This study investigates how streams retain “memory” of nitrogen pollution from past land use. Using long-term data, it identifies a 3–5 year lag between nitrogen inputs and water quality impacts. It highlights the role of forests as natural filters and emphasizes managing both current and historical pollution to protect water supplies.

Road salt, widely used for winter safety, contaminates waterways and drinking supplies by increasing sodium and chloride levels. This year-long study of Pennsylvania watersheds found consistent exceedances of EPA guidelines, posing risks to human health and aquatic ecosystems. The research highlights the need to reduce salt use and adopt more sustainable deicing practices.