On Golden Swamp

Rebuilding Gulf Coast wetlands means enhanced protection from future storms and healthier ecosystems

• By Katie McCarthy
• Oct 01, 2006

Hurricane Katrina left a wake of devastation in its path -- thousands dead, New Orleans flooded, a whole population displaced, and billions of dollars in destruction all along the Gulf Coast. A true national disaster, Katrina revealed the coast's vulnerability. It also opened up discussion on some key environmental issues. A recent poll conducted by Zogby shows that not only are Americans more convinced that global warming is happening than they were two years ago, they also are linking recent intense weather events to global warming. The discussion extends further than the American public -- some of the best technical minds are working to prevent another disaster.

The process has already started. A year after the hurricane, people are rebuilding, not just their homes, but their lives. The Bush administration has committed more than $110 billion dollars to help rebuild the Gulf Coast. The U.S. Army Corps of Engineers will receive $6 billion to repair levees and restore wetlands near New Orleans.

The Corps plans to finish its hurricane protection system by 2010. Levees will protect the city, and wetlands will be restored to help absorb hurricane surge. Congress has also pledged an additional $20 million for a study on how to build even more comprehensive hurricane protection.

One area that the federal government will need to invest in is the region's infrastructure. The landscape of Louisiana has changed dramatically since the Mississippi River's channelization, a reaction to the flood of 1927. Many of the state's swamps have faded into marshes or disappeared altogether. Other contributors to the reduction of Louisiana's natural wetlands include increased development, rising sea levels, and hypoxia (oxygen-deficient waters) in the Gulf.

With the recent hurricane activity, wetlands are being talked about once more. Restoration of wetlands means better storm protection. Restoring the coast should not only be an effort to rebuild the levees, but an effort to create wetlands that offer benefits for defense against destructive weather events such as hurricanes. Restoring wetlands also gives Louisiana the chance to develop rich environments preserving diverse species.

Katrina has brought attention to the importance of wetlands, and it also has brought funding to the area. Now, environmentalists are faced with the challenge of how they will develop the Gulf Coast for the future.

Ecological Effects
When Katrina made landfall on Aug. 29, 2005, the storm surged into the coastal areas, causing ecological devastation to much of Louisiana and Mississippi. The winds destroyed forests that were havens for wildlife and migratory birds; saltwater and polluted floodwaters from New Orleans poured into Lake Pontchartrain.

The effects of the hurricane can be traced to a changing environment along the Gulf Coast. Rising sea levels and continued development are a deadly combination.

"When people look at the Gulf Coast today, they don't realize that it's just a snapshot at one point in time," said Paul Keddy, PhD, and Edward G. Schlieder endowed chair for environmental sciences at Southeastern Louisiana University. "I don't think the message has got out about how serious this level of rising is."

Since the end of the last Ice Age, 20,000 years ago, sea levels have steadily been climbing. The sea level is currently 100 feet higher along the Gulf Coast. The earth does go through warm periods that cause shorelines to move in and out along coastal areas, but this warm period isn't necessarily just a natural phenomenon.

The rise of carbon dioxide (CO₂) levels in the atmosphere is making the planet warmer. As a result, ice sheets are melting all over the world. One of the most important pieces of supporting data, according to Keddy, is the Vostok Ice Core drilled in Antarctica in 1998. Scientists drilled three kilometers into the ice, uncovering more than 400,000 years of Earth's history. The four ice ages are represented with CO₂ levels cycling up and down naturally. In the last 100 years, the CO₂ levels go off the chart and the conclusion is that we're living in an era of unprecedented levels, Keddy said. And with the earth warming, sea levels will continue to rise.

The problem is that small changes in sea level have a devastating effect on coastal cities and natural ecosystems, including wetlands.

"Well, what would have happened in the past is that the wetlands would have moved inland, but now we have cities stretched along," Keddy said. "So the wetlands can't move inland and they're getting flooded out by rising sea levels. We're probably going to have to recognize and delineate an area all along the coast as some sort of storm zone or flooding zone where we recognize that everything in there is increasingly at risk."

