What is LID - Low Impact Development?

Climate change is currently the greatest threat to our planet, and existence. Studies show that the past decade was the hottest on record and Earth’s temperature has risen by 0.08 degrees Celsius per decade since 1880. At this current rate, if climate change is not reduced, there will be a decrease in sea ice and an increase in heat waves. This leads to heavy precipitation which ultimately causes flooding. To stop climate change, drastic changes need to be implemented world wide which is difficult to do. However, we can adapt to the current climate changes to provide safety for our societies. One method implemented in the US, New Zealand and Canada is a Low Impact Development system or LID for short. 

The term LID defines systems and practices that use or imitate natural processes that help manage stormwater runoff and pollution. The enactment of LID preserves “predevelopment hydrological and ecological functions.” LID removes all sediments, nutrients, pathogens and metals in the stormwater runoff hence reduces the volume and intensity of the stormwater flows. Not only is LID ecologically effective, it is also lower in cost compared to the traditional grey infrastructure. 

A few examples of practices which are considered LID include rain gardens, bioswales, infiltration trenches, rainwater harvesting and permeable pavements. The evident benefits of LID are improved water quality and groundwater recharge, reduced urban heat island effect and number of floods, a restored aquatic habitat and increased habitat for pollinators and other wildlife. 

In Ontario, many cities have implemented LID strategies to help better their communities. The Toronto and Region Conservation Authority (TRCA) is working to incorporate LID into its Restoration Projects portfolio by installing more rain gardens in and around the city. In 2016, TRCA built a rain garden at Black Creek Pioneer Village which captures roof run-off and retains the stormwater on site rather than letting it exit into a storm drain. 

Also, TRCA collaborated with the City of Markham and constructed a rain garden at Glencrest park in 2018 which provides habitat for wildlife, reduces the need for lawn mowing and improves the hydrological function of the lower planes in the park. 

In the region of Waterloo, the Upper Cedar Creek Scoped Subwatershed was approved in 2019. The project incorporated LID to help manage the stormwater runoff by integrating green infrastructure within the urban areas to promote infiltration and remove pollutants from the runoff such as TSS (toxic shock syndrome caused by bacteria getting into one's body and releasing harmful toxins), nutrients and metals. 

https://www.regionofwaterloo.ca/en/doing-business/resources/Upper_Cedar_Creek_Scoped_Subwatershed_Study2.pdf

https://trca.ca/conservation/restoration/low-impact-development/