Vintage photos show how one of the world’s greatest engineering feats was created in 1915 to bring water to New York City

• Two hours by car from Manhattan, 40% of New York City’s water supply sits in the pristine Ashokan Reservoir.
• From there, it travels through more than 100 miles of tunnels to reach the city’s 8.4 million residents.
• Remarkably, the Catskill Aqueduct, which brings water from the Ashokan and Schoharie reservoirs, has been in operation since 1915.
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In 2016, the New York Public Library released almost 200,000 digitized images, and among them were these incredible photos of the Catskill Aqueduct construction, which began in 1906.

These vintage images show how this engineering feat was completed back then to keep providing clean water to New Yorkers to this day.

About 100 miles from Times Square, pristine water sits in a reservoir in the Catskill Mountains.

The NYC aqueduct system uses the same basic principle that the Romans used to bring water to their capital city: gravity.

Only 5% of New York’s water needs to be pumped; the rest simply flows downhill.

But New York engineers had one thing the Romans didn’t: dynamite. It allowed construction workers to bury the tunnels underground instead of needing to construct elevated aqueducts that snaked around mountains.

The Catskill Aqueduct tunnels are 30 feet across at their widest points — enough to make men standing inside them look tiny.

To make them, workers first dug a trench as deep as the tunnel would be. They used steam shovels to dig, and dynamite when the rock needed persuading.

They filled the bottom of the trench with concrete, and then the sides.

The workers poured concrete on the top of the tunnel, using steel forms to make it circular. Then they covered the whole thing back up with dirt.

This method of construction required completely removing the vegetation on top of the tunnel. The city did plant 3 million trees around the two reservoirs that feed into the Catskill Aqueduct, though.

Source: Catskill Water Supply: A General Description and Brief History

To gather the surrounding rivers and streams into one water supply, enormous dams had to be constructed. The Ashokan Reservoir that resulted held 132 billion gallons of water.

Source: Catskill Water Supply: A General Description and Brief History

While they did have the benefit of some electricity, workers still used horses for some projects, like pulling contraptions to flatten the earth.

They also used this fun looking bucket pulley system to transport dirt.

When the Catskill Aqueduct was completed, it could send 640 million gallons of water to New York City per day.

But today it only delivers ​​about 400 million gallons on average per day​​, because microorganisms​​ have built up on the miles of tunnel over the years, ​​slowing the water flow​​. (The water gets ​​treated​ before it reaches the city).

Source: NYC Water for the Future

The city is now cleaning up the Catskill Aqueduct so it can hopefully provide clean, fresh water to New York City for another 100 years.

Source: NYC Water for the Future