Read the full post at The Conversation.
The United States has made enormous progress in reducing water pollution since the Clean Water Act was passed nearly 50 years ago. Rivers no longer catch fire when oil slicks on their surfaces ignite. And many harbors that once were fouled with sewage now draw swimmers and boaters.
But as Earth Day approaches, it is important to realize that new, more complex challenges are emerging. In a study published earlier this year, we found that a cocktail of chemicals from many human activities is making U.S. rivers saltier and more alkaline across the nation. Surprisingly, road salt in winter is not the only source: construction, agriculture, and many other activities also play roles across regions.