Coastal Restoration Part II – Pass-a-Loutre

Stories and Photos by Gabe Giffin

In 1833, James Buchanan Eads had his first experience with the Mississippi River. While on a steamboat crossing the river to St. Louis, the boiler exploded and the steamer sank. Along with his entire family, Eads was rescued from the river. At the age of 13, Eads decided to begin his great conquest of the river.

By the age of 20, Eads had a successful salvage boat business on the river. When the Civil War approached Eads foresaw the struggle that would take place for the Mississippi. He designed the first ironclad steam powered warships to be used by the Union and eventually in foreign affairs. His next accomplishment was building the first bridge over the Mississippi in St. Louis. In 1874, the world’s largest steel bridge was completed at the direction of Eads.

Not long after completing his bridge he made his way down to New Orleans to embark on a shipping channel that could run year-round. Eads knew the river; he understood its currents, forever changing depths and unpredictable eddies. However, his next endeavor would require him not to work with the river, but to change the river.

Eads made his way down to the mouth of the river and began to understand the delta. After hundreds of miles, sediment would come to rest here, making navigation unpredictable. It was not uncommon for ships to wait several months in the river or just outside for the right conditions in which to cross the sand bars to reach New Orleans. Eads knew the power of the river both physically and economically.

In 1875 Eads began the construction of jetties to help direct the river. The plan was to channel the power of the river to dig out shallow sand bars, thus creating a navigational pass. To construct the jetties he hired labor to cut willows at the Venice Jump and haul them to the end of South Pass to construct the necessary willow mattresses used in the project. In less than one year, all the necessary pilings were driven, and many of the willow mattresses were laid. Not yet complete, the mattresses were beginning to fill with sediment and compress the current of the pass and scour the bottom.

Eads’ plan was met with resistance by the United States Corps of Engineers (USACE or Corps), which preferred the method of dredging the river to create a navigational pass. Without the financial support of the government, but confident his idea would work, Eads self-funded the project. As the construction neared completion, Eads invited a group of investors to Port Eads to see the navigational success he had developed. But before Eads could demonstration his project, the Corps had dispatched a boat to take soundings in full view of Eads’ investors.

Upon returning from their data gathering excursion, the Corps landed at Port Eads and told investors they were only reaching a depth of 12 feet, not the 16 feet Eads had promised. In addition, the Corps reported that a new sand bar was forming just down river of the jetties. Despite the Corps refusing to show it’s actual data, word traveled fast up river to New Orleans and eventually across the nation. Instead of Eads confirming much needed investors, he found himself on the verge of financial collapse, and completion of the project was all but denied.

On May 12, 1876 the ocean going steamer Hudson was due at the mouth of the river. The ship was 280 feet long, weighted 1,182 tons, and drafted 14 feet and 7 inches. The captain of the ship was a friend of Eads, Captain E.V. Gager. Outside the pass, Eads boarded the ship with a few reporters and a river pilot. The pilot reported that the tide was falling fast and he did not recommend the attempt to gain access to the river.

Gager ordered the pilot “Head for the jetties.” The pilot obeyed.

“Shall we run in slow?” the pilot asked.

“No! Let her go at full speed.”

There was a large crowd gathered at Port Eads. If the Corps’ report was correct the ship would run aground and probably be destroyed. When the ship reached Port Eads cheers erupted from the ship and Port Eads. Wires quickly traveled upriver stating that the river was open!

Pressing Congress, Eads finally received the Corps’ report. It showed 16 feet of depth and no sand bars south of the jetties. The final depth at completion of the jetties was found to reach 23.9 feet. In 1875, when Eads began his jetties, 6,875 tons of goods were shipped from St. Louis out to the gulf. One year after completion of the project, 453,681 tons were shipped along the same route. From the days of Eads until now, there has rare been a day that the river is not monitored or modified for navigation.

When Eads created his project the river ran wild in certain areas, floods would occur, pouring sediment out to rejuvenate marshland, the river was a land building source. Today, levees line either side of the river, and even floods like 2011 Mississippi Alluvial Flood are nearly contained within these levees. While the levees have kept us mostly safe, they have prevented the river’s nutrient rich sediments from restoring marsh, instead channeling it all to the delta.

Dredging boats spewing out sediment are a common sight along the curvy path of the river. At the mouth of the Mississippi a different type of dredge awaits the miles of sediment build up, hopper dredges. Similar to their counterparts upriver these dredges collect sediment but don’t disperse it. If hopper dredges didn’t collect the sediment we would be faced with the issue Eads faced, a non-navigable channel.

The natural history of the river created three main passes at the delta. Splitting off to the east, Pass-a-Loutre, to the south, South Pass and Southwest Pass, the western most pass and the shipping channel today. Before the days of channelization the sediment that would make it to the delta would work it’s way through these passes and into crevasses to build land. A crevasse is a cut in the bank of a river. Overtime, sediment and fresh water flow through the cut and begin to accrete land. On a map, one can see the main passes and the marsh area between them which has been created through crevasses.

