Invasion on the Bayou Securing Louisiana's Drinking Water from Storms, and Plants

Elephant ear plants may be ornamental on your coffee table, but in a major Louisiana bayou they’re an invasive species that could choke the waterway—the source of drinking water for 300,000 rural residents of the state.

A new water diversion project is sending Mississippi River water down Bayou Lafourche (pronounced “lah-FOOSH”), which empties into the Gulf of Mexico. It will help to purify the drinking water and keep the elephant ears and other invasives at bay.And it is hoped that the project will later help to restore the area’s wetlands, which are disappearing faster than any other land on Earth.

The bayou was once a main channel of the Mississippi River (its name means “fork” in French), but it was dammed off in 1904, after area residents complained of the great increase in annual flooding; the entire river to the north had been enclosed with levees to prevent upstream flooding and almost 2,300 miles of riverwater were coursing into the bayou. Fifty years later, after residents complained that the bayou had become a small, stagnant stream, pumps were installed in Donaldsonville, at the site of the original closure, and began pumping 340 cubic feet of water per second down the bayou—just 4% of its original flow. Over the years, as the bayou began silting in, the water flow diminished.

Then two devastating hurricanes—Gustav and Ike—slammed directly into the bayou in the summer of 2008, doing even more damage to the area than the two “girls gone wild” (according to a T-shirt sold in New Orleans’ French Quarter), Katrina and Rita, did in 2005. The storms stirred up sediment, creating a black, putrid-smelling mess that made the water undrinkable. Residents had to drink bottled water for several months until the sediment resettled, but the situation made politicians and policymakers take notice.

Elephant ear plants

Enter the Emergency Bayou Lafourche Capacity Restoration Project. By dredging the bayou, its short-term goal is to re-establish the former 340 cubic feet-per-second (cfs) flow along the first 6.2 miles of the bayou, which is enough to protect the water supply. The long-term goal is to bring in enough water to increase the flow to 1,000 cfs. “That would aid in reducing coastal land loss,” says Kerry St. Pé, program director of the Barataria-Terrebonne National Estuary Program (BTNEP). The estuary has lost more than 1,900 square miles since the 1930s—almost the size of the state of Delaware—and is still losing a football field’s worth every 40 minutes.

“As we lose land masses to the south, saltwater is able to intrude up Bayou Lafourche,” St. Pé continues. “That would never occur—and has never occurred— “til we started losing all this land.”

The $20 million in funding to dredge the first 6.2 miles of the bayou is coming from the state of Louisiana, part of the $300 million Gov. Bobby Jindal dedicated to wetlands restoration when the state was flush with revenue in 2008 from a surge in payments from the high-riding oil and gas industries. The whole project, along the entire 52 miles of Bayou Lafourche, is slated to cost $150 million.

For the past decade, BTNEP has sponsored a four-day canoe trip down the bayou as a way to raise environmental awareness among residents and encourage stewardship, since the water has collected the flotsam of everyday use, from discarded fishing gear to furniture. In recent years participants have also come from as far away as Mexico, Indiana and Connecticut.

The bayou by canoe

Michael Massimi, BTNEP’s invasive species coordinator, explained on one such trip that invasives like elephant ears, hydrilla and water hyacinth don’t just out-compete native plants in the bayou, like arrowhead (known locally as “duck potato,” because it’s a favorite food of ducks), but, “They’re actually modifying the habitat,” Massimi says. “For example, elephant ears can tolerate growing in standing water, so they grow out from the banks and shoot up their stems, which collect sediment close to the bank, narrowing the stream, and keep growing out farther unless you dredge them.” And, unlike what it replaced, elephant ears provide no food for bayou inhabitants.

Hydrilla presents its own set of problems, Massimi says. It can grow in great mats that cover big sections of the water surface. “It makes fishing impossible and impedes recreational uses. If it’s too thick you can’t even get a boat through it. And if we have a particularly dry summer,” he says, “the water flow slows down, allowing more sunlight to penetrate, promoting growth of hydrilla. The water backs up and you get high water events near the headwaters, and saltwater intrusion from the Gulf; since freshwater can’t move down, saltwater moves up.”

St. Pé, a seventh-generation resident like many others who live among the bayous of southeastern Louisiana, adds that this project is an important first step, but much more must be done to restore the wetlands.

“We need to harvest sediment from the bottom of the river and pump it out to build back what we lost and then sustain that with freshwater diversions,” he says. “We need to build new land. We need to get land between us and the massive storm surges we get from these hurricanes. People have always been concerned about hurricanes, but they’re deathly afraid of them now.”