Gulf of Mexico “Dead Zone” Among Largest Ever,
but Illinois Can Help

Champaign, IL – A team of researchers just finished mapping the size of the “Dead Zone” in the northern Gulf of Mexico, and at 7900 mi2, it is the third largest since monitoring began in 1985.  The Dead Zone is an area of hypoxic water that forms every summer along the Gulf Coast and robs ocean life of oxygen.  Species that cannot escape the hypoxia may perish, and those able to migrate may have to swim outside of the Dead Zone to survive.   

The Gulf of Mexico Dead Zone is of enough concern to the U.S. Environmental Protection Agency that an independent team of scientists was assembled to study the causes and nature of the hypoxia.  The team, known as the Science Advisory Board Hypoxia Advisory Panel, recently released a second draft of their report.

The report concludes that recent increases in the hypoxic area are primarily due to nitrogen and phosphorus inputs from the Mississippi and Atchafalaya River Basin, which drains approximately 40% of the United States and empties into the Gulf of Mexico.  The nutrients fuel high phytoplankton production, and the eventual death and decay of these microscopic plants results in low dissolved oxygen levels. 

The report suggests that a 45% reduction in nitrogen inputs and at least a 40% reduction in phosphorus will be necessary to reduce the size of the hypoxic area to the current goal of 5000 km2.  “This reduction of inputs should not only help the Gulf, but will have the simultaneous benefit of a cleaner Mississippi River and its tributaries,” according to Stacy James of Prairie Rivers Network.   

The report found that point sources such as sewage treatment plants and industry contribute approximately 22% of the nitrogen and 34% of the phosphorus inputs to the Gulf of Mexico.  Among the report’s proposed options for nutrient management is a recommendation for tighter limits on the concentrations of nitrogen and phosphorous discharged from sewage treatment plants.

Non-point sources such as crop production and urban landscaping contribute the majority of nutrients to the Dead Zone.  Regulation of these sources is more difficult, but can be achieved through voluntary efforts such as fertilizer application management and enrollment of acreage into state and federal land conservation programs.     

The report states that the Upper Mississippi River sub-basin is one of the top two sub-basins contributing nutrients to the Gulf of Mexico.  “Efforts made in Illinois to reduce nutrient loss to waterways could have important benefits at the state, regional, and national level,” James said.

The Illinois Environmental Protection Agency (IEPA) regularly monitors the health of the state’s waterways, and summarizes the data every 2 years.  In 2006, IEPA found that phosphorus is a potential cause of impairment for 14% of the streams surveyed, and nitrogen is a potential cause of impairment for 11% of streams. 

Instead of a well-documented “dead zone,” Illinois residents may see signs of excessive nutrients in the form of algal blooms, fish kills, and bad-tasting water.  “The quality of life in Illinois stands to benefit from efforts to better manage nutrients, and we hope that IEPA and other government agencies will implement the suggestions of the Hypoxia Advisory Panel report,” James said.

The IEPA not only assesses the health of Illinois’ waters, but also sets limits on the amounts of pollutants allowed in waterways.  However, IEPA has not developed statewide criteria for phosphorus and nitrogen.  IEPA plans to develop criteria by 2008, but as earlier proposed deadlines have not been met, it is unclear whether this one will be either. 

“When Illinois finally adopts nitrogen and phosphorus criteria, IEPA will be able to reduce nutrient pollution coming from sewage treatment plants and other facilities; however, the agency’s ability to reduce nutrient pollution from agricultural sources will still be very limited.  We will need other solutions to address the most important contributor to the Dead Zone and to make a real difference for Illinois waters, the Mississippi River, and the Gulf.” said Glynnis Collins of Prairie Rivers Network.

The draft report of the Science Advisory Board Hypoxia Advisory Panel is available online at http://www.epa.gov/sab/pdf/hap_draft_advisory_report_7-24-07.pdf.

Prairie Rivers Network is Illinois’ statewide leader in river protection, conservation, and restoration.  Prairie Rivers Network works to protect water quality and river habitats, helping to make communities better places to live.

Contact Info: 

Stacy James – 217-344-2371
                                                                                                Glynnis Collins – 217-344-2371