landing approach to MSY. It was always fun to sit on the left-hand side of the plane as it always provided a good look at the nest and its occupants as you landed. It was the presence of this eagle’s nest that mandated the location of the I-310. The irony is that when the interstate opened, the eagle had abandoned the nest!!!

I-310 (red) from I-10 above to US 90 below.

When you drive to the river from I-10 on I-310, note the wonderful swamp through which you pass. In most places it has a nice density of cypress trees, but with marsh plants (lots of bulltongue, Sagittaria lancifolia) spread about. The area is arguably at it prettiest in the fall when many species of fall flowers (especially those that are yellow) are in bloom: goldenrods (Solidago) and beggartick which are also called bur-marigold (Bidens). The forest habitats line the interstate for 6.1 miles, with the swamps dominating from I-10 to the U.S. 61 exit, and thereafter being dense forests.

Did landowners and the state take any positive steps to protect LaBranche Wetlands from higher saline waters? Once they realized that the salinities of Lake Pontchartrain were rising and that the more saline waters are deleterious to the freshwater marshes of the wetlands, their approach was to take steps to protect their wetlands from the inundation by salt water. The dilemma was how to stop salt water but allow those organisms to enter that rely on the LaBranche Wetlands for nursery purposes or important habitat during certain periods of the year. They used weirs, systems that at least partially block the inflow of unwanted waters but allow critters to move back and forth. Two weirs used in LaBranche Wetlands during the 1970s-80s are shown in the next two photos.

Fixed-crest weir – Attached to the columns are boards that act as a dam for incoming water. The top of the weir is 4 inches below the surface so such critters as blue crab, pogie, shrimp, and more can move from saltier water on the left to fresher water on the right, and vice versa.

This flap-gate weir functions as the fixed-crest weir above, but water flow can be stopped by closure of the flap gates. Some of these were remotely controlled so didn’t require managers to visit the site to close or open. Photo by Richard Carriere.

Years 1699-1720 Resource as a Portage

We all know that New Orleans is located where it is because Bayou St. John was used as a portage from Lake Pontchartrain to the Mississippi River by Native Americans long before Europeans arrived. When Jean Baptiste Le Moyne, Sieur de Bienville; Pierre Le Moyne, Sieur

d’Iberville; Pierre-Charles Le Sueur; and Father R. F. du Ru (a Jesuit priest) first began seeking the perfect portage between the two bodies of water, their Native American guides (local native peoples of the time included Quinipissa, Acolopissa, Quacha, Chaouacha, Bayougoula, and others) took them past Bayou St. John (which was then called Choupitcatcha by Native Americans or Rivière d’Orléans by the French) to a wetland area at the southwest area of Lake Pontchartrain that we call Bayou LaBranche today (at that time cartographers and explorers called it by a variety of names including Portage des égaréz [Portage of the Lost], Tigonillou portage, Bayou or River Tigouyn, or Ravine du[de] Sueur).

Development of the LaBranche Wetlands

During the 1700 and most of the 1800s, todays LaBranche Wetlands largely functioned as a variety of sugar plantations. To learn more about the succession of ownership and leases of this region, see Pearson et al. (1993).

A significant development was the introduction of train access on the site where it exists today, paralleling I-10 between Kenner and LaPlace and beyond. It was the New Orleans-Jackson- Great Northern railroad and opened in August 1854. Among its many passengers was Illinois native Edward Wisner, a businessman who moved to New Orleans for health reasons.

The next major change began during the acquisition of Louisiana wetlands by Edward Wisner. It is believed that his view of Louisiana wetlands from the train stimulated his interest in investing in their agricultural potential. Between 1900 and 1915 he purchased one million acres of wetlands, and his first major agricultural development was near the mouth of Bayou LaBranche. He consolidated ownership of most of the wetlands along Lake Pontchartrain, thus the formation of the LaBranche Wetlands instead of a family of parcels with differing names. His experience in LaBranche convinced him that wetlands could be drained to become the site of productive agriculture, and he did these projects in several places throughout coastal Louisiana.

