Keep Your Hands Off My Water Supply

New York City’s vaunted water may be too dirty for the feds:

New Yorkers are endowed with certain inalienable rights, among them bragging about the city’s water — so pure it doesn’t need to be filtered, so delicious it is better than bottled.

So it may surprise, perhaps even insult, proud residents to hear that federal officials are worried that the fabled water — coming from the largest unfiltered system in the country — is getting muddier and may have to be completely filtered, at a cost of billions of dollars, if it cannot be kept clean.

For much of the last year, the century-old water system that delivers 1.3 billion gallons a day to the city has been clouded by particles of clay, washed into upstate reservoirs by violent storms in quantities that make the water look like chocolate Yoo-hoo.

To keep the tap water running clear, the city has been dumping 16 tons of chemicals a day, on average, into the water supply as an emergency measure to meet federal water quality standards. The treatment does not change the taste of the water, but the city cannot rely on this stopgap approach forever.

Turbidity — the condition that makes water cloudy and interferes with chlorination to eliminate contaminants — appears to be getting worse because of changing weather patterns and increasing runoff from land development upstate.

If the city cannot find a permanent solution to the silt, it may not be able to avoid building a huge filtration plant that could cost about $8 billion.

Because its water has historically been so pure, New York has largely been exempt from federal rules created in the late 1980’s that require all water systems to be filtered. (A small part of the system, in Westchester, will be filtered in a few years.)

But as federal officials review the city’s five-year exemption, which expires at the end of this year, they have openly expressed concern about the water quality.

“The single most important item we’re looking at, and the one that could be a problem for the city, is turbidity,” Walter Mugdan, a local director of the Environmental Protection Agency, testified at a City Council hearing this spring. His office, the Division of Environmental Protection and Planning, will decide early next year whether the city’s water is clean and clear enough to avoid filtration for another five years. (Only four other major cities — Boston, San Francisco, Seattle and Portland, Ore. — are also exempt.)

The city is confident that it will win renewal. Emily Lloyd, commissioner of the city’s Department of Environmental Protection, which runs the water system, said that the department was working on plans to reduce turbidity without chemicals, particularly in two big reservoirs in the Catskill Mountains.