One evening in early spring, Gary Francis hopped over the fence at the end of Douglass Street in Brooklyn, near the edge of the Gowanus Canal. Rain was coming down in thick sheets. But instead of the fresh smell of April storms, an aggressive, sulfurous odor billowed up from the waterway below.

Gary shimmied up a stone wall on the other side of the fence and stared downward like a gargoyle, infatuated by the army-green water.

“This is… pretty bad,” he muttered, watching debris race by. He pointed out toothpicks, menstrual pads, even decomposing sewer rats bloated with water—or, as Gary refers to them, “Gowanus footballs.” 

Rain droplets speckled the lenses of Gary’s thick eyeglasses as he peered into the profaned canal. Every few seconds he’d point out something new to me, and from his tone of voice you’d think he’d just been lucky enough to catch sight of a rare bird.

“Look! There’s a Coney Island whitefish right there!” he shouted with glee as a used condom bobbed by, whisking downstream past buildings and under bridges, through the meandering 1.8 mile-long waterway considered to be one of the country’s most foul.

Gowanus wasn’t always this way. Before concrete and chemicals, the area was a lush intricate patchwork of tidal creeks, salt marsh, meadows, freshwater streams, and wildlife, before the Dutch colonized Long Island’s western end in the early 1600s. The area that the Dutch called Gowanus—a name likely referencing a leader of the indigenous Lenni-Lenape here, called Gouwane—comprised the bay, the coast of Brooklyn, hills that are now part of Prospect Park and The Green-Wood Cemetery, and parts of Sunset Park. The Lenape band called Canarsee farmed on the territory. In the seventeenth century, Dutch settlers farmed tobacco and harvested oysters there. But by the 1800s, after New York became an English colony and then part of the United States, several of these creeks were dammed, dredged, and converted into one of the busiest waterways in the country.

Gary Francis with his Duro Kit on the canal, 2024.

Photo: Amy Pedulla

In 1869, the Gowanus Canal was a bustling thoroughfare of commerce. More than 100 ships passed through every day. All kinds of business operated there: coal gas manufacturing, oil refineries, cement makers, sulfur production, and soap factories, all of which produced pollutants that ended up in the canal. Then, with the explosive development and building of homes along the canal, the new buildings needed a sewer connection. This was the beginning of the waterway’s downfall: the city’s sewage system was constructed to empty directly into the channel.

By the time Mayor William Jay Gaynor erected a flushing station to address it in 1911, the canal’s stench was notorious. In his 1940 novel, You Can’t Go Home Again, Thomas Wolfe described the canal’s “huge symphonic stink” of waste. It earned the nickname “Lavender Lake” for its unnatural color. The term “black mayonnaise”—referring to the thick, dark, and smooth toxic industrial sludge that sits at the bottom of the canal—became ubiquitous in popular media descriptions. The chemicals and the sewage combined gave the gunk a soft texture, the black color forming from the liquid tar of gas plants, petroleum, and decomposed sewage.

At the start of World War II, roughly 18,000 boats entered the canal, which was a drop from the bustle of decades prior. Then in the 1950s, that number continued to fall. After 1955, the Army Corps of Engineers did not gather data on which boats were trafficking on the water. Around 1960, a propeller drive shaft in the Flushing Tunnel (the canal’s northernmost point) broke and wasn’t repaired. For decades after, the waters remained stagnant, abandoned. The Gowanus was essentially left to perish.

By 2010, the Environmental Protection Agency had deemed the canal a Superfund site—a threat to public and environmental health, requiring long-term response and funding for cleanup efforts, which began with dredging work in 2020. These efforts have been organized by government agencies, but have also seen the Gowanus Dredgers Canoe Club, an intrepid group of citizen scientists led by Gary Francis, play an increasingly vital role.

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Every bit of Brooklyn rainwater, whether it falls on a roof, a sidewalk, a street, or runs down the smooth glass sides of high-rise buildings, goes directly into the sewer. The combined sewer system sends all water, as well as raw sewage, through one pipe. But when it rains really hard, and residents of Gowanus flush their toilets during a bad storm, sewage flows into the nearest channel. As weather intensifies as a result of climate change, millions of gallons of waste are churned into the Gowanus Canal every year. Hence why Gary Francis and his fellow Dredgers walk and paddle its length every day. The water eventually empties into Gowanus Bay, and then into Upper New York Harbor, just above Sunset Park.

Undeterred by odor, trash, and layers of poisonous mayonnaise, Gary has journeyed up and down the canal every day for the last few years, no matter the weather. He carries a water-testing box called a Duro Kit—a lunchbox-like pack which he held on the rainy night we met. I watched him, his back slick with water, blue eyes wide and searching, as he plugged small probes into the little blue box, then lowered it gingerly into the canal. Holding tight to the attached rope, he was fishing for data—information about the water’s pollution levels—and awaiting the canal’s confession.

Gary is not a trained scientist, nor does he work for a city environmental agency. But as the captain of the Dredgers, he hosts meetings for current members, newcomers, local Gowanus residents, and anyone else inclined to take a new look at the much-maligned waterway running through the center of Brooklyn. Members can learn to canoe on the canal, but they can also get involved with the daily efforts to measure, analyze, and publish the water pollution levels online—which they do every single day, from various water-lined streets. Gary also tends to the canal’s mussels—some ribbed and red, others rare, small, and blue—which he nurtures in a cage and returns to the water once they’ve grown and spawned safely.

The Dredgers want to turn the waterway back into the lush, wildlife-rich habitat it used to be. They embody a mantra: What can be thrown away can be reborn. Mussels will spawn in these pitiful waters. A family of geese perched along the shore will grow watching boaters paddle canoes. The Dredgers believe there’s a way to resurrect something rotten, to make new life from seemingly primordial ooze.

