THE FIRST DECADE OF PHILADELPHIA’S GREEN CITY, CLEAN WATERS PROGRAM: “We had sold people on the concept, but we did not expect the level of complexity that was required, the level of partnership. We had no idea,” said Paula Conolly, director of the Green Infrastructure Leadership Exchange

Note to Reader:

Rising temperatures create more frequent intense downpours that overwhelm urban systems, sending raw sewage into waterways. Many cities, from the District to Chicago and San Francisco, have been scrambling to find ways to slow the flow.

Some are building huge storage basins; others are renegotiating their legal obligations to limit pollution; and many are developing green solutions to stanch rainwater runoff before it enters drains. For those involved in such efforts, Philadelphia has literally been unpaving the way with its Green City, Clean Waters program for a decade/

Green City, Clean Watersis a first-of-its-kind combined sewer overflow compliance approach based primarily on green stormwater infrastructure. Implementation commenced in 2011. The story below includes an extract from an article published in the Washington Post in April 2020.

Green City, Clean Waters

Hundreds of historic cities like Philadelphia experience combined sewer overflows during heavy rainstorms. Philadelphia Mayor Michael Nutter gave the green light to explore reverting from “gray,” or traditional stormwater management infrastructure, to “green” or sustainable infrastructure that mimics the natural water cycle.

In 2011, Philadelphia reached an agreement with the Pennsylvania Department of Environmental Protection and the U.S. EPA to explore a largely green stormwater management infrastructure plan to reduce sewage overflows. As a result, an ambitious and comprehensive attempt to overhaul stormwater infrastructure was developed.

Green City, Clean Waters (GCCW) has not only made Philadelphia the first city in the U.S. to meet both state and federal water quality mandates through green interventions, but it will also save the city an estimated $6.5 billion in construction costs over building new pipes.


Philadelphia has produced a video that explains how this green vision will be accomplished over time. To view it, click on on the image below or click

To download a presentation by Howard Neukrug that laid out the vision in 2010, click on Clean Water….Green City: Blending the interests of land and water in Philadelphia.

To view Philadelphia’s Mayor Michael Nutter’s “Charting New Waters” speech in 2010, click on

A Green Solution to an Aging Stormwater System

Climate change means more floods, which overwhelm urban sewers and send raw sewage into rivers and streams. Philadelphia is aiming to capture rainwater before it flows into city drains.

“In a typical year, Philadelphia used to release more than 13 billion gallons of effluent into its open waterways. GCCW aims to capture and treat 85 percent of the combined sewer flow, or about 8 billion gallons a year by 2036. So far, it is on track,” wrote Francis Stead Sellers, Washington Post senior writer on the America desk.

“In the first five years of the program, the volume was reduced by 1.71 billion gallons, and the water department should exceed its 10-year goal of an annual reduction of more than 2 billion gallons.

“The challenge of reinforcing Philadelphia’s 3,000-mile pipe network with green infrastructure, it turns out, lies not so much in re-engineering the existing system as in building the municipal, commercial and residential partnerships necessary to make a new system work.”

A Perspective on Creating ‘Greened Acres’

In the article, Sellers quoted Paula Conolly, director of the Green Infrastructure Leadership Exchange, who used to work at the Philadelphia Water Department:

“We had sold people on the concept, but we did not expect the level of complexity that was required, the level of partnership. We had no idea.”

“The program involves creating ‘greened acres’ — expanses of impervious land that are transformed either to absorb the first 1½ inches of rainfall or send it into rain gardens or other local green infrastructure systems. By the end of 2019, the city had created more than 1,500 of a projected 10,000 greened acres.

“From the planning stage through the construction and ongoing maintenance, the installations have required coordination among city agencies and with schools, businesses, nonprofit entities, politicians, residents, developers and landowners.”

To Learn More:

To read the complete article by Frances Stead Sellers, download A Green Solution to an Aging Stormwater System

June 2016 marked the five-year anniversary of Philadelphia’s groundbreaking agreement with regulators. GreenTreks has been involved in documenting the Green City, Clean Waters program from the beginning, and this video offers a glimpse at the transformative effects that have taken place throughout the region over the years.