Low Impact Development (LID) is an innovative stormwater management approach that treats, infiltrates, filters and retains runoff at the source. LID is rapidly becoming the new norm in Ontario. Urbanization and traditional development practices bring with them more hard or impervious surfaces that water cannot soak through, such as rooftops, parking lots, roads and driveways. This increase in hard surfaces changes the flow of water from urban lands during storms and snow melt events. The result is more water running off land faster and more frequently, causing erosion and increasing the risk of flooding. As well, when water flows down city streets, it picks up chemicals, trash and bacteria, and carries those pollutants into the storm drain system, where they are carried directly out to our creeks, the Thames River and, eventually, to Lake Erie.
LID uses Best Management Practices (BMPs) – small, simple designs and landscape features at the lot level to infiltrate, filter, store, evaporate and detain runoff close to its source. These BMPs can be used in new development, urban retrots and redevelopment projects, on lawns, streets, sidewalks, medians, roofs and in parking lots. Examples of LID BMPs include:
- Rain garden – small depression planted with native flowers, grasses and shrubs, designed to temporarily hold and soak in rain water from a roof, driveway or open area
- Bioswale – wide, shallow channel planted with grass or other vegetation, that stormwater runoff flows through
- Downspout redirect – extension or bend in the gutter to redirect rain water to a grassy or permeable area
- Rain barrel – tank attached to the end of the downspout to collect rain water from the roof
- Porous or pervious pavement – concrete or asphalt that allows rain to infiltrate to the soil