The New York City Department of Environmental Protection shut down Monday a portion of the 92-mile Catskill Aqueduct, which feeds drinking water from the Catskills through Westchester County to New York City.
The shutdown is part of a multi-year rehabilitation project of the aqueduct that the city estimated will cost about $158 million.
The Catskill Aqueduct carries drinking water from Ashokan Reservoir in Ulster County to Hillview Reservoir in Yonkers. The aqueduct conveys about 40 percent of New York City’s drinking water on an average day, and can deliver up to 590 million gallons per day.
The work will focus on a 74-mile stretch between Ashokan in Ulster County and the Kensico Reservoir in Westchester. DEP workers will clean the aqueduct’s inside and repair a number of leaks, replace 36 valves at chambers connected to the aqueduct and perform other structural and mechanical upgrades.
This 10-week shutdown is the first of three, with the others coming in the autumns of 2019 and 2020. Each of the shutdowns coincides with the annual period of lowest demand on the water supply system, DEP officials said.
The DEP said its work on the Catskill Aqueduct is part of preparations to shut down the Delaware Aqueduct in 2022. The 85-mile-long Delaware Aqueduct begins at Rondout Reservoir in Ulster County and conveys about half of New York City’s drinking water every day.
Once the Catskill system is improved, the DEP plans to spend about $1 billion to repair two areas of leakage in the Delaware Aqueduct. That involves building a 2.5 mile bypass tunnel 600 feet under the Hudson River from Newburgh to Wappinger that will convey water around the leak.
The Delaware Aqueduct will stay in service over the next several years while DEP builds the bypass tunnel. Once the tunnel is nearly complete, DEP said it will shut down the Delaware Aqueduct for five to eight months to finish the connections on both sides of the Hudson River.
The DEP said it coordinated the Catskill Aqueduct repair work over more than a decade in close coordination with communities in the Hudson Valley that will host the work, especially the 20 Hudson Valley towns, cities, villages and water districts that draw drinking water from the Catskill Aqueduct. Each will utilize backup water supplies during the 10-week shutdown.
The Catskill and Delaware construction plans are among several big-ticket projects the DEP has planned to help secure the region’s water supply.
In July, the DEP announced plans to spend $1.2 billion building a water tunnel that will connect the Kensico Reservoir to a water treatment facility in Eastview. That project is a ways off though, with no plans to start construction until 2025.