New York City closes tunnel that supplies half of its water for major repairs

The temporary closure of the Delaware Aqueduct in upstate New York has been in the works for years, and officials are continually increasing capacity from other parts of the city’s sprawling 19-reservoir system.

Water will flow continuously from city faucets after the shutdown begins this week, officials said. However, its famously crisp taste may be compromised as other sources become more exploited.

“The water will always be there,” said Paul Rush, deputy commissioner of the city’s Department of Environmental Protection.

“We will be changing the mix of water that consumers receive.”

The Delaware Aqueduct is the longest tunnel in the world, carrying water over 85 miles from four reservoirs in the Catskill region to other reservoirs in the city’s northern suburbs.

In operation since 1944, it supplies about half of the 1.1 billion gallons per day consumed by more than eight million New York City residents. The system also serves some upstate communities.

But the aqueduct releases up to 35 million gallons of water every day, almost all of it from a section well below the Hudson River.

The major leak has been known for decades, but city officials faced a dilemma: They couldn’t decommission the critical aqueduct for years to repair the tunnel. Instead, they began building a parallel 2.5-mile bypass tunnel under the river about a decade ago.

The new tunnel will be connected during the decommissioning, which is expected to last up to eight months.

More than 40 miles of the aqueduct that descends from the four hinterland reservoirs will be out of service during this time, but a section closer to the city will remain in use.

Additional leaks further north in the aqueduct will also be repaired in the coming months.

Mr Rush said the work had been planned to avoid the summer months when demand was higher. The city has also spent years making improvements to other parts of the system, some of which are more than 100 years old.

“There is a lot of thought going on about where the alternative supply will come from,” Mr Rush said.
The capacity of the supplemental Catskill Aqueduct has been increased and more drinking water will come from the Croton Watershed’s dozen reservoirs and three lakes in the city’s northern suburbs.

Greater reliance on these suburban reservoirs could affect the taste of the water because more minerals and algae are present in the Croton system, city officials said.

“While some residents may notice a temporary, subtle difference in taste or smell during repairs, changes in taste do not mean there is something wrong with the water,” DEP Commissioner Rohit Aggarwala said in a prepared statement.

“Just as different brands of bottled water taste a little different, our different reservoirs taste a little different.”