Information Exchange: Publications

Protecting the New York City Water Supply Through Negotiated Watershed Agreement

Author: Rutherford H. Platt

"Nine million people in New York City and nearby areas enjoy access to abundant, clean, and inexpensive drinking water from that city’s farflung and internationally-admired water supply system. As early as the 1840s, New York constructed the original Croton River Dam and Aqueduct to divert water 40 miles southward to the fast-growing metropolis. As enlarged between 1885 and 1911, the Croton River system east of the Hudson River today provides about 10-12 percent of New York’s water. The other 90 percent is drawn from sources west of the Hudson River in the Catskill Mountains and the headwaters of the Delaware River. Five large reservoirs impounding the runoff from nearly 1,600 square miles of watershed discharge into two aqueducts (the Catskill and the Delaware) which plunge beneath the Hudson River enroute to Kensico Reservoir, near White Plains, New York. At Kensico, both streams of water from west of Hudson are combined, stored briefly, treated with chlorine, and released to the city distribution system. Altogether, the New York City System provides about 1.3 billion gallons per day (Hazen and Sawyer, 1997).


New York City’s water is not filtered. Like Boston, Portland, OR, San Francisco, and a few other cities, New York has relied on the natural purity of its hinterland sources, as reinforced by chlorine disinfection, to provide high-quality water without filtration. In the 1990s, that modus operandi has been shaken by new health concerns about disinfection byproducts, giardia, and cryptospiridia, among other threats. Federal regulations pursuant to the Safe Drinking Water Act of 1974, as amended, now mandate filtration for public surface water supplies. This requirement, however, may be waived by the U. S. Environmental Protection Agency (EPA) and state health agency if a water supplier demonstrates that it will “maintain a watershed control program which minimizes the potential for contamination by giardia lamblia cysts and viruses in the source water” (40 Code of Federal Regulations Sec. 141.71(b)(2)). New York’s Croton System has been held ineligible for a waiver and the city is obligated to construct a filtration plant for that source (currently delayed by NIMBY objections)."

Date Created: October 2001; Date Posted: March 2002





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