In the short-term, the agricultural development near the mouth of Bayou LaBranche was successful in providing vegetables and possibly beef to the New Orleans market. The great Hurricane of 1915 caused irreparable damage to the operation, and it was abandoned.

St. Charles Hurricane Protection Levee. Back in the 1970s and 1980s, there was discussion about the need for a hurricane protection levee to protect St. Charles Parish from flooding from Lake Pontchartrain during a storm. Many wanted the levee to be at the edge of the lake (now the area to the east of I-10). The environmental community, fishers, and others who saw the value in the LaBranche Wetlands were opposed to that suggestion because they all knew that if that was the location, the time would come when developers would push to drain the LaBranche Wetlands in lieu of development of the land for profit. A strong indication of that goal is that a sizeable area of the wetlands was platted out in lots for home construction, despite the entire area being under water. The lots were relatively cheap due to being inundated and were snapped up as investments that would pay off when the levee was built (at taxpayer expense) and the wetlands drained.

Eventually the hurricane protection levee was built parallel and close to U.S. 61, thus saving the LaBranche Wetlands.

What came of the privately owned lots? Many are still owned by the original landowners. When the Bayou Sauvage National Wildlife Refuge was in its final stages before being official, then Congressman Billy Tauzin made a move to add the LaBranche Wetlands to the refuge. This had immediate appeal as it would save additional important parts of the ecosystem. We did fear that this last-minute move might jeopardize the approval of the refuge, and there was a rumor that the move behind this request was that the “submerged property owners” hoped it would happen and they would be able to sell their properties to the refuge system. All this was averted, and the rest is history – we have our Bayou Sauvage NWR. In the late 1990s, the Lake Pontchartrain Basin Foundation (now Pontchartrain Conservancy) worked with St. Charles Parish Planning Department to receive the donation of some of the submerged properties. This allowed the investor donors to stop paying taxes and St. Charles Parish enjoyed the conservation effect.

Was there any follow-up to the levee built along U.S. 61? The federal government bought (with the use of eminent domain) the property on which the levee was built from the landowner of the LaBranche Wetlands. Later, the family complained that the price they had negotiated and accepted from the government was not fair, and they wanted more money. It went to court and failed.

Note cypress trees at MM 219.4 – 219.8 near I-10/I-310 junction. This was a healthy developing stand of cypress prior to Hurricane Katrina in 2005. Winds were so strong they blew the bark off these trees. Many trees died, those that did not die were weakened, and some in 2021 are struggling to survive.

MM 219.5 on the river side of I-10: This photo was taken October 17, 2005 – less than one month after Katrina passes Greater New Orleans. All these trees were alive before the storm. Note how the bark was blown off by hurricane force winds.

Same trees, same views April 30, 2008. Some survived, but most died.

Same spot, different angle. Very few of the original trees survived. Note the density of the brackish indicator grass, Spartina patens.

Taken November 30, 2022.

Keep your eyes peeled for distinctive flora and fauna in LaBranche Wetlands. As you speed (hopefully) across this section of I-10, note a wide variety of birds (egrets, heron, ducks, gulls, red-winged blackbirds). As you learn your wetland plants, many of the species growing alongside the highway may be identified at normal speeds. Two species of flowering plants (spring through summer) that are obvious include crimsoneyed rosemallow (Hibiscus moscheutos) and Virginia saltmarsh mallow (Kosteletzkya virginica). Throughout the summer, naturalists can see a vine growing on top of other plants in the marsh that appears to be spaghetti

- scaldweed or common dodder (Cuscuta gronovii). Dodder is a native parasitic vine with tiny white flowers that is often common along our roadways in many types of habitats.

