Mark specializes in natural resource and environmental economics.
Green infrastructure, which utilizes natural processes to treat stormwater, potentially offers a number of benefits over the equivalent gray infrastructure. In this report, we investigate the types of benefits, and where possible, quantify and value the benefits green infrastructure provides for three case studies in the Chesapeake Bay watershed. We describe green infrastructure projects and their benefits in Montgomery County, MD, Washington DC, and Prince George’s County, MD.
Montgomery County’s RainScapes Program promotes green infrastructure projects on residential, public, and commercial property, including rain gardens, rain barrels, permeable pavements, trees, and other techniques. Other projects exist outside of the RainScapes Program, including bioswales and wetlands. Of identified projects, hundreds of millions of gallons of stormwater are retained each year, as well as providing energy savings, air and water quality improvement, carbon absorption, and habitat for nearly a million dollars a year in quantifiable benefits. Green infrastructure also improves community livability, heat island reduction, education opportunities, and flood prevention in Montgomery County, but the value of these benefits cannot be quantified with available data at this time.
Washington DC provides incentives for homeowners and schools to reduce stormwater runoff through the RiverSmart programs. Resulting projects include rain gardens, trees, permeable pavement, and others. The city also directly supports green roofs. A number of federal facilities have green infrastructure, including EPA and Navy facilities. These programs reduce millions of gallons of stormwater each year, as well as reducing energy costs from heating and cooling, improving air and water quality, and reducing carbon emissions. Based on a study of potential green infrastructure, the net present value of quantifiable services provided by green infrastructure in Washington DC would be nearly $100 million.
Decatur Street in Edmonston, Prince George’s County includes bioretention cells, additional trees, improved and pedestrian paths, open space, and permeable bike lanes. The reduced stormwater runoff benefits are likely nearly half a million gallons per year.
The projects across these three areas provide benefits at multiple scales, and the majority of quantifiable benefits accrue to the community as a whole or even more widespread. Efficient green infrastructure implementation requires coordination as near to the geographical scale of benefit as possible. Community-wide benefits require community- wide coordination. Public incentives, financing, and regulation all appear to facilitate this process. It appears difficult for onsite benefits by themselves to sufficiently motivate home and business owners to provide green infrastructure to the level that makes economic sense. Communities in the Chesapeake basin have found ways to implement green infrastructure, and there is potential to greatly expand the role of green infrastructure in these areas over the coming years.Download PDF