Twenty-four kilometres from Chicago’s downtown waterfront and iconic Navy Pier Ferris wheel, there is a little-known toxic waste dump. Located in the Southeast Side neighbourhood that once hosted the city’s steel manufacturing plants, the dump sits along Lake Michigan’s shoreline just north of Calumet Park’s popular beaches. Unlike many landfills, where human detritus piles up, this one contains material dredged from the Calumet River — the stuff pulled from riverbeds to ensure the commercial waterway remains navigable. It appears like a benign dry retention pond surrounded by barbed wire and fencing. But beneath the surface sit decades’ worth of highly toxic sediments, and like any landfill located next to where kids play, it has drawn the rightful ire of local residents and environmental justice advocates who want to see it transformed. The landfill is called a confined disposal facility (CDF) — one of dozens of “bathtubs” in the Great Lakes region that hold half of the roughly 1.5 to 3.8 million cubic metres of industrially contaminated sediments scooped from the bottoms of lakes, rivers and other tributaries each year.

They are not well understood by the public; often located in industrial harbours near under-resourced communities, they are at once invisible and highly active.

Like Sisyphus with heavy machinery, dredgers face an inevitable and unending process. But many of these muddy landfills are filling up; sources say 80 per cent of Great Lakes’ CDFs are full or reaching capacity and require newfound attention. Some are located in harbours that have been listed as Areas of Concern (AOCs) by the U.S. Environmental Protection Agency, noted for their significant environmental degradation. But CDFs also present an unprecedented opportunity: Cities that historically turned their back to their waterways, using them as industrial dumping grounds, are coming around to the vital ecological and economic benefits of waterfront property.

Researchers, planners and scholars have then turned their attention to CDFs; acting as ecological underdogs punching above their weight, CDFs are being embraced, and their toxic histories and possible futures could become critical tools for conservation, activism and, importantly, innovative methods to revive once-discarded ecosystems.

In the grand scheme of modern cities, CDFs are relatively young. They were made possible by the Rivers and Harbors Act of 1970, passed by U.S. Congress, which authorized the U.S. Army Corps of Engineers to erect them in order to deal with sediments cleared away for federal waterway navigation projects. The 1972 and ’78 Great Lakes Water Quality Agreements between the U.S. and Canada regulated pollution sources and types; Environment Canada followed suit to contain its contaminated sediments in CDFs. To construct these facilities is akin to building a giant, expensive bathtub on the shoreline filled with dredged muds, but prior to this system, highly contaminated dredged materials would often be dumped back into open water. The assumption was that CDFs would become a temporary “fix” to the old days of heavy industrial pollution; as updated environmental regulations yielded less toxic waste deposited into rivers, sediments would naturally become cleaner.

That’s not necessarily true, explains Sean Burkholder, a landscape architecture practitioner with more than 20 years of experience working with CDFs. “The sediment did get cleaner, but what we called ‘clean’ back in the ’50s and what we call ‘clean’ now are really different,” he says. “As the baselines for what we consider toxic change, the need to keep storing the material has expanded, so all of this material that they’re dredging out is a lot cleaner, but it’s still too dirty to put into the open environment.”

The Chicago lakefront CDF had one such temporary lifespan. The state of Illinois passed a law to allow the Corps to construct it in the 1980s under one condition: Once it was full, it would have to be given to the Chicago Park District to be converted into a public park. To date, no transfer has occurred. Though the CDF is technically “full,” the Corps intends to keep the site active: In 2020, it filed a permit request to begin piling up to 765,000 cubic metres of dredged material vertically (as high as seven and a half metres) atop the existing CDF. To stop what they have dubbed “the toxic tower,” community groups — co-led by the local organization Alliance of the Southeast and citywide parks advocates Friends of the Parks (FOTP) — filed a lawsuit in 2023; they were represented by the Environmental Law & Policy Center.

