Imagine New York Harbor, the Hudson River and the East River as open sewers.
It may well be in our future. A definitive government report on climate science makes clear that the frequency and intensity of precipitation in the northeast (already the highest in the nation, with a 17% increase in the last 25 years) will only grow dramatically in years to come.
In New York City, we should brace ourselves. Our aged sewer system is already overwhelmed by normal rains, flooding our neighborhoods and spewing 20 billion gallons of untreated sewage into our waterways every year. That’s more water than 30,000 Olympic swimming pools. And it’s not only sewage; it includes massive volumes of toxic chemicals.
Three quarters of our dense, built city is covered with asphalt and concrete. As rain pours off these impermeable surfaces, our old gray infrastructure — concrete pipes, wastewater treatment plants and massive holding tanks — tries to manage the stormwater.
But waste still gets dumped straight into our rivers.
A new approach called green infrastructure solves the problem. Strategically placed trees, grass, rain gardens, permeable pavement and green roofs absorb and filter rain. And not only does it help control flooding; it lowers temperatures, improves air quality and beautifies our neighborhoods.
The nation’s largest city has a huge opportunity to lead the country — to plant and build such green infrastructure on public and private property throughout the city.
Unfortunately, we’re playing a climate change catch-up game. The New York City Department of Environmental Protection, a sprawling agency with a $3 billion annual budget and almost 6,000 employees, has been great at building massive, multi-billion-dollar public gray infrastructure like expensive water treatment and filtration plants.
But figuring out how to intelligently green the city — even this city, which has been planting trees at a rapid clip since Mike Bloomberg was mayor — has been hard.
In 2011, the agency committed to spend $1.5 billion on green infrastructure, “stimulate” private investments of $900 million and green 8,000 acres by 2030.
After six years, DEP has greened just 437 acres, largely by building bioswales (essentially, enhanced tree pits). And it has spent $15 million on only 34 projects in a private property grant program.
More than 50% of land in New York City is privately owned. With so much at stake financially and environmentally, we need to do better.
New York City’s problem has a Philadelphia solution. Federal law requires Philly, like New York, to fix sewer overflows and stormwater pollution. And, like New York, Philly is building both gray and green infrastructure.
But unlike New York, Philly is also motivating private property owners to build green infrastructure, at less cost and more quickly than city government.
First, Philly changed its water and sewer fees. The city now uses a “stormwater fee” to charge fairly for the cost of runoff that a property creates. It reduces those fees when a property owner takes steps to manage stormwater onsite — usually with green infrastructure. And it requires green infrastructure be used in new construction.
Second, Philly launched cost-effective grant programs targeted at private property owners. Since the city was paying $250,000 or more to green a single publicly owned acre, Philly believed that the private sector could do much more for less money. It now pays less than $150,000 to green one privately owned acre.
Philly’s program has greened almost 840 acres and is committed to about 10,000 acres over 25 years.
We urge New York City: Outdo Philly. Mobilize private property owners with financial grants. Begin to charge New Yorkers more fairly for stormwater costs. And require green infrastructure in development projects.
Despite sewer overflows, our waters are the cleanest they have been in a century; humpback whales have been spotted swimming in New York Harbor. Over the last three decades our waterfront — filled with new parks, greenways and buildings — have flourished.
We can and must transform our whole concrete city into a living green space for our future.
Koval is a senior research scholar and Whelan is the founding director of the NYU Stern Center for Sustainable Business. Valderrama is a senior policy analyst at the Natural Resources Defense Council.