The area at the mouth of the river is a constantly changing land mass. Land accretes and disappears, islands move and subsidence is always at work. The mouth of the river and Pass-a-Loutre Wildlife Management Area (WMA) in particular, have the highest subsidence rate in the state. Yet the constant flow of sediment coming down the mouth of the river can create new land in spite of these factors.

When a hopper dredge has finished collecting sediment in the Southwest Pass, it moves north to the head of passes to deposit that sediment on the east bank of the river. So much sediment has been deposited there that it has flowed down and created two small islands in the eastern pass, Pass-a-Loutre. This has slowed the current in Pass-a-Loutre as well as caused the pass to shallow in many areas, thus starving the associated marshes of life sustaining sediment and freshwater.

The shipping channel is dredged out in order for the flow of the river to head toward the Southwest Pass. Therefore more sediment and flow curves toward the Southwest Pass as the river comes down its last bend north of Venice. This coupled with the sediment buildup in Pass-a-Loutre has slowed the water current that Pass-a-Loutre would normally receive. The infilling of Pass-a-Loutre starves the marshes of needed freshwater and sediment that simply doesn’t reach this area of the delta. To the west of South Pass, land accretes through crevasses, but to the east it doesn’t receive enough push from the river to make it past the islands in Pass-a-Loutre and into crevasses.

CREATING LAND

Taking a ride through a crevasse, one can see the different types of habitat growing. From South Pass, our airboat curves into what looks like a canal. The reeds lean as the propellers whiz through the cut. Once past the bank of reeds, submerged aquatic vegetation begins to subtly appear under water. As the vegetation pokes out of the water, mud flats appear a few hundred yards down stream. Vegetation begins to sprout out of the flats, and eventually willow trees sparsely dot the muddy plain. As we run along the crevasse, diverse habitats like this form in different areas on either side of the original cut of the crevasse. Blooming outward in both directions, the crevasse has built multiple stages of habitat and created land with rooted plants to stabilize the area.

Floods normally mean bad news for most that live along levees or anywhere that’s a flood zone, but events like the 2011 Mississippi River flood actually create land at a rapid pace in an area like the delta. With the increased current, sediment was pushed at a faster rate through crevasses and passes. Within a few months certain passes had significantly extended their lengths, slowly building a bank, whereas before the pass just widened to open water. This happened enough, that there are even areas where two crevasses have sprouted out enough land to connect the area in between them.

Not all sediment from the hopper dredges is dropped near Pass-a-Loutre. When funding is available, the USACE will pump the sediment into designated areas. One area they have done this is at the foot of South Pass. In both 1997 and 2007, the Corps pumped sediment to create islands. Those islands have stayed and also accreted land from the tidal flow coming in from the gulf. To the west of the island, a spit forms slowly gathering sediment and lengthening the island.

While pumping dredged sediment into areas of the delta helps create land, it normally only creates one type of habitat. Meanwhile, a crevasse will develop over time creating different elements of a marsh, thus attracting a diverse mix of wildlife and aquatic species. These elements combine to create a healthy marsh and mix of habitat.

LOUISIANA MASTER PLAN

“We can build land there,” says biologist Todd Baker. “It’s a constant changing landscape; land can form and disappear, we have the highest subsidence rate statewide. We’re fighting the biggest fight and can still beat it.” Many eyes have been on the coast lately as the Coastal Protection and Restoration Authority (CPRA) has recently published its plan of restoration for the coast, the Louisiana Master Plan. A few of the techniques laid out in the plan call for river diversions, additional water control structures and bank stabilization.

While river diversions are included in the project list, there are no plans for sediment disposal collected by the USACE at the delta. For many years the state has openly stated the Corps is non-consistant on the dumping of sediment into Pass-a-Loutre. The theory is simple: dredging of the river and dumping in Pass-a-Loutre is causing the pass to infill, which is increasing salinities, therefore decreasing abundance and diversity of vegetation, leading to rapid shoaling infilling the pass, and increasing erosion rates.

The state knows that the dredging and dumping technique is not the best for the delta or Pass-a-Loutre WMA, yet cannot justify projects in an area that can easily be impacted by sea level rise. The Master Plan instead focuses on flood risk reduction and land building for both the short and long term. An area like Pass-a-Loutre cannot be guaranteed as sustainable for the long term under the plan.

A DELICATE DELTA

Lack of funding has prevented more to be done on the east side of what could be the healthiest and most profitable delta in the gulf. Meanwhile, the shipping channel is maintained regularly and sediment deposited daily. Sea level rise and hurricanes are two unpredictable factors the area faces, but it also has a land building technique not many areas in the state can boast.

A sediment rich river pounds it’s way into crevasses daily creating various habitats and eventual land. When the funding is there, the Corps can deposit its sediment in numerous areas in the delta. And while floods keep us all on edge, the delta watches the land appear. The area can continue to provide for all, but at a cost to whom and how much?

It’s estimated that three-quarters of a million waterfowl and hundreds of thousands of other birds come through the Mississippi River Delta each year. For many birds, this area is their last stop before heading to areas of Central and South America. An economic staple for commerce and a true paradise for a sportsman, the area holds value for all. It is one of the few places in the state that has both fresh and salt water fishing within a mile of each other, deer and duck hunting, as well as millions of dollars of trade taking place on the very same passes.