The Tidal Basin sea walls are a real fixer-upper – get the latest updates on the project and its ties to the climate crisis.

Flooding near cherry trees at the Tidal Basin. photo credit: Geoff Livingston CC BY-NC-ND 2.0

The Tidal Basin seawalls are more than 100 years old and in need of an upgrade. photo credit: Geoff Livingston CC BY-NC-ND 2.0

If you were around the Tidal Basin on August 15 2024, you might have felt the ground shake as a 90-foot column was driven into the river bottom.

The tremor as the pile reached bedrock marked the launch of the National Park Service (NPS) Tidal Basin seawall rehabilitation project. The seawalls currently receiving a facelift include those around the popular Tidal Basin (an extension of the Potomac River), as well as along the Potomac River in West Potomac Park.

The need for upgraded seawalls is one of many signals that the climate crisis has reached – and is overflowing – our doorstep.

“Raising the seawalls of the Tidal Basin will help the District be better prepared for rising water levels in the Potomac River by providing an enhanced barrier against flooding,” Seri Worden, senior director of preservation programs at the National Trust for Historic Preservation, said. She added it will “improve the resilience of the area against regular tidal events and the projected impacts of climate change, like more intense storms and rising sea levels.”

An Innovative Ideas Lab Centers the Tidal Basin

Rising waters inundate pedestrian infrastructure like sidewalks and benches. photo credit: angela n. CC BY 2.0

Funding to improve about 6,800 feet of seawall comes from The Great American Outdoors Act. With a $112.76 million price tag, this is NPS’s priciest rehabilitation project, ever. Worden said funding “is due, in part, to the expansive reach of the Tidal Basin Ideas Lab.”

The lab is a partnership between the National Trust for Historic Preservation, the Trust for the National Mall, and the National Park Service working to increase engagement around the future of the Tidal Basin. It brought together five landscape architecture firms to brainstorm designs for the Tidal Basin (many of them are nature-centric).

Teresa Durkin, executive vice president of the Trust for the National Mall, said these firms focused on how to potentially preserve cultural resources “when faced with nature’s unrelenting and undeniable forces that will ultimately reshape the landscape without intervention.”

The Tidal Basin seawall rehab is a tangible example of the climate crisis’ real-time costs in the Potomac River watershed. And, it's an opportunity to consider potential responses, including effective nature-based solutions that tap into the inherent superpowers of local forests and wetlands.

Climate Crisis Worsens Local Flooding

Signs of construction around the Tidal Basin, summer 2024

Anyone who knows the Tidal Basin knows it floods daily, hiding the sidewalks and inundating iconic cherry blossoms with brackish water. This historic basin, a key section of “America's Front Yard,” was originally built in response to the flood of 1881.

But some of the silt-rich basin has sunk as much as 5 feet since then. Also, thanks to sea level rise driven by climate change, the Potomac River has risen about 11 inches in the last century, meaning some areas have lost about 6 feet of flood protection.

Tidal Basin flooding is more than just messy. It's unsafe for pedestrians; bad for the popular cherry blossoms, which represent America’s friendship with Japan; and threatens monuments, including those to Thomas Jefferson, Franklin Delano Roosevelt, and Martin Luther King, Jr. Thankfully, the new seawalls will have a pile-supported foundation in bedrock intended to support height extensions over time.

Tidal Basin Renovations Promise Improved Visitor Experience

This beloved, asymmetrical tree was removed as part of the sea wall reconstruction. More new trees will be planted as the project moves forward. photo credit: Victoria Pickering CC BY-NC-ND 2.0

Hundreds of cherry trees are being removed to facilitate the project, including the long-persevering and asymmetrical favorite, “Stumpy.” The silver lining is that the improved seawalls will better protect the lion share of the Tidal Basin’s more than 1,500 cherry trees. And, a greater number of trees, including new cherry trees (also gifted from Japan), will be planted, and some will be grown from cuttings of the originals, including Stumpy.

The plan is for the project to take three years and to extend the life of the sea walls by up to a century. Upgrading seawalls is just one part of a big infrastructure spruce-up plan for the National Mall leading up to the 250th anniversary of American independence in 2026. Other goals include improving walkways, and regrading landscaping near the seawalls to promote drainage.

“Once the Tidal Basin seawall project is complete, visitors and residents can look forward to a vastly enhanced experience… The National Trust views this rehabilitation as just the beginning of comprehensively addressing the full set of challenges at the Tidal Basin, from exploring new ecological systems to a more flexible approach to circulation and connectivity,” Worden said.

Answering the Climate Crisis With Nature-Based Solutions

As rising sea levels, stronger storms, higher tides, and other factors bring excess water to the Potomac River, the climate crisis can feel overwhelming. The good news is that there are already many nature-based solutions available, including the Potomac Conservancy’s initiatives to plant trees, establish greener streets, and collect acorns.

While revamping infrastructure is important, so is protecting and expanding the wetlands and forests of the Potomac River region. Their natural superpowers include absorbing excess rainwater to reduce flooding, and filtering pollution to increase clean water. For example, during Hurricane Sandy in 2012, coastal wetlands were found to have prevented $625 million in property damage.

Learn more about how the climate crisis is hitting home in the Potomac River region and how we can use our amazing natural defenses to respond in the Potomac Conservancy’s Climate Report.

💙 Learn more about how the climate crisis is hitting home in the Potomac River region and how we can use our natural defenses to respond 💧

Read on