The City is embarking on an ambitious green infrastructure project to daylight parts of Tibbetts Brook in the Bronx that have been covered for more than a century. Stream daylighting is the process of restoring a stream to a more natural state by removing any obstructions covering it, such as concrete or pavement.
Daylighting Tibbetts Brook will remove the brook’s clean water from the sewer system and help to reduce CSOs into the Harlem River. It may also help lessen flooding along Broadway and other areas of the Tibbetts Brook Watershed.
DEP and NYC Parks have formed a community advisory group to help guide discussions and planning for the Tibbetts Brook daylighting project.
About Tibbetts Brook
Tibbetts Brook is a small stream that begins its journey in the City of Yonkers and flows south into Van Cortlandt Park in the Bronx. The stream cuts through the middle of the parkland into Van Cortlandt Lake, then dips underground beneath Tibbett Avenue, flowing southwest into the Harlem River Ship Canal. In the 18th century, Tibbetts Brook was dammed to create the lake that still exists in the park, and part of the brook was buried underground in 1912.
Tibbetts Brook is a major link in the natural drainage pattern of Van Cortlandt Park, which encompasses a watershed of slightly under 850 acres. Runoff collects in the stream, drains into Van Cortlandt Lake, and eventually empties into the Harlem River via a network of underground sewers. Development along the waterway, such as highway construction, often creates new sources of highly concentrated runoff that disrupt the delicate balance of the Harlem River ecosystem, causing erosion and contamination with salt, oil, and roadside debris.
Tibbetts Brook and Our Sewer System
Approximately 60% of New York City has a combined sewer system. This system uses a single pipe or a “combined sewer” to carry the flow of wastewater and stormwater to the local wastewater treatment plant. Managing stormwater in this system can pose challenges because during heavy rainstorms, combined sewers receive higher than normal amounts of stormwater.
During periods of heavy rainfall, a mix of stormwater and untreated sewage could flow directly into local waterways to prevent damage to our wastewater infrastructure. These events are called Combined Sewer Overflows.
At the southern end of Van Corlandt Lake, Tibbetts Brook enters the sewer system at a rate of 4 to 5 million gallons of water per day on dry days, amounting to 2.1 billion gallons per year. This water is then treated at Wards Island Wastewater Resource Recovery Facility. When it rains, a combination of stormwater, sewage, and the brook enters the combined sewer, bypassing the treatment facility and flowing directly into the Harlem River.