Like an agent trying to preserve the reputation of a client, they work daily to combat the waterway’s poor image, an image that has been tarnished for decades by even the most loving locals. Despite that long-standing baggage, Gary tests the water as many days in the week as possible, at multiple locations along the canal: 9th Street, 4th Street, 2nd Street, and Douglass Street. He says that his measurements are more accurate than the scant public information about the waterway’s pollution levels.

Gary says agencies like the EPA measured dissolved oxygen levels for a short period, but they do not collect data on their own. They rely on the Gowanus Remediation Team's contractors to gather and share information about water quality, and the NYC Department of Environmental Protection doesn’t seem to publish its own data at all. The NYC Open Data portal has a Harbor Water Quality section, but the most recent information about the canal is from December 2024. The variables they test for are not consistently measured: "Dissolved Oxygen," for example, was last reported on September 28, 2006.

In other words: No entity gathers data as consistently or comprehensively as Gary and the Dredgers do.

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If Gary’s job is to fish for data, fellow Dredger Corinne Brenner’s role is to study the catch. Corinne was the director of learning for an edtech company and now teaches at NYU. She first became connected to the group over a decade ago, in 2014. Her focus is the memory card inside Gary’s water-testing kit. “With my slightly more delicate fingers than Gary’s,” she told me, “I take out the little memory card and put it into my computer.” She then takes the CSV files and labels the data for each stop on the canal Gary has measured. Finally, she makes his findings into a graph and publishes it.

The kit measures water’s temperature, pH, Oxidation-Reduction Potential (used to measure water’s ability to gain or lose electrons, which affects its ability to break down waste or other contamination), Electrical Conductivity (how easily the water can carry an electric current), and TDS (total dissolved solids in the water). It also measures salt content and, perhaps most crucially, dissolved oxygen levels.

This last measurement is essential for the survival of fish and other marine life. “ I think the EPA and also the city are doing various kinds of data collection and using really good methods to do that,” Brenner said. “But they're not doing it at a pace that is necessarily helpful to the people living around here and using the canal like we are.”

The Dredgers are all volunteers working independently. What these citizen scientists lack in official status, they make up for in personal investment: What happens to the canal directly affects their lives. “It’s the people who walk across the canal rather than scientists who may be based in Albany or maybe are in an office in Manhattan,” Eymund Diegel said, a fellow Dredger and forensic hydrologist.

The Dredgers’ decision to gather and publish their own data daily came in response to a startling moment back in the summer of 2023. When thousands of fish bobbed up in the murky water, belly-up and dead, it wasn’t the first time marine life had expired here: A decade earlier, an unlucky and very ill dolphin, affectionately named Mucky by locals, had turned up in the canal and died. But this time, alarm at the mass death of fish sparked action. The Dredgers launched a community-driven mission to gather, process, and share water-quality data online.

Studying the data after the mass fish killing, they learned that the water had dissolved oxygen levels of about 1.0 mg/L, a level considered hypoxic, or too low to support life. The toxic levels back then were likely caused by hot temperatures, increased rainfall, and sewer overflow that summer. With continued housing development and increased rainfall in recent years, the Dredgers anticipated that the canal would face even further stress. Collecting and analyzing data was one thing they could do to protect it.

Eymund thinks the Dredgers are uniquely positioned to change the way people interact with the Gowanus Canal safely. The first step, he says, is challenging the water’s reputation. “Even in its worst state, your hand will not suddenly turn into a skeleton if you dip your hand in,” he told me—joking, though the strategy is a smart one. By regularly canoeing on the polluted water, the Dredgers increase pressure on the city and state to do what’s necessary to improve its quality. You can imagine the bumper sticker: Will canoe on safe water, if the water is safe, will canoe.

The Dredgers are demonstrating their gusto and willful public engagement with the waterway. By doing so, they are proving that the canal needs to stay clean for locals to be able to use it.

Gary’s mission is perhaps grander still. What he does in his spare time is not merely a compulsion to sound alarm bells about the corrosive effects of climate change or to put pressure on city institutions to speed up their own cleaning project. To him, the canal may be the dirtiest waterway in New York right now, but it doesn’t have to be. His is a practice and ritual of care for a neglected piece of Brooklyn.

By providing a healthy habitat for life to grow, as for the mussels he is spawning in the water, Gary hopes other creatures will follow. He focuses on supporting the natural life that is already there in order to increase the overall biodiversity, which is good for all.

One evening, a few weeks after I watched Gary test the water, the Dredgers gathered on a blustery night under a full Moon. For the first official sail of the season, everyone donned puffy coats and pulled wool hats snug around their heads.

“It is windy!” Gary smiled as he approached the group, humming cheerfully to himself.

For the Dredgers, it was a night to welcome newcomers into their little family— pirates of trash, stewards of canal cleanup. It was just over 50 degrees on the water, close to the hypothermic tipping point. Folks clipped on their red life jackets and made their way down to the bottom of the dock. First, one canoe plopped into the water, then another.

“We're going to be going under some bridges on a little tour,” one of the Dredgers announced. “If you're afraid of trolls, let me know now. Because I can assume they've been gentrifying everything!”

Gary tied up a canoe bobbing in the water to the side of the dock and attended to volunteers as they climbed into their boats. As one pair nestled into their seats, a crumpled I Can’t Believe It’s Not Butter! container floated up dockside. He watched with hawk eyes as one pair paddled out. This was not yet the canal Gary and the Dredgers dreamed about—but it was the one they worked for and gave themselves to every day.

That it might remember and renew itself: a life-giving tributary in the city’s midst. I looked at Gary as he looked at the horizon. His sharp eyes gazed at the water, the scatter of people and objects and stories it carried. The surface rippled a pale lilac, reflecting the sky and the setting sun. ♦