The Impact of Climate Change on Ground Water and Surface Water Quality

Recent scientific research suggests that a new climate, quite distinct from that present at the turn of the 20^th Century, may be already in place in the Great Lakes basin ¹⁷. Of great importance is the potential change in water supply that may occur in parallel with increased demand for water as population increases in the basin ¹⁸.

In 2001, the Commission identified the impact of climate change and variability for the Great Lakes region and its residents as a key priority to be addressed by the Water Quality Board during the 2001-2003 priority cycle. In response, the Water Quality Board developed a detailed report, Climate Change and Water Quality in the Great Lakes Basin 2003. The board's key findings indicate the potential for climate change to profoundly affect all aspects of the natural and built environment in the Great Lakes basin ¹⁹.

Climate change scenarios continue to evolve as predictive capabilities and scientific models improve. The impact on urban areas, with their extensive hardened surfaces and inadequate storm water infrastructure to manage urban runoff, could be significant if total annual precipitation and the intensity of specific storm events increase as predicted. Extreme weather events can readily mobilize contaminants that have accumulated on hardened surfaces, and can increase the quantity of water bypassing water treatment facilities during storm events. Under such scenarios, the potential for more polluted runoff to bypass treatment is of real concern.

A full understanding of, or appreciation for, the magnitude and consequences of climate change is yet to emerge, and therefore there is no consensus on how to best adapt or mitigate its impacts at a local, regional, national or global level. However, best management practices at the local level could be effective in adapting locally and managing the impact of excessive storm water runoff due to extreme weather events. In the absence of scientific certainty and consensus for action, such practices could represent “no regret” decisions that, in some instances, could provide cost-effective alternatives to major new investments in urban storm water infrastructure.