February 5, 2026

Restoring History: A Community Effort to Keep the Old Croton Aqueduct Graffiti-Free

By the Friends of the Old Croton Aqueduct and the Historic State Park Manager

A Cleaner, Brighter Future for the Aqueduct Trail

For nearly two centuries, the Old Croton Aqueduct (OCA) has stood as a testament to New York’s innovation, engineering, and community spirit. Built in the 1840s to deliver Manhattan’s first clean water, the Aqueduct today serves a new purpose — as a 26-mile historic trail and state park where people walk, bike, learn, and connect.

Yet, as has happened with many public spaces, many of the Aqueduct’s historic ventilators, weirs, and stone structures have long suffered from graffiti and grime – marks that distract from the beauty and dignity of this National Historic Landmark.

The cleaning of graffiti along the OCA has long been a goal of both the State Parks’ Taconic Region and of the Friends of the Old Croton Aqueduct. The Friends, in partnership with the New York State Office of Parks, Recreation and Historic Preservation and supported by a grant from Parks & Trails New York *, have made it their mission to change that.

More about the project

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From Pilot Project to Preservation Success

The Friends have worked with architectural conservators and preservation experts at Parks’ Peebles Island Resource Center to research and test minimally invasive yet effective cleaning methods that respect and preserve the Aqueduct’s historic stonework.

Two ventilators were selected as subjects for dry-ice blasting. (Ventilators were built to bring air into the tunnel to keep the water fresh). They were chosen for both their location—places where neighborhood watchers could generally look after them—and for their composition. In the original construction of the Aqueduct in the 1840s, contractors were given some leeway with materials and design, and the contractor in Irvington chose igneous rock for ventilators, while the Hastings builder used a local marble, of a variety quarried adjacent to the Aqueduct.

The first attempt at removing graffiti involved the Irvington ventilator in April 2022 and used the dry-ice process. Paint removal should have been most effective on its less-porous material, but the results were disappointing, and the method abandoned.

In September of 2022 an attempt was made using a different method that was receiving good reviews in the preservation field: Rotec Vortex. It uses a fine, soft media and a low-pressure vortex to remove paint, and was being used successfully on preservation projects in Europe and the US, including those involving limestone and marble. New York City has used the process to clean the High Bridge, a significant structure of the original Croton Aqueduct between Manhattan and the Bronx.

The September trial showed that Rotek Vortex method did a spectacular job of removing graffiti and the organic grunge that had built up over nearly two centuries of exposure. The cleaning process caused no damage to even the soft marble or the lime putty mortar. The pilot program has produced a winning method! The next goal was to expand to a full graffiti-removal program.

This photo shows the Irvington Ventilator being cleaned using the Rotec Vortex method.

The Hastings Ventilator

The two photos below show the Hastings ventilator before and after the work was done using the Rotek Vortex process.

Expanding the Effort

With the pilot program complete, The Friends of the Old Croton Aqueduct sought and received a grant from Parks and Trails New York * to fund a cleaning of four additional ventilators and one weir along the trail. These sites were chosen for both their visibility and community support — several local volunteers and neighbors have committed to keeping an eye on them and to quickly report to State Parks staff any graffiti that re-appears so that it can be removed in a timely and effective manner.

Protecting for the Future

Immediately after the cleaning, the State Parks staff, in coordination with the contractor and with the Friends, applied a protective coating that will make future graffiti removal quick and harmless to the stone. This innovative approach, recommended by Architectural Conservator at NY Office of Parks, Recreation and Historic Preservation, Erin Moroney, ensures that the Aqueduct’s unique structures can remain beautiful for generations to come.

Community in Action: Yonkers “Scrub Series” Launch

The next phase began in August 2025 when volunteers and conservators gathered in North Yonkers — just south of Odell Avenue — to kick off the “Scrub Graffiti Series.” Two Yonkers ventilators were the first of four cleaned that summer.

Here are photos of the two Yonkers ventilators, before they were scrubbed

Photo by L Walter

Photo by L Walter

The next ventilator to be cleaned was just south of the Croton Dam, at the start of the trail.

Photo by: Jonathan Nettelfield

Photo by James Falk

This photo shows the preparation process for the cleaning

Photo by: James Falk

Here it is having been thoroughly cleaned

Photo by Diane Alden

Here is a photo of the very challenging Ossining / New Castle Ventilator where black paint that had been applied by a neighbor to cover some offensive graffiti.

Photo by Tom Wills

This photo demonstrates just how much preparation was involved and how complex the process was; one of the workers was preparing to put on the yellow protective suit.

