Book excerpt: Those who control water, hold power. Complicating matters, water is a flow resource; constantly changing states between liquid, solid, and gas, being incorporated into living and non-living things and crossing boundaries of all kinds. As a result, water governance has much to do with the question of boundaries and scale: who is in and who is out of decision-making structures? Which of the many boundaries that water crosses should be used for decision-making related to its governance? Recently, efforts to understand the relationship between water and political boundaries have come to the fore of water governance debates: how and why does water governance fragment across sectors and governmental departments? How can we govern shared waters more effectively? How do politics and power play out in water governance? This book brings together and connects the work of scholars to engage with such questions. The introduction of scalar debates into water governance discussions is a significant advancement of both governance studies and scalar theory: decision-making with respect to water is often, implicitly, a decision about scale and its related politics. When water managers or scholars explore municipal water service delivery systems, argue that integrated approaches to salmon stewardship are critical to their survival, query the damming of a river to provide power to another region and investigate access to potable water - they are deliberating the politics of scale. Accessible, engaging, and informative, the volume offers an overview and advancement of both scalar and governance studies while examining practical solutions to the challenges of water governance.