Two common shrubs are very identifiable during a drive by. Black elderberry (Sambucus nigra ssp. canadensis) has dark green leaves and is most identifiable when in flower, spring through summer. It has umbrella-shaped clusters of very white flowers that become their dark purple/blue berries. The other is groundsel, locally called manglier or mong bush (Baccharis halimifolia), that is a lighter green and denser with much smaller leaves, and just blends into the scenery during much of the year. As fall approaches, Baccharis begins to flower and is much more obvious. It is a dioecious species (male and female flowers on separate plants), and the more conspicuous of the two are females as their flowers are larger and look like grass skirts.

Male flowers are different and smaller but are obvious when viewed closely.

Two of the non-flowering, tall species that one easily recognizes (with practice) are California bulrush (Schoenoplectus californicus) and giant reed, locally called roseau cane, or simply roseaus (Phragmites australis).

Crimsoneyed rosemallow, Hibiscus moscheutos – large white (sometime pink) flowers.

Virginia saltmarsh mallow Kosteletzkya virginica. Pink and smaller flowers than Hibiscus.

Scaldweed or common dodder, Cuscuda gronovii – we call it “marsh spaghetti.” Nothing else this color and form exists along our highways.

Black elderberry, Sambucus canadensis ssp. canadensis flowering.

Groundsel, Baccharis halimifolia, female flowers along Wisner Blvd. October 2011.

Reliable bald eagle nesting and activity. Most bald eagles arrive in Louisiana September- October and in recent years as many as 10,000 nests have been reported in the state. Successful young fledge in April-May and leave soon after. Adults leave a bit later, and increasingly some stay year-round. There are no strong data on how many individuals stay, but those who study eagles in the state believe these are older eagles that simply choose not to expend the energy it takes to fly north. Those who do leave go as far as northern Canada and all parts in between.

During winter, the most reliable nest sightings on the drive are MM 219.8 on the river side of the interstate, and in the open brackish marsh in the former lone tree at MM 218.1 when the photo below was taken (March 2012). A bald eagle often rested on this tree, and eventually a nest was built on it. In 2021, the weight of the nest presumably caused the tree to break in half, so all you see now is the bottom half of the former tree. Keep your eyes on this spot to see if another eagle constructs a new nest there. The good news is that there are many small trees emerging in the high marsh.

High brackish marsh (primarily Spartina patens) with a lone tree that often had either an eagle or eagle nest in it. March 2012. In 2021, it broke in half. This habitat is going through plant succession and is how hosting many woody plants.

Ecological transition around the edge of Lake Pontchartrain. Montz & Cherubini (1973) noted that study of their transects across the LaBranche Wetlands showed that cypress tree size diminishes from the river toward the lake. Near the lake, there are many “dwarfed” cypress (Tyrone Foreman called them bonsai cypress). In the photo above the lone cypress tree was a renowned perch for bald eagles, and the vegetation is primarily wire grass, Spartina patens. This species often dominates in marshes with a salinity of 10-20 parts per thousand (ppt). Many restoration or management projects have been done in the Lake Pontchartrain Basin over the last few decades, and they have had a profound impact on the ecology of the lake’s wetlands. This area was shown as “prairie” in a map of the area done by Carlos Trudeau in 1803 (see Pearson et al. 1993: 32).

We know the impacts, although short-term, of opening the Bonnet Carré Spillway (see the commentary on that structure below). Again, when closed, its impact diminishes over time. As a result of saltwater damage in St. Bernard Parish caused directly by saltwater intrusion via the Mississippi River Gulf Outlet (MRGO) and other marshes, the Lake was getting saltier all the time creating much concern about its ecology. Things began to improve when a rock barrier slowed the infusion of saltwater along the MRGO, then took another step to improvement (fresher water) when the IHNC-Lake Borgne Surge Barrier was built post Katrina. The latter mentioned 23-foot-high barrier not only protects New Orleans from hurricane related surges, but

also stops continual intrusion of saltwater beyond its site. Now saltwater only passes through the small boat gates and those that allow commercial traffic on the Gulf Intracoastal Waterway (GIWW).

