Rick Relyea, an environmental scientist at Rensselaer Polytechnic Institute, is tackling similarly thorny questions in upstate New York’s Lake George, which has been called the Queen of American Lakes. Relyea leads the Jefferson Project, a collaboration among RPI, IBM, and the FUND for Lake George, a nonprofit focused on conserving the lake. The project has outfitted the lake with more than 500 “smart” environmental sensors during the past four years to monitor human influence on it. Over the past four decades, according to data from the Lake George Offshore Chemical Monitoring Program, chloride levels have tripled in Lake George, adding to other environmental effects on the lake. These effects include the rise of invasive species and the delivery, through stormwater runoff, of pollutants and nutrients that can stimulate algal blooms. Because it’s hard to tease apart the impacts of these various stressors on the lake’s water quality and wildlife, Relyea’s team has done a bevy of experiments in the lab and in large outdoor tanks to isolate and examine the consequences of increasing salt.

Salts that de-ice roads, parking lots and sidewalks keep people safe in winter. But new research shows they are contributing to a sharp and widely rising problem across the U.S. At least a third of the rivers and streams in the country have gotten saltier in the past 25 years. And by 2100, more than half of them may contain at least 50 percent more salt than they used to. Increasing salinity will not just affect freshwater plants and animals but human lives as well—notably, by affecting drinking water.