2026 ‘Dead Zone’ May Remain Three Times Larger than the Goal Established in 2001

BATON ROUGE - A recent forecast of the size of the “Dead Zone” in the northern Gulf of Mexico for late July 2026 is that it will cover 7,532 square-miles of the bottom of the continental shelf off Louisiana and Texas.

The Mississippi River discharge of nitrogen in May controls the size of this zone, which will be the 7th largest zone since systematic measurements began in 1985. The water mass with oxygen concentrations less than 2 parts per million forms in bottom waters each year primarily as a result of nitrogen loading from the Mississippi River watershed, which fertilizes the Gulf of Mexico’s surface waters to create excessive amounts of algal biomass. The decomposition of this plant material in the bottom layer and sediments leads to oxygen loss. The expected effects of ocean warming are predicted to be mild this year because of this year’s cooler than normal spring weather. 

The low oxygen conditions in the Gulf of Mexico’s most productive waters stresses organisms and may even cause their death, threatening living resources, including fish, shrimp and crabs caught there.

Low oxygen conditions started to appear 50 years ago when agricultural practices intensified in the U.S. Midwest. No significant reductions in the nitrate loading from the Mississippi River to the Gulf of Mexico has occurred since the Hypoxia Action Plan was adopted in 2001.The predicted hypoxic area is about three times the land area of Vermont and New Hampshire combined, and more than three times the size of the Hypoxia Action Plan goal of 1931 mi2 established in 2001. This estimate assumes that there are no significant tropical storms in the two weeks before or during the annual monitoring cruise planned for July 25 to August 2. The estimate is made each year by LSU scientists R. Eugene Turner and Nancy N. Rabalais.

The full prediction report is posted at https://gulfhypoxia.net/research/shelfwide-cruises/.