The ecological impacts of organic and inorganic pollutants on freshwater ecosystems have attracted immense scientific, regulatory, and public attention over the past fifty years. In part, this reflects the significant role that freshwater ecosystems play as a repository for anthropogenic chemicals relative to other systems. Fresh water is a common pool natural resource for which everyone is responsible. In this book we review documented and potential ecological impacts of heavy metals in freshwater ecosystems. We focus predominantly on effects at the population, community, and ecosystem levels. Freshwater management and governance is of critical importance to avoid artificial freshwater shortages.