About Philadelphia Water Departmentís Green City, Clean Waters



Photo Location: Rain Garden at 12th and Reed
Photo Credit: Philadelphia Water Department

In 2011, the Pennsylvania Department of Environmental Protection (PADEP) and the Philadelphia Water Department (PWD) entered into a Consent Order & Agreement (CO&A) to address Philadelphia’s combined sewer overflows. The CO&A requires PWD to implement the Long-Term Control Plan Update (LTCPU), known as Green City, Clean Waters, which is a first-of-its-kind combined sewer overflow compliance approach based primarily on green stormwater infrastructure.

A combined sewer overflow (CSO) occurs when a combined sewer system (that is, a system that carries both stormwater and wastewater in the same pipe) becomes overwhelmed, and overflows into the nearest waterway. This can occur during periods of rain or snowmelt, when the volume of water inside the sewer pipe exceeds the capacity of the system to transport it to the treatment plant. These overflows can contain untreated human waste, bacteria, trash and debris.


Green City, Clean Waters is based on a detailed analysis demonstrating that it is the most cost-effective and technically feasible option to reduce sewage overflows to Philadelphia’s rivers and streams and comply with the federal Clean Water Act. Of the alternatives originally analyzed, Green City, Clean Waters was by far the least expensive. And it was the option that provides the most comprehensive “triple bottom line” benefits – social, economic, and environmental – to city residents.

The goal of Green City, Clean Waters is to increase green stormwater infrastructure in Philadelphia to make it a significant portion of the EPA mandated goal to reduce the amount of polluted stormwater overflows discharging into the creeks, streams, and rivers in and around the city by 85% by 2035. By using green stormwater infrastructure, residents will not only see clean water improvements, but also other “triple bottom line” benefits, including more green spaces, reduced heat island effects, and more local jobs to maintain the sites.

After the first eight years of Green City, Clean Waters implementation, the PWD has successfully surpassed its targets of installing enough green stormwater infrastructure to manage runoff of over 800 impervious acres across Philadelphia’s combined sewer areas (referred to as “greened acres”). But we can’t take Green City, Clean Waters early successes for granted. De-prioritizing green stormwater infrastructure may result in fewer green jobs in our local economy, a degradation of our rivers and creeks we use for recreation, and poorer air quality as climate change intensifies. Sign the petition to city council in support of green stormwater infrastructure.

Learn more about Philadelphia’s Green City, Clean Waters program.

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