Before there were buildings, roads and hundreds of thousands of people, there was Tibbetts Brook. Its marshes and wetlands stretched from what is now a park in Yonkers to Spuyten Duyvil Creek.
Today, however, a lot of the brook is underground, a victim of urbanization, but still finding a way to pull water through Van Cortlandt Park into the Harlem River.
But the free-flowing water doesn’t have to stay hidden, and two advocacy groups — City As a Living Lab and Friends of Van Cortlandt Park — are collaborating on ways to “daylight” Tibbetts Brook once again. And it’s important, because the brook is now part of the sewer system on its southern end, and heavy rainfalls are problematic.
“We want to take that water out of the sewer system and daylight it, so we can have it flow above ground to the Harlem River,” said Friends executive director Christina Taylor.
During those rains, storm water and sewage combine to overflow into the Harlem River. At times, runoff pools up around neighborhoods, and there’s nowhere for the water to go.
The project to bring Tibbetts Brook back to the surface is gaining steam. Taylor has helped organize a coalition with more than 24 elected officials and organizations. The group’s mission? To elevate parts of the brook, returning the water to the surface.
It’s a project similar to one completed near the Yonkers portion of the stream that returned parts of Saw Mill River to the surface in Westchester County.
But it’s not cheap. Daylighting the Saw Mill River cost $19 million. Doing the same for Tibbetts Brook, Taylor said, could cost even more. Yet, it’s important for a number of reasons, not just flooding.
“This is not just for combined sewer overflows reasons, but also for the aesthetics and ecology of the community,” she said. “This will provide a better ecosystem, more green space, and blue space for a land that has been neglected for many years.”
Each Friday, the community groups collect water samples to test acidity levels.
“We’ve been doing water testing once a week in the Harlem River, and we found that on days that it rains, the bacteria levels are sky high,” Taylor said.
Having high amounts of nutrients in water might sound good, but it’s actually not, according to John Butler, project manager of Friends of Van Cortlandt Park.
“It is basically the excess of nutrients,” he said. “So having a lot of that in a water body can lead to heavy, dense plant growth.”
Butler extracts about 4 ounces of water from each site he studies, delivering those samples to the civil and environmental engineering department at Manhattan College. There, students and professor Jessica Wilson measures how much nutrients and bacteria is found in the water.
Common vegetation at Van Cortlandt Lake — which is along the Tibbetts Brook path — includes green algae, duckweed and other plant blooms, Butler said, a result of nutrient levels that may be too high
Daylighting is a three-part project, and one — at least for Tibbetts Brook — that has no cost estimate as of yet. But the price tag could climb over $50 million, Taylor said. Restoring Tibbetts Brook should be a high priority, but finding the money to complete it could slow that process.
“I don’t see it happening in the next couple years,” Taylor said. I would “love to see it happen within the next decade. (But) the sooner we do it, the better.”