Nutrient Delivery to the Gulf of Mexico Among Highest Measured

6/16/2009 1:33:31 PM
Contact Information:
U.S. Department of the Interior, U.S. Geological Survey
Office of Communication
119 National Center
Reston, VA 20192

Brent Aulenbach
Phone: 770-903-9148

Jennifer LaVista
Phone: 703-648-4432

Too many nutrients, which are essential for plant growth, are not necessarily a good thing. Excessive nutrients can be harmful by decreasing the amount of oxygen in the water, also known as hypoxia. This can result in an area experiencing stress or death of near or bottom dwelling organisms called a hypoxic zone, or dead zone.

The amount of nutrients transported from the Mississippi River Basin to the Gulf during the spring is a major factor controlling the size of the hypoxic zone. The northern Gulf of Mexico hypoxic zone is the second largest in the world, and threatens the economic and ecological health of one of the nation’s largest and most productive fisheries.

USGS releases estimates of nutrients from the Mississippi and Atchafalaya Rivers to the Gulf of Mexico in early June each year. The estimates are used by the National Oceanic and Atmospheric Administration, Louisiana Universities Marine Consortium, and other researchers to predict the areal extent of the hypoxic zone.

The amount of nutrients delivered to the Gulf each spring depends, in large part, on precipitation and the resulting amounts of nutrient runoff and streamflow in the Mississippi-Atchafalaya River Basin. Streamflows in spring 2009 were about 17 percent above average over the last 30 years. Last years elevated levels were most likely due to the flooding during the spring.

USGS has monitored streamflow and water quality in the Mississippi River Basin for decades, to access more information visit the USGS nutrient flux webpage.

For an even larger variety of USGS data, such as for ground water and water quality, access the National Water Information System Web Interface, which contains over 1.5 million sites, and averages over 25 million hits per month.