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Near-Record Dead Zone Predicted This Year

The dead zone mapped in 2017, above, measured 8,776 square miles -- the biggest on record. Scientists from LUMCON predict this year's dead zone to be just a tad smaller: 8,717 square miles.

The dead zone in the Gulf of Mexico is predicted to be the second biggest in history, according to a new forecast from the Louisiana Universities Marine Consortium (LUMCON).

The dead zone is mostly caused by agricultural run-off from the Mississippi River; nutrients from fertilizers like nitrogen and phosphorus enter the water, causing algae to bloom once it slows and heats up in the Gulf of Mexico. When the algae decays, it uses up oxygen in the water which can stress and kill some sea creatures. The condition of reduced oxygen is known as hypoxia.

LUMCON’s forecast predicts this summer’s dead zone to reach 8,717 square miles. That’s about the size of New Hampshire, and would be just smaller than the 8,776 square miles measured in 2017. The 5-year average is 5,770 square miles -- still well above the Hypoxia Task Force's target of shrinking the dead zone to 1,930 square miles.

LUMCON researcher Dr. Nancy Rabalais says a flooding Mississippi River and high nutrient load are the reasons for the near-record prediction. She and her team have been monitoring the Mississippi River discharge and nutrient levels since the first big pulse of flood water in the spring, so they “weren’t necessarily surprised” by the results of their models.

The model is based on data observed during the month of May, so the measured size typically differs slightly from the forecast.

Rabalais says the dead zone will likely be even bigger if the the Army Corps of Engineers opens the Morganza Flood Control Structure, commonly called the Morganza Spillway, to relieve the flooding Mississippi River. That would likely cause the dead zone to expand farther west.

Rabalais and her team will spend 10 days mapping this year’s dead zone at the end of July.

Support for the Coastal Desk comes from the Greater New Orleans Foundation, the Walton Family Foundation, and local listeners.

As Coastal Reporter, Travis Lux covers flood protection, coastal restoration, infrastructure, the energy and seafood industries, and the environment. In this role he's reported on everything from pipeline protests in the Atchafalaya swamp, to how shrimpers cope with low prices. He had a big hand in producing the series, New Orleans: Ready Or Not?, which examined how prepared New Orleans is for a future with more extreme weather. In 2017, Travis co-produced two episodes of TriPod: New Orleans at 300 examining New Orleans' historic efforts at flood protection. One episode, NOLA vs Nature: The Other Biggest Flood in New Orleans History, was recognized with awards from the Public Radio News Directors and the New Orleans Press Club. His stories often find a wider audience on national programs, too, like NPR's Morning Edition, WBUR's Here and Now, and WHYY's The Pulse.

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