Salinities before closures on the MRGO could be high. One 2002 study by the Army Corp of Engineers for the LaBranche area of the lake cited salinities of 5.4 ppt in October. After the closures referenced in the paragraph above, lake salinities have diminished to 0.5 ppt or below. We have watched the wetlands of the nearby Turtle Cove Environmental Research Station (on Pass Manchac) change from intermediate marsh to freshwater marsh, with many vegetative signals demonstrating a freshening of those marshes. There are signs that the once brackish marshes between the lake and I-10 are transitioning to a higher grassland with less influence from the presence of salt. When you drive from MM 219 to MM 215, note the increasing presence of woody plant, as seen in the next photo.

Marsh between the I-10 and Lake Pontchartrain at MM 218.8. There is still Spartina patens present, but there is more woody vegetation and obviously freshwater species. Photo taken November 30, 2022.

Dead trees around MM 215 to the right as you return to New Orleans. These trees are obviously in decline. There is a notable stand of dead cypress trees in the distance (toward the river) that was noticed by two of our 2017 Fall LMNGNO participants – Susan Hill and Nijme Rinaldi-Nun. It is assumed that the damage to the trees occurred in one of the hurricanes, as this

is the typical aftermath of hurricanes. If you look closely, you will see many such leafless trees for a mile or so, but the one referenced above is a dense stand.

Shell Norco facility – MM 215 in the distance next to the Mississippi River. The first chemical plant constructed on this site was the New Orleans Refining Company (acronym, and name of the community at the site - Norco) in 1916. Over time it has changed hands with new owners and names, and today is called the Shell Norco Plant (with more than one facility on its campus, including the refinery and Shell Norco Chemical NP).

Bayou Trepagnier. Bayou Trepagnier is still listed as a Louisiana Scenic River, and in the 1970s was a lovely canoe site loaded with birds and alligators and other wildlife. It ends at Bayou LaBranche just west of the I-10 and begins at the east end of the Shell Norco plant. When I became the founding director of the Louisiana Nature Center in 1978, we identified this bayou as a perfect place for canoe trips as it was remote and easily accessed by canoe. In the beginning, all the canoe guides were Ph.D. students and technicians in the Department of Biochemistry at L.S.U. Medical Center! Imagine the range of topics that were discussed with our clientele.

Bayou Trepagnier and its contamination. In days gone by, chemical companies released lots of hydrocarbons, other chemicals, and hazardous waste into their surrounding areas. When we began leading tours on Bayou Trepagnier, we did not go all the way up the bayou to the oil facility, but I ventured there a few times and what I encountered was a 30-inch pipe gushing what looked like water. The effluent from this pipe served as the headwaters of the bayou. Of course, all areas along the bayou drained into and added to the content of the bayou.

I contacted Shell and asked about the outflow and was assured that it complied with environmental laws and was water runoff from the plant’s grounds. At that time (1980s), the bottom of the bayou reeked of oil – sticking a paddle into the bottom and lifting it into the air left a strong oil odor. Refinery officials believed that this contamination had occurred before environmental laws prohibited such discharges. These conditions still exist today.

Attempt to clean Bayou Trepagnier. In the early 1990s, the environmental community was upset about the contamination of Bayou Trepagnier and was considering a lawsuit to get it cleaned up. In a meeting with Shell employees, we discussed the bayou, and they expressed an interest in addressing its contamination, while mentioning that they were not the culprit, but they were the operator now of the site that caused the situation. Hearing both conversations, I decided to see if we could get them together and find a solution. I arranged a meeting at the Louisiana Nature & Science Center’s Louisiana Wildlife & Fisheries Museum in Kenner and about 20 people attended. Shell had a new government affairs person, Don Baker, and he asked to be informed of the issues. We had flip charts and Don wrote down every concern expressed. We closed the meeting by setting another in two weeks, with Don’s promise that he would get answers to all comments and share them with us. He did, and we decided to form a committee to pursue a solution to the bayou’s problems. The only rule about being a committee member was that you had to understand science and read scientific data. Shell agreed to pay for a study of the bank and bottom soils along the bayou, and it was commissioned. Everyone agreed that the study of contaminates would be confidential, shared with no one outside the committee.

