Water diversions facilitate spread of non-native species

Many countries/areas are experiencing or may soon experience water scarcity owing to rapid population growth, urbanization and/or climate change. Currently, almost one-fifth of the world's population (1.2 billion) live in areas of physical water scarcity. Water diversions have become a commonplace solution proposed by governments for alleviation of physical water scarcity. Thus far, more than 80 major projects are completed or under construction globally, including the world's largest diversion: South-to-North Water Transfer Project (SNWTP) in China. Negative effects associated with water diversions, such as habitat loss and transfer of pollutants, have been recognized. However, it has been largely overlooked that invasion highways are created when water diversions link biogeographic regions. These invasion highways can facilitate spread of an array of non-native species. Although previous experiences have provided clear warnings regarding spread of non-native invasive species through artificial waterways, these lessons have been largely ignored by governments when resolving water scarcity problems. Here we use SNWTP, which will likely facilitate spread of invasive golden mussels, as well as many known examples of non-native invasive species spread through artificial waterways in other water systems, to call on governments to formally establish policy and seek management solutions to considering spread of non-native species when planning water diversions.