New York City Department of Environmental Protection

10/03/2023 | Press release | Distributed by Public on 10/03/2023 13:33

New York City to Increase Use of Downstate Reservoir Water for Three Weeks During Preparation for Major Work on Delaware Aqueduct

October 3, 2023

Increased Amount of Water from Croton Watershed in Westchester and Putnam counties from October 16th to early November May Result in Temporary Taste Difference in NYC's Drinking Water.

Photos of the Delaware Aqueduct Bypass Tunnel are Available here and a Map of the NYC Watershed is Available here.

The New York City Department of Environmental Protection (DEP) today announced that for three weeks starting October 16th there will be a significant increase in the amount of water coming from the Croton Watershed, a group of 12 reservoirs in Westchester and Putnam Counties to feed New York City's water supply as engineers prepare for planned work on the Delaware Aqueduct, a primary water supply tunnel from reservoirs in the upstate Catskill mountains.

Due to the increase in Croton water, New York City residents may notice a slight taste difference in their tap water due to different characteristics between upstate reservoir systems.

The increased reliance on Croton water is part of DEP's largest-ever capital repair project, which calls for connecting a bypass tunnel around known leaks in the Delaware Aqueduct, the world's longest tunnel. As part of the project, engineers will temporarily shut down the aqueduct for three weeks, as a planned test, and then for eight months starting in the fall of 2024 to make the final connections with the new bypass and decommission the leaking section under the Hudson River.

"We have a critical responsibility to provide high-quality water to nearly 10 million New Yorkers every day, without exception. The complex repair to the Delaware Aqueduct will ensure that we can continue fulfilling this vital mission for future generations," said DEP Commissioner Rohit T. Aggarwala. "The testing slated for this month will help confirm the preparedness of our equipment and procedures, setting the stage for the final bypass connection to the aqueduct scheduled to begin next fall."

About the Delaware Aqueduct repair project

The 85-mile-long Delaware Aqueduct generally delivers about half of New York City's water supply using only gravity from four western Catskill Mountain region reservoirs. The older and complimentary Catskill Aqueduct, carrying water from two reservoirs in the Eastern Catskill Mountain region, generally provides about 40 percent of the water consumed each day in the City and will remain in operation throughout the three-week Delaware shutdown as well as the final repair project.

In 2010, New York City announced a $1 billion plan to repair the leaking sections of the Delaware Aqueduct by connecting a 2.5-mile-long bypass tunnel around known leaks discovered in the 1990s deep under the Orange County Town of Newburgh adjacent to the Hudson River. The new bypass, being connected 600 feet beneath the river's surface, is the first tunnel built under the Hudson since 1957, when the south tube of the Lincoln Tunnel was completed. A separate smaller leak in the Ulster County Town of Wawarsing will also be repaired during the eight-month shutdown starting next fall.

Since 1992, DEP has continuously monitored the leaks, which can release upwards of 35 million gallons per day, the vast majority of which is through the leaks near the Hudson River in Newburgh.

DEP has been working closely with Hudson Valley municipalities that rely on the Delaware Aqueduct for their water supplies to activate backup plans during the temporary shutdowns as well as working with the U.S. Geological Survey to continually monitor groundwater levels in communities where the Delaware Aqueduct leaks are located

The major repair work and eight-month shutdown is scheduled to start in Oct. 2024 because demand for water is at its lowest all year. Even during the testing and shutdown, DEP will continue releasing water into Delaware River tributaries pursuant to the Flexible Flow Management Program, a water allocation agreement between the states of New York, New Jersey, Pennsylvania and Delaware, and the City of New York.

The eight-month shutdown to make the final bypass tunnel connections had been planned for this year but was shifted to 2024 to allow for the installation of additional equipment to manage groundwater infiltration to keep the construction zone dry and ensure worker safety during this complex repair project.

About DEP and NYC's Water Supply

DEP manages New York City's water supply, providing approximately 1 billion gallons of high-quality drinking water each day to nearly 10 million residents, including 8.5 million in New York City. The water is delivered from a watershed that extends more than 125 miles from the city, comprising 19 reservoirs and three controlled lakes. Approximately 7,000 miles of water mains, tunnels and aqueducts bring water to homes and businesses throughout the five boroughs, and 7,500 miles of sewer lines and 96 pump stations take wastewater to 14 in-city treatment plants. DEP also protects the health and safety of New Yorkers by enforcing the Air and Noise Codes and asbestos rules. DEP has a robust capital program, with a planned $31.3 billion in investments over the next 10 years. For more information, visit, like us on Facebook, or follow us on X, formerly known as Twitter.