The History of the Old Croton Aqueduct

The last few years I’ve become increasingly interested in the Old Croton Aqueduct (NYC’s first reliable source of clean water). My first interaction with the aqueduct was an Urban Park Rangers tour of The High Bridge (we went on their first first tour of it). If you haven’t been to The High Bridge, it’s incredible. Then I started exploring the entire OCA – most of it is now a trail and most of the trail is really wonderful. In the process of figuring out the path of the OCA I discovered The Friends of the Old Croton Aqueduct which is an organization that supports, cares, and advocates for everything related to the OCA. I’ve since gone on their walking tour of the Upper Manhattan portion of the OCA and in the near future I plan to go through the OCA Keeper’s House in Dobbs Ferry and do a tour of the weir in Ossining – both of which are organized by the Friends of the OCA.

The goal of this post is simply to give a big-picture timeline of the history of the OCA – placing those events into a larger historical context. I’ll follow up with posts detailing physical aspects of the lower sections of the aqueduct.


The City decides that the wells it uses for water aren’t sufficient and they want to come up with a more reliable and safer source of water. A plan is devised, but of course two years later war breaks out during which 1/3rd of the city’s population flee the City, so the plans for a better water system wait for another day.


The City experiences the first of three waves of Yellow Fever. All combined they killed thousands of New Yorkers.


The second of the three waves of Yellow Fever hit New York and people start talking seriously again about improving NY’s water supply.

Aaron Burr personally pushes a law through Albany to improve the city’s water supply. Thing is, he didn’t seem to be motivated by clean water – he was motivated by his rivalry with Alexander Hamilton (who he later killed in the infamous duel when Burr was Vice President). Hamilton had founded a bank (The Bank of New York), and Burr wanted a bank too. So the bill that Burr pushed through Albany specified that a private company, The Manhattan Company, would be in charge of the project and there was a provision that the profits could be used for things other than water. Burr used that provision to turn The Manhattan Company into a bank. That bank is now known as Chase Bank. Instead of the intended capitalization of one million dollars with 1/3rd of the company being owned by the City, he capitalized it with two million dollars and City didn’t get anywhere near 1/3rd ownership.

Everyone was under the impression that the Manhattan company was going to dam the Bronx River at West Farms (in the Bronx) at which point water would flow into a canal down to the East River where it would be piped into Manhattan. Compared to what came later with the OCA that was a comparatively small task. But no – The Manhattan Company just dug a few more wells in Manhattan and basically called it a day. New York was left with a continuing water problem, but hey – you got that Chase credit card in your wallet, so it wasn’t a total loss.

[Learn more about the history of the Manhattan Company here.]


The third of the three waves of Yellow Fever hit New York.


The Manhattan street grid is approved up to 155th Street.


There’s a stock market crash followed by a depression.


People still aren’t happy with the water supply and a few proposals are put forward, but nothing really happens (source).


A white landowner sells 200 plots of land in what was then the rural countryside – 82nd to 89th Street between 7th and 8th Avenues. The buyers are free black men and the area becomes known as Seneca Village.

The Erie Canal opens which greatly increased New York’s importance as a trading center.


July 4th – Slavery in New York ends.


A huge fire results in calls for a reservoir just to fight fire. The reservoir was then built at Broadway & 13th Street (source).


A cholera epidemic kills 3,500 New Yorkers. Half the population of the City fled the City to avoid illness.

DeWitt Clinton proposes daming the Croton River and using that as a source of water for the City.


New York State approves a bill to do something about the City’s water supply but doesn’t specify the precise solution.


The City chooses the Croton option and decides to build what we now know as the OCA. They choose David B Douglas to plan and oversee the project.

There are a series of three fires that year culminating in The Great Fire Of New York in December when 17 blocks and hundreds of buildings (1/4 of the City) is destroyed. It was so severe because firemen couldn’t get water from the river because it was frozen over.

Needless to say, with 1/4 of the City in ruins all eyes turn to the aqueduct project but Douglas doesn’t have much of anything to show for his work up to that point. He’s asked to resign, refuses, then fired, and John B Jervis is put in his place.


Meanwhile the City is starting to grow outwards. The New York & Harlem Railroad is founded in 1831 and reaches up to East 85th Street by 1834 and up to East Harlem by 1837.


There’s another stock market crash followed by a depression, but work on the OCA starts in 1837 and continues through the depression.


The OCA goes into service despite parts of it not being completed…

  • June 22nd – Water started flowing in the aqueduct.
  • June 27th – Water started flowing into the receiving reservoir in what is now Central Park.
  • July 4th – There are celebrations as water flows into the distributing reservoir on 42nd Street.

It should be noted that the original route of the OCA went right through Seneca Village just before it reached the receiving reservoir.


The aqueduct is complete except for one important piece – The High Bridge over the Harlem River.


The Great Famine strikes Ireland and New York sees an influx of immigrants – some of whom move into Seneca Village, despite it being a black community.


