A new paper published in Environmental Science & Technology Letters warns of an emerging global threat posed by salt contamination of water supplies in tidal rivers worldwide. The paper, co-authored by David Ralston, Department Chair in the Applied Ocean Physics & Engineering Department in the Woods Hole Oceanographic Institution, along with an international team of partner institutions, highlights how a combination of climate change impacts—including prolonged drought and rapid sea-level rise—along with localized human activities, are intensifying the increase in salt in vital freshwater sources.