Hiking recently through one of the last large, wooded tracts inside Washington, DC, Josh Burch halted at a jarring sight: a concrete culvert herding a steady cascade of water into a narrow creek.
Engineers probably entombed the unnamed waterway in a pipe several decades ago, Burch suspects, when the property was sculpted into a golf course. But with the course long-shuttered and converted into a public park, he said, the pipe no longer makes sense.
“The stream is right here,” said Burch, an environmental protection specialist with the District’s Department of Energy and Environment. “All we have to do is set it free.”
The district’s plan at Fort Dupont Park, an oasis of green just east of the Anacostia River, involves exhuming the buried stream and bringing it back to the surface. Planners hope that unearthing the creek will improve the natural filtration of pollutants within its drainage area, reduce flooding and create badly needed habitat for aquatic creatures.
Across the Chesapeake Bay watershed, untold miles of headwater streams have disappeared. In most cases, developers and urban planners in the 1800s and the first half of the 1900s forced their flows underground. Where lands were once laced with marsh-fringed waterways, they now conceal an underground network of pipes.
Most stream restoration experts say that “daylighting” a waterway like the one proposed in DC is the near-ideal remedy for bringing a buried stream back to life. But a series of constraints, ranging from conflicting regulations to fears of public backlash, have frustrated efforts to put it into practice beyond a handful of sites in the Chesapeake watershed.
“There’s a part of me that wants to say every stream that is piped should be daylighted,” said Adam Nabors, project manager with Environmental Quality Resources LLC in Millersville, MD, and president of the Maryland Stream Restoration Association. But “there are compromises we make and that planners make regarding the value of natural resources versus the needs of the community.”
Converting dry land back into streams and marshes often would be highly disruptive to the urban landscape, said Joe Arrowsmith, deputy director of water resources engineering for Straughan Environmental, based in Columbia, MD.
“It’s not as easy as breaking the pipe, spilling it out, and seeing what happens,” Arrowsmith said. “We must ensure we’re not impacting people’s lives and property.”
The creation of pollution highways
Arrowsmith said humans have been burying streams around the world for thousands of years. Such projects were critical for creating enough dry land for large populations to crowd in large cities.
Before they were paved over, small streams were natural pollution fighters, experts say. Their marshy shorelines and meandering courses helped slow the stormwater rush, trapping much of the nutrient and sediment pollution before it could flow into downstream water bodies.
And the Chesapeake Bay was almost certainly cleaner for it, they say.
By design, the pipes moved stormwater faster than they usually would have traveled at the surface. By accident, the pollution within that water also moved faster, often straight into the Bay and its web of major rivers.
Excess sediment smothers oyster reefs and keeps sunlight from reaching underwater grass meadows. Nutrients cause algae blooms to flare, sometimes triggering fish kills. When the algae die, it triggers a chemical reaction that soaks up most of the water’s dissolved oxygen. Nearly all life flees or expires, inspiring the phenomenon’s ghoulish name: “dead zones.”
Then came another problem. Beginning in the late 1800s, Arrowsmith said, many burgeoning cities around the Bay — and elsewhere in the United States — were forced to reckon with an escalating public health crisis: the human and animal waste piling up in their streets and gutters. Water-borne diseases were running rampant.
So, local authorities turned to their fledgling subterranean drainage systems.
They reasoned that the stormwater flowing through those pipes could be harnessed to carry sewage away from where people lived. Simply pair the sewage pipes with the stormwater pipes, and – voila! – goodbye waste problem.
The pipes greatly reduced human suffering. But downstream from the pipes, streams, and rivers became open sewers.
The tsunami of urban pollution contributed to the Chesapeake Bay’s ecological tailspin.
“It seems so obvious now that these resources are precious, but we had different challenges then,” Arrowsmith said. “We were worried about people’s health, and we didn’t have the information we do now.”
But related problems persist. Many cities in the Bay region continue to employ underground systems that carry both sewage and stormwater in one piping system. Heavy rains can overwhelm the system and cause it to overflow, discharging raw sewage into nearby waters. DC, Baltimore, Harrisburg, Richmond, and other cities continue to pour millions of dollars into efforts to control combined sewer overflows.