The High Bridge over the Harlem River is finally complete which meant the entire OCA was now “finished”.


New York State approves building Central Park. One of the reasons that location was chosen for the park rather than others was because the reservoir for the aqueduct was there.


The residents of Seneca Village are forced from their homes under eminent domain. Earlier that year it is established there were about 50 homes in the area and over two hundred residents – 2/3rds of the residents are black, 1/3rd are Irish, with a few Germans in the mix. While there are a few “shanties” most of the homes are of a fairly high quality. Some are multi-story.


The original six Keeper’s houses (which were wooden) were torn down and replaced with masonry houses (source). The locations were:

  • The Croton Dam
  • The Sing Sing (Ossining) Weir
  • The Mill River Weir
  • Dobbs Ferry
  • Yonkers
  • Tibbett’s Brook

Most keepers made $1.25/day (the keeper at the dam made $600/year).


Yet another stock market crash followed by a depression.


Frederick Law Olmstead is chosen as the designer for Central Park. And work begins to implement his plan.


Civil War breaks out, but work on Central Park continues.


What we now know as the Jackie Onassis Reservoir is completed. It becomes part of the Croton Aqueduct system and the path of the OCA changes to incorporate the new, Upper (Onassis) Reservoir (aka “Lake Manahatta”).

The original route of the aqueduct arced from 90th Street just west of 9th (Columbus) Avenue over to 85th Street and 8th Avenue (CPW). When the new reservoir was completed a junction gatehouse was put in at 92nd Street that could divert water into either the Upper or Lower Reservoir. Pipes were laid under 90th Street – some went straight into the Upper Reservoir, others turned, went down 8th Avenue (CPW) and then turned again at 85th Street to connect with the Lower Reservoir.

The new Upper Reservoir can hold over 5 times the water of the older Lower Reservoir (1 billion gallons vs 180 million gallons).

A 90″ pipe was added on top of the two 36″ pipes going over the High Bridge (source, illustration).


The Westside and Yonkers Patent Railway was built going up 9th (Columbus) Avenue. It was an odd railroad that was basically an elevated, single track affair pulled along by a cable system (similar, but different to San Francisco cable cars). By 1871 it had gone bankrupt and the new owners replaced it with steam engines on an elevated track.


A reservoir was added to the OCA system at the top of the hill immediately west of the High Bridge. Pumps were required to get the water from the aqueduct up to the reservoir.


A water tower was added between the High Bridge and the reservoir in order to pressurize the water supply in Upper Manhattan.


By the 1870s NY was growing rapidly and becoming a major hub of commerce. People started to realize that the City was growing fast enough that it wouldn’t be long before the OCA wouldn’t be able to supply enough water for the City.


There was another stock market crash with a depression lasting until 1877, so it wasn’t really the time to spend money, but projects that were already in progress continued.

1870 to 1876

In 1870 the legislature passed a law to change the route of the OCA in Manhattan yet again – this time between 92nd Street and 113th Street. The original route involved a stone bridge (The Clendenning Bridge) about a hundred feet west of 9th (Columbus) Avenue stretching from just north of 95th Street to just south of 102nd Street. While there were underpasses at 98th, 99th & 100th Streets, the bridge blocked 96th, 97th and 101st Streets. Given that 96th Street was a major arterial the bridge was a problem. Then the aqueduct angled over to 10th (Amsterdam) Avenue between 104th and 107th Streets.

As a result the Clendenning Bridge and the section of masonry aqueduct between 107th and 113th Street were demolished and replaced by an “inverted siphon” made up of four 48″ pipes running under 10th (Amsterdam) Avenue and 93rd Street. Gatehouses were built at each end of the siphon – one at 93rd street just west of 9th (Columbus) Avenue next to the existing junction gatehouse at 92nd Street, and another at 10th Avenue and 113th Street. Construction of the siphon was completed in 1875. Construction of the gatehouses was completed the next year – 1876.

While the 92/93rd Street gatehouses have been demolished, the gate house at 113th still exists today. [You can see the route of the OCA and the location of the gatehouses on this old map of NY from circa 1940.]

1876 to 1885

The Church of St Paul the Apostle was built at 60th & 9th (Columbus) using stone from the OCA. Stone from the Clendenning Bridge was in the lower part of the church between 1876 and 1885 when the church was dedicated. And stone from the Distributing Reservoir was used in the church’s towers many years later (probably around 1898 to 1900).

Other parts of the aqueduct between 92nd and 107th Streets were demolished sometime before 1896 (e.g. demolition at 104th Street).


A severe drought hits New York and people once again start talking about building another aqueduct (source).

Early 1880s

The weirs were modified (e.g. with new steel gates). The weir in Ossining was completely replaced with a new weir south of the original weir (1882).


A new, higher dam is proposed to make the Croton Reservoir larger.


New York State approves building another aqueduct – the New Croton Reservoir.


Construction on the New Croton Aqueduct begins.


