[Reference: Jones, Phillip. 2004.
Low Impact Development: Stormwater Management Meets Environmental
. CE News
. July 2004.]
(Link to publication)
Low Impact Development (LID) is a relatively new practice that attempts to
unite site planning,
land development, and stormwater management with ecosystem protection.
It was first
developed in the 1990s in response to the economic and environmental impacts of conventional
stormwater management techniques. Put briefly,
LID is a comprehensive development and
design technique with the goal of preserving predevelopment hydrology and water quality
through a series of small-scale, distributed structural and non-structural controls.
Numerous local jurisdictions around the country also have expressed a continuing interest in LID
training and demonstration projects. Several branches of the armed services have recognized LID
as an important planning and design tool for their facilities.
Low Impact Development Center
is a nonprofit organization dedicated to research,
development, and training for water resources and natural resource protection issues.
represents an excellent resource for additional information about low-impact development.
the Center at
Benefits of the LID Approach
LID projects commonly are implemented because they reduce lifecycle costs for stormwater
infrastructure and shifts maintenance burdens away from local governments.
provide superior control of non-point-source pollution, and hydrologic control of small,
frequently occurring storms and their effects on downstream ecology. Other benefits include
National Pollution Discharge Elimination System (NPDES), Phase II Final Rule
Combined Sewer Overflow (CSO) mitigation, community development, and watershed pollutant
The EPA has established a web site dealing with storm water management at
that serves as a resource for ideas on conserving water and
managing storm water.
The site includes a link to the
A primary concern with the traditional "pipe-and-pond" approach to stormwater
management has been poor control of small, frequent storms.
Because the minimum design
storm is often the one- or two-year storm, the peak rate, the runoff volume, and the pollutant
loading of small, frequent storms is not attenuated, even though they account for the majority of
the annual precipitation volume.
(For example, 70 percent of the annual precipitation volume in
Washington, D.C., comes from storms of 1 inch or less.)
Most urban pollutants are conveyed in the first ½-inch to 1-inch of rainfall. Because
conventional management strategies are intended for larger storms, they do little to address non-
point-source pollution from these "
" events and may not assist with NPDES Phase II
compliance. Additionally, failing to adequately manage small storms contributes to stream