Existing development, especially in urbanized and urbanizing areas, is responsible for currently degraded water quality and stream conditions. Changes in land cover and the increased imperviousness of the urban environment have resulted in larger volumes of runoff traveling at faster velocities. This has caused serious streambank erosion and has compromised aquatic habitat. Many of these areas were developed without adequate stormwater controls and must be addressed if urban streams are to be restored and water quality is to be improved nationwide. It should be noted that most stormwater regulations are intended to limit the increases in pollution associated with new development, or to curb flooding, but do not specifically address the hydrologic modifications associated with runoff from existing development.

"December 2008." "EPA-833-F-08-008"

This chapter explores policies and incentives used by municipalities to facilitate green retrofits within their stormwater programs. This document also troubleshoots the institutional and regulatory challenges of incorporating green retrofits into municipal infrastructure, and provides some solutions and case studies.