Drinking Water Security and Climate Change Adaptation in Canada: Developing Best Management Practices for Active Source Water Protection and Treatment Resilience in Forested Watersheds

点击翻译按钮获取中文摘要

The value of natural storage and filtration of water by global forests has been estimated at $4.1 trillion. The health of forests and the water they supply is threatened by many pressures, including climate change-exacerbated disturbances such as wildfires and hurricanes, which result in more variable and deteriorated source water quality that can challenge drinking water treatment plants beyond their abilities. Increased delivery of fine sediments and nutrients (carbon, phosphorus) to receiving waters is especially concerning. Fluctuations in dissolved organic carbon make it difficult to optimally dose chemical coagulants during treatment and can lead to increased formation of disinfection byproducts of potential health consequence. Elevated bioavailable phosphorus promotes algae (cyanobacteria) growth; blooms reduce treatment process efficiency and can produce unpleasant tastes and odors, or toxins. Their removal from water requires costly advanced technology not found in most treatment plants, and thus can lead to service disruptions or even outages. Increases in the frequency and severity of climate change-exacerbated wildfires have revealed an urgent global need for greater resilience in the provision of safe drinking water-techno-ecological solutions that synergistically integrate green (forest) and grey (in-plant) treatment capacities are increasingly viewed as offering those solutions. In Canada, the drinking water for >58% of the largest cities and most small systems originates in forested watersheds. Despite their critical role in the provision of water, these regions are the only major landscapes with no requirements or guidance for best management practices (BMPs) to protect drinking water sources as a primary priority. As forests are especially vulnerable to severe climate-exacerbated disturbances, the goal of this research is to deliver the new, actionable knowledge and technological innovation needed to develop BMPs that integrate forest management and water treatment resilience approaches to ensure drinking water security. In addition to wildfire-induced shifts in organic carbon and associated increases in treatment costs, algae have bloomed annually in Fort McMurray's reservoirs since the fire. In 2021, their ability to produce toxins was shown. There is a time-sensitive opportunity to learn from these unprecedented, potentially toxic post-fire algae blooms-while they are the first globally, they will not be the last. Lab-, pilot-, plant-, and watershed-scale research is proposed to develop mitigation strategies, evaluate algae-mediated changes in source quality and treatability, and investigate novel coagulants and biological treatment approaches to increase treatment resilience. Multi-stakeholder partnerships will be leveraged to train a new generation of engineers and scientists in the development of techno-ecological solutions for climate change adaptation to ensure drinking water security in Canada now and in the future.