The Runoff Reduction Method

In 2008, the Center for Watershed Protection and the Chesapeake Stormwater Network developed the Runoff Reduction Method. The method was developed as part of a project to research and update best management practice (BMP) performance and, in particular, ascertain the ability of various BMPs to reduce post-development runoff volumes. The method focuses on the capability of conventional and innovative stormwater management practices (e.g., permeable pavement, green roofs, rainwater harvesting, bioretention, downspout disconnection, etc.) to reduce runoff, as well as remove pollutants, and incorporates built-in incentives for environmental site design, such as forest and open space preservation. Because of the high runoff reduction capabilities of various site design and innovative stormwater practices, implementing these innovative practices at a site reduces the overall number and size of structural BMPs required. This approach helps put innovative stormwater management practices on a level playing field with conventional stormwater management practices, such as wet and dry ponds. Currently, various state programs are in the process of using or adopting the Runoff Reduction Method as part of regulatory and non-regulatory programs. The Virginia Department of Conservation and Recreation (DCR) is integrating the Runoff Reduction Method into proposed stormwater management regulations and an updated stormwater management handbook. The Georgia Department of Natural Resources is modifying the method for a new Coastal Stormwater Management Manual Supplement. The State of Delaware is using the concept of runoff reduction in proposed statewide regulations. With the incorporation of the Runoff Reduction Method into these programs, communities are poised for the wide-spread implementation of low impact development and innovative stormwater management practices on development sites.