To make a long story short, progress was made, a study was done on the contaminants present along the bayou, solutions discussed, differences in opinion shared, suspicion arose wherein the environmental members suspected that Shell had influenced the outcome of the study they paid for, and the committee stopped meeting. Shell wanted to monitor the area to learn if and how the contaminates would be mobilized, and the others wanted Shell to remove all the soil to a hazardous landfill.

Twenty-five or so years later and Bayou Trepagnier is still contaminated – no progress.

Bayou Trepagnier landowner lawsuit against Shell Oil Company. “Somehow,” a prominent family that owned land along the bayou got a copy of the contaminant study, and they filed a

$200 million lawsuit against Shell alleging that they intended to build an elevated housing development beside Bayou Trepagnier, and the contamination deprived them of this dream. If constructed, owners living in the development would enjoy living in a wetland area and enjoy the views of nature. The issue went to court and the family ended up settling for $6 million. Other than that exchange of money, noting has changed about the contamination and the proposed development along the bayou has not pursued by the landowners.

Restoration projects in the LaBranche Wetlands. Two important projects have been done along the I-10 in attempts to restore marshes where there was then open water:

He developed a research project in open water to try to duplicate what the Dutch had done, and he chose an area in the LaBranche Wetlands between I-10 and the lake spanning MM 215.5 and 216.2 as his experimental area. He put the sediment fencing in place in the winter months and used three configurations. His research was to evaluate which configurations were superior.

In the first stages of this experiment, Dr. Day planned the work for the winter months (the water was cold, but less interference from vegetation), and the fences were constructed by interweaving the limbs of black willow (Salix nigra) in a fashion like the limb weavings in The Netherlands. This was a difficult, uncomfortable process. In early December 1989, Dr. Day, the late Allan Ensminger, and I were discussing this project over coffee and one of us suggested using old Christmas trees that could just be dropped into wire enclosures, thus saving the scientists from standing chest-deep in cold water! I volunteered to obtain the trees, and I was on WDSU TV two mornings later laying out the plan. It caught the attention of Waste Management who volunteered to make a Saturday, Christmas trees only, pick up. At the same time, St. Charles Parish coordinator Gretchen Hebert Binet set up a drop-off spot in James Business Park. Soon about 10,000 trees were available for the project.

Since it relies on used Christmas trees, the project had several advantages:

MM 215.5 - The first Louisiana Coastal Wetland Planning, Protection & Restoration Act (CWPPRA) project (referred to as PO-1) was implemented here in 1993-94, on the site discussed above which was Edward Wisner’s first major wetland development. A triangular area (shown in the image below as Project Area) was enclosed in a levee and at first the sedimentation fences continued to work, then sediment was pumped in, and marsh grasses began to grow. The concept was to use levees that would gradually collapse as the marsh developed, thus letting marsh water move into the marsh grasses. It worked very well and is still an obvious marsh. The Reference Area in the figure below is where the X- & V-shaped sedimentation fences were sited; they did not work well so the area is still open water (the lower right arm of water that approaches the I-10 is at MM 216.3).

Project Area finished in 1993 (PO-1), followed by filling the Reference Area in 1994.

Just after the levee was constructed, before the levees collapsed as scheduled. March 1994.

The restored Bayou LaBranche Wetland Creation (PO-17), taken in about 1997.

From La Coastal Wetlands Conservation & Restoration Task Force brochure, Mar 2010.

MM 216.2 – LaBranche East Marsh Creation Project (PO-75).

Seeing the success of the nearby (MM 215.5) PO-1, the LaBranche East Marsh Creation Project is being built using similar techniques. Look closely at the photos below to see rings of levees now under construction (March 2024) with the vision that soil pumped in will allow marshes to form before the planned collapse of the levees reunites the newly stabilized marshes with others in the area. PO-75 is much larger than PO-1 constructed some 35 years ago.

