On a raw winter’s day, the water riffling over the spillway of the Ashokan Reservoir looks icy and pure. Set at the eastern end of this vast artificial lake in Ulster County, the spillway curves and drops like a wedding cake, in four tiers, before sending its flow through a narrow granite passage flanked by evergreens. The setting is grand, as befits an enormous public work, a manipulation of nature for the benefit of humanity — or at least for the 8.2 million residents of New York City, 100 miles to the south.

Or perhaps they are just suckers for ads that equate glaciers with purity and tropical islands with smooth taste. In 2003, Brita ran an ad campaign in the subways claiming that its filters turn “even New York tap water into drinking water.” Incensed, Christopher Ward, then the city’s environmental protection commissioner, accused the company of fear-mongering, at which point the company withdrew the ads.

But the fact is, over the years New York has not delivered consistently good water. In the last five decades, so much of Westchester has been paved over, sending fertilizer, sewage and road salt into reservoirs, that at certain times of the year Croton water has had an odd color, taste and odor. From 1989 to 1999, the city had to increase the amount of chlorine it added to the system by 35 percent.

To deal with the problem, the city in 1998 committed to building a filtration plant for this “East of Hudson” system, under Mosholu Golf Course in the northern Bronx. The plant will begin operations in 2011, and Croton water will once again flow to the city — but it will be filtered.

Meanwhile, New Yorkers continue to drink unfiltered “West of Hudson” water, also known within the department as “Cat/Del” water, short for the Catskill and Delaware Watersheds. But is Cat/Del water clean? And is it as clean today as it was 10 years ago?

“It’s better now,” said Steven Schindler, the city’s director of drinking water quality control. “Before 1997 when we adopted new regulations, construction, development and land use in the watershed were much looser.”

For instance, so much phosphorus from dairies reached the Cannonsville Reservoir that the city used copper sulfate to combat the growth of algae and the taste and odor problems it produced. After the local wastewater treatment plants were upgraded and farms’ management practices were improved, the amount of phosphorus declined and the copper sulfate was no longer considered necessary.

Nevertheless, the city faces challenges in the West of Hudson system. “City water is still blue-ribbon quality,” said Alex Matthiessen, executive director of Riverkeeper, an environmental group. “But,” he added, “we can’t let our guard down.”

The biggest challenge is cloudiness, or what scientists call turbidity. Tiny particles in the water may seem harmless, but they can interfere with chlorine disinfection, and they serve as food for disease-causing organisms. The city has long controlled occasional turbidity by adding to the water a substance called aluminum sulfate, which makes particles clump and sink. But alum is no panacea. Heavy use of alum can make water more acid, and acidic water can corrode pipes and make it hard for fish to breathe. Moreover, alum is accumulating on the bottom of the Kensico Reservoir, in Westchester; the city plans to clean up that sludge, which is six feet in some places and is smothering aquatic life.

Natural conditions make the city’s job harder. The clay soils and steep topography of the Catskill watershed are the root cause of the water’s cloudiness. Engineers noted the turbid character of the clay-bottomed Esopus Creek as far back as 1903, and to compensate they designed the Ashokan with two basins. Turbid water entering the reservoir from the creek settles in the western basin, where it sits until the sediment sinks. Then, a low dam between the basins drops, and clearer water flows into the eastern section. After a few weeks’ further settling, it flows into the Catskill Aqueduct, and from there into the Kensico Reservoir.

The two-basin system worked fine until recent decades, when developers began clearing more land, paving more surfaces and building more roads, all of which increase erosion and speed the flow of sediment into creeks and streams. Climate change, in the form of stronger and more frequent storms, has made the problem worse. Between September 2004 and last June, four major storms dumped highly turbid water into upstate reservoirs.

The Five-Year Jitters
There are plenty of certainties in New York’s water future. In 2011, the Croton filtration plant will begin operating. In 2012, the city is scheduled to open its third water tunnel — a 60-mile conduit, 50 years in the digging — and that would finally enable it to take water tunnels 1 and 2 offline for repair and cleaning. And, perhaps the greatest future certainty of all, the city will need to secure new sources of water, as it did when the English governor dug that first well in 1666. By the year 2020, about 9 million people will be living in New York City. They’ll all want something to drink.

But filtering is a question mark. Every five years, the city’s environmental officials sweat out the federal decision over the quality of New York water, and this is one of those years. The federal environmental agency will either issue another permit allowing the city to avoid filtration, or it will order the city to build a huge filtering plant for the Cat/Del system. The ruling is preliminary, and will be followed by a monthlong comment period and then a final federal pronouncement.

According to Ms. Lloyd, avoiding an order to filter is both easier and harder than it has been in the past. It is easier because the city agency has a track record of protecting the watershed. It is harder because the regulations have gotten stricter and technology allows finer monitoring of water quality.

For example, since 2002, when the city got its last E.P.A. ruling, the federal agency has required cities that drink unfiltered surface water to use two disinfection methods instead of one. In addition to chlorine, which New York already uses, it will soon be running its famous water through the world’s largest ultraviolet-light plant.

“It’s a belt-and-suspenders approach,” said Alan Steinberg, the federal administrator whose region of responsibility includes New York and New Jersey. Ultraviolet light adds another level of protection to water quality by killing cryptosporidium, a microscopic parasite that can cause disease but is resistant to chlorine. Reliance on ultraviolet light will also let the city use less chlorine, which can contribute to the formation of possibly carcinogenic organic chemicals in the water.

