South Coast scientists: To improve bay health, start at the source

MATTAPOISETT — Peering over the edge of a stone bridge, Francesca LoPresti cast a bucket into the Mattapoisett River. She pulled it up slowly and grabbed a syringe, filling it with the clouded water. She then squirted the water back out onto the river below, the stream forming a clean, unbroken arc.

“This is scientific,” she assured with a laugh. “We have to get a clean sample, so we rinse out the first take.”

LoPresti is a fellow with the Woodwell Climate Research Center in Falmouth. For the past week, she and her colleagues at the Buzzards Bay Coalition had been visiting the rivers and streams that make up the Buzzards Bay watershed, collecting water samples and testing them for contaminants.

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Her work is part of a much larger attempt to improve water quality in the region. To restore the bay’s health, researchers, advocates, and city and town officials are working together to clean up pollution in these smaller, urban waterways, including New Bedford’s Buttonwood Brook.

“We’ve done a really good job of monitoring water quality in the bays, but we haven’t monitored the quality of the water and done the measurements that allow us to figure out how much nitrogen is coming down the rivers,” said Chris Neill, the lead scientist on the Woodwell Climate Research Center’s Rivers project.

Trudging through wetlands on a cold April day, LoPresti and her colleagues noted time of day, water temperature, and other factors.

“Tomorrow better be warm and sunny,” LoPresti said.

Respecting the balance

The substances Neill and LoPresti are testing for aren’t necessarily bad for the environment — it just depends on their quantities.

For every body of freshwater, Neill looks at the different nutrients and nitrogen in each sample. Nutrients and nitrogens are necessary for plant life to grow, but too much of them can lead to an overgrowth of algae that can cloud the water, block sunlight, and choke out other organisms. 

Nitrogen is naturally found in decaying leaves and other organic matter, but the main source of nitrogen in our waterways is from agricultural fertilizer, sewers and septic systems — which are much more harmful to water quality.

On the western side of Buzzards Bay near the Westport River, septic tanks, which create a constant leak of nitrogen into the groundwater, pose the biggest threat, followed by fertilizer runoff from local agriculture. In New Bedford, the city’s older sewer system is prone to combined sewer overflows during rain, causing both sewage and stormwater to flow into the surrounding waterways.

Closer to Wareham, Neill looked at the region’s cranberry industry to see if its agricultural practices, which all take place in wetlands, has an adverse impact on water quality. He found that fertilizer used on cranberries is actually less harmful than the fertilizers used in traditional agriculture.

“There’s no one source we can point to,” Neill said. “Every area has its own unique problems and solutions.”

How to clean up Buttonwood Brook?

Neill’s work depends heavily on data that Dan Goulart gathered while at the Buzzards Bay Coalition. He is now a coastal project manager at The Nature Conservancy, but nearly a decade ago he began the work of monitoring water quality down the entire length of Buttonwood Brook.

The numbers he found were “staggering,” Goulart said.

“As a kid [the brook] was something I used to play in,” he said. “Now it’s something that if you touch, you could get sick and die.”

Buttonwood Brook begins near I-195 and spills out into the Apponagansett Bay by Padanaram Village in Dartmouth. Throughout its course, Goulart found three major sources of contamination: the Hidden Brook apartment complex, a neighborhood of roughly 100 houses in Dartmouth, and New Bedford’s Buttonwood Park Zoo.

“We had found that at the upper end of the system, north of Buttonwood Park, most of the bacteria was coming in during bad [rainy] weather,” Goulart said. “But in the south end in Dartmouth, nitrogen was entering the system in dry weather, too, which tells you that it’s happening all the time.”

Goulart pursued three initiatives to clean up its waters. Two made little progress.

The first was an attempt to clean up the sewage system around Hidden Brook apartments. True to its name, the complex had been built directly on top of Buttonwood Brook, before the state had created building regulations for wetlands. For this reason, the apartments were prone to flooding, and their owner was eager for a fix, Goulart said.

Goulart said he ran into difficulties buying the wetlands neighboring the complex to complete the necessary upgrades, so he abandoned the project.

The second project was an incentive program for about 100 Dartmouth residents to connect to the town’s sewer system. A partnership with the town’s Department of Public Works, called “Connect to Protect,” offered $6,000 to residents willing to ditch their leaky septic tanks.

Still, even with a cash incentive, Goulart and town leadership had trouble drumming up interest. The Buzzards Bay Coalition is continuing to recruit new homeowners for sewer upgrades under the direction of former Dartmouth Town Administrator Mike Gagne.

Dartmouth’s Director of Public Works Tim Barber said that just three residents have connected to the town sewer through the program since its inception, although he expects more residents will apply.

“Even with the discounted program, there are still out-of-pocket costs that can be difficult for residents to afford,” Barber said in an email.

Goulart said the neighborhoods still in need of a sewer hookup tended to be lower-income, working-class areas of Dartmouth. He said he regretted not having time to canvas on foot and spread the word about the program.

“I wanted to get a ground game going, but that takes a lot of time and resources,” Goulart said. “It’s tough to walk away from.”

Addressing the elephant in the room

Goulart did succeed in addressing one major source of nitrogen pollution: elephant poop.

During his monitoring, Goulart found that the water exiting the Buttonwood Park Zoo was a lot higher in bacteria than the water entering it. When he looked into it, the reason was fairly obvious: water passed right through the buffalo and elephant habitats, two species capable of producing, well, a lot of nitrogen.

So Goulart worked with the City of New Bedford, which owns and manages the zoo, to help keep animal waste out of the brook. Goulart secured funding for green infrastructure upgrades and helped design them. The zoo recently began preliminary steps to install several stormwater upgrades, including a rain cover over the dumpster that stores the elephant Emily’s excrement.

Goulart said these improvements to the Buttonwood Brook area, while important, are only a “surface touch.” The real work is never-ending.

Other waters, other efforts

New Bedford has spent hundreds of millions of dollars to reduce combined sewer overflows, just a portion of the $1.2 billion needed.

Chance Perks, the city’s conservation agent, spends hours on top of his official duties cleaning up urban forests, wetlands and streams that form a patchwork through New Bedford.

That’s because both Neill’s and Goulart’s research found that forested areas, even very small ones, successfully reduced nitrogen levels when the water ran through them.

For Perks, who has a background in forestry, it’s all the more incentive to continue to protect New Bedford’s green space. That includes chastising the occasional resident dumping their hydrangea trimmings in the stream by their backyard, but it also means a regional land use plan that accounts for the next 100 to 500 years of conservation.

“We need to bring attention to our stream courses, these watersheds, these little emerald ribbons that run through our city,” Perks said. “As our country evolved and advanced, we learned that we’re only hurting ourselves when we try to use our waterways as cesspits and waste disposal. So as we get better, we’re trying to strike that balance between humanity and the rest of creation.”

Email Brooke Kushwaha at bkushwaha@newbedfordlight.org.

Editor’s Note: The story was updated on Friday, May 8, 2026, with the Buzzards Bay Coalition’s involvement in the river monitoring and Connect to Protect programs. The story has also clarified that septic systems are the number one source of waterway contamination over agricultural runoff.

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