New York, NY —
Ever since the concept of global warming was first introduced to the public 15 years ago, most strategies to combat the buildup of greenhouse gasses have focused on cutting emissions at their source. Now as the inevitability of climate change sinks in, people are talking more and more about reducing our vulnerability to the harmful effects of a changing climate and finding new ways to protect the existing infrastructure.
Today in our series Degrees of Concern, John Rudolph reports that one of New York's most vulnerable systems is the city's water supply. One place where this weakness would first be detected is along what's knows as the "salt front" on the Hudson River.
My name is John Cronin and I'm the Director of the PACE Academy for the Environment at PACE University. And where we're standing right now is - we're standing in the midst of the Hudson Highlands, which is one of the narrower sections of the Hudson River Estuary. So, what we're looking at when we're looking at the water here on the Hudson River we're looking at sea level. The Hudson River is at sea level. And the glacier tore through the Appalachian Chain here below sea level. The bottom of the river is below sea level straight to the ocean.
John Cronin has spent most of his adult life educating people about the Hudson, and fighting to protect the river from various threats. These include proposals to divert huge amounts of river-water for power plants, factories and drinking water supplies. Diversions like these would have changed the Hudson's basic ecology by altering the mix of fresh and salt water. It is this mix, says Cronin that makes the Hudson such a rich environment wildlife.
Where that salt is located is key to the development of fish at certain life stages. So, when they are little hatchlings and are ready for the big, broad shallow area of the Hudson, which is the nursery, the water is of a certain salinity that they can tolerate just in time for them to be there where they're going to be doing their feeding. So, it's an extraordinary piece of ecological choreography.
Fresh water flows down the Hudson from the Adirondack mountains, salt water moves up from the mouth of New York harbor. The place where these two forces meet is an invisible line in the river called the salt front. The salt front is constantly in motion.
In spring when snows melt, the heavy flow of fresh water pushes the salt front down the river to a point about 30 miles north of the city. When there's a drought, and the flow of fresh water is reduced to a relative trickle, the ocean pushes the salt front upstream, as much as 80 miles up the Hudson.
There's even a web site where you can keep track of the Hudson River salt front.
The salt front isn't the only thing that moves on the Hudson. Trains run on tracks on both sides of the river. And there are lots of barges, tankers and pleasure boats on this busy waterway.
The movements of the salt front, however, are of special concern to John Cronin, especially the possibility of an irreversible change in the salt front's location.
It would have a permanent ecological effect on the Hudson River, probably unlike any other that we've ever seen on the Hudson; unlike anything caused by pollution or power plants or even development. This would be a permanent alteration of how the ecosystem operates in the most fundamental way.
Rising sea levels amplified by climate change could have a lasting impact on the salt front. If high tide becomes consistently higher than it is now, the salt front will be permanently pushed up the river. In addition to changing the Hudson's ecology, the supply of drinking water in the New York metropolitan area will also be affected.
New York City's water supply system is huge and complex. 22 reservoirs and lakes provide water to more than nine-million residents of the city and four suburban counties, as well as the hundreds of thousands of commuters and tourists who visit the city every day.
In an emergency, such as a severe drought, the city has the ability to tap the Hudson River. The city maintains a river water pumping station in the tiny town of Chelsea, about 65 miles upstream. The Chelsea pump station came on line in the mid 1960s during the worst drought to hit the city in the 20th century.
Good evening my fellow New Yorkers. We the people of New York City face the danger of a serious water shortage. This shortage is due to entirely to the most prolonged drought in the history of this region...
When Mayor Robert F. Wagner delivered this address on July 22, 1965 it was clear that city officials saw the Chelsea Pump station as a vital safety net.
It will provide 100 million gallons of water per day. This amount, I remind you, is less than 10 per cent of our daily consumption. The use of the Hudson river water is our only practical means of increasing our supply from inland water resources
In the mid 60s this back-up plan seemed to make sense. The Chelsea Pump station was built near a major underground aquaduct that carries water from the Catskill Mountains to the city. During a drought, all that was needed was to turn a valve, and river water would be there to help quench New York's thirst.
But today, many people argue, water from the Chelsea Pump Station is virtually unusable. That's because during severe droughts the salt front moves several miles upstream from Chelsea. When it's needed most, John Cronin says, the Chelsea Pump Station would be adding salty water to the city's fresh water supply system
There's really a harsh irony. The Chelsea pumping station was built to address drought conditions and give New York City a supplemental water supply during drought. And they put it in exactly a section of the river that is guaranteed to be salty during drought conditions. So, it was a poorly thought out plan.
New York City has only pumped Hudson River water a few times since the 1960s. But in the city of Poughkeepsie it happens every day. Poughkeepsie gets all of its water from the Hudson. Randy Alstadt manages the city's Water Treatment Plant.
The pump station pumps a thousand feet out, 50 feet down, about the middle of the river. We pull of about 8 to 90 million gallons a day from the Hudson River
The ever-changing salt front is one of several factors Alstadt monitors to ensure the quality of Poughkeepsie's water. During three separate droughts over the last decade Poughkeepsie officials issued health advisories about high levels of salt in the city's water supply. People on low salt diets were advised to check with their doctor and drink bottled water.
That's because Poughkeepsie's water is filtered and treated for a wide range of impurities, but salt is not one of them. Desalinization is expensive, and Alstadt says so far, it hasn't been needed.
We've been drinking this water in this area since 1872, and the river is going up and down. And you can look historically, if there is a drought, yeah we can have it. And I guess one of the things you're looking at is maybe long term something could happen to the climate. People believe that, people don't believe that. It's hard to know what the climate's gonna do. And I think as the climate changes we may have to adjust.
Today, increased salt in drinking water caused by the movements of the salt front is an occasional nuisance that affects a relatively small number of people who live in the mid-Hudson Valley.
But increasingly the Hudson River salt front is drawing the attention of researchers and government officials.
Another salt front, on the Delaware River, is also a cause for concern. The Delaware River watershed is a major source of drinking water for New York, as well as Philadelphia and a number of other cities and towns.
Bob Alpern recently retired from the city's Department of Environmental Protection, where he was involved in water supply planning. In addition to the salt front Alpern says the city needs look at a wide range of climate-related issues that could affect water resources in the future..
Uncertainty about whether we're gonna get more rain or much less rain, whether we're gonna get rain at the right time of year, whether we're gonna get snow melt at all, whether we're gonna get sudden violent, extreme events - storms - or a kind of steady input into the reservoirs, those are the kinds of issues which are still very uncertain, by and large, but they loom large as probably the most important environmental impacts that we've got to deal with in the metropolitan area.
In a year such as this - when the reservoirs are full - threats to the water supply system from rising seas, shifting salt fronts or other potential effects of global warming seem remote. Since the attack on 9/11 a more immediate concern has been guarding against terrorists who might try to sabotage the water supply. Recently the hottest controversy has been over the city's plans to build it's first-ever water filtration plant.
And so for now, it seems, planning for the potentially far-reaching effects of climate change on New York's water supply, will have to wait. For WNYC, I'm John Rudolph.