Second Act for Seawalls

A comparison of current conditions with a rendering of the completed seawall rehabilitation.

 

The National Park Service is preparing for a three-year, $113 million rehabilitation of the seawalls around the Tidal Basin and along the Potomac River through West Potomac Park. This 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.

Initial construction activity will begin in late spring and early summer 2024 and will focus on establishing a construction staging area in West Potomac Park and site preparation around the Tidal Basin. Site preparation at the Tidal Basin beginning in late May 2024 will require the removal of 158 of the nearly 3,700 Japanese flowering cherry trees on the National Mall. Around the Tidal Basin, the trees will be removed between the Thomas Jefferson Memorial and Franklin Delano Roosevelt Memorial. When the project is completed, 274 cherry trees will be replanted in the area.

 

Swan Song for Stumpy

Among the cherry trees that will have to be removed from the work zone is the popular folk-hero tree that has been known as "Stumpy" since 2020. Approximately 25 years old, "Stumpy" is a victim of the failing seawalls. Twice daily, climate change in the form of sea level rise finds “Stumpy” unnaturally standing in brackish waters that breech the seawall around the Tidal Basin during high tide. Additionally, with a reduced protective canopy of sun-blocking leaves, the direct solar radiation on bark causes sun scalding, also a major tree stressor. These factors, combined with depleted and compacted soils and old age, compounded with advancing fungi, Stumpy has entered what arborists refer to as a “mortality spiral.”

The National Mall’s in-house arborist team gives special attention to Stumpy, providing regular care and pruning to remove the dangerous dead portions of the tree. With there being enough feeder roots present, along with the tree’s natural ability to transport cells, water, and nutrients immediately inside the layer of bark, the tree remarkably sustains life and puts out beautiful blossoms each spring.

The National Park Service is often asked why the trees in the construction zone have to be removed; can’t they be transplanted to another area? There are a couple of reasons transplanting the trees isn't a viable option. Of greatest concern, removing a tree's roots from the ground for transplantation to a new location risks severing the roots of nearby trees that aren't slated for removal. In the end, an attempt to transplant this many trees could actually result in the loss of even more trees.

Additionally, cost would have to be weighed against anticipated survivability. Given the age of the trees and the condition of the existing soils, transplanting to a new location would not be conducive to their health. It would be doubtful that the roots and woody portions of the trees would stay intact during such a move. Science tells us that survival would be doubtful and perhaps financially irresponsible. Regarding “Stumpy” specifically, due to its loss of structural integrity and its extremely weakened condition, it simply would not survive an attempt to move it, much less the transplant shock that would be sure to follow.

However, we are working with the National Arboretum to preserve "Stumpy's” legacy. They will propagate clippings from its living sections to create trees that are genetic matches, and when the seawall reconstruction is complete, we will plant them in the park. Additionally, Stumpy and the other removed trees will be mulched and returned to the National Mall, providing root protection and enriching the soil for living trees for generations to come. We believe this is an appropriate and beneficial second life for the felled trees, in keeping with the National Park Service’s century-old legacy of conservation and reuse of the natural resources under our care.

The park replaces about 90 cherry trees every year and looks forward to completing the Tidal Basin work and not only planting more than 270 new cherry trees, but creating conditions where the trees can thrive for generations to come.