Low-impact development (LID) is a term used in the United States to describe a land planning and engineering design approach to managing stormwater runoff. LID emphasizes conservation and use of on-site natural features to protect water quality. This approach implements engineered small-scale hydrologic controls to replicate the pre-development hydrologic regime of watersheds through infiltrating, filtering, storing, evaporating, and detaining runoff close to its source.[1]
LID is similar to sustainable urban drainage systems (SUDS), a term used in the United Kingdom, water-sensitive urban design (WSUD), a term used in Australia, natural drainage systems a term used in Seattle, Washington [2] and "Onsite Stormwater Management", a term used by the Washington State Department of Ecology.[3]
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A concept that began in Prince George's County, Maryland in 1990, LID began as an alternative to traditional stormwater best management practices (BMPs) installed at construction projects.[4] Officials found that the traditional practices such as detention ponds and retention basins were not cost-effective and the results did not meet water quality goals. The Low Impact Development Center, Inc., a non-profit water resources research organization, was formed in 1998 to work with government agencies and institutions to further the science, understanding,and implementation of LID and other sustainable environmental planning and design approaches, such as Green Infrastructure and the Green Highways Partnership.
The LID design approach has received support from the U.S. Environmental Protection Agency (EPA) and is being promoted as a method to help meet goals of the Clean Water Act.[5] Various local, state, and federal agency programs have adopted LID requirements in land development codes and implemented them in public works projects. LID techniques can also play an important role in Smart Growth and Green infrastructure land use planning.
Planning practices include several related approaches that were developed independently by various practitioners. These differently named approaches include similar concepts and share similar goals in protecting water quality.
Planners select structural LID practices for an individual site in consideration of the site's land use, hydrology, soil type, climate and rainfall patterns. There are many variations on these LID practices, and some practices may not be suitable for a given site. Many are practical for retrofit or site renovation projects, as well as for new construction. Frequently used practices include: