The Challenge

Green Infrastructure: Getting to Scale

Flooded city block

Cities and towns across the U.S. are grappling with more intense storm events and aging water infrastructure with a $100 billion price tag. Combined sewer systems are commonplace and lead to stormwater overflows that cause water pollution, beach closures, and property damage.

Community leaders and city planners are beginning to invest in green infrastructure as a cost-effective means of addressing water management challenges. Green infrastructure includes trees, green roofs, rain gardens and other nature-based structures that can reduce stormwater and pollution at its source while providing added benefits to communities. While interest in green infrastructure is growing, limited access to rigorous data to ensure real-world performance presents a major barrier to adoption.


Our Idea

Harnessing Data on Performance

Constructed wetland

The Science Policy Exchange convened a team of scientists to address the green infrastructure data gap by mining published studies and existing databases. The team analyzed performance data for eight types of green structures from 121 sites encompassing 4,200 water quantity and 35,000 water quality observations.

The results confirm that green infrastructure holds great promise as an innovative approach to stormwater management. They also reveal important variations in performance by technology, season, and site. The data provide important benchmarks for aligning predicted and actual green infrastructure performance — a prerequisite for public trust and regulatory compliance.

Green roof, Syracuse New York

Key Findings

  • Green roofs, porous pavement, and bioretention cells remove the largest volume of stormwater of the structures analyzed. Cold-season performance is lower but can be improved through design and maintenance.
  • Swales, wetlands, detention and retention ponds are generally less effective at removing stormwater but can augment water storage capacity.
  • Most green structures effectively remove suspended solids and trace metals. Bioretention cells, retention and detention ponds, and media filters show the highest contaminant removal.


Our Impact

Linking Science and Practice

Green Infrastructure Report Cover

The Science Policy Exchange is working to advance green infrastructure by increasing access to real-world performance data. We’re linking science to practice by sharing data with non-scientists through our report, “Green Infrastructure: Lessons from Science and Practice.”

Gathering and communicating existing science is an important start but more can be done to take green infrastructure to scale through data, outreach, and monitoring.