Rising seas, changing salt lines, and drinking water salinization

As sea level rise drives saltwater farther inland, drinking water supplies of some coastal cities will be contaminated. This paper evaluates how climate change is shifting the location of ‘salt lines,’ the zone where coastal fresh water meets the ocean, and implications for drinking water management. It focuses on changes from climate, as opposed to water overuse or water quality mismanagement, and reviews recent literature along three dimensions. Firstly, the paper reviews regulations on salinity in drinking water. Secondly, the paper summarizes studies on surface water and groundwater salinization, as it relates to both slow-onset change and extreme events. Thirdly, it reviews management responses. To minimize risk to potable water supplies,the paper suggests layered adaptation: managing for periods of short-term water loss, while fundamentally changing drinking water systems at risk of long-term salinization; implementing local, technical solutions to avoid or remove salt, while transforming regional watershed freshwater flows.