A solution emerges
Amid such headaches, some localities have tried to reverse course. The first documented “daylighting” project was performed on California’s Napa Creek in the 1970s, said Luna Khirfan, a researcher at the University of Waterloo in Canada who has examined the history of the practice.
Adoption remained slow over the next few decades. But it began to catch on in the 2000s after a handful of large-scale projects gained public attention, most notably (partly because of its eye-popping $384 million price tag) the 2005 restoration of the Cheonggyecheon stream in Seoul, South Korea.
Some of the most prominent examples in the Bay watershed include a 1,500-foot section of Broad Branch in 2014 in DC, a 250-foot pipe at Ray’s Meadow Local Park in 2019 in Chevy Chase, MD, and about 800 feet of pipe at the Eisenhower Golf Course in 2021 in Crownsville, MD.
Despite a regionwide mandate to reduce stormwater pollution to help clean up the Chesapeake Bay, daylighting has remained mostly on the sidelines, according to interviews with several stream restoration contractors and experts.
One reason is that the projects are inherently “messier” than other stream restoration efforts, said Erik Michelsen, head of the watershed restoration program in Anne Arundel County, MD. After all, it involves re-wetting dry land, posing an at-least theoretical risk of flooding neighboring properties at some point.
But daylighting faces a thornier problem, he said. Each Bay state administers stormwater permits, which require that most urbanized cities and counties take steps toward reducing pollutants, such as nutrients and sediment. But the scoring system used to determine a project’s worth, at least when it comes to meeting Bay pollution reduction goals, is stacked against daylighting, Michelsen said.
The reasoning? A stream with eroding banks is fouling downstream waters with silt, so fixing that stream gets more pollution reduction credit. But an existing metal or concrete pipe has no such obvious problems, as far as the current system is concerned.
“Daylighting projects tend to be less generously credited than dealing with a site that is actively eroding,” Michelsen said. “If a [daylighting] project is going to cost just as much as a [streambank] stabilization project but is worth half the amount of credits, that may be a driving force that determines whether a project moves forward.”
The Chesapeake Bay Program’s Urban Stormwater Workgroup, a panel of experts that helps set the parameters for the permitting process in the region, does not give daylighting projects pollution reduction credits toward meeting Bay goals, said David Wood, executive director of the nonprofit Chesapeake Stormwater Network and the workgroup’s coordinator.
The main hurdle is that the practice is still so new that there remains scant scientific evidence to back up the environmental benefits of releasing a stream from its pipes and returning it to a more natural channel, Wood said. More research also needs to be done to nail down where the sediment originates in storm sewer lines, which could help build the case against piped systems and help encourage daylighting.
Science is beginning to catch up. For example, a 2015 study by the U.S. Environmental Protection Agency compared the nutrient-filtering capabilities of piped streams and their open-air counterparts in six waterways in Baltimore and Cincinnati. It showed that nitrogen, the major form of nutrients plaguing the Bay, traveled an average of 18 times farther inside pipes than in open streams, raising the likelihood of pollution escaping into waters like the Chesapeake.
“It’s the source of many of our water-quality issues,” said Sujay Kaushal, a University of Maryland hydrologist and one of the study’s authors. “Stream burial is probably the most severe in terms of stream degradation because you’re putting it underground, and you’re also putting it in a channel.”
The lack of daylight inside pipes blocks the growth of algae. In open environments, the tiny organisms help remove nitrogen in its nitrate form, Kaushal said. The channelization disconnects the stream from its historic floodplain, where slower flows and interactions with organic material would further serve to halt nitrogen.
A capital effort
Buried streams are more than a historical curiosity. They can be a hazard, too.
DC officials learned that lesson the hard way a few years ago after an aging stormwater pipe collapsed in the city’s Northwest section, unearthing a sinkhole on private property. An investigation showed that the pipe was carrying the remnants of a stream that had been filled in during the neighborhood’s construction, Burch said.
The incident drove the government to undertake an ambitious project to map the extent of its underground waterway network. It wouldn’t be easy. In most cases, private developers had interred the waterways in the days before stormwater permits would have left a paper trail for researchers to follow. Officials decided early on that it would be too expensive to dispatch inspectors to survey every corner of the nearly 70-square-mile jurisdiction physically.
