One rain garden at a time, residents work to clean up polluted Green Hill Pond
SOUTH KINGSTOWN — Gathering in Norma Roelke's clamshell driveway on Saturday morning, more than a dozen volunteers grabbed shovels and wheelbarrows and quickly got to work digging up a section of the grassy lawn.
Within a matter of hours, they'd installed a brand new rain garden below her roof gutter, designed to capture stormwater before it can enter nearby Green Hill Pond.
"If this could be replicated over and over again for hundreds of residents in this area, we could really make a difference," said Zach Henderson of engineering firm Woodard & Curran.
Since 1994, Green Hill Pond has been closed to shellfishing. Studies have shown the pond's bacteria counts routinely spike after it rains, indicating that stormwater runoff is a major part of the problem, said Dennis Bowman, the president of Friends of Green Hill Pond.
And since the surrounding area is almost exclusively residential and has minimal municipal infrastructure, Henderson noted, individual homeowners will have to be part of the solution.
"It’s on all of us to do our part," he said.
Recruiting neighbors to help reduce runoff
Roelke didn't need much convincing when Richard Bourbonnais, South Kingstown's director of public services, attended a recent community meeting and asked if any Green Hill residents would be willing to install a rain garden on their property.
Rain gardens are effectively catchment basins, planted in shallow depressions to collect runoff. Hardy native plants help drink up the excess water, while also adding aesthetic appeal. (As an added bonus, homeowners won't have to spend much time watering them.)
"It was absolutely serendipitous," Roelke said. "I never thought about it, but as he was talking about it, it made a lot of sense."
Elevated on pilings, Roelke's simple green ranch house sits near the edge of Teal Pond, which is known locally as Teal Lake and flows directly into Green Hill Pond. She's lived there for three years, she said, but has been in the area for more than two decades — so she's well aware of the longstanding problems with pollution.
"I think one of the things that’s good about this is that it’s a combination of private and public," she said of the rain garden initiative. "I think we have to think more about doing that."
Roelke purchased the plants, choosing from a list of recommended native perennials and selecting milkweed to attract butterflies, and dogwood and winterberry for the birds. On Saturday, a group that included Bourbonnais, Bowman, multiple Woodard & Curran engineers and their families, and enthusiastic neighbors arrived to help plant and mulch the new garden before the clouds opened up.
"I think it's a fabulous move for everybody," said Susan Dey-Sigman, who lives down the street from Roelke and already has two rain gardens of her own.
A 'two-pronged solution' for perennial problems with pollution
Woodard & Curran has developed a number of designs for rain gardens that homeowners can install on their own, and Saturday's event was intended to serve as a demonstration.
"It's not exceedingly complicated," Henderson said, noting that he's planted rain gardens on his own property without following a specific plan. But homeowners who aren't quite sure where to start — how deep to dig, what plants to incorporate and where to buy them — can turn to the handouts for guidance.
So far, 10 residents have signed up to install one of the rain gardens that the engineering firm designed, said Mary-Gail Smith, a director of Friends of Green Hill Pond.
Green Hill Pond is unique among Rhode Island's salt ponds because it lacks a direct connection to the ocean. Tidal waters have to travel about half a mile through the Charlestown Breachway and Ninigret Pond before they enter Green Hill Pond through a narrow inlet.
As a result, there's less opportunity for fresh ocean water to flush out nitrogen and bacteria.
A 2005 study found that septic systems were overwhelmingly responsible for the problems with excess nitrogen — another issue that Friends of Green Hill Pond is trying to address. Meanwhile, high bacteria counts are mainly linked to stormwater runoff.
In 2020, the nonprofit teamed up with the town of South Kingstown to commission a detailed report from Woodard & Curran that determined that rooftops, driveways and roads in the residential neighborhoods surrounding the pond were major sources of runoff.
They landed on what Bowman described as a two-pronged solution — constructing municipal stormwater filtration sites on public property, while also encouraging residents to take matters into their own hands by installing rain gardens.
Friends of Green Hill Pond and the town of South Kingstown are each contributing $16,500 toward the project, which received a $99,000 federal grant from the Narragansett Bay Estuary Program.
"Together, we think it will make a material difference in the pond’s water quality," Bowman said.
'People want to do the right thing'
Green Hill Pond was once a prime spot for harvesting oysters, quahogs and soft-shell clams. But it's unclear if the efforts to improve its water quality will allow it to reopen for shellfishing.
"If it happens, that would be great," Bowman said. "The problem is that the state’s shellfishing standards have been tightened."
Instead, he said, the goal is to make the 430-acre salt pond safe enough in which to fish and swim.
Green Hill Pond isn't officially closed to swimming, Bowman said, but his advice to friends and neighbors is to swim in the much cleaner waters of the ocean-facing beach, and "leave the salt pond for kayaking."
It's a strong incentive for people who live on the pond to embrace environmentally-friendly measures.
"The vast majority of people want to do the right thing," Bowman said. "They just need to be educated about what the consequences are, and what the benefits are. I’ve been heartened by that."
This article originally appeared on The Providence Journal: Green Hill Pond neighbors turn to rain gardens to fight bacteria
