Bring back this Bronx stream

Hurricane Ida came through last month with record-breaking rainfall and major flooding, leading to more than a dozen deaths and tens of millions of dollars in damages. It made clear that New York City is not prepared to withstand extreme weather brought on by climate change. It also made clear that we must urgently rethink our relationship to water, where it goes, and how we manage it. Daylighting Tibbetts Brook in the Bronx would be a great first step.

To daylight a stream is to reintroduce it back above ground to its original, natural course. In the Bronx, the Tibbetts Brook meanders through Van Cortlandt Park from its origins in Yonkers. It once terminated in the Harlem River, but now disappears into a sewer tunnel at the southern edge of the park, about a mile short of its original length.

This unnecessary diversion sends approximately 2 billion gallons of clean water a year to be needlessly treated at a wastewater plant on Wards Island. That works out to about 5 million gallons per day. And that’s on a dry day. When it rains, that number can be five times as high.

Daylighting Tibbetts Brook, on the other hand, would allow the water to go where it wants to go naturally. It would also create new parkland in the Bronx by connecting the Harlem River to Van Cortlandt Park. This would be great for the human beings of the Bronx, not to mention all the other mammals, birds and fish that call the borough home. Creating this green corridor would not only absorb stormwater and storm runoff, but it could also mitigate high temperatures, reducing the urban heat island effect. (Research shows that many U.S. cities have temperatures up to 10 degrees Fahrenheit warmer than their surrounding natural land cover.)

Daylighting would also reduce combined sewer overflow events. Any time it rains more than half an inch in New York City, stormwater mixes with human waste and overflows into the rivers and harbor. Removing Tibbetts Brook out of that equation won’t solve those overflow problems by itself, but it would be an improvement. After all, when it comes to untreated human waste mixing with rainwater and overflowing into our rivers and harbor, every last drop really does count.

Advocating for this daylighting proposal is the Van Cortlandt Park Alliance. The plan would have Tibbetts Brook bypass the sewer and run south through the remainder of the park and on to the Putnam right-of-way, an abandoned rail line alongside the Major Deegan Expressway. These tracks, which are currently owned — but not used — by the CSX Corp., could bring Tibbetts Brook back to life, and back to the Harlem River.

This isn’t about just flipping a switch. The city would need to acquire that land to make daylighting a reality. Negotiations between the city and CSX have stalled lately, though there is a precedent for cooperation. For example, the High Line in Manhattan was made possible when CSX donated those unused tracks to become a city park.

But otherwise, it wouldn’t take much work. The water already wants to go that way, as evidenced by the inundated Major Deegan Expressway after Hurricane Ida, where cars and trucks were stranded for hours until the floodwaters receded. However, it wasn’t necessarily floodwaters that covered the expressway, so much as it was the Tibbetts Brook reclaiming its original course. The historic rainfall, which is becoming unfortunately more common, caused the old, buried stream to daylight itself.

Daylighting projects like this have worked all over the world. The most famous example is the Cheonggyecheon River in Seoul, South Korea. Twenty years ago, it was a freeway. Today, it is a lush green corridor and waterway through the heart of the metropolis. Closer to home, the Saw Mill River was daylighted in Yonkers. It’s all part of a growing movement to rethink hydrology and how we manage water in our cities.

Of course, daylighting alone won’t make the city prepared for extreme weather events brought on by climate change. The city must also invest in green roofs, create streetside bioswales and rain gardens, and replace as much asphalt as possible with more absorbable surfaces in order to naturally manage stormwater. When billions of gallons rain down on us or flood us from the shoreline, we’ve got to give far more places for that water to go other than our limited sewer systems, our basements and our subways.

Hurricane Ida showed that we can’t stop the water from coming. However, New York City does have the opportunity to adapt our approach to climate change. We can let the water overwhelm us, or we can choose to course correct.