Low impact development (LID) uses practical, site-design practices at the lot level neighbourhood level and watershed level, to mimic the natural hydrology of the land prior to urban development. The low impact "tool box" includes a variety of practices- from green roofs to road way bioswales to wetlands- that work to control the volume of water leaving the land, reducing the movement of contaminants to downstream lakes and rivers and replenishing natural soil moisture. Steph Neufeld, a watershed specialist by day and ALMS president by night, attended the conference and notes "with improvements in managing point sources such as waste water treatment plant effluent there is an increased focus on reducing non-point source contaminants to water bodies, and in urban environments that is achieved by focusing on stormwater management".  Case in point, over 80 percent of the suspended solids load that enter the North Saskatchewan River within the City of Edmonton boundaries is from the stormwater system. 

 

 

An example LID in action- a green roof Chicago's City Hall 

 

Dr. Lyndon Gyurek, a supervisor of environmental planning for the City of Edmonton, a ALMS director, and the keynote speaker for the workshop noted that "as a result of conventional storm drainage practices, as the city of Edmonton continues to grow we will have incrementally more total suspended solids and other pollutants reaching the North Saskatchewan River. This is due to increased volumes of water leaving the land base post-development. The multi-barrier approach of LID changes that because it focuses on volume reduction." He went on to add that "the traditional gutter and pipe system was not intended for ecosystem protection. We are seeing effects in downstream waterbodies that are receiving heavy loads of stormwater sediments and pollutants, such as erosion in small tributaries and declining water quality."  Dr. Gyurek's presentation outlined that although end of pipe treatment wetlands- such as the recently constructed Kennedale wetland in Edmonton- and community based wetlands are some barriers that help reduces loads to the receiving waterbodies, to achieve volume reductions and reduce contaminant loads, lot level (ex. rain garden) and neighbourhood (ex. bioswales near roadways) LID approaches are also needed.

 

 
Liliana Bozic and Bert Van Duin of the City of Calgary, present on 'How to Analyze and Design LID for Clay Soils and Cold Climate Conditions'.

The workshop provided an overview and background of LID principles, explored design criteria for LID features to achieve predevelopment runoff volumes, and provided case studies where stormwater is being managed using LID techniques.  Examples from the City of Calgary, included the use of stormwater retention ponds water for irrigating sports fields and neighbourhood designs that incorporate bioswales -vegetated areas where stormwater is directed to and uptaken by plants. Many of these approaches can be used in new lakeside developments within Alberta, reducing the footprint of these developments and helping to maintain lake water quality and aquatic ecosystem health. 

In summary, the workshop brought to light that- through promoting the recharging of aquifers, the protection of riparian areas and wetlands, and the maintenance or improvement of the aquatic health of our water bodies- the implementation of low impact development practices will lead to healthier, more sustainable watersheds and limit water quality degradation in receiving waterbodies. Implementing LID remains a challenge though and requires integrated planning between different municipal branches (ex. drainage, planning, and transportations). For more on low impact development in Alberta visit www.alidp.org. 

Better communication and education the foundation for future success of provincial water strategy