Rising sea levels present a challenge to the future of the Gulf Coast. Without wetlands as buffers, urban centers along the coast may have only levees to protect them. For communities further inland, large areas of wetlands and forests may be the answer.
Wetlands absorb storm surge. And one of the best examples of this is from the 2005 hurricane season. Hurricanes Katrina and Rita had two different effects in the Louisiana area, mostly because of where the storms hit.

Rita hit along Louisiana's southwest wetlands, which slowed the hurricane down tremendously. The 30 kilometers of wetlands decreased Rita's storm surge by 1.5 meters. Five centimeters of surge reduction per kilometer helped protect inland populations from the storm.

Sentinels Along the Coast
The area along the Mississippi River changed drastically in the last century. Up until the 1920s, cypress logging around Lake Pontchartrain was particularly heavy. Wetlands that were essentially forests with 20 to 30 meter-tall trees are now open ecosystems resembling marshes and grasslands. The conversion allows the Gulf of Mexico to flood in toward Lake Pontchartrain, bringing saltwater that kills the area's vegetation. The key to restoring these areas will be to bring back the cypress swamps, which held their own during Katrina and Rita.

"They almost acted as sentinels protecting the coast as they stood there in a line almost fighting back the waves, the wind," said Gary Schaffer, PhD, a professor of biological studies at Southeastern Louisiana University.

Research on hurricane protection found that during Hurricanes Andrew (1992) and Betsy (1965), it was the cypress forests that survived. While 80 percent of hardwood forests were knocked to the ground, less than 10 percent of cypress swamps were affected. Comparing satellite imagery from 2004 to 2005, the landscape is astounding. Marsh areas are missing, hardwood forests are mostly knocked over, and the cypress and tupelo forests are essentially completely intact.

Cypress trees hold up well to high winds, and that's important because the more trees that fall, the more flooding and the more loss of soil.

"Hurricane Katrina was kind of a test. No experiments were in place, but it was a good test for how these wetlands systems resist hurricanes," said Colin Jackson, PhD, an assistant professor of biology at University of Mississippi.

Bringing back the swamps will take fresh-water diversion. Water will wash out some of the salinity caused by the Gulf and bring in nutrients. According to Jackson, one idea is to divert some of the flow of the Mississippi River into the wetlands surrounding Lake Pontchartrain.

Diverting a small portion of the river will bring much needed fresh water with more nutrients and oxygen. Diversion has been an ongoing process; the Corps is actively pursuing several projects that will channel the water into new areas. Hopefully, diverting the water will be the first step in restoring Louisiana's wetlands.

Restoration Projects
Smaller cities in Louisiana are already pouring money into wetland restoration projects.

Hammond began a project that uses treated domestic wastewater to encourage growth. Cypress and tupelo swamps do well with wastewater, providing tertiary treatment for that takes essential nutrients and filters out water that is drinkable, fishable, and swimmable. Started at the end of September, the Hammond project pipes treated wastewater into a marsh 10 miles away and releases it into the wetlands. The project is basically a giant showerhead, 10 feet off the ground, running for 3/4 of a mile spreading nutrients. Shaffer and his colleagues plan on planting 7,000 cypress, tupelo, ash, and maple trees within the first year and expect the trees to reach 30 feet within 10 years.

Shaffer, who has been advising state and federal agencies about wetland restoration since 1990, wants the Hammond project to serve as a prototype for the rest of costal Louisiana. The project is a how-to guide on converting historic swamps that have converted to marsh and open water back into swamps.

The city of Thibodaux has seen great success with a similar project. There trees near Lake Maurepas are gaining tremendous thickness each year. Cypress trees usually put on the thickness of a credit card in diameter each year. Due to the nutrient-rich effluent, Thibodaux's trees are putting on 1/2-inch in diameter each year. The project is also saving the city $2 million in sewage treatment costs a year, according to Shafer.

