Keeping winter roads clear is turning freshwater salty across the northeastern U.S. Ecologists at the Institute of Ecosystem Studies in Millbrook, N.Y., and their colleagues investigated salinity increases in streams in Baltimore County, the Hudson River Valley and the White Mountains of New Hampshire over the past 30 years. Chloride levels approached up to a quarter the concentration of seawater during the winter. Saltiness was strongly linked to the number of roads, parking lots and other impervious surfaces nearby, which overall in the U.S. cover an area roughly the size of Ohio; that area is expected to expand this decade with one million new homes and 16,000 kilometers of new roads. At this rate, many rural streams in the northeastern U.S. will become toxic to sensitive freshwater life and unfit for human consumption within the next century, the scientists reported online September 12 in the Proceedings of the National Academy of Sciences USA.