The freshwater-saltwater nexus: the ocean as a sustainable source of water?

Freshwater systems have significant impacts on the marine environment, especially in terms of transport of pollution, sediments, and nutrients. Increasingly, freshwater supplies are also being affected by or sourced from the marine environment. Examples include saltwater intrusion due to sea-level rise and land subsidence, desalination and offshore freshened groundwater. Such a seawater-freshwater nexus, in which the two are interdependent, will only grow stronger with time, as populations and consumption grow, the climate changes, and technologies are developed. Current legal and institutional governance frameworks are fragmented and insufficient in addressing the role of seawater and marine environments in freshwater planning and management. There is a critical and urgent need to update and integrate these two fields, including monitoring, reporting, and emergency response plans. The sooner that these are incorporated into planning and policy, the better the chances are for effective and sustainable management of waters, both fresh and marine.