New USGS Report on Nitrate Trends in Mississippi River and Tributaries

The U.S. Geological Survey (USGS) has released a new report entitled, “Nitrate in the Mississippi River and Its Tributaries, 1980–2010: An Update.” The report describes 30-year, 20-year, and 10-year annual and spring (April through June) trends at eight sites in the Mississippi River basin from 1980 to 2010. These results reflect the cumulative changes over time in nitrate sources and conservation practices throughout the Mississippi River basin, and highlight the need for comprehensive nutrient management strategies that will reduce nutrients in both streams and groundwater. According to the study, key nitrate concentration trend findings at long-term USGS monitoring sites were as follows:

• Nitrate concentrations steadily decreased by 21 percent in the Illinois River from 2000 to 2010. Decreases were also noted in the Iowa River during this time, but the declines were not as large (10 percent).
• Consistent increases in nitrate concentrations occurred between 2000 and 2010 in the upper Mississippi River (29 percent) and the Missouri River (43 percent).
• Nitrate concentrations in the Ohio River are the lowest among the eight Mississippi River Basin sites and have remained relatively stable over the last 30 years.
• Nitrate concentrations increased at the Mississippi River outlet by 12 percent between 2000 and 2010.

To view the report, visit the USGS web site at: http://water.usgs.gov/nawqa/pubs/nitrate_trends/. For more information about this study, contact Lori Sprague of USGS at lsprague@usgs.gov or 208-387-1358.