Nitrate pollution still rising

Last week, U.S. Geological Survey scientists provided an update on 30 years of water quality tests that show a continuing increase in nitrate pollution at many points on the Mississippi River and its tributaries. Overall, nitrate levels in the river increased 14 percent from 1980 through 2010.

Increases were greater in the upper reaches of the Mississippi, including Minnesota. Read a National Geographic report on the briefing.