The Chesapeake Bay Journal: Rising waters trigger change for DC's Tidal Basin
Rising waters trigger change for DC's Tidal Basin
Landscape architects reimagine future of DC's Tidal Basin
By Whitney Pipkin, published by The Chesapeake Bay Journal, March 30, 2021
A visit to the Tidal Basin in the District of Columbia should deliver sweeping views of cherry trees heavy with pink and white blooms this time of year, drawing millions of onlookers to the concrete shorelines annually.
But not this spring. For the second straight year, festival organizers are warning people to stay away, encouraging them to visit virtually. This is not only because of the coronavirus pandemic. The popular gathering spot also faces growing problems with accessibility and safety hazards caused by regular flooding. The water flowing into the basin from the Potomac River rises up and over its sea wall twice daily, at each high tide.
Visitors to the Tidal Basin in Washington, DC, splash in tidal waters rising over the walls during the peak of the Cherry Blossom Festival on April 1, 2019. The festival will primarily offer virtual visits to the blossoming hotspots this year. (Sam Kittner, courtesy of the Tidal Basin Ideas Lab)
The Tidal Basin — flanked by stately memorials to Thomas Jefferson, Franklin Delano Roosevelt and Martin Luther King, Jr. — is a gateway to more than peak blooms. But its paths, when they aren’t underwater, are cratered with muddy holes and, in places, eroded away entirely, replaced by debris-littered beaches. The regular brackish-water baths have also wreaked havoc on the cherry trees closest to the basin.
“At high tide today around 4 o’clock, this will completely disappear,” said Teresa Durkin, executive vice president of the Trust for the National Mall, during a walk on one of the now-sandy paths around the Tidal Basin in March. “All of this area that’s like beach now … it had cherry trees.”
The Tidal Basin was carved into this landscape in the late 1800s as an engineered solution for tidal flooding from the Potomac River. But the seawalls built by the U.S. Army Corps of Engineers are now regularly overwhelmed by the waters they were meant to contain. That’s in part because the tide levels are rising while the land and structures — situated like much of the city on hundreds of acres of former wetlands — are sinking, a phenomenon that’s exacerbated by heavy foot and vehicle traffic.
For these reasons, the National Trust for Historic Preservation named the Tidal Basin one of America’s most endangered historic places in 2019. The 107-acre landscape is in need of an estimated $500 million in repairs and upgrades. Though it’s located in the nation’s most-visited national park, many don’t realize the ground they’re standing on while taking in the blossoms is in such bad shape.
A cherry tree in the Tidal Basin of Washington, DC, where visitors typically flock for the annual Cherry Blossom Festival, struggles to survive amid the damage dealt by increased flooding from the Potomac River.
“I think people tend to gloss over [these issues] when they go to the basin,” said Seri Worden, senior field director for the National Trust for Historic Preservation. “It’s such a beautiful place, and you may not be aware of these challenges unless you’re there at high tide.”
Increasing public awareness of the problems is one of the reasons these two trusts teamed up with the National Park Service to reimagine the Tidal Basin’s future.
Given predictions that climate change will push high tides even higher in coming years — placing the Jefferson Memorial under as much as 4 feet of water at times by 2040 — repairs won’t go far enough to save the historic landscape. In response, the trusts and park service recruited some of the country’s top landscape architects to rethink the Tidal Basin’s relationship with the river — and the public.
‘Draw outside the lines’
A $750,000 grant from American Express helped the groups launch a three-year project to gather creative solutions for the site, culminating in the Tidal Basin Ideas Lab. The effort asked five landscape architect firms to “draw outside the lines,” Durkin said, producing futuristic renderings of a basin that would accommodate the river’s natural contours and hydrology, and perhaps at the same time tell a more diverse set of U.S. stories.
“We’re going to have to be flexible moving forward,” Worden said, adding that even the most meticulous repair and restoration of the monuments and infrastructure is of little value when “they’ll be underwater.”
The concepts the five firms released to the public in October reflect more modern and ecological approaches to landscape design. The ideas are not in competition but more of a collaboration, intended to generate a solution that will free the Tidal Basin from perpetual repairs and adaptations.
“At high tide today around 4 o’clock, this will completely disappear,” said Teresa Durkin, executive vice president of the Trust for the National Mall, during a walk on one of the now-sandy paths around the Tidal Basin in March. “All of this area that’s like beach now … it had cherry trees.” Photo: Whitney Pipkin
Almost all of the ideas would replace some of the concrete bulkheads around the basin with natural perimeters that disappear and reappear with the tide. The cherry trees — originally gifted to the United States from Japan as a token of friendship more than a century ago — would still have a place in the concepts. Some would distance a more diverse selection of the sensitive trees from the water’s edge or cluster them around new landscape features, incorporating meadows and even small patches of forests into the National Mall.
A couple of the concepts would create a substantial levee between the basin and the Potomac River that would protect more of the National Mall as a whole, which currently sits in the 100-year floodplain, while making room for marshlands.
