Low-Impact Development: An Innovative Alternative Approach to Stormwater Management

Abstract

To assist local governments in their efforts to develop more effective stormwater management programs, Prince George’s County, Maryland Department of Environmental Resources (PGDER) in cooperation with the United States Environmental Protection Agency (EPA) has recently developed a guidance manual for an innovative alternative comprehensive approach to stormwater management referred to as Low-Impact Development (LID). We believe that this new approach is a significant step forward towards advancing the state-of-the-art of stormwater management and will be a valuable and useful tool for local governments in their efforts to control urban runoff. This new urban runoff control manual was adapted from PGDER’s 1997 LID Design Manual. EPA provided grant funding to assist PGDER in their efforts to develop a general manual of LID’s principles and practices to make LID technology available to other local governments throughout the nation. Some practitioners have found LID’s site oriented micro-scale control approach to be controversial, as it often conflicts with or challenges conventional stormwater management technology and site development practices. However, many have found LID’s source control techniques to be an economical common sense approach that can be used to better manage new development or retrofit existing development. It is hoped that the LID manual will help to stimulate debate on the state of current watershed protection technology and its future direction. This paper only briefly outlines the development of LID technology and its basic source control principles. Prince George’s County received EPA’s 1998 First Place National Excellence Award for Municipal Stormwater Management Programs for its pioneering work on LID. Efforts are currently underway with EPA to further advance LID technology to improve the sensitivity of current hydrology and hydraulic analytical models such as TR-55 for application on small sites and to develop new micro-scale control approaches and practices for urban retrofit. Additional efforts are also underway to develop to demonstrate how LID principles and practices can be used to control highway runoff and retrofit existing development.