“The addition of a toxic waste site on top of another toxic waste site on our lakefront — it just doesn’t compute,” says Gin Kilgore, senior advisor of FOTP. The lawsuit is the latest in what FOTP board member Fred Bates describes as a multi-decade push to get the Corps to fulfill its transfer promise. “The entire 10th Ward and area adjacent to the CDF are all environmental justice areas with deep histories of contamination,” says Bates. The area includes two Superfund sites, petcoke and coal storage; air quality monitors pick up toxins like manganese; and asthma rates are some of the highest in the city. Citing these issues, the suit asserts that the toxic tower would simply continue the environmental exploitation residents have endured for decades. It’s not unusual, says Burkholder, for CDFs to be located in places where the poorest or most marginalized people reside.

CDFs are an environmental justice issue, but also an ecological one that connects the health of our harbours with what’s taking place upstream. According to Steven I Apfelbaum, senior ecologist with Applied Ecological Institute, CDFs are often present in places where there was once abundant life; there exists early Indigenous documentation of lush wild rice growths, waterfowl havens, and fish spawning areas in these harbours. “River mouths are centres of biodiversity and life in most of the Great Lakes,” he explains. “The nexus between the river and the delivery of nutrients and carbon material creates the opportunity for biodiversity.”

But upstream development and agriculture along with storm intensification have changed both what gets carried by rivers into harbours, and how much. Historically, substrates eroded from the land were transported down the river and, Apfelbaum says, would accumulate and be utilized by other wildlife as a source of nutrients. As humans have converted portions of the watershed into agricultural land or development, we now have “large areas of the entire harbour that are covered over with topsoil and the runoff from developed landscapes” which can be inhospitable to life and increases the amount of ‘stuff’ ending up in our harbours, as well. More material means more dredging, and in some cases, CDFs can cause unintended ecological problems.

In the 1980s, a Cleveland CDF called Dike 14 had reached the same levels as Lake Erie, which kept the dredged materials from being able to de-water and dry out. The dredged muds had become anaerobic under warmer temperatures, killing the insects, which then became hosts to Clostridium botulinum. It caused, says Apfelbaum, an avian botulism outbreak. Hundreds of ducks, geese, and swans were dying.

Using a series of strategic plantings like the common reed and sandbar willow, Apfelbaum’s team was able to quickly resolve the botulism problem, but he highlights how a shift in how we dredge and store these sediments could allow us to manage navigable waterways and restore ecosystems simultaneously.

Apfelbaum advocates for other ways of dealing with sediments, including separating topsoil and sands to be used for other, more productive purposes. He’s also interested in building deltas — a ‘naturebased solution.’ “Over time, there’s a continuous drawdown of the material that comes into the delta, and a continuous replenishment,” he explains. Building a “delta CDF” would allow sediments to slowly pass through the CDF; they wouldn’t make their way back into the harbour and require re-dredging, finally giving Sisyphus a rest. Mild contaminants would be filtered out naturally, he says.

This is to say that the “original sin” of the CDF’s ethos — that they would become obsolete over time — is replicated in their design. Holding mud forever won’t work; Apfelbaum emphasizes that climate change, which brings all sorts of unpredictable and extreme weather, as well as coastal erosion, strains existing facilities. Continuing dredging ad nauseam will require building costly facilities at the expense of environmental health, and how we deal with existing facilities also requires a new dose of imagination.

The years-long transformation of Cleveland’s Dike 14 exemplifies the change needed. What was once a CDF where birds were dying by the day is now the Cleveland Lakefront Nature Preserve, a 36-hectare habitat for more than 280 migratory avian species. Burkholder, who began working at Dike 14 early in his career, was hired to put together a plan for it to be more welcoming of visitors. It’s where, he says, he first realized the potential for CDFs to be more than just landfills. “The sediment from an entire watershed comes together and [is made into] a waterfront landscape in the city, so that whatever weird plants want to show up do.”

As CDFs fill up and sit idle, they can become curious micro-ecosystems. They’re not dissimilar to many other urban brownfields that are too toxic for human habitation yet host indigenous flora and fauna because they are left fallow after their “productive” use expires. Because the most toxic materials are contained at the bathtub’s bottom, the less-contaminated “topsoil” can easily host reeds, cottonwoods and poplars, as well as birds and bugs (barring events like those at Dike 14 in the ’80s). In this way, CDFs can passively become an “accidental wilderness.”

