Canadian Low Impact Development Retrofit Approaches: A 21st-Century Stormwater Management Paradigm

摘要

Southern Ontario and, more generally, urban areas throughout Canada, have seen the implementation and successful operation of a number of pilot scale low impact development (LID) projects. Despite demonstrated success and a proclivity to outperform design expectations, adoption of LID practices--particularly on predeveloped private property--has not occurred. This is true even in the face of ongoing urban flooding and water quality impairment issues. While several factors have been identified as barriers hindering broad scale LID implementation, market research conducted in the Greater Toronto Area (GTA) indicates that the high up-front costs and long or non-existent payback period are the largest barriers inhibiting LID adoption. To address this, a mix of innovative policy and market-based tools, incentives, and approaches are needed. The Drainage Act, a 183 year old piece of legislation unique to the Province of Ontario, has been intensely scrutinized and found suitable as a vehicle to facilitate cost-optimized, community-based retrofit implementation. However, to incentivize the use of the Drainage Act process, a paradigm shift in how municipalities approach stormwater management is required to address the up-front costs and long payback periods associated with LID retrofits. Recognizing the offsite benefits provided by private property adoption and rewarding appropriately will promote an approach to managing stormwater that is not only cost effective and affordable, but linked and integrated at a watershed scale in a way that meets water quality targets in the face of increasing urbanization and climate change.