This report demonstrates how to quantify the benefits and costs of natural infrastructure as a strong complement or a viable alternative to grey infrastructure option for flood mitigation.

Natural infrastructure can be a cost-effective way to mitigate material financial losses that would otherwise result from flooding Moreover, natural infrastructure can offer other valuable environmental and social benefits that are often not attainable through the implementation of traditional, grey-engineered solutions.

A thorough cost-benefit analysis should measure all infrastructure options through a common cost-benefit lens. For example, although naturally occurring ponds provide stormwater storage capacity, which helps attenuate flooding, they also create habitat for aquatic species, improve biodiversity and provide aesthetic benefits to the community. These additional benefits are not available through a grey infrastructure solution, such as a stormwater storage tank, and this needs to be reflected in a cost-benefit analysis.

A comprehensive assessment of the financial, environmental and social costs and benefits (i.e., a total economic value [TEV] assessment) is required to illuminate these otherwise uncaptured benefits. Canada will continue to experience loss and degradation of its natural infrastructure assets if it does not start to apply a robust TEV assessment for natural versus grey infrastructure solutions.

To assist governments, practitioners and investors with land-use planning and infrastructure investment decisions, this report includes a framework for natural infrastructure project implementation