Standing on a marshy shoreline, Eva Hillmann tosses a long cord into an old bayou that tells tales of New Orleans’ entire history.

She and her colleagues are hoping that their work along Bayou St. John will soon tell a few more.

Hillmann, chief scientist for the Pontchartrain Conservancy, is involved in a project aiming to determine the health of the waterway that winds through the heart of New Orleans. The results will be highly personal for anyone who has ever fished, paddle boarded or simply strolled along it.

“We do recognize this is a valuable waterway in our community,” said Kristi Trail, the executive director of the Pontchartrain Conservancy who accompanied Hillman on a recent demonstration of the environmental group’s testing. “The community’s curious about it, but we are curious too.”

The conservancy, a decades-old organization known for reviving Lake Pontchartrain in the 1990s, is collecting monthly water samples along different sections of the bayou, testing for qualities including heavy metals, bacteria, nutrients and algae.

An outgrowth of an earlier marsh creation project, it will offer insights into the health of habitats along the waterway, from transitional marshes to more hardened shorelines. Funding for the project came from a roughly $100,000 grant from the Coypu Foundation, Trail said.

The project began last year and will continue until November.

Residents have good reason to be concerned about the condition of the water in the bayou. In one famous example in 2019, crews removed about 750 tons of junk from the Lafitte Canal near the bayou, including a crushed car, a second car’s chassis, a truck bed and a sofa.

It is too early to say what the complete test results will show. But preliminary numbers have been good omens. 

‘Nothing drastically negative’

The cord Hillmann threw into the bayou near where it meets Lake Pontchartrain was connected to a handheld water meter. The meter collects real-time data on qualities including temperature, salinity and pH.

During the monthly samplings, a team of field scientists log these metrics and collect a water sample, which they send off to a lab. Hillmann stressed that the team is still in the first portion of the sampling and that the scientists haven’t analyzed the entire dataset.

“I wouldn’t want to say anything too soon, but nothing drastically negative for sure,” Hillmann said of the preliminary results.

The scientists have also not yet had the chance to investigate another important question: What happens to the water quality during a storm? The group received additional funding to sample the water after heavy rainfall, which they defined as two inches an hour. That hasn’t happened since the group started sampling.

Heavy rain could alter the makeup of the bayou, as water flows from the streets to the drainage system and into Bayou St. John.

“There may be pollution in our streets that drain into our sewer into the bayou,” Hillmann said. “And so there might be a spike, for instance, in nitrogen if people fertilize their lawns and that then makes its way into the bayou.”

This could add to existing debris in the bayou, such as underwater bicycles or old cars releasing metals, Hillmann said. These conditions could be exacerbated with heavy rainfall. 

Integral to New Orleans

The upper section of Bayou St. John – where Hillmann demonstrated the collection process – holds a rich history foundational to the city itself.

Until the late 1800s, it was the main drainage outfall for the city, intaking water from a network of bygone tributaries and discharging it into Lake Pontchartrain, explained Tulane geographer Richard Campanella. 

Indigenous travelers had long used the bayou as a path for trade and exploration. A portage road between the bayou and the Mississippi River served as a navigational shortcut that allowed people coming from modern day coastal Mississippi to bypass part of the journey up the winding river. French colonizers continued to use the path as their burgeoning settlement grew along the Mississippi River.

“In 1718, Bienville established New Orleans on account of that portage and that Bayou St. John connection,” Campanella said. “If it weren’t for Bayou St. John, New Orleans would have been located elsewhere.”

In the 20th century, the bayou was dammed off from the lake during construction of the city’s modern drainage system, ceasing its function as a natural outfall and navigational route, Campanella said. The bayou remained severed from the lake until 2013, when Louisiana officials dismantled the dam as part of a management plan crafted in the aftermath of Hurricane Katrina. 

That’s when the Pontchartrain Conservancy stepped in, too, creating the marsh beneath the Lakeshore Drive bridge over the bayou to establish habitat for fish, waterfowl and crab, as well as to improve the bayou’s water quality before it meets the lake. Grassy marsh filters the water as it flows through it.

The environmental group gathers water samples along different sections of the bayou – the marsh they created, a natural marsh area and more hardened shorelines.

The findings have been broadly positive, with low metal levels, Hillmann said. But the scientists wondered whether the data was “a one-time snapshot.” The current water testing in the next year will offer a deeper understanding of the conditions in the city’s historic and beloved bayou.

“If I was someone who recreated in Bayou St. John, like a paddleboarder or whatnot, I would be very interested in this water quality data,” Hillmann said. “The metals, the bacteria, the nitrogen, all of it is an indicator of how dirty or clean the water is.”