We have changed Lake Ontario - and it has changed us. The Lives of Lake Ontario details the lake's relationship with the Indigenous nations, settler cultures, and modern countries that have occupied its shores. Lake Ontario has so profoundly influenced the historical evolution of North America that it is arguably the most important, yet most unappreciated, of the Great Lakes.

For centuries Lake Ontario has enabled and enriched the societies that crowded its edges, from fertile agricultural landscapes to energy production systems to sprawling cities. Daniel Macfarlane examines the myriad ways Canada and the United States have used and abused this resource: through dams and canals, drinking water and sewage, trash and pollution, fish and foreign species, industry and manufacturing, urbanization and infrastructure, population growth and biodiversity loss. Serving as both bridge and buffer between the two countries, Lake Ontario came to host Canada's largest megalopolis. Yet its transborder exploitation exacted a tremendous ecological cost, leading people to turn their backs on the lake. In the later twentieth century, innovative regulations such as the Great Lakes Water Quality Agreements partially improved Lake Ontario's health.

Despite signs that communities are re-engaging with Lake Ontario, it remains the most degraded of the Great Lakes, with new and old problems alike exacerbated by climate change. The Lives of Lake Ontario demonstrates that this lake is both remarkably resilient and uniquely vulnerable.