NARROWSBURG, NY — This June, the $1 billion Delaware Aqueduct project—a 20-year effort to repair the longest tunnel in the world—will enter its final phase.

The NYC Department of Environmental Protection (DEP) will connect a new 2.5-mile bypass tunnel to structurally sound portions of the aqueduct, permanently rerouting water around a leak that releases some 35 million gallons per day.

Making the connection will require shutting down the Delaware system for eight months, starting in October.

Unforeseen complications—such as an unusually dry, hot summer—will drive all “go-no-go” decisions throughout the shutdown, says the DEP.

The Upper Delaware Council (UDC) will host Jennifer Garigliano, DEP’s Water Resources Management director, for an update on the repairs. The public is invited to attend the session, set for 7 p.m. on Thursday, May 2, at the Upper Delaware Council office, 211 Bridge Street, Narrowsburg, NY.

A Zoom option is offered upon request.

Twice delayed

Originally set to begin in October 2022, the repair project has been delayed twice. A March 2023 dewatering exercise, when the tunnel was not at full capacity, revealed more extensive and faster infiltration of groundwater than expected. Extra time was needed to install additional pumps to safeguard workers, who will be 700 feet underground.

Before the shutdown, all four Delaware system reservoirs—Cannonsville, Pepacton, Neversink, and Rondout—will be drawn down more than usual, depending on the amount of rainfall, to create voids that will help to reduce the effect of storms. DEP says the shutdown will not affect public recreation.

The Delaware Aqueduct bypass tunnel is the largest repair project in the 177-year history of New York City’s water supply system. It runs 600 feet under the Hudson River from Newburgh to Wappinger. The 85-mile-long aqueduct typically conveys about half of New York City’s drinking water each day from reservoirs in the Catskills.

After Garigliano’s presentation, the UDC will hold its regular monthly business meeting, which will include status reports from the Delaware River Basin Commission, NYS Department of Environmental Conservation, the PA Department of Conservation and Natural Resources, the National Park Service, and the UDC executive director, and an opportunity for public comment.

To request the Zoom link, call Stephanie Driscoll at 845-252-3022 or email stephanie@upperdelawarecouncil.org.