15 Years of Green City, Clean Waters: Transforming Philadelphia’s waterways through innovation and investment
For more than fifteen years, PWD’s Green City, Clean Waters (GCCW) program has been transforming the way the city manages stormwater, protects waterways, and invests in neighborhoods.
Since the program began in 2011, the Philadelphia Water Department has implemented one of the nation’s most ambitious green stormwater infrastructure programs while simultaneously advancing major traditional infrastructure improvements to reduce combined sewer overflows (CSOs), improve water quality, and strengthen the city’s resilience for future generations.
Today, GCCW has delivered thousands of green stormwater management systems across Philadelphia, prevented billions of gallons of polluted stormwater from reaching local waterways each year, and created cleaner, greener, and healthier neighborhoods throughout the city.
As the program reaches its Year 15 milestone, Philadelphia has successfully achieved the Greened Acre Performance Standard required under its Consent Order and Agreement with the Pennsylvania Department of Environmental Protection (PA DEP), representing a major achievement in the City’s long-term commitment to improving water quality.
While several large-scale infrastructure projects are in their final stages of completion, the City remains on track to realize significant additional water quality benefits through investments already under construction.
15 Years by the numbers
- 3,850+ Greened Acres achieved (representing 1,100+ projects completed)
- Numerous significant Water Pollution Control Plant and Collection System Enhancement Projects completed
- The collection of projects completed and in construction are anticipated to exceed the Year 15 target with more than 4 billion gallons per year managed.
- 14+ miles of interceptor inspection and rehabilitation completed or underway
- Hundreds of public and private partners
Key accomplishments at Year 15
| Metric | Units | Base line value | Year 5 Performance Standard | Status | Year 10 Performance Standard | Status | Year 15 Performance Standard | Status |
|---|---|---|---|---|---|---|---|---|
| Miles of interceptor lined | miles | 0 | 2 | Exceeded target | 6 | Exceeded target | 14.5 | On target to meet |
| Overflow Reduction Volume | million gallons per year | 0 | 600 | Exceeded target | 2,044 | Exceeded target | 3,619 | On target to exceed |
| Total Greened Acres | Greened Acres | 0 | 744 | Exceeded target | 2,148 | Exceeded target | 3,812 | Exceeded target |
Greened Acre Performance Standard achieved
Philadelphia has exceeded its Year 15 Greened Acre target through the implementation of more than 1,100 public and private stormwater management projects throughout the combined sewer area.
Year 15 Greened Acre results
- These projects help capture and manage stormwater before it enters the sewer system, reducing pollution and helping protect local waterways.
- Surpassed the requirement of 3,812 Greened Acres with more than 3,860 Greened Acres completed
- Thousands of green stormwater infrastructure installations throughout Philadelphia neighborhoods
More than green infrastructure
While Green City, Clean Waters is best known for green stormwater infrastructure, the program also includes significant investments in traditional wastewater infrastructure designed to maximize water quality improvements.
Major infrastructure investments delivering water quality benefits
Why additional time is needed
The Philadelphia Water Department has requested and received a ten-month extension for completion and reporting of the Year 15 Performance Standards and the associated Evaluation and Adaptation Plan.
The extension reflects the complexity of delivering major infrastructure improvements in the post-industrial conditions present in older cities like Philadelphia. Philadelphia’s industrial history has left behind real challenges in implementing subsurface infrastructure. Several projects required additional time to safely address site-specific construction conditions and complete final operational readiness activities.
Most notably, during excavation at the Frankford Creek Crossing Improvement Project, PWD encountered unexpected levels of soil contamination that required enhanced environmental monitoring and worker protection measures. The project team quickly adapted, implementing industry-leading safety protocols that allowed work to proceed safely while maintaining progress toward long-term water quality goals.
Importantly, the projects responsible for achieving the remaining overflow reduction benefits are already funded, underway, and advancing toward completion.
Looking ahead
Green City, Clean Waters has demonstrated that green infrastructure, traditional infrastructure, and strong community partnerships can work together to improve water quality and strengthen Philadelphia’s environment.
As the City completes the final Year 15 projects and evaluates their performance, Philadelphia remains committed to delivering measurable environmental improvements, reducing combined sewer overflows, and building a cleaner, greener, and more resilient future.
Strong partnerships drive results
The success of Green City, Clean Waters has been made possible through partnerships with:
- Property owners and developers
- Schools and universities
- Community organizations
- Businesses and institutions
- City agencies
- Residents throughout Philadelphia
Together, these partnerships have transformed stormwater management from a utility function into a citywide environmental investment.
Frequently asked questions
Green City, Clean Waters is Philadelphia’s long-term program to reduce combined sewer overflows and improve water quality through a combination of green stormwater infrastructure and traditional wastewater infrastructure investments.
In some parts of Philadelphia, stormwater and wastewater share the same sewer pipes. During dry weather conditions, flow in this system goes to the Water Pollution Control Plant (WPCP) for treatment. However, during wet weather (when it is raining or during ice/snow melt conditions) the flow can temporarily exceed the capacity of the pipe, causing the pipe to overflow into the waterway. GCCW is designed to reduce the frequency and overall volume of these events.
PWD has achieved the Year 15 Greened Acre Performance Standard and continues to advance infrastructure projects needed to achieve sewer lining and Year 15 overflow volume reduction requirements.
Although PWD had sufficient projects funded and in construction, several major projects experienced unforeseen construction challenges, including significant contaminated soil conditions that required extensive worker safety protections and additional construction time. Because these projects are directly tied to the Year 15 overflow reduction target, additional time is needed to complete construction and evaluate final performance.
The final overflow reduction calculation requires post-construction system modeling and performance evaluation. That work cannot be completed until construction is substantially complete and the infrastructure is operational. The additional time allows PWD to perform the required analysis and include the results in the Year 15 Evaluation and Adaptation Plan.
As of the last required regulatory reporting period in 2021, PWD reduced the annual average CSO volume by 3.08 billion gallons, exceeding the required CSO volume reduction target of 2.044 billion gallons by more than 1 billion gallons. The collection of projects completed and in construction are anticipated to exceed the Year 15 target with more than 4 billion gallons per year managed.
No. The extension does not change PWD’s commitment to achieving the program’s goals. Major projects are already under construction, significant milestones have already been achieved, and the City continues to invest in both green and traditional infrastructure improvements that will provide long-term environmental benefits.
What happens next?
By April 2027, PWD will complete the remaining Year 15 projects, conduct the required performance evaluations and modeling, and submit its Year 15 Evaluation and Adaptation Plan to PA DEP in August 2027.