“Whiskey is for drinking, water is for fighting over.” These famous words, attributed to Mark Twain, summarize perhaps the most critical environmental issue of the coming decades: the scarcity of available freshwater. Today, nearly one billion people — roughly one out of seven people on the planet — are “water deprived,” meaning they do not have enough freshwater to ensure their basic sanitation, irrigation, or drinking needs. With the world’s population expected to grow by 2.5 billion people by 2050 (mostly in areas of the world that are already water deprived), freshwater will be the critical challenge of the 21st century. Overpopulation, urbanization, pollution, food security, corruption, politics, technology, human rights, and governance, just to name a few issues, are all intimately connected to water availability. This course will intertwine these and other issues with four main themes: ensuring human and environmental health, balancing competing demands for freshwater, managing across borders, and coping with climate change.