What is LID?

Low Impact Development (LID) is an approach to environmentally friendly land use development. It includes a suite of landscaping and design techniques that attempt to maintain the natural, pre-developed ability of a site to manage rainfall. LID techniques capture water on site, filter it through vegetation, and let it soak into the ground.

 

Roadside swale captures water
An important LID principle is the idea that stormwater is not merely a waste product to be disposed of, but rather that rainwater is a resource. LID protects the natural ability of the site to capture precipitation, keep it clean and allow it to recharge the local water table. Often LID techniques require less constructed infrastructure, increase the value of properties, and preserves valuable site features like trees.

The LID approach is different from conventional development which often clears trees along with valuable topsoil from a site and re-grades it so that all water ends up in a large detention basin. Resulting problems include loss of recharge, increased water temperature, decreased water quality, and higher run-off volumes.

LID can save money over conventional approaches through reduced infrastructure and site preparation work including reductions in clearing, grading, pipes, ponds, inlets, curbs, and paving. In addition, long term maintenance costs involve landscaping which is less expensive than infrastructure repair.

Collage of LID techniques

Where should LID be used?

LID can be applied to new development, urban retrofits, and redevelopment / revitalization projects at many scales. At a small scale, LID techniques can be used to better handle rainfall for a single family lot through rain barrels and rain gardens. At a larger scale, proper site design in combination with many landscaping and infiltration techniques distributed throughout a subdivision cumulatively improve rainfall and stormwater run-off management. Even in the coldest months, LID techniques still encourage retention and, ultimately, infiltration.

The LID Approach

 

Diagram of LID infrastructure
The LID approach protects the natural ability of the site to capture precipitation, keep it clean and allow it to recharge the local water table. This is achieved by applying a suite of tools including:

  • Planning: preserve the site's natural features such as wetlands, native vegetation, flood plains, woodlands and soils to the greatest extent possible;
  • Landscaping: plant native vegetation in buffer strips and in rain gardens (small planted depressions that can trap and filter runoff);
  • Prevention: use vegetated areas to slow down runoff; maximizing infiltration and reducing contact with paved surfaces;
  • Innovating: reduce impervious surfaces wherever possible through alternative street design, such as omission of curbs and use of narrower streets, and through use of shared parking areas.

LID Techniques including Green Roofs and Green Buildings

 

Diagram of Green Roof System
LID techniques include site design, open channels, rain barrels and cisterns, vegetated buffers and swales, rain gardens, and green roofs. Green roof systems (or roof gardens) are an LID technique where the building's roof is planted with vegetation on a specialized drainage infrastructure. Green roofs capture, filter, and temporarily store rainwater. Green roofs are being combined with other green building techniques to conserve the natural resources through the efficient and intelligent use of energy, materials, water, and the building site.

LID Information and Resources

Low Impact Development (LID) Working Group - a network of practitioners, policy-makers, and local officials that share resources, information, and experience with LID issues. For more information, contact Eric Hove.

Other resources include the following:




This information is provided by the Executive Office of Energy and Environmental Affairs, Office of Water Policy.