Another Louisiana city, Breaux Bridge, is saving $1 million by using a similar process.
Planting trees also provides longevity to the region. Cypress and tupelo trees grow for centuries, and that change in the landscape will help ensure protection.

The Future
Pitched to Congress as the "Louisiana Coast Area Project," restoring Louisiana's wetlands will cost $14 billion. Shaffer has been asking for $2.8 billion for projects that will have immediate benefits. And after Katrina, the marriage between wetland restoration and hurricane damage reduction is solid. But wetland restoration won't be enough to protect the Gulf Coast.
Keddy believes that we have to start prioritizing how we treat the coast. Along with restoration, we need to consider where we build in relation to undeveloped natural areas. If we take steps to help ensure space between the coast and the population, hurricane surges might not have such a tremendous effect. Also with efficient levee systems and additional wetlands, more protection can help. But all of that progress will depend on how the area is restored and if it is restored correctly. It is also about learning our limitations as humans living in an ecosystem. That may mean reduced building along the coast.

"If we just live in denial, then we are just going to end up with areas that look like New Orleans today, which are heartbreaking," Keddy said. "There's no power still, block after block of wrecked houses, many of which people drowned in, and we're going to see more of that."

Protecting the Gulf Protects Biodiversity While restoring the Gulf Coast, providing protection for the diverse regions should be taken into consideration. The Gulf Coast provides a habitat for many unique plants and animals. Scientists studying the area have found that as sea levels rose and fell, the rivers in the Gulf States served as a natural corridor for plant life spreading throughout the region. "The Gulf Coast has been underappreciated as to how important it is as a diverse area," said Paul Keddy. "Biologists have not done a good job of explaining to the public how important these areas are on a national scale." Florida's largest river, the Apalachicola, contains a very diverse biota. Ecosystems range from upland forests, swamps, and marshes, to floodplain wetlands. Some sections of the watersheds along the coast provide the richest biodiversity in all of North America. The highest density of amphibian and reptile species in the country occurs here, and barrier islands provide an important habitat for the Gulf migratory birds. Old deposits of the Apalachicola River contain carnivorous plants that exist nowhere else in the world. Of more than 110 different plant species, 58 are threatened or extremely rare. To start restoration, natural areas have to be blocked out for conservation planning. Keddy recommends raising the number of acres under protection from 500,000 to 1 million. Providing more acreage for natural areas allows for more animals to be protected and at-risk animals to flourish. Keddy believes with more habitat animals like panthers, wood storks, and red wolves could thrive.

Wastewater Treatment: The Cypress Method Before finding its way to cypress forests, municipal wastewater first undergoes primary and secondary treatment at a wastewater treatment traditional facility. Wastewater is treated though a series of outdoor open treatment tanks, including an aerated lagoon, a primary clarifier, a biological rock filter, and a final clarifier. It then moves through an ultraviolet light treatment chamber and control room in order to disinfect it. Sludge drying beds prepare the biosoilds for composting before a spillway releases effluent into the cypress and tupelo swamp for tertiary treatment. Saving cities in Louisiana the cost of tertiary treatments, the adjacent wetlands become tertiary treatment facilities. Tertiary treatment involves the removal of inorganic nutrients including nitrate and ammonia as well as phosphorous. "The idea is that you have to do a couple of things to spread the nutrients out over the wetlands effectively," said Gary Shaffer. Treatment is natural in wetlands and consists of two processes, according to Shaffer. The first is a microbial process that involves denitrification where the microbes metabolize with nitrate rather than oxygen. The second process uses assimilation by the plants. The plants turn nutrients (fertilizer) into the tissue of the ecosystem (wood and leaves). Shaffer predicts that, by letting the wetlands do the work, a city can save more than $2 million dollars per year and provide excellent clean water. The process also ensures healthier swamps. The city of Thibodaux saved a swamp that had lost its water source. Today, the city is providing nutrient-rich water and once again the ecosystem is thriving.

This article originally appeared in the 10/01/2006 issue of Environmental Protection.