Increased Risks of Waterborne Disease Outbreaks in Northern Ontario due to Climate Change

Drinking water advisories (DWAs) are issued when source water turbidity is high, because of concern for waterborne disease outbreaks. Small drinking water treatment systems (SDWTS) for First Nations communities in northern regions in Ontario that rely primarily on surface water sources are at risk during heavy storm events due to erosion in the catchment area which causes poor intake water quality to the SDWTS. This study presents a novel method for assessing the potential contribution of climate change to an increased risk of DWAs being issued for rural communities. Trend analysis using rainfall records at three climate stations located in Northern Ontario shows increasing trends of annual maximum five-day cumulative rainfall amounts over the last 3 decades. The 1 d cumulative rainfall amounts for events occurring 2 times/y on average indicate statistically significant increasing trends of heavy rainfall events, and therefore potentially higher risks of waterborne disease outbreaks.