The Delaware Aqueduct, the world’s longest tunnel at 85 miles (137 kilometers), will undergo a $2 billion repair project this winter to address significant leaks beneath the Hudson River.
The aqueduct, which has been in operation since 1944, supplies approximately half of the 1.1 billion gallons (4.2 billion litres) of water used daily by more than 8 million New York City residents and some upstate municipalities.
The temporary shutdown of the Delaware Aqueduct has been planned for years, with officials gradually increasing capacity from other parts of the city’s extensive 19-reservoir system. Despite the shutdown, water will continue to flow uninterrupted from city faucets, although the taste may be slightly affected as other sources are relied upon more heavily.
“The water will always be there,” Paul Rush, deputy commissioner for the city’s Department of Environmental Protection, told AP. “We’re going to be changing the mix of water that consumers get.”
The aqueduct loses up to 35 million gallons (132 million litres) of water per day, primarily from a section deep below the Hudson River. To address this issue without taking the critical aqueduct offline for an extended period, authorities began constructing a parallel 2.5-mile (4-kilometer) bypass tunnel under the river about a decade ago.
During the shutdown, which is expected to last up to eight months, the new tunnel will be connected, and more than 40 miles (64 kilometres) of the aqueduct running down from the four upstate reservoirs will be out of service. However, a section closer to the city will remain operational.
In addition to the bypass tunnel, other leaks farther north in the aqueduct will also be repaired in the coming months. The work has been scheduled to avoid the summer months when water demand is higher. The city has also invested years in improving other parts of the system, some of which are more than a century old. “There’s a lot of work done thinking about where the alternate supply would come from,” Rush said.
To compensate for the shutdown, capacity has been increased for the complementary Catskill Aqueduct, and more drinking water will be sourced from the dozen reservoirs and three lakes of the Croton Watershed in the city’s northern suburbs.
The increased reliance on these suburban reservoirs may result in a slight change in the taste of the water due to a higher presence of minerals and algae in the Croton system. However, DEP Commissioner Rohit Aggarwala reassured residents in a prepared statement, saying, “While some residents may notice a temporary, subtle difference in taste or aroma during the repairs, changes in taste don’t mean something is wrong with the water. Just like different brands of bottled water taste a bit different, so do our different reservoirs.”