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Gulf of Mexico Hypoxic Zone

The hypoxic zone of the Gulf of Mexico is a temporary area of low oxygen – there is not enough oxygen available to support fish and other aquatic species – which is why it is sometimes also called a "dead" zone. The oxygen becomes depleted when an overabundant amount of nutrients in the water causes excessive growth of algae. The algae die and during the decomposition process (called eutrophication), the oxygen levels drop too low to sustain aquatic life.

The nutrients are delivered to the Gulf by the Mississippi River, which drains 41 percent of the continental U.S. Excess nutrients may come from a wide range of sources, including runoff from developed land, atmospheric deposition, soil erosion, manure, agricultural fertilizers, and sewage and industrial discharges. In 2007, the hypoxic zone was the third largest on record – bigger than the State of Massachusetts.

The Mississippi River/Gulf of Mexico Watershed Nutrient Task Force was established in the fall of 1997 as part of the government's plan to address hypoxia in the Gulf of Mexico. The Task Force has issued the 2008 Action Plan, which provides mechanisms for maintaining and tracking progress between reassessments, state-led nutrient reduction strategies, complementary federal agencies and an outreach plan to engage stakeholders.


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