The Ample Hills ice cream shop in Gowanus now features a flavor, “It Came From Gowanus” — a salty dark chocolate ice cream combined with orange-scented brownies, hazelnut crack cookies, and white chocolate pearls — inspired by the brown, deeply polluted canal nearby. But the pearls, designed to represent the growing colony of oysters installed to help clean up the infamous waterway, serve as a speck of hope that one day, the Gowanus Canal may truly be clean.

The oysters growing in the Gowanus Canal are part of the Billion Oyster Project, which is a larger effort to restore the oyster reefs and population in the New York Harbor for the purpose of filtering filthy water and stabilizing shorelines. Oysters are natural water filters, and a single oyster can clean 30 to 50 gallons of water in a single day.

Oysters have been a staple in New York’s history since the very beginning. To aid the building of a growing city, oyster shells were sometimes burned for lime and mortar paste. Many restaurants featured oysters on their menu. And much like hot dog stands of today, oyster carts and vendors could also be found on every other corner. At one point, nearly half of the world’s oyster population were in New York, and there were roughly 350 square miles of oyster reefs in the harbor, according to author Mark Kurlansky. In his book “The Big Oyster: History on the Half Shell,” Kurlansky discusses how New York was essentially the oyster capital of the world.

But by the early 1900s, the oyster population significantly decreased due to sewage pollution and overharvesting. In other words, New Yorkers had eaten too many oysters, and the water was far too toxic for new generations of oysters to grow. In 1927, New York oysters were deemed too polluted to eat. It was not until almost half a century later — when the 1972 Clean Water Act was passed — that things began to improve.

The Billion Oyster Project aims to repopulate at least 1 billion oysters in the New York Harbor by 2035. Since 2014, the program has successfully restored over 30 million oysters. They have also launched various STEM education programs, teaching thousands of students and volunteers through their hands-on curriculum and restoration work.

More than 70 restaurants across New York City participate in the project through oyster shell donations. Instead of dumping the shells in the trash, they’re saved and used as a crucial step in the restoration process, serving as a bed for up to 20 new oysters to grow.

Every month, shells are collected from restaurants and transported to the curing site on Governors Island. Here, the shells are cleaned and prepared for reuse over the course of a year.

After the curing process, the oyster shells are returned to their natural habitat or used for educational purposes. Some of the shells are seeded with larvae. Those that return to the water will hopefully grow and become a “self-sustaining population.”

The Lobster Place, located in Chelsea Market, was one of the first restaurants to participate, and organizes shell collection. “We collect shells from participating restaurants, consolidate the shells, and then deliver them to a collection point where they’re ultimately delivered to Governor’s Island to cure,” said Davis Herron, the restaurant’s director.

The project was a light lift for The Lobster Place, because they already ran a large fleet of trucks in the city and delivered to many restaurants, Herron said. “We were approached by [the Billion Oyster Project] and it seemed like a no brainer to us.”

For him, the project is a worthwhile cause. “We’re committed to supporting ocean-friendly seafood while restoring and protecting our coastal environments,” he said. “Once you break the process down to restaurants, they quickly find that this is not difficult and a little effort has an outsized impact on our local environment. Overall, I think restaurants want to help out in any way they can, provided you give them a platform to do it on.”

Following the success of oyster repopulation elsewhere, the Gowanus Dredgers Canoe Club, a volunteer organization that raises awareness about environmental issues and advocates for the restoration of the Gowanus Canal, began their oyster program in the canal with the help of the Billion Oyster Project team.

This wasn’t the first time oysters were reintroduced into the canal. Around 1997, before pumping stations and the Billion Oyster Project, a group of volunteers put their first colony of oysters on the banks of the Gowanus Canal. Unfortunately, the oysters didn’t survive because of poor water quality and critters.

Oysters also used to be naturally abundant in the Gowanus Canal, but decreased due to pollution, according to volunteer Jean-Dominique Bonnet. “There used to be oysters everywhere where you could pick them up and eat them, and they would be the size of the plate,” he said.

Bonnet and his volunteer partner, Delancey Nelson, conduct a monthly monitoring of the oysters’ growth and progress. During an event along the banks of the Gowanus Canal on October 5, Bonnet pulled a roped cage filled with oysters out of the water and demonstrated ways to inspect their growth. Clumps of oysters are attached with a paper tag, which details the original number of oysters and the date they were installed.

He explained the project to the attendees, consisting of mostly young children and their parents, about the project. Holding a clump of oysters in his gloved hands, he pointed out other organisms that are also present in the cage. Some, such as oyster drill snails, are predatory and inhibit the oysters’ growth, but volunteers assure that this is a natural part of the water’s ecosystem, integral to the success of the program.

Unlike the New York Harbor where sewage discharge is now prohibited, sewer waste frequently overflows into the Gowanus Canal. As a result, oysters in Gowanus may have a lesser likelihood of survival. Bonnet said that oysters in the Gowanus Canal “would probably do worse, as they could get some kind of diseases” because of their exposure to human waste and accumulation of contaminants. However, he added that oysters that could potentially adapt more to local conditions are being grown.

“You wouldn’t eat these oysters because this is an industrial site, so maybe in 100 years, you could eat oysters that are grown here,” Bonnet said.

Owen Foote, co-founder of the Gowanus Dredgers Canoe Club, agrees that the oysters in the Gowanus Canal are facing an uphill battle. “I would say Gowanus oysters that are surviving are a bit stronger than your typical oyster,” he said.

However, there is hope. Foote notes that the volunteers have found oysters growing naturally on their own under the Ninth Street Bridge. “So that would basically mean that the oysters that we’ve seeded through our little cage on the Second Street dock could have potentially produced offspring, who would then have floated downstream to where the water quality is slightly improved near the Ninth Street Bridge, and the Ninth Street Bridge has some nice concrete that they can latch onto.”

He added, “It was quite exciting, as you can imagine, that oysters were growing there. And you have to realize that this is the most contaminated sediment of New York Harbor. It’s so contaminated that nothing grows here.”

Throughout the years, there have been many attempts — some more successful than others — to clean up the Gowanus Canal. After the Environmental Protection Agency declared it a Superfund site in 2010, many government-funded plans were swiftly put into place. Cleanup costs are estimated to potentially exceed $1 billion, but the agency is hesitant to declare an expected completion date due to delays and setbacks. That is to say, there are long ways to go.

But instead of waiting for the government to move forward, the oyster project in Gowanus — even if it ends up being a less immediate or impactful method — provides residents an opportunity to contribute to cleanup efforts in a more hands-on way and to ultimately become more informed citizens on local environmental issues.

If anything, the oyster program is one way to bring people together, Foote said. The club also hosts many other events, including arts and music programs, to encourage people’s engagement with the shoreline and their environment.

“Even though we might have diverging opinions on many, many different topics, the one thing we can all agree on is we all have the same planet,” he said. “And perhaps we should be doing things that can potentially improve, in some small way, the health of our planet. In that aspect, I think we find common ground, and also come together as humans.”