Saturday, November 3, 2018

New York City water supply

I've noticed that NYC and Los Angeles have to pay a lot for water supply whereas Chicago has to pay a lot for water removal. I knew NYC dammed rivers in the mountains that are north of the city and then used tunnels (aqueducts) to transport the water into the city. What I did not know, until I studied the Cannonsville Dam, is that they also get water from the Delaware River watershed, which is a lot further away. Since I found this overview map, I'm writing this post to record it.

Project Description, page 6 from nyc.gov
A NY Times article about a leak in the Cannonsville Dam focuses on the people aspect of the dam. If you look at the map, Deposit, NY is downstream of the Cannonsville Dam. The residents are still bitter that 1000 people, including entire towns, were displaced over a half-century ago when the dam was built. Now they are bitter that they have to worry about the risk of living downstream of a dam. Since a big river flows right through them, they question why NYC doesn't build water purification plants (WPP) like most cities do. I also wonder why they refuse to build WPPs. It doesn't take that much flat land for a big WPP. Not only is the Chicago metro area served by just three plants, DuPage County cities also get their water from the Jardine WPP by pumping water into big water towers during the night. Is it because the Hudson is too polluted with heavy metals like mercury and pharmaceutical drugs? I can imagine that the WPP technology doesn't exist to remove those impurities. (Distillation would be way to energy intensive, and I understand that pure water tastes "funny." Our tap water generally contains trace amounts of minerals. River and lake water is around 8 grains, which is considered "just right" for laundry and showers. Before DuPage County switched from well water to lake water, our water was 30 grains.) Maintenance costs alone are rather staggering. The NYC Department of Environmental Protection plans to spend $14 billion dollars over the next 10 years to keep the system from falling apart. Yet the system provides just a billion gallons a day to NYC and 70 upstate consumers. Remember, the Jardine Plant alone produces a billion gallons of water a day. [nyc.gov, last paragraph]

(Los Angles has to pay a lot for their water supply because the closest river of any size, the Colorado River, is not big enough to supply the interested consumers.)

It is not just the towns close to the Cannonsville Dam that are at risk if a dam would fail. It has a capacity of 95.6 billion gallons, which is 1/8 of NYC's water supply. If the reservoir was full and the dam would fail, towns all the way down the Delaware River, including Philadelphia, would experience flooding. [DeBruler]

Dams I have studied so far:






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