To win another five-year reprieve from filtration, the city, working with federal officials, has drawn up a detailed plan to regulate the upstate watershed. It includes managing farms and forests to keep manure and fertilizer out of streams; controlling erosion along stream banks; chasing migratory waterfowl from reservoirs; buying land within the watershed to prevent development; repairing leaky septic tanks on private land; and cleaning the water in sewage treatment plants even more thoroughly before it is discharged into the watershed.

“I’ve heard of plant operators drinking it on a tour,” said Mr. Schindler, referring to the last plank of the plan. That’s reassuring, but more than two dozen of the roughly 100 wastewater treatment plants that discharge into the city’s watershed still use a suboptimal cleaning process.

‘A Spray of Silver Beadies’
Then there is the matter of stronger storms, which will continue to dump vast quantities of silt into the reservoirs. To keep the city’s water clear, Ms. Lloyd’s agency is closely studying its reservoirs and streams, and contemplating several engineering fixes that would hold the water longer in the west basin of the Ashokan and give the sediment more time to settle. If the problem isn’t fixed upstream, where it occurs, it will have to be remedied near the end of the line — with filtering. And that, said Ms. Lloyd and others, is a far less attractive option.

“If you are able to keep the drinking water at high quality with minimal treatment, without using all that energy and chemicals, that’s better than having to bring it back to high quality,” Ms. Lloyd said.

That ounce-of-prevention job is not one big task but many small ones. “You want to limit phosphorus, reduce turbidity and prohibit human and animal waste from entering the system,” said James Tierney, the state assistant attorney general charged with enforcing environmental laws within the watershed. “It’s not a silver bullet that will take care of the system; it’s more like a spray of silver beadies.”

What if the beadies miss their target, and federal officials order New York to filter its water? The city would not be unprepared. A preliminary design for a plant, to be located in Mount Pleasant and Greenburgh in Westchester County, already sits in a drawer; the plant would cover an area larger than 15 football fields and be capable of filtering 2.4 billion gallons of water a day.

But, financially speaking, a federal directive to filter West of Hudson water “would be like a bomb going off,” Mr. Tierney said. The plant would cost more than $6 billion to build, and the cost of staffing, operation, maintenance and debt service would reach $1 billion annually.

Ms. Lloyd, however, refuses to cast filtering as a failure. “It’s my primary responsibility to deliver the best drinking water I can to New York City,” she said. “If filtering is the best way to go, that would have to be the decision.”

If the Ashokan is not the one true source of the city’s drinking water, akin to Perrier’s Vergèze or the original Poland Spring, it is still evocative shorthand for the sprawling upstate waterworks that have long quenched New York’s thirst. The city has the largest drinking-water system in the country, an engineering feat on a par with the Panama Canal, delivering 1.2 billion gallons of water a day through 300 miles of tunnels and aqueducts and 6,000 miles of distribution mains.

Moreover, as city officials, water connoisseurs and native boosters have long declared, New York tap water is among the world’s purest and tastiest. It is praised in foreign-language guidebooks, and some city bakers credit its mineral content and taste for their culinary success. “It’s delicious,” said Emily Lloyd, commissioner of the city’s Department of Environmental Protection.

The upstate water is of such good quality, in fact, that the city is not even required to filter it, a distinction shared with only four other major American cities: Boston, San Francisco, Seattle and Portland, Ore. New Yorkers drink their water from Esopus Creek, from Schoharie Creek, from the Neversink River, straight from the city’s many reservoirs, with only a rough screening and, for most of the year, just a shot of chlorine and chasers of fluoride, orthophosphate and sodium hydroxide.

But that state of affairs may not last. In late spring or early summer, the United States Environmental Protection Agency will decide whether New York water is still pure enough to drink without filtering. Development in the city’s upstate watershed areas, as well as the increasingly stormy weather that comes with climate change, is threatening the water’s mythic purity. If the federal agency does conclude that city water is too sullied to be consumed directly, New York will have to spend huge sums on filtering, close the book on 165 years of filter-free taps — and absorb a major blow to its hometown pride.

When the Dutch arrived in Manhattan four centuries ago, they drank from the same creeks and springs as the Algonquin Indians who preceded them. As the colony grew, these local sources became polluted. Residents collected rainwater for drinking, but the preferred beverage during those years was beer.

In 1666, the new English governor of New York dug the city’s first public well. Wells would provide water for the next two centuries, but the water, distributed through wooden mains, was brackish and hard. Eventually the wells became contaminated by industrial byproducts and by animal and human waste; in the 18th century, New York was desperate for a new approach.

For decades, city planners squabbled over alternative sources of water, looking as far away as Lake George in the Adirondacks and the Housatonic River in Connecticut. Finally, in the 1820s, they decided to impound the waters of the Croton River in northern Westchester County and send 90 million gallons a day through an aqueduct to the city. But by the time the system was completed in 1842, Manhattan already needed more water.

From that point on, the water system grew just as New York did. The city expanded its watershed into the Catskills, built immense aqueducts and relocated thousands of people, and even graves, to create huge reservoirs like the Ashokan.

Today, New York water originates in watersheds that sprawl over nearly 2,000 square miles, filling 19 reservoirs and three controlled lakes. The aesthetic and mechanical beauty of the system — 95 percent of which is gravity-fed — causes some officials to wax sentimental. “It’s miraculous that the system replenishes itself,” Ms. Lloyd said. “And if we take care of it, it will provide drinking water for New York forever.”

Whatever the fabled deliciousness of New York’s water, its residents, like other Americans, are drinking more and more of the bottled variety. “I think it’s convenience more than anything,” Ms. Lloyd said about the trend. “New Yorkers spend very little time at home — they’re the great grab-and-go eaters and drinkers.”
(Por Elisabeth Royte, The N.Y.Times, 18/02/2007)