Others would allow the river to take back portions of the landscape or would replace the existing infrastructure with a mix of wetlands and sidewalks connecting a string of monument islands with raised walkways. A couple of concepts would make them accessible only by boat tours.
The Tidal Basin’s beginnings were the fruit of an imaginative landscaping project. The land that is now the National Mall was filled with dredge materials to create a “Potomac Park” in 1897, according to archives. But access was for decades subject to racial discrimination. The Tidal Basin’s whites-only beach was eventually closed in 1925 after Congress, initially proposing the District’s Black residents swim instead in the Anacostia River, reached an impasse over the issue.
A view of the Jefferson Memorial from the eastern edge of the Tidal Basin shows how the daily high tides have covered the walkway and exposed the roots of the ever-more vulnerable cherry trees. Photo: Whitney Pipkin
One architect participating in the Ideas Lab has proposed that new pathways at the Tidal Basin — already anchored by the MLK Memorial — be used to tell more African-American stories. The California-based Hood Design Studio would use the walkway to share information about segregated beaches at the basin and other related aspects of the African-American experience, such as how wetlands were used as “hush harbors” where enslaved people could gather to practice religion.
Ideas from the landscape architects, the partners say, are meant to set the stage for an inspired discussion. They also help make the point that this work is urgent.
“At the extreme end of the spectrum, the designers asked, ‘If we do nothing, what will happen?’” said Durkin, who is also a landscape architect. “It will disappear. This ‘made’ land will just become the river again.”
That process is already under way. A portion of the sidewalk west of the Thomas Jefferson Memorial that used to teem with cherry trees is covered with sand, intermittent pools of water and, on a recent visit, a gaggle of geese. Around the bend, some of the dirt is caving in directly behind the seawall, which is also crumbling in places. Durkin said immediate repairs are planned for some problem spots like these, especially where they could cause injury to pedestrians.
The portion of the seawall in front of the memorial was rebuilt in 2006, with piles driven down into the bedrock, and it should “stand the test of time,” Durkin said. But the Park Service knows not all of these stopgap measures will keep up with the pressure of rising water.
Even as work is under way to rethink the basin, Durkin said national and regional approaches are also needed to alleviate flooding concerns.
“When this was built, this was a relatively rural region. And that’s not the case anymore,” Durkin said, noting the rise of water levels in the Potomac River, especially during storm surges. “We are in the lower Potomac here, so it’s all coming down to us on its way to the Chesapeake.”
The partners on the Tidal Basin project are hopeful that dreaming about the need for changes here will inspire changes elsewhere, too.
Bright ideas
The landscape architects’ ideas were released in October and are available for the public to digest and comment on through the Ideas Lab website. The architectural concepts were originally going to be presented as part of an in-person exhibit in 2020 before the pandemic made that untenable. But the website has expanded the audience and created new opportunities.
A rendering submitted by the Reed Hilderbrand landscape design firm imagines an elevated pedestrian walkway along a modified north corner of the Tidal Basin, roughly where the bridge carrying eastbound Independence Ave. crosses the edge of the basin. Reed Hilderbrand
A rendering submitted by the Reed Hilderbrand landscape design firm imagines an elevated pedestrian walkway along a modified north corner of the Tidal Basin, roughly where the bridge carrying eastbound Independence Ave. crosses the edge of the basin.
Reed Hilderbrand
Video presentations by the architects cast beautiful visions for the space and explain the sense of urgency associated with sea level rise. One presentation by the firm that designed New York City’s High Line park, James Corner Field Operations, depicts one of three options as a dystopian “do nothing” approach that urges its viewers to, instead, do something.
This approach imagines the existing monuments are regularly flooded and covered in moss over time and visited only from a raised walkway. Another option the firm presents — and acknowledges is “more practical” — involves preserving the existing monuments while protecting them with a new levee on the Potomac, creating expanded gathering areas and ribbons of walkways with vistas over both the basin and the river.
The approach, architect James Corner says in the video, “is to help construct an argument for the urgency of new investment, as well as create a new vision for what the Tidal Basin could be.”
Rising tides overwhelm portions of the sea wall twice daily at the Tidal Basin, leaving holes and crumbling pavement in their wake. Photo: Whitney Pipkin.
Comments on the Ideas Lab website so far indicate that not everyone is ready to dream about sweeping changes to the Tidal Basin. Hugh McAloon, who works as a tour conductor in the District, wrote that, while he likes the ideas, he sees problems with transportation and parking if roads are removed in favor of sidewalks. He’s also not sure that visitors — many of whom have a hard time not trampling cherry tree roots — would stay out of open wetland areas.
The dreamy presentations will ultimately inform a more formal planning process for the park that will take years. Those who can’t imagine the cherry trees being moved — let alone broader changes to the Tidal Basin — might be shocked on their next personal cherry blossom visit (in 2022?) to see how many changes the rising water are already making in the infrastructure.
“Other places are going to arrive at the conclusion that the only way to deal with rising water is to give the land back to the river or the sea,” Durkin said. “But we can’t really do that here, because this is our National Mall.”