In early 2020, the District hired Arrow-smith and his firm for the project. The effort relied largely on historical maps that depicted where the waterways had once been and modern records showing the current extent of the city’s underground pipe network. Newspaper accounts and old images, ranging from oil paintings to black-and-white photographs, helped fill in the details.
The analysis found that about 70% of the original stream network has vanished from sight. The findings mirrored what Kaushal and another colleague reported in a 2008 paper about Baltimore. There, the burial rate was 66%.
DC’s landscape was never the same, Burch said. Most streams were either filled in or corralled into pipes; others dried up from the lack of rain infiltration onto lands now slathered with hard, impenetrable surfaces, such as rooftops and asphalt.
Arrowsmith said the earliest map used in the project, drawn in 1792, portrays a DC very different from today. At that time, when the city’s development was still in its infancy, the landscape was what he called “a mosaic of marsh and upland forest.”
The poster child for Washington’s lost rivers may be Tiber Creek, said David Ramos, a graphic design professor at DC’s American University who collaborated on the mapping project.
The Tiber, originally known as Goose Creek, was once formidable enough to appear on maps. It was the second-largest stream in the district after Rock Creek, measuring 200 yards in width at its intersection with the Potomac River near the Washington Monument.
A public works scheme in the early 1800s lassoed the creek into a straight canal, freeing up dry land for the National Mall and creating a fetid, exposed sewer. Eventually, the city’s post-Civil War urbanization forced virtually its entire length into underground pipes. Today, there’s little evidence that Tiber Creek ever existed, Ramos said.
A subtle dip in the terrain, an unusual arrangement of manhole covers – these are the few reminders of the Tiber’s former course, he pointed out.
“There’s nothing concrete to see except the highest reach of the stream. It’s an exercise of suspending your disbelief for a moment and looking for tiny clues,” he said.
The districtwide search for lost streams culminated in 2021 with the debut of an interactive online map. Burch said that he hopes it offers residents and property owners a window into the past to help shed light on present-day stormwater issues.
The mapping effort also might pave the way toward a future with more visible streams. As part of the project, the expert team recommended locations where long-lost waterways could be daylighted. Four were selected for initial design: a 900-foot storm pipe beneath the Langston Golf Course, a 1,300-foot storm sewer under Anacostia Park, 360 feet of an outfall pipe at Glover Archbold Park, and a stretch of the former Tiber Creek near its headwaters on the Old Soldiers’ Home property.
Burch said that, for now, there are no plans to carry those daylighting proposals any further. The design work was only intended to demonstrate the realm of possibility.
Grappling with loss
Burch said the Fort Dupont Park project could provide a roadmap for future daylighting efforts across the city.
He said the proposal faces fewer financial and regulatory hurdles because nearly all of the land involved is already owned by the public. Fort Dupont is part of the National Park Service’s lands around the capital. Reintroducing water at ground level won’t imperil any buildings or public infrastructure.
The project will dig up a roughly 450-foot-long section of stormwater pipe. That excavation will require felling a relatively small number of trees, Burch noted. But much of that portion of the forest canopy remains open from its days as a golf fairway. He added that many of the trees that have sprouted along the pipe’s path are invasives that should be removed anyway.
Work is expected to begin in early 2024, Burch said. It is part of a larger project to restore about 18,000 linear feet of small waterways in the park, including Fort Dupont Creek. The effort is one of the centerpieces of the District’s Anacostia River Watershed Implementation Plan.
The weather had been abnormally dry during Burch’s visit to the shade-dappled site in early June. Clear water flowed out of the culvert.
But nature has a long memory. Heavy rainfall still manages to collect along the fissure in the terrain above the pipe’s length, Burch said.
“Water consistently does one thing,” he said, trudging his way through the waist-high brush. “It flows downhill.”
Daylighting projects can have a host of localized benefits, Kaushal said. But he added that the urban headwaters around the Bay lost to burial are likely too widespread for such efforts to make much of a dent in improving the Chesapeake’s water quality.
“They’re so ubiquitous that you don’t think about them,” he said during an interview on his cellphone. “I’m walking Rock Creek right now with my dog. They’re just everywhere.”
This article was originally published on BayJournal.com and is republished with permission.