Flooded Benches in Philadelphia 640 x 400
Philadelphia Flood: Water surrounds city benches during a flash flood in Philadelphia. © Reggie/Creative Commons

Stories in Pennsylvania

Natural Solutions to Stormwater Pollution

We are employing nature to soak up stormwater around Philadelphia.

Philadelphia is the sixth largest city in the United States. Like many large cities, it faces a host of environmental challenges. One of the biggest is water pollution stemming from stormwater.

During even moderate rain events, aging sewer systems are overwhelmed by the rapid influx of stormwater. As a result, millions of gallons of highly polluted water flow into creeks and rivers, and even onto low-lying, densely developed areas.

Breaking with Tradition to Improve Philadelphia's Infrastructure 

During especially severe summer storms, torrential rains move through Philadelphia, flooding streets and clogging stormwater drains. With nowhere to go, the dirty water rushes into the Schuylkill River, and ultimately, the Delaware Bay.

City agencies are not alone in addressing this challenge. Stormwater runoff is one of the nation’s leading causes of water pollution.

“Cities with aging infrastructure face water pollution challenges due to combined sewer overflows,” says Julie Ulrich, director of The Nature Conservancy’s urban conservation program in Philadelphia. “Heavy rains flow rapidly off hard surfaces to overwhelm systems before flooding and polluting streets, homes, businesses and local waters.”

Water flows through a large pipe into a creek.
Culvert A stormwater culvert flows with stormwater in Phiiladelphia. © Dawn Whitmore

Philadelphia is legally obligated, under the Clean Water Act, to mitigate stormwater pollution by 85 percent over the next two decades. In response, the Philadelphia Water Department (PWD) launched Green City, Clean Water (GCCW), an initiative aimed at putting soil, grasses, plants and trees to work at naturally absorbing stormwater.

The PWD plans to measure progress based on data highlighting that a city acre receives approximately one million gallons of rainfall each year. "Greening" the city, acre-by-acre, with rain gardens, small parks, living roofs and similar features, is expected to sharply reduce the amount of stormwater pollution reaching local waterways. A more natural infrastructure also reduces the urban heat island effect to mitigate air pollution.

The PWD aims to manage 10,000 greened acres by 2036.

“Thanks to PWD, Philadelphia is the only U.S. city committed to solving this problem primarily through green stormwater infrastructure,” adds Ullrich. “I am excited about this big, bold and unprecedented step in exploring whether green infrastructure can work at a comprehensive scale across an entire city landscape, complimenting traditional approaches to water pollution management.”

These efforts have received a generous boost thanks to  grants from the William Penn Foundation. Support like this makes it possible to work at an unprecedented scale and pace in order to achieve the PWD's ambitious goal. 

“Adding more nature to the built environment delivers benefits that reach beyond pollution control,” adds Ulrich. “It also beautifies neighborhoods, enhances public and recreational spaces and even spurs job creation—all at a lower cost than traditional engineered solutions.”

Sharing Solutions

TNC's urban conservation work in Philadelphia has caught the attention of peers throughout the country, including the Puerto Rican-based non-profit, Corporación del Proyecto ENLACE del Caño Martín Peña (ENLACE). During 2019, the organizations participated in a learning exchange to share knowledge about stormwater management, participatory decision-making, environmental justice and how to make cities more resilient in the face of a changing climate.

 “Our partners at ENLACE helped establish and continue to work closely with the Caño Martín Peña Community Land Trust—known as the world’s first community land trust of an informal settlement,” says Julie Ulrich. “A board that includes residents manages the land trust and has a mandate to preserve and develop affordable housing in the face of gentrification and land scarcity—all issues we face in Philadelphia.”

Puerto Rico Learning Exchange The Nature Conservancy's Cities team visits Puerto Rico to share knowledge with Corporación del Proyecto ENLACE del Caño Martín Peña (ENLACE) as part of a learning exchange be
Puerto Rico Learning Exchange
Puerto Rico Learning Exchange Representatives from the Puerto Rican non-profit organization, ENLACE, visit Philadelphia as part of a learning exchange about managing stormwater. © The Nature Conservancy

In return for gaining knowledge about community land trusts, the TNC team shared strategies in planning, managing and implementing green stormwater infrastructure projects with a community-centered approach. ENLACE intends to use the information to address ongoing flooding and pollution issues while bringing additional benefits to residents of the Caño Martín Peña.

Carlos Muñiz Perez, ENLACE’s urbanism and infrastructure program manager, says, “The exchange is an opportunity to learn from Philadelphia’s nature-based solutions framework to comply with federal water quality standards and better position San Juan and the G-8 communities to be responsive to infrastructure challenges exacerbated by extreme rainfall events.”

We truly feel we are focusing on a more sustainable vision for the infrastructure of our communities that deserve a healthier and fairer city.

Deputy Director of ENLACE

As part of the learning exchange, representatives from ENLACE visited Philadelphia to learn about TNC's stormwater management work and to study the GCCW initiative. During the visit, Marc Cammarata, Deputy Water Commissioner,  and Tiffany Ledesma, Public Engagement Team Manager for the PWD,  shared insights on the context, challenges and successes of the initiative.

Both partners agree that adding nature to their urban infrastructure will benefit the health and quality of life for local communities and the surrounding landscape. 

Ulrich adds, "This is not a quick fix. Achieving results will take decades, but when it’s done, we’ll have reduced stormwater pollution entering Philadelphia’s waterways by 85 percent, leaving them swimmable, fishable and drinkable on a level most of our citizens have never known.”