Photo by: Lynn Salmon

Scaffolding having been built, here is the worker all suited up cleaning the top

Photo by: Lynn Salmon

Lynn photographed it toward the end of the day, freshly cleaned.

Ossining Weir

One of the most significant structures slated for cleaning was the 1842 Weir, the only original weir still standing. (Weirs contain metal gates that could be lowered to stop the flow of water in the aqueduct tunnel to permit inspection and make repairs). The others were demolished and rebuilt in the 1880s when the system was modernized. This surviving weir, saved by circumstance and community stewardship, is an essential piece of Aqueduct history — and a perfect symbol of preservation in action.

Work needed to be done to prepare this site for graffiti removal; it was covered in vines although fortunately it turned out that none were actually growing on the structure itself.

photo by Diane Alden

Board member Diane Alden, who arranges for a local arborist to cut vines on various sections of the trail each winter, came up with a solution involving community participation. Since our arborist, Pete Ström, is skilled in working with volunteers to enhance his efforts, Diane called on Ossining Youth Bureau members, with whom she had previously worked, to work on the vines.

During one chilly morning in March 2025, Lesley Walter, President of the Friends, Diane Alden and Adrianna Waitkins, Board Members, arborist Peter Ström, community volunteers and many OYB participants gathered to tackle the vines.

Photo by OYB Youth Advocate, Jeffrey Santos

They went to work enthusiastically.

Photo by Diane Alden

They also went on a treasure hunt and jubilantly gathered up lots of trash along the trail.

Here are photos, front and back, of the weir, free of vines.

Photo by Diane Alden

Photo by Diane Alden

When the summer arrived, the weir was ready for cleaning.

photo by L. Walter

Ossining Weir being cleaned

Ossining Weir on its way to being fully cleaned.

Coda:

This initiative celebrates not only cleaner stonework but also renewed connection to the landscape and history around us. It is the beginning of a new era of respect, restoration, and pride. Erasing graffiti attracts heritage tourism, lifts local economies, and fosters a sense of shared ownership.

The cleaned ventilators and weirs have already transformed parts of the trail, enhancing the visitor experience and renewing community pride. As one trail user remarked, “It feels like we’re seeing history come alive again.”

Proof of Concept

The graffiti removal project was designed to begin the process of making our lovely historical architectural structures free of graffiti, with real world reality built into the procedures. It was a given that some of the first 7 structures cleaned would have ended up with new graffiti on them, so a special protective coating was placed on the cleaned structures to both protect them and to facilitate an effective, efficient and cost-effective removal procedure when and if needed. In 2026 we had the opportunity to test the technique.

Although graffiti was removed from 7 structures in 2025, unsightly graffiti appeared on two of them. Here is the worst one, appearing on Ventilator 19 in Yonkers.

It was cleaned by State Parks’ staff when the temperature was ideal, using specialized equipment to apply a liquid formula under pressure. The staff members then quickly re-applied the special protective coating. The low-cost equipment and materials were paid for by the Friends.

This is clearly going to be on ongoing saga, but one which we will continue to manage, and manage it we will!

The Friends are now in the process of seeking grant funding to clean more structures with some funds in the pipeline to clean three more. Nominations for the specific structures are welcome. It also might be worthwhile to consider doing a deep cleaning of some of the structures that do not have graffiti on them, but that currently have layers of dirt and grime marring their appearance; they would look so much more beautiful if cleaned. That would be the time to put on the protective coating to ensure that we could maintain them graffiti -free in the future.

* The Graffiti Removal and Fund-Raising Campaign project was supported with funding from the NYS Park and Trail Partnership Grants and New York’s Environmental Protection Fund. Park and Trail Partnership Grants are administered by Parks & Trails New York, in partnership with the NYS Office of Parks, Recreation and Historic Preservation.

Your Park. Your Backyard. Graffiti-Free.

The Friends have now restored seven historic structures – but fifteen more still need attention. We are eager to continue this process to make the trail enjoyable for all. Therefore, we have initiated a fundraising campaign so we can keep up the momentum. We have the expertise, the contractors are waiting in the wings, and we have the support of State Parks and the crew. Every contribution, large or small, helps keep the Aqueduct trail safe, clean, and inspiring.

We gave Manhattan its first clean water – and this trail keeps leading the way.

Help Make It Happen Here.

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Contact

Lesley Yu Walter
President, Friends of the Old Croton Aqueduct
sprouts123@msn.com

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