Future changes in climate of the magnitude projected by most global climate models would impact our water resources, and subsequently affect food supply, health, industry, transportation and ecosystem sustainability. Problems are most likely to arise where the resource is already under stress, because that stress would be exacerbated by changes in supply or demand associated with climate change. Particular emphasis needs to be placed on the impacts of extreme events (drought and flooding), which are projected to become more frequent and of greater magnitude in many parts of the country. These extreme events would place stress on existing infrastructure and institutions, with potentially major economic, social and environmental consequences.

A relatively high degree of uncertainty will likely always exist regarding projections of climate and hydrological change at the local management scale. Focus must therefore be placed on climate change in the context of risk management and vulnerability assessment. The complex interactions between the numerous factors that influence water supply and demand, as well as the many activities dependent upon water resources, highlight the need for integrative studies that look at both the environmental and human controls on water. Involvement of physical and social scientists, water managers and other stakeholders is critical to the development of appropriate and sustainable adaptation strategies.