LaBranche East Marsh Creation (CWPPRA PO-75) project site, preconstruction, both sides of I-10 at MM 216.2. Photo by Patrick Quigley, 10-17-2017.

LaBranche East Marsh Creation (CWPPRA PO-75) project site, during construction, lake side of I-10 at MM 216.2.

Note the backhoes at work in the lower open water areas. Photo by Patrick Quigley, 10-17-2017.

LaBranche East Marsh Creation (CWPPRA PO-75) project site, during construction, river side of I-10 at MM 216.2.

Note the newly constructed low levees that encircle most of the visible open water areas.

Photo by Patrick Quigley, 10-17-2017.

MM 214.8 – Bayou LaBranche crosses under the I-10. Note the “camps” that sit beside Bayou LaBranche and the I-10.

MM 214.6-7 – On the lake side of the I-10 one can see relatively large bald cypress trees that were planted by Tyrone Foreman in 2008. They are stimulating dense growth of other vegetation in the area

Bald cypress planted in 2008 by Tyrone Foreman and this photo taken December 2, 2022.

MM 214.4 - View from I-10 on the lake side of the parking and pier area for the Wetland Watchers Park, St. Charles Parish. A project imagined and shepherded by Milton Cambre of Norco, this park affords citizen an opportunity to visit a wetland area with views from a boardwalk and the presence of a pavilion. Wildlife observation, fishing, and picnicking are the attractions.

To get to this destination from Airline Highway in Norco, turn onto the Lower Guide Levee Road on the Bonnet Carré Spillway guide levee and drive to the end at the lake.

The story of the Bonnet Carré Spillway. Between MM 214.4 and 212.3 on the west side of I- 10 lies the Bonnet Carré Spillway, an important part of the federal Lower Mississippi River Flood Control System. This land was formerly part of the LaBranche Wetlands and was acquired by the feds and designed to shunt up to 250,000 cubic feet per second (cfs) of Mississippi River water to the lake as a safety value when the river reached flood stage. If not opened to avert down river flooding, it exists as a wonderful wildlife area enjoyed by fishers, birders and other nature lovers, and dirt-bikers. While the spillway is operating, sand from the river settles out and is then available post-opening to businesses and citizens to sell and use – an economic benefit. When operating, water flows from the river through a 350-bay control structure and empties into the lake between the two MM mentioned above, flowing between levees on the southeast (the Lower Guide Levee) and northwest (Upper Guide Levee) lateral margins.

In the 1990s, there was consideration (and federal authorization) of adding inside its Upper Guide Levee a Bonnet Carré Freshwater Diversion structure that would eventually periodically (possibly continuously) shunt up to 30,000 cfs toward the lake while creating 10,500 acres (16.4 sq. mi.) of renewed marsh. The primary proponent of this diversion was the State of Mississippi, believing this diversion would benefit their fisheries (this is in opposition to recent policy from the State of Mississippi regarding too frequent opening of the entire spillway). Opposition came

from Louisiana fishers who feared that more consistent flow of river water would introduce too many nutrients into the lake (stimulating excessive algal growth) and contaminants.

Effort was made by the Lake Pontchartrain Basin Foundation (now Pontchartrain Conservancy), ecologists, me, and others to instead move the flow of water directly through the LaBranche Wetlands to slow the movement of the water, freshen the wetlands that had become too salty, and allow standing wetland vegetation to remove nutrients and chemicals from the water before it enters the lake. This effort failed (but should not be forgotten).

Open Bonnet Carré spillway, March 17, 2011, illustrating the movement of Mississippi River water into Lake

Pontchartrain. NASA Photo.

MM 214.1 – Stand of cypress in the lake surrounded by water. Before the I-10 was built, this stand of cypress had a dense marsh of emergent plants inside and on its lake side. The lake was much more saline, but the plants buffered the impact of salt on the cypress. When the marsh died back due to increasing salinity, the cypress began to decline. Now that the lake is fresher, it will be interesting to see if the cypress stands have a positive response.

