A report released by the Financial Accountability Office of Ontario (FAO) earlier this month suggests that the cost to maintain the province’s public linear storm and wastewater infrastructure could balloon to as much as $6.2 billion by 2030 if more isn’t done to combat climate change.

The FAO’s Costing Climate Change Impacts to Public Infrastructure: Linear Storm and Wastewater report is the latest in a series of reports analyzing climate impacts on public infrastructure. It examines the impacts of more extreme rainfall on the long-term costs of maintaining public linear storm and wastewater infrastructure in a state of good repair.

Ontario's stormwater assets of pipes, ditches and culverts, and wastewater assets of sewer pipes and sanitary force mains, are owned by the province's 444 municipalities and valued at $124 billion (all costs are in 2020 real dollars). Maintaining public infrastructure in a state of good repair helps to maximize its benefits in the most cost-effective manner over time.

In the short term, climate-related impacts from more extreme rainfall are projected to increase infrastructure costs by $0.7 billion annually across the medium and high emissions scenarios, which would accumulate to $6.2 billion by 2030 in the absence of adaptation. This is a 27 percent increase in municipal infrastructure costs relative to the stable climate projection.

Over the long term, additional climate-related costs will depend on the extent of global climate change.

In a medium emissions scenario, where global emissions peak by mid-century, more extreme rainfall will raise the average annual cost of maintaining the existing portfolio of public storm and wastewater infrastructure in a state of good repair by $1.1 billion per year, totalling $88 billion over the century, in absence of adaptation.

In a high emissions scenario, where global emissions continue rising throughout the century, these costs would increase by $1.8 billion per year, totalling $145 billion by 2100.

As extreme rainfall increases, unadapted assets will increasingly face capacity constraints, raising the flood risk to surrounding areas. The cost of flooding damages to households and businesses are also likely to be substantial.

Depending on the emissions scenario, proactively adapting public storm and wastewater infrastructure will add between $71 billion to $127 billion to infrastructure costs relative to the stable climate scenario by 2100. This represents a cost increase between 29 and 53 per cent.

While significant, the report says, these additional climate-related costs are lower (in real dollars) than those incurred in the absence of adaptation or if adaptation was undertaken at a more gradual pace. A proactive adaptation strategy would also reduce flood risk more rapidly.

The FAO’s Costing Climate Change Impacts to Public Infrastructure project (CIPI) analyzes the costs that climate change impacts could impose on Ontario’s provincial and municipal infrastructure, and how those costs could impact the long-term budget outlook of the province.

Previous reports released under the project looked at the effects of climate change on maintaining key infrastructure such as public transportation and buildings.

The recent water report is the final sector report. A project summary report will be released in 2023.