Water quantity as a driver of change in the Great Lakes-St. Lawrence River Basin

This article aims to evaluate and illustrate the state of water quantity in the Great Lakes-St. Lawrence River basin in the past, present, and future. Historical water levels in the Great Lakes basin since 1963 are presented and the interrelationships among the main factors regulating water levels are explored. These factors include both natural processes (over-lake precipitation, lake evaporation, and land surface runoff) and anthropogenic activities (consumptive water use, lake level regulations, and water diversions). The impacts of each of these factors on the historical levels, as well as their influences on future trends are assessed. Linear data trends from 1963 to 2013 were found to adequately represent past data and indicate that overall the basin is in a state of increasing precipitation, runoff and evaporation. Informed by these trends, and also taking into consideration other impacts on water levels within the Great Lakes basin, three future scenarios are presented describing projections to the year 2063 - status quo, dystopia (water scarcity), and utopia (water surplus). These future scenarios consider both the natural and anthropogenic controls impacting water levels in the Great Lakes basin, while also considering the relationships among variable water levels and other defining characteristics of the system and providing a creative means to project alternate water realities into 2063.