The remains of cypress stand, now with no marsh buffer (L); remains of dead trees just to their north (R). Photo by Aimée K. Thomas, May 8, 2021.

MM 212.1: What was the purpose of those pilings into the lake on the east side of I-10? In Louisiana, lines of parallel pilings usually indicate the former location of a pier or walkway. We have not definitively answered the purpose of these pilings, but we have an educated guess based on local lore and knowledge of past construction in the area. According to Milton Cambre, what appears to be parallel lines of pilings into the lake today are remnants of pilings installed in healthy marsh in the 1920s during construction of the Bonnet Carré Spillway. Many construction supplies arrived on site via barges in the lake. There was a need for a road passing through the marsh from the edge of the lake. The pilings were installed to stabilize an earthen roadway. Since that time, the marsh has eroded into open lake water, and the dirt has washed away, leaving mysterious lines of pilings.

Milton remembers old bougres (Cajun for older, more experienced people – pronounced “bougs”) reminiscing about standing on the waning levee and using cast nets to catch shrimp.

Pilings at MM 212.1, I-10 west that extend into the lake in line with the Bonnet Carré Spillway Upper Guide Levee.

Left photo December 1, 2022, right photo March 13, 2022. Each pole is often a bird perch: brown pelicans, cormorants, gulls, terns, and more.

Canadian National Railway Bonnet Carré Spillway Bridge is upgraded. The railroad that parallels the I-10 from LaPlace past the Bonnet Carré Spillway is very old (mentioned above as the New Orleans-Jackson-Great Northern Railroad, 1854) and was elevated on trestles made of creosote pilings (across the spillway mouth) and rock-covered spoil bank (the rest of the way). It is a very important railway as it serves Amtrak and the Port of New Orleans. On February 13, 2016, a 400-foot section of the elevated bridge burned and had to be replaced. The rail traffic

was redirected to other railways and was reactivated along its original path before the end of February.

The fire began during service work by railroad workers using heavy duty grinding tools. Between 2019-2021, it was upgraded to a 2.3-mile-long elevated bridge composed of concrete trestles. Going back to lessons learned from the I-10 construction and implemented in the I-310 construction, no canals were created to allow barges during the project. Instead, a large, sophisticated bridge-building apparatus was used that did not require dredging since it was supported by the structures it was constructing. During construction, the old, repaired railway was used for the usual rail traffic.

An old portion of the Bonnet Carré Spillway Bridge.

Fire on the old, creosote trestle Bonnet Carré Spillway Bridge on the Canadian National Railway. February 13, 2016.

Photo by Jack Ferry.

Bridge-building apparatus constructing the concrete trestles on the new bridge. Photo by Erik Coleman.

The new (2021) Canadian National Railway Bonnet Carré Spillway Bridge.

MM 210.6 – Latest emerging change in the landscape along this drive – the West Shore Lake Pontchartrain levee protection project.

At long last, there is movement on building levees that will ultimately protect St. John the Baptist, St. Charles, and St. James parishes from the constant threat of flooding. 60,000+ citizens have little, if any, hurricane risk programs in place, and a principal conduit for evacuation from Greater New Orleans is threatened by the same lack of protection. The design is projected to provide a 100-year level risk reduction that extends from the Bonnet Carré Spillway to Garyville.

N.B. (nota bene) – Make sure you know what a “100-year level risk reduction” means. It is a structural/infrastructural design that reduces “risk from a storm surge that has a 1% chance of occurring or being exceeded in any given year” https://www.mvn.usace.army.mil/Missions/HSDRRS/Risk-Reduction-Plan/100-Year-Level- Protection/

The path for the levee system has been defined. Keep an eye out as the levees are constructed. This photo was taken on December 1, 2022,

at MM 210.6 of I-10 (east of LaPlace).

West Shore Lake Pontchartrain hurricane levee. The levee will pass back under the I-10 at MM 203.6 west of LaPlace.

