US groundwater is getting saltier—what that means for infrastructure, ecosystems, and human health

Scientists from the U.S. Geological Survey (USGS) have been monitoring groundwater quality in wells across the country for more than three decades, looking for harmful chemicals or residual substances that may cause harm to ecosystems or humans. In all, they have measured up to 500 chemical constituents, including major ions, metals, pesticides, volatile organic compounds, fertilizers, and radionuclides.