Daylighting Tibbetts Brook: Green infrastructure as both a climate and environmental win
On September 21, 2021, Hurricane Ida dumped more than seven inches of rain on New York City. At the height of the storm, three inches of rain fell in a single hour. The massive deluge produced flooding across the city. One flood-prone stretch of the Major Deegan Expressway in the Bronx was swamped by more than three feet of water. This was not a one-time catastrophe. As the climate changes, New York City can expect more frequent, and stronger storms. The good news, however, is that Hurricane Ida might mark the last time a storm causes this portion of the Major Deegan Expressway to flood.
Climate change has undermined some of the engineering strategies that humans have long used to control their environment. The impervious concrete, pavement, and hardscape that makes up so many of our cities amplifies our vulnerability in an era of climate change. These highly constructed environments are particularly susceptible to flooding, polluted runoff, and overwhelmed sewer systems.
Recognizing the need for change, cities across the world have turned to daylighting—a process for bringing all or part a buried stream above ground and restoring it to something like a natural state. The process can be expensive and requires significant modification of the built environments of highly urbanized areas. However, daylighting is an effective method of flood control and sewer overflow management, and unlike hard infrastructure, daylighted streams provide multiple environmental co-benefits (like the cooling effect and the creation of green space). Daylighted streams can be critical green infrastructure that are cost effective and transformative in the long run.
Although hard to imagine now, New York City was once covered with small creeks and streams. As the city grew, these creeks and streams were buried, either because they were polluted or because they were inconvenient. Most were forgotten. But as Dr. Eric Sanderson of the New York Botanical Gardens cautions, during a storm “water will go where water has always gone.” Every major rain event now reminds New Yorkers that their highly modified cityscape is no match for excess water. Predictable flooding patterns routinely follow the path of those pre-development streams.
Tibbetts Brook in the Bronx is one such stream. Called Mosholu (smooth stones) by the Lenape, this stream originally flowed from Yonkers through the Bronx, emptying into the Harlem River at the northern tip of Manhattan. For millennia, the brook’s fresh water mixed with the salt water of the river, supporting salt marshes in a tidal estuary the Lenape called Muscoota (flat place).
In the early 18th century, wealthy landowner (and slave-holder) Jacobus Van Cortlandt dammed Tibbetts Brook to create a mill pond that until recently bore his name. In 2021, the mill pond was renamed Hester and Piero’s Mill Pond to honor the enslaved miller and his wife who lived there and ran the mill.

Even after the dam, Tibbetts stream remained a fishing, transportation, and recreation resource for the small, rural neighborhood for decades. By the end of the nineteenth century, however, things had changed. The Harlem Ship canal turned the area into a commerce and manufacturing hub, while trolley lines, and a new elevated railroad connected the previously isolated area with rapidly growing New York City.
These changes made the area increasingly attractive to developers and land speculators. However, they viewed Tibbetts Brook as an obstacle for their lucrative development plans. Because of the brook, mosquitos were abundant, with all the disease ramifications that entailed. Plus, the salt marshes fed by the brook flooded during storms and high tides. Developers pushed for engineering changes to the land and water. Dry land, after all, was worth far more than swamp or marshland.
Politicians listened, and by 1912, Tibbetts Brook was wholly buried–diverted into the Broadway sewer. The area became a dense urban environment and Tibbetts Brook faded into obscurity. Until that is, flooding from recent heavy rainstorms forced the city to remember it.
It turns out that burying streams generates many unexpected and negative externalities. When a stream is buried, the surrounding trees and vegetation are typically replaced with roads, parking lots, and buildings. The proliferation of impervious surfaces means that the natural drainage system is gone. When major storms create rapid and increased flows of water, the paved area becomes susceptible to flash floods. Inundated communities suffer costly damage, and are exposed to floodwaters contaminated by oil, heavy metals, and other toxins from pavement runoff.
Daylighting formerly buried streams can undo these negative externalities. Successful daylighting experiments around the world have demonstrated that daylighted streams mimic how the unmodified landscape land would have dealt with water. By restoring a greenway, these daylighted streams slow the rush of water during a storm and provide storage capacity for excess water. This means decreased flooding. In addition, the banks and streambeds of daylighted streams provide new greenspaces that can improve the livability of dense urban environments.
Daylighting Tibbetts Brook will not only minimize flooding, but will also help address another environmental issue that plagues the city. A daylighted Tibbetts Brook will reduce sewage overflows into the Harlem River from the city’s antiquated combined sewer/stormwater system. The clean water from Tibbetts Brook will now flow directly to the river, rather than dumping raw sewage into the river during a storm event.
Daylighting Tibbetts Brook will provide multiple additional environmental benefits. The brook will lower ambient temperature during hot summer months. Its banks will provide much needed greenspaces in dense a urban neighborhoods. This “greening” might help revitalize the formerly redlined and historically under-resourced urban neighborhood it will call home.
This ambitious project will make a big difference both for the surrounding community and for the Harlem River. The buried Tibbetts Brook is a principal culprit for flooding in this part of the Bronx. By daylighting it, New York City is embracing the transformative potential of green infrastructure. There is a pleasing symmetry in a stream that was buried in the name of development a century ago becoming the center of a climate resilience plan. Moreover, this has been a bottom-up process, driven by the community most affected by the flooding and with the most to benefit from the transition. The robust community engagement in the Tibbetts Brook daylighting project reflects the Jemez Principle that communities speak for themselves. As such, it offers a model for community-led climate resilience elsewhere.
It took years of advocacy to get to this point, but daylighting Tibbetts Brook is now a critical part of the city’s climate resilience plan. The daylighting project is set to begin in 2025.
The next time a climate-enhanced storm dumps unprecedented rains, Tibbetts Brook will be an ally working on city’s side.
About the authors:
Jaclyn Spencer is a 3L at the CUNY School of Law. As a long-time NYC resident and former public school teacher in the city, she is committed to helping find creative, equitable solutions to environmental problems.
Rebecca Bratspies is a Professor at CUNY School of Law and the founding director of the Center for Urban Environmental Reform. A scholar of environmental justice, and human rights, she has written scores of law review articles. Her most recent book Naming Gotham: The Villains, Rogues and Heroes Behind New York Place Names.won the New York Public Historians’ 2023 Excellence in Local History Award. Bratspies is best known for her EPA award-winning comic books The Environmental Justice Chronicles (with artist Charlie LaGreca-Velasco.) Learn more at https://www.rebeccabratspies.com/.