Such is the case of Toronto’s Tommy Thompson Park, a coastal landfill that, since the early 19th century, hosted the discards of urban development. After years of its use as a dumping ground for human and animal waste, efforts to improve public health and safety led to the creation of a spit that stretched as a breakwater into Lake Ontario. By the mid-1900s, the spit had expanded to nearly 500 hectares; in 1959, when the St. Lawrence Seaway opened, a hydraulic dredge was completed in the Outer Harbour to reach shipping depths. The resulting sand material was deposited as the peninsulas on the city-facing side of the landform.

When the shipping boom never manifested in Toronto, nature reclaimed the site instead. The 1970s brought a renewed excitement for the birds and plant life that emerged among the landfill, prompting the provincial government to ask the Toronto and Region Conservation Authority (TRCA) to take over. “People began knowing how significant this site would be. It was mostly colonial waterbirds that were occupying the site, because it was open, sandy and free from a lot of vegetation,” says Karen McDonald, senior manager of the ecosystem management team for the TRCA. “The park’s original master plan, which was developed in the late ’70s and early ’80s, was really water recreation–focused, and it had only a tiny, little natural area. And that’s when community advocacy groups started coming out, strongly advocating for nature conservation,” she continues.

Three CDFs were built in the spit, beginning in 1979. Two of those — one that reached capacity in 1985, and the other in 1997 — were drained and capped with more than a metre of clay and silt material; the addition of various rocks, aggregates and wood bits, as well as the planting of thousands of native species, produced two new wetlands. Contamination is sealed in, and the wetlands are maintained to keep invasive species from overtaking them. Today, the park hosts more than 300 types of birds, as well as painted turtles and river otters; a pedestrian path allows visitors to traverse the park’s five kilometres, where they can also find eroded bricks and rebar hearkening to the site’s past.

Though the third CDF is still active and has what McDonald says is another 30 to 50 years of usability ahead, Tommy Thompson Park is now a case study for repairing our often-sacrificed wetlands. “It’s an opportunity to give back to nature,” she says. “We took over for a little while, we created this waste space for our dredge aid, but now we’re done with it, and we want to give it back.”

Back in Chicago, activists protesting the toxic tower on the lakeshore also believe their CDF could become something more: Their “Last Four Miles” proposal — which refers to the final four miles of lakefront property before reaching the Indiana border — would also involve capping it to seal in dangerous contaminants and transform the site into parkland, creating continuous lakefront access from Chicago’s north shore to the Indiana border. While more human-oriented than that of Tommy Thompson Park, the ambitious plan would add more than 140 acres of green space in marginalized communities. Their proposed design would require the U.S. Army Corps of Engineers to fulfill its promise of allowing the Chicago Park District to take possession of the reclaimed land and convert it into a public park — something already underway 160 kilometres north.

In Milwaukee’s industrial harbour, a CDF is expanding — not up, like the toxic tower, but outward. Beginning in 1975, the city’s original CDF was constructed in phases to hold the highly toxic post-industrial sludges pulled from Lake Michigan and its surrounding rivers — now, it’s reaching capacity. “None of these facilities want to close because they’re very expensive to build and they’re needed on an ongoing basis,” says James Wasley, a professor of architecture at the University of Wisconsin–Milwaukee who collaborates with UW’s School of Freshwater Sciences. In a somewhat ironic twist, much of the expanded CDF will hold materials dredged as part of the city’s attempts to delist the area’s waterways as an Area of Concern, which requires the removal of industrial pollutants.

