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.
Photo by L Walter
Photo by L Walter
Photo by: Jonathan Nettelfield
Photo by James Falk
This photo shows the preparation process for the cleaning
Photo by: JJames 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.”
Post script
Our neighborhood watchers discovered two ventilators which had been re-graffitied. The one close to the Croton Dam was identified in the fall of 2025 with a small graffiti and the State Parks crew quickly sprang into action. They were able to remove the graffiti and reapply the coating, which can only be done when the temperature is above 41 degrees.
Photo by James Falk
Although the weather was cold, the State Parks crew members were motivated to attempt to remove the new graffiti and quickly sprang into action, improvising a variation on the standard method. They did their best to remove the graffiti and reapplied the coating, which is supposed to be done when the temperature is above 41 degrees. Even though the graffiti disappeared for a while, it re-appeared, as can be seen in the photo taken below by our graffiti-watcher, James Falk. So, this was a good learning experience: it is necessary to wait until the weather is warmer to do the cleaning. The crew will return as soon as they can.
Photo by James Falk
The second incident, in Yonkers, was more dramatic and discouraging. Because it occurred after the temperature had fallen considerably, the State Parks crew wisely postponed the cleaning until the weather warms up (not likely to happen during this unusually cold weather of the winter of 2026!) But this will be cleaned and the sacrificial coating reapplied as soon as this can be done. This is clearly going to be on ongoing saga, but one which we will continue to manage, and manage it we will!
Photo: Lesley Walter
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.
Why It Matters
- Heritage Preservation: Protects unique 19th-century engineering landmarks.
- Community Pride: Builds stewardship and reduces vandalism through engagement.
- Sustainable Practices: Uses non-toxic, low-impact conservation methods.
- Tourism & Education: Enhances the experience for thousands of trail users every year.
Get Involved
Join the Friends of the Old Croton Aqueduct in protecting this historic treasure.
- Volunteer to keep watch on newly cleaned ventilators
- Volunteer to take photos on future cleaning days
- Contribute to our restoration fund
- Share your photos and stories on social media using #BeCrotonProud
Visit www.aqueduct.org for updates, events, and ways to get involved.
Contact
Lesley Yu Walter
President, Friends of the Old Croton Aqueduct
sprouts123@msn.com
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