The Old Croton Aqueduct and the New Croton Dam

The Old Croton Aqueduct and the New Croton Dam

The Croton Dams and Aqueduct (Images of America: New York)The Croton Dams and Aqueduct by Christopher R. Tompkins

My rating: 4 of 5 stars

The Old Croton Aqueduct trail runs behind my house, and I’ve been walking along its tree-shaded way for well over a decade now. As a kid, I thought “aqueduct” was just a name, until my mom told me that, buried underneath the pebbly ground, there is a tunnel that used to carry water to New York City from Croton, a few dozen miles north. Even so, it never occurred to me to learn about the aqueduct. This a striking but common phenomenon: we travel to foreign cities and go on tours, but neglect the history in front of our eyes. It wasn’t until I began traveling abroad that I started to realize the scale and significance of the old aqueduct, and set myself to investigate it.

Weir Graffiti
Weir with graffiti

The first step was to walk it. The original aqueduct ran about 40 miles from the Croton Reservoir down to the Receiving Reservoir (now the Great Lawn in Central Park), and further along to the Distributing Reservoir in Midtown Manhattan (which is now the Main Branch of the New York Public Library; parts of the old reservoir are preserved in the building’s basement). After the reservoir was phased out of service in the 1960s, a large chunk of the land—26.2 miles of trail, to be exact—was donated to New York State, to form a historic park that stretches from Croton, through Ossining, Scarborough, Tarrytown, Irvington, Dobbs Ferry, all the way past Yonkers to Van Cortland Park in the Bronx. I have walked most of this, first going south to Yonkers and then north to Croton. If you walk all it you can get a certificate from the Friends of the Old Croton Aqueduct.


For most of the way, the Old Croton Aqueduct is a dirt or grass path, about ten feet wide or narrower, with a well-worn channel in the middle. It goes through some historic areas, taking the walker alongside the Sleepy Hollow Cemetery, through the park of Lyndhurst (former residence of Jay Gould, railroad baron), and near Sunnyside (former residence of Washington Irving), as well as into the wonderful Rockwood Park. The trail is not always so scenic; sometimes you are basically walking through people’s backyards, and there are a few intervals where you have to exit the trail and walk through a neighborhood to get to the next stretch.

The walker will notice a few different structures along the way. The most common are the ventilators, which are hollow stone cylinders with a shaft that allowed fresh air to reach the water below. I believe these were built to prevent pressure from building up inside the tunnel. Less frequent are the weirs, square stone buildings with metal gates inside, that could be dropped like a guillotine to divert the water in case repairs were needed (and since the growing population of New York put heavy strain on the aqueduct, they frequently were). In this way, the entire aqueduct could be drained in two hours. These weirs are situated above rivers, where the waters could be redirected. There is one above the Pocantico River in Sleepy Hollow, another in Ossining over the Sing Sing Kill, and another in the Bronx over the Harlem River, all tributaries of the Hudson.

A weir

In Dobbs Ferry stands one of the old Keeper’s Houses, where the aqueduct’s superintendents used to stay. There used to be six of these along the aqueduct, but the one in Dobbs Ferry is the only one that still stands. It is an inconspicuous white house now, but not long ago it lay completely in ruins; the restoration was just completed in 2016, by the Friends of the Old Croton Aqueduct along with the State of New York. This house is open on weekends and is well worth a visit. It contains many exhibits about the aqueduct, with historical photos, engineering drawings, and maps, and also has several short videos you can watch.

A ventillator

Much further north, in Ossining, is an impressive bridge that carries the water over the Sing Sing Kill. Below, there is a raised walkway where you can stroll alongside the brook. Three times a year there are guided tours of the aqueduct that actually bring you inside the tunnel. I haven’t gone yet but I plan to.

Croton Dam
The New Croton Dam

The most impressive structure along the way is, of course, the New Croton Dam—a beautiful and massive monument of the previous century. Made of cyclopean stones, standing at almost 300 feet tall, and stretching to 2,188 feet (almost the exact altitude of Madrid, coincidently) the dam is still immensely impressive. It is also beautiful, with the stair-like spillway allowing water to cascade down to the river below in an artificial waterfall. This dam, begun in 1892 and completed in 1906, replaced the Old Croton Dam, a much smaller structure completed 50 years earlier, now submerged and invisible under the expanded Croton Reservoir. This old dam was briefly put back into use in the 1950s, when a severe flood put cracks in the new dam, necessitating repairs. Standing on top of the new dam, hearing the rushing water below you, looking out at the massive reservoir, you get a sense of how much water a major city like New York needs.

