NYC Resources 311 Office of the Mayor

Catskill Aqueduct Repair & Rehabilitation

Through the Water for the Future program, DEP will construct a bypass tunnel that will replace a two and a half mile section of the Delaware Aqueduct in the town of Newburgh, in Orange County, where leaks cannot be repaired from within the existing aqueduct. Before the new bypass tunnel can be connected, additional water sources will need to be developed to compensate for the water that will be unavailable during the period when the Delaware Aqueduct is shut down, sometime around 2021. One of the options we’re moving forward with is the repair and rehabilitation of the Upper Catskill Aqueduct, the other main aqueduct that delivers 500 million gallons of water every day, to ensure its reliability and restore its historical capacity. It is critical to the success of the Water for the Future Program that this aqueduct is restored to full capacity when the Delaware Aqueduct goes offline for repair and upgrades to ensure continuous, safe, clean, reliable water service to our nine million customers.

The goal of the Upper Catskill Aqueduct Optimization project is to increase the carrying capacity of the aqueduct by improving the speed at which water flows. It will consist of three main components: (1) cleaning and/or lining the aqueduct, (2) chemical addition, and (3) constructing and replacing air vents. These components would occur in the section of the aqueduct between the Ashokan and Kensico Reservoirs.

At a Glance

  • The Upper Catskill Aqueduct extends approximately seventy four miles from Ashokan Reservoir to Kensico Reservoir.
  • The aqueduct has a historical capacity of about 640 million gallons per day (mgd), but over time, naturally occurring deposits (biofilm) on the interior surface have developed, reducing its capacity.
  • Over the next several years leading up to the shutdown of the Delaware Aqueduct, DEP will conduct a full inspection of the Catskill Aqueduct, make mechanical and structural upgrades, and remove the biofilm to restore its historical flow capacity and extend its useful life

What to Expect

In order to access the tunnel for the repair and rehabilitation work, sections of the Catskill Aqueduct will be shut down for short durations, generally about six to eight weeks. The shutdowns will be kept to a minimum to reduce impacts where possible. Upstate communities who use Catskill Aqueduct water for normal supply should not expect an interruption as the community water supplier will use existing backup supplies while repairs are happening. There will be no interruption of water quality or service for NYC Residents. Our commitment is to ensure NYC has a reliable water supply system for generations to come, and can enjoy the best drinking water in the world – before, during, and after repair of the Delaware Aqueduct.

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