EPA Announces Action Plan to Reduce Gulf of Mexico Dead Zone

Jennifer Harr

In January 2001, the Environmental Protection Agency (EPA) released its "Action Plan for Reducing, Mitigating, and Controlling Hypoxia in the Northern Gulf of Mexico." "Hypoxia" is a condition in which dissolved oxygen levels are below those necessary to sustain most animal life, and occurs when the amount of oxygen consumed by the decomposition of organic materials exceeds the amount produced by photosynthesis and introduced into water from the atmosphere. Every summer, hypoxia in the Gulf causes a massive "dead zone" that stretches from Louisiana's Mississippi Delta to the Texas border, and which threatens the nation's most productive and valuable fishing grounds. The largest dead zone measured to date was in 1999, and measured roughly 8,000 square miles.

The hypoxia in the Gulf is caused by excess nutrients delivered by the Mississippi River, combined with stratification of Gulf waters. The dead zone occurs each year when warmer, nitrogen-rich fresh water from the Mississippi River moves over Gulf waters, which are cooler and saltier (and therefore heavier). The excess nutrients cause algae to multiply rapidly. As it dies and sinks to the bottom, the algae is eaten by bacteria that use up the limited amount of oxygen available.

A significant portion of the nutrients entering the Gulf from the Mississippi River come from human activities: discharges from sewage treatment and industrial wastewater treatment plants, and storm water runoff from city streets and farms. Nutrients from automobile exhaust and fossil fueled power plants also enter the waterways and the Gulf through air deposition to the vast land area drained by the Mississippi River and its tributaries. About 90 percent of the nitrates entering the Gulf come from runoff, and about 56 percent of the nitrates enter the Mississippi River above the Ohio River.

EPA, along with nine other federal agencies, nine states along the Mississippi River, and two tribes, agreed to work towards the goal of reducing the size of the dead zone to 1,930 square miles, or about half its average size, by the year 2015. They also agreed to develop strategies to reduce nutrients entering the Gulf, particularly the amount of nitrogen, by 30 percent. The Action Plan calls for continued research and monitoring to better understand the problem, and to use the information as a basis to modify the goals and actions as may be necessary in the future.

The Action Plan will be implemented in large part through existing State and Federal laws and programs, as well as private initiatives. For example, the Clean Water Act, Farm Bill, and Coastal Zone Amendments and Reauthorization Act contain provisions aimed at reducing nonpoint source pollutants, and implementation of the Conservation Reserve Program, Wetlands Reserve Program, Army Corps of Engineers Environmental Restoration Programs, and Agricultural Extension Education Programs can promote restoration and enhancement of natural systems for nitrogen reduction and denitrification.

Congress will rewrite federal farm programs over the next two years, and EPA is calling for provisions in the next Farm Bill that will pay farmers to restore lost wetlands, retire environmentally sensitive lands, install buffers of trees and grasses along streams, and undertake other practices that would reduce fertilizer use or filter runoff. A 1999 White House study concluded that the most cost-effective way to protect the Gulf would be to reduce fertilizer use by 20 percent, and to restore 5 million acres of wetlands that could trap nutrients before they reach the Mississippi River and its tributaries.

The Action Plan was mandated by the Harmful Algal Bloom and Hypoxia Research and Control Act, Pub. L. 105-383, which was passed by Congress in 1998. The plan and additional information are available on EPA's Office of Water Web site at: http://www.epa.gov/ow, under "What's New."