Croton Dam Side
The New Croton Dam from the top

Another monumental structure sits on the southern end of the old aqueduct: the High Bridge. This bridge, opened in 1848, is the oldest bridge still standing in New York City. It originally resembled a Roman aqueduct, with tall stone arches carrying the water high overhead, just like the famous aqueduct in Segovia. Indeed, one remarkable thing about the Croton Aqueduct is that it uses the same principle the Romans used all those centuries ago—namely, gravity—transporting the water on its 40 mile trip with a slight incline, 13 inches per mile. The bridge had to be built so high (140 feet) to maintain this slope. However, in the 1920s people began to complain that the bridge’s arches were an obstacle to ships traveling through the river, so the middle stone pillars were demolished and replaced with a long steel arch. The bridge was officially closed in 1970, apparently because of vandalism, and wasn’t opened until 2015—an astonishingly long time, if you ask me.

High Bridge Ground View
The original arches of the High Bridge

The man primarily responsible for planning and engineering the original aqueduct was John B. Jervis, who must be one of the great engineers of 19th century America. The water tower he designed still stands on the Manhattan side of the High Bridge, looking like the turret of some erstwhile castle. Upon completion of the project, Jervis himself rode in a rowboat through the tunnel all the way from Croton to New York. I don’t know how long it took him, but it takes the water 22 hours to make the journey.

High Bridge Top
The High Bridge from the top

The original aqueduct and dam were commissioned in the 1830s after it became apparent that New York badly needed more water. Outbreaks of yellow fever and cholera, caused by contaminated water, killed thousands; and the Great Fire of 1835 destroyed hundreds of buildings, largely because the fire department lacked the water to stop it. Manhattan is an island of marshy ground surrounded by brackish water, and before the Croton Aqueduct was built the only water supplies were local wells which could be easily polluted. The opening of the aqueduct was something of a sensation. People used to visit the main reservoir on 42nd street to stand atop the pharaonic structure—inspired by Egyptian architecture—and see Manhattan.

Water Tower
John Jervis’s water tower

The scale of the project is impressive: stretching about four times longer than the Aqua Appia in Rome (although, to be fair, I think the Romans built several aqueducts longer than the Croton Aqueduct), and requiring whole landscapes to be reshaped to maintain the aqueduct’s incline. The tunnel underground is made of brick and waterproof concrete, and was constructed mostly by 4,000 Irish laborers who made a dollar or less for ten-hour days. At the time, it was one of the biggest engineering projects in the United States; nevertheless it wasn’t long until the ever-growing population of New York outstripped the capacity of the aqueduct. Indeed, it was largely thanks to the increased supply of fresh water that the city was able to grow so quickly. Thus the aqueduct, designed to be used for centuries, was supplemented in 1890 by the New Croton Aqueduct, a larger tunnel that runs parallel to the old one. The Old Aqueduct stopped delivering water to the city in the 1950s.

This book, part of the Images of America Series, is mostly focused on the construction of the New Croton Dam. The story of this construction is told with dozens of old photos, along with commentary by Christopher Tompkins. You don’t exactly get a linear narrative this way, but the images alone are worth the price. It baffles the mind to think of what these men accomplished—redirecting a river, and erecting a structure 300 feet tall with cut stones, flooding an entire valley and displacing many communities, using technology that looks, to my eyes, scarcely more advanced than the Egyptians. That’s an exaggeration, of course; they had steam shovels to excavate and the railroad to bring stone from the quarry. But I can’t imagine how difficult it would have been to move those massive stones in a time before modern cranes, using only wooden derricks and pulleys and counterweights.

It is amazing to me that so much history—an engineering feat and a chapter in the history of New York—lay buried right behind my house, and that I’ve been walking along this trail for so many years, oblivious. Don’t wait until you travel to learn about history, to explore and go on tours. Take Thoreau’s advice: “Live at home like a traveler.”

Below are images taken from the High Bridge of informative plaques in the walkway.



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