Photo courtesy of the National Park Service
Old age, rising sea levels and poor drainage have all combined to exact a toll on the Tidal Basin and West Potomac Park seawalls. Portions of them have settled as much as 5 ft. since their initial construction from the late 1800s to the early 1900s.
The National Park Service (NPS) announced March 13 that it is preparing to begin a three-year, $113 million rehabilitation of the seawalls around Washington, D.C.'s Tidal Basin and along the Potomac River through West Potomac Park.
Funded by the Great American Outdoors Act Legacy Restoration Fund, the NPS noted that the "critical investment will ensure the park is able to protect some of the nation's most iconic memorials and the Japanese flowering cherry trees from the immediate threats of failing infrastructure and rising sea levels for the next 100 years."
According to a news release from the federal agency, part of the U.S. Department of the Interior, initial construction activity will begin late this spring and early summer.
Once under way, it will focus on establishing a construction staging area in West Potomac Park and site preparation around the Tidal Basin. Following the staging's completion, work will first get going at the Tidal Basin, followed by the Potomac River work in West Potomac Park.
None of the construction activity in 2024 will affect visitors to the National Cherry Blossom Festival, which runs from March 20 to April 14, the NPS assured, and the trail around the Tidal Basin will remain open through the duration of the work, although temporary pedestrian detours will be constructed in some areas.
The seawall restoration is projected to be finished in 2027, the agency noted.
Site preparation at the Tidal Basin will commence in late May and will unfortunately require the removal of approximately 140 Japanese flowering cherry trees between the Thomas Jefferson Memorial and the Franklin Delano Roosevelt Memorial.
NPS added that tree locations and topography were considered in the construction planning, and every effort was made to minimize the number of trees that must be removed.
In all, approximately 300 trees are slated for removal in the work zones, but when the project is completed, according to the park service, 455 new trees will be replanted in the area with 277 of them being cherry trees.
Well Over a Century Old, Both Seawalls Need Upgrades
Old age, rising sea levels and poor drainage have all combined to exact a toll on the Tidal Basin and West Potomac Park seawalls. Portions of them have settled as much as 5 ft. since their initial construction from the late 1800s to the early 1900s.
As a result of the settling and sea level rise, Potomac River water flows over portions of the seawalls twice a day during normal tidal conditions. Despite various repairs over the decades, however, the seawalls are no longer structurally sound and threaten not only visitor safety and the historic setting, but the Tidal Basin's iconic cherry trees themselves.
The rehabilitation of the Tidal Basin and West Potomac Park seawalls is part of nearly $500 million in planned infrastructure improvements at Washington's National Mall prior to the 250th anniversary of American independence in 2026.
The repairs will include:
- Removing and reconstructing the existing stone masonry seawalls to include a pile-supported platform foundation that will prevent the seawalls from settling, and support height extensions of the walls if needed due to future rising sea levels or increasing storm surge.
- Salvaging and reusing stones from the historic walls for use in the rehabilitated seawalls, when possible.
- Repairing, replacing and widening walkways around the Tidal Basin to provide smoother, more accessible connections to other pathways.
- Re-grading landscaping adjacent to the seawalls, as necessary, to provide proper drainage.
The Great American Outdoors Act is part of a concerted national effort to address the extensive maintenance backlog in America's national parks.
Supported by revenue from energy development, the fund provides the NPS with up to $1.3 billion per year for five years to make significant enhancements in national parks that will ensure their preservation and provide opportunities for recreation, education, and enjoyment for current and future visitors.
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