Full steam ahead for the Delaware Aqueduct shutdown
The public is invited to three New York City DEP presentations on its repair plans for the fall.

The temporary shutdown of the Delaware Aqueduct that was postponed last year is scheduled to happen on Oct. 1, and continue for five to eight months.

All the details from last year’s shutdown are the same.

During the shutdown, the water that usually flows from all of the West of Hudson reservoirs won’t.

Instead, the New York City Department of Environmental Conservation is emptying each system before Oct. 1 to enable each reservoir to hold more water as the “new” tunnel is completed.

The aim is to have all of the reservoirs 30 percent less full at the start of the shutdown.

[Read more Delaware Currents coverage about the planned repairs.]

Of special interest to many residents of the Delaware watershed are the reservoirs that connect to the Delaware River: the Cannonsville, the Pepacton and the Neversink. 

At the time, there were some concerns about any overflow of those reservoirs, leading to a risk of flooding especially in the upper river.

The DEP announced in June that the temporary shutdown would be pushed back a year to allow more time to prepare for the monthslong closure.

In an information sheet prepared for the coming shutdown, the DEP said, “Independent studies and decades of gage data show that the reservoirs do not cause flooding when they spill, their dams always provide significant attenuation of peak flows from large storms and runoff events.”

Of course, the same fact sheet warns: “Although NYCDEP will operate the reservoirs to minimize their likelihood of filling and passing water through their spillways, there is always a chance that large runoff events could happen during the Delaware Aqueduct shutdown.” 

To outline its plans and alleviate concerns, the DEP is hosting three presentations. (There may be more. We’ll add those when they are scheduled.) 

A session will take place at 6 p.m. on April 11 at the Town Hall, 661 West Main St., Hancock, N.Y.

The Regulated Flow Advisory Committee of the Delaware River Basin Commission will hear the same presentation at its meeting on April 26. The meeting is scheduled from 1-3 p.m., with other items on the agenda. This meeting is open to the public and will be held via Zoom. You can register to attend remotely on this page.

And the last scheduled session will be at 7 p.m. on May 4 at the Upper Delaware Council offices in Narrowsburg, N.Y.

Normally, the Delaware reservoirs send water to the Rondout Reservoir, and from there the waters flow through the 85-mile-long Delaware Aqueduct, under the Hudson River. The Delaware reservoirs supply about 50 percent of New York City’s water needs.

The Delaware Aqueduct leaks in two locations, in Newburgh, N.Y., near the Hudson River, and in Wawarsing in Ulster County, N.Y. 

According to its fact sheet on the project, the NYCDEP has been working for nearly two decades on the design and implementation of the $1 billion repair. The aqueduct was put into service in 1944.

The largest leak, in Newburgh, is being repaired by the construction of a bypass tunnel that will connect to the structurally sound portions of the Delaware Aqueduct. The bypass tunnel is 2.5 miles long and about 600 feet below the Hudson River.

And this from the same fact sheet: “NYCDEP has performed capital projects on other parts of its water supply system, complex modeling and dozens of other tasks to ensure the system and the city are prepared for the Delaware Aqueduct shutdown.”

One of those tasks was to increase its use of the east-of-Hudson reservoirs for two weeks in preparation for the work on the repair. The DEP warned New York City water users that there might be a slight difference in taste because of different characteristics among upstate reservoir systems.

Here is the DEP press release about the difference in taste.