NYC Green Infrastructure Program — Rain Gardens and Permeable Surfaces to Cut Combined Sewer Overflows

NYC's Green Infrastructure Program, run by the Department of Environmental Protection under a state consent order, retrofits streets, sidewalks and public properties with rain gardens, infiltration basins and permeable pavements to absorb rainfall before it enters the combined sewer system, and incentivises green infrastructure on private property.
In 2021 the constructed assets were certified as meeting the 1.5% application-rate milestone: 1,181 greened acres managed and about 507 million gallons per year of CSO volume reduced. DEP now tracks more than 17,000 assets covering over 3,000 managed acres in combined sewer areas.
The 2012 order required the programme to be completed by 2030; the 2023 modification restructures it, requiring a citywide CSO reduction of 1.67 billion gallons a year by 2040 (with a possible extension to 2045 subject to state approval), expenditure of $3.5 billion, and extends the geographic scope beyond combined sewer areas. The deadline extension signals that delivery has been slower than originally planned, although the DEC notice itself calls it a restructuring and does not state that milestones were missed. Evidence is regulatory reporting by the operator and modelled CSO volumes; no carbon or biodiversity outcomes are quantified here.

Read the full analysis: https://www.nyc.gov/assets/dep/downloads/pdf/water/stormwater/green-infrastructure/gi-annual-report-2021.pdf