The Times-Picayune/nola.com, B1, December 23, 2022.

There is consideration to connect this West Shore Lake Pontchartrain hurricane levee to the future Morganza-to-the-Gulf system (aka The Great Wall of Louisiana) to the west. Without this conection of both levees, a large, populated area between Lockport and LaPlace will have no protection from surging waters.

The Morganza-to-the-Gulf levee project will protect the towns shown in the map above.

This sign at MM 210.2 marks the end of the LaBranche Wetland coverage.

Continue to follow the evolution of the LaBranche Wetland story!

Acknowledgments: Thanks especially to Pontchartrain Conservancy staff for their help and comments – Kristi Trail, Dr. Brady Skaggs, and Dr. Eva Hillman. Thanks also to Carlton Dufrechou, Mark Davis, Tyrone Foreman, and Dr. Aimée K. Thomas. Dr. Karen Wicker has been helpful with information packed reports, including those in the Literature Cited. Jessica Diez provided updated photos by Patrick Quigley of PO-75.

LITERATURE CITED

Coastal Environments, Inc. 1978. Final Supplement to the Final Environmental Impact Statement. State project No. 700-07-72, Federal Aid Project No. I-410-4(67)217, Interstate Route 310 (formerly I-410) Junction Interstate 10-Junction U.S. 90, St. Charles Parish. Prepared for U.S. Department of Transportation, Federal Highway Administration and Louisiana Department of Transportation and Development, Office of Highways. FHWA-La-EIS-71-10-F (Final Supplement), Federal Highway Administration, Region 6, Fort Worth, Texas 76102. Volume 1.

Montz, Glen M. and Arthur Cherubini. 1973. An ecological study of a baldcypress swamp in St.

Charles Parish, Louisiana. Castanea 38(4): 378-386.

Pearson, Charles E., William D. Reeves, and Allen R. Saltus, Jr. 1993. Remote-sensing survey of Bayou LaBranche wetlands restoration borrow area, St. Charles Parish, Louisiana.

Cultural Resources Series Report COELN/PD-93/06. 78 pp.

RECOMMENED DOCUMENTARY

Bayou of the Lost: The Legacy of the LaBranche Wetlands. 1998. A production off the Coalition to Restore Coastal Louisiana and LaBranche Wetlands Coalition in association with WYES TV. Produced and directed by Stephan Tyler, written by Dinah Maygarden and Stephen Tyler, Executive Producers Mark Davis and Tyrone Foreman. Premiered on May 6, 1998.

FOR MORE STORIES ON NATURE IN COASTAL LOUISIANA:

NATURE NOTES – A PERIODIC TREATISE ON NATURAL HISTORY TOPICS

FOCUSED ON SOUTHEAST LOUISIANA by Bob Thomas. To subscribe to this archived, digital nature column, click here. https://signup.e2ma.net/signup/52789/31166/

To visit archived Nature Notes, go to https://lucec.loyno.edu/natural-history-writings.

You may also subscribe (free) to our podcast, The Southern Naturalist (SoNat), which you can hear on many podcast sites, especially Apple Podcast and Spotify. It is hosted by Dr. Aimée K. Thomas (my biologist daughter, also a professor at Loyola University New Orleans) and me.

Produced by Emma Reid and several Loyola students. Google for its many related sites.

Want to learn more about the natural history of southeast Louisiana. Visit the website of the Louisiana Master Naturalists of Greater New Orleans and consider registering for a fall or spring workshop series to become a Certified Louisiana Master Naturalist (https://louisianamasternaturalistsgno.org/). It is a gathering place for like-minded nature enthusiasts!

TO SEE ALL OCCASIONAL PAPERS IN THIS SERIES:

https://lucec.loyno.edu/publications-media/lucec-publications/occasional-publications-lucec

Aimée Thomas, Shannon Fortenberry, and I also host the website Tropical Natural History (https://tropicalnaturalhistory.org/) if you are interest in the flora, fauna, and funga of the tropics.

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