Unlike most CDFs, where the “cleaner over time” principle is at play, this new one will contain some of the area’s historic worst. “They’re cleaning out a whole watershed of material that has not been touched in a long time. It’s really dirty, and no one should get near it,” explains Burkholder. But the CDF expansion is strategically aligned with the city’s waterfront development plan: Unlike other coastal industrial reimaginings that turn brownfields into high-end mixed-use developments, “what Milwaukee has done that’s been kind of unusual is really focused on keeping industry and keeping jobs,” Wasley explains. While the new portions will contain contaminated material, the old section, he says, will return to the City of Milwaukee when decommissioned.

In time, it could become a wetland park (just like Toronto’s Tommy Thompson Park) — or, as he is researching now, a solar field. “There’s a big movement in the Midwest to do agrivoltaics, where you’re essentially fallowing land to build a solar farm,” he explains. “You’re putting [solar] in native prairie, providing habitat and doing all kinds of great soil restoration; could we do that on these hydric, squishy soils?” To explore these solutions, Wasley has been collaborating with other design professionals like Burkholder, as well as Doug Voigt, an urban design and planning partner at Skidmore, Owings & Merrill’s Chicago office.

SOM has been working on a Great Lakes visioning plan as part of the urban planning studio’s research practice since 2002. His team researched four Great Lakes cities — Chicago, Cleveland, Milwaukee and Toledo — and mapped out each city’s Areas of Concern, alongside where CDFs and dredging sites are located, as well as where industry is located and whether or not changes were planned to former industrial sites. “As you see in many cities, former industrial land is being repositioned for housing and other uses. You may see an increase in population where the need for open space and recreation — as well as a healthy environment — is even more important,” explains Voigt.

Importantly, his team discovered just how complex these sites are politically: There are, Voigt says, around 15,000 unique jurisdictions involved in Great Lakes CDFs; each site has political, economic and ecological stakes that require deep collaboration — not just across city or state lines but across professional fields. Each lake within the Great Lakes has its own regulations around dredging, says Wasley. It’s a chaos that would require choreography to transform into something that serves both community and environment.

At the heart of this organizing, however, are the activists who push for better stewardship of these swampy, uneasy landscapes. “The point comes down to: What do you want in your community? What’s your vision? And is industrial, contained sediment part of that vision or not?” asks Apfelbaum.

Burkholder cites Times Beach in Buffalo, New York, where an aging, abandoned 1970s CDF sat for years — not yet at capacity. Like fallow land, nature returned, carrying the migratory bird population. Birders took notice. “Basically, the birding community of Buffalo turned it into a nature preserve,” he says. They formed an advocacy group to pass legislation, develop budgets and design a trail system to address the CDF’s second life, he explains; today, the beach hosts millions of migrating birds and pollinators, as well as manufactured trails, boardwalks and observation areas. The grassroots case study, Burkholder says, “is unprecedented and hasn’t happened anywhere else.”

Activists in Chicago pushing for the lakeshore CDF to finally close have recently gotten some good news: After the Illinois Environmental Protection Agency denied all state water quality permits required for the Army Corps’ proposed toxic waste mountain, the Corps announced in March that they would “pursue alternative solutions.”

“We’re now in a lawsuit where the Illinois EPA has said, clearly and meaningfully — based on legislation that is more specific about where toxic waste can be placed — that Cook County is not a place where you can put toxic waste,” says FOTP board member Bates. In a separate statement, FOTP comments that members are “heartened to learn the U.S. Army Corps of Engineers is doing the right thing,” and will “turn our sights to capping the existing Confined Disposal Facility and making it into the park [residents] deserve and was promised to [them] decades ago.”

Their “Last Four Miles” plan might still be a long way off, but it’s the first step that Burkholder says is needed to transform CDFs into any other type of use — whether it be a solar field, a public park or a lightly landscaped sanctuary for a city’s human and nonhuman residents.

The common thread between projects in Toronto, Buffalo, Cleveland and numerous other CDF transformations, he says, is the presence of a local partner who can push for a meaningful use for this extra land by choreographing the myriad regulators and stakeholders. Doing so might reshape these under-discussed, unseen, unappreciated 1,620 hectares of waterfront property — located across the largest freshwater source in North America — into some of the region’s most valuable tools for ecological restoration and environmental justice.