NCCOS scientists are forecasting this summer’s Gulf of Mexico hypoxic zone or "dead zone"—an area of low to no oxygen that can kill fish and other marine life—will be approximately 7,829 square miles, or roughly the size of Massachusetts. The annual prediction is based on USGS river flow and nutrient data during the month of May.

The 2019 forecast is close to the record of 8,776 square miles set in 2017 and larger than the 5-year average of 5,770 square miles. This is the second year NCCOS is producing an independent forecast, the culmination of a multi-year academic-federal partnership to develop a suite of hypoxia forecast models. The partnership included teams of researchers at the University of Michigan, Louisiana State University, William & Mary’s Virginia Institute of Marine Science, North Carolina State University, Dalhousie University, and USGS. The NOAA forecast integrates the results of these multiple independent models into a separate average forecast and is released in coordination with these external groups.

The Mississippi River watershed drains 1.245 million square miles, including all or parts of 31 U.S. states and two Canadian provinces. This map generally illustrates how runoff from farms (green areas) and cities (red areas) drains into the Mississippi River, delivering nutrients into the Gulf of Mexico and fueling the annual hypoxic zone. Credit: NOAA.

The dead zone in the Gulf of Mexico affects nationally important commercial and recreational fisheries and threatens the region's economy. NOAA issues a dead zone forecast each year, and refines the models used by the Hypoxia Task Force to set nutrient reduction targets and better understand the link between hypoxia and nutrients. A NCCOS-supported monitoring survey will confirm the size of the 2019 Gulf dead zone in early August, a key test of the accuracy of the models.

NCCOS and its partners continue to develop additional hypoxia forecast capabilities to understand impacts on living marine resources, better evaluate the role of phosphorus on the dead zone size, and understand the relationship between hypoxia volume and area.