July 15th – the New Croton Aqueduct goes into service.

The original Distributing Reservoir at 42nd Street was taken out of service.


The Stock Market Panic of 1893 starts one of the most severe depressions in US history that lasts until 1897. [All of these crashes and depressions are why the Federal Reserve exists.]


The gatehouse at 119th Street was demolished and replaced by another one which is still standing today. [The original 1840 gatehouses that were built along 10th (Amsterdam) Avenue were built literally in the middle of the street and impeded the flow of traffic, which is why they had to tear it down and build another one off to one side.]

The Harlem Ship Canal was completed, changing the course of the Harlem River between Inwood and the Bronx. Marble Hill, which was part of Manhattan is made an island. [In 1914 the old riverbed is filled in and Marble Hill becomes connected to the Bronx, but remains to this day part of the Borough of Manhattan.]


Further changes are made to the Harlem River in the vicinity of The High Bridge as The Harlem Speedway is completed along the Manhattan side of the river. The Speedway becomes a popular place to race carriages, and people flock to the area to watch the many rowing clubs along the river compete.

Demolition of the Receiving Reservoir at 42nd Street begins and is completed two years later. Parts of the old reservoir can still be seen in the basement of the New York Public Library which now stands in the same location.

The five boroughs are combined and become New York City.


The New Croton Dam was completed – the largest masonry dam ever constructed.

The Jerome Park Reservoir was completed. It was originally designed in 1875 and construction started in 1895 (source).


Construction begins on the Catskill Water System.


The Catskill aqueduct is completed. (92 miles, 60% cut-and-cover, 15% gravity tunnel, 18% pressure tunnel, 10% siphon). It brings water from the Eastern Catskills, crosses the river near Storm King Mountain and then goes on to the Kensico Reservoir in Valhalla and then South to the City. The portion in the City is also known as “Tunnel 1”. It currently supplies about 40% of NYC’s water.


The original Lower Reservoir in Central Park is deemed obsolete.


The Catskill Water System is completed. (Sources differ on the date of completion).


The arches of the High Bridge are declared a hazard to ship navigation in the early 1920s and in 1927 five of them are torn out and replaced with a single steel arch.


The Great Depression starts.


The original Lower Reservoir in Central Park is drained, but at that point in The Great Depression there isn’t money to do anything with it and it becomes a homeless encampment (aka Hooverville).


The High Bridge Reservoir is decommissioned and turned into a swimming pool.


The original Lower Reservoir in Central Park is finally demolished and turned into The Great Lawn and Turtle Pond.


The Delaware Aqueduct is completed, but the system of reservoirs takes another 20 years to be finalized. It is a deep-rock, pressurized tunnel that ranks as the world’s longest tunnel. Like the Catskill Aqueduct, it brings water from the Catskills (the Western Catskills in this case) to the Kensico Dam in Valhalla, but it takes a different route to get there. It crosses the Hudson River at Newburgh, then goes through a large part of the Croton watershed to finally get to the Kensico Reservoir. The Catskill and Delaware waters mix in the Kensico Reservoir, then then there are separate Catskill and Delaware aqueducts running between Kensico Reservoir and the Hillview Reservoir on the Bronx/Yonkers border where multiple mains connect to the City’s water system.


The High Bridge pumping station is decommissioned, which means the water tower was no longer used to pressurize the water mains in the area.

[Question: What exactly was going on between 1949 and 1955? Wikipedia says the High Bridge stopped being used to deliver water in 1949, but most sources say the OCA continued to be used until 1955. Was the OCA only in use to the Bronx or is Wikipedia wrong and only the water tower was decommissioned in 1949?]


New York City stopped using the Old Croton Aqueduct as a water source, but parts of it were still used to distribute water within Manhattan and the upper portion continued to supply water to Ossining. [The New Croton Aqueduct is still used today and supplies 10-30% of New York’s water.]

[Question: Why did NYC stop using the OCA? Why didn’t they see the value in having a redundant supply for Croton water? Did Robert Moses just think it was old and in the way?]


The Cross Bronx Expressway was built in the vicinity of the OCA which would have involved demolition of the OCA in that area.


Ossining stops using the OCA as a water source.

The Delaware River reservoir system is completed. It currently supplies about half of NYC’s water, but it leaks so badly the water it leaks could supply water for a half million people.


New York State purchases 26.2 miles of the OCA and turns it into a park.

1970 (possibly sooner)

The High Bridge is closed and doesn’t reopen until 2015.


Police find the carcasses of “carefully mutilated German Shepards” in the aqueduct in the vicinity of Untermyer Gardens in Yonkers. Apparently satanic rituals were happening in the park which the Son of Sam may have participated in.


The northernmost three miles of the OCA are put back in service to supply water to the town of Ossining.


The 119th Street gatehouse ceases operation.


The Upper (Onassis) Reservoir is decommissioned, though it is still connected to the water supply. (Water in the reservoir is chlorinated tap water.)