Gulf of Mexico 'dead zone' could explode to the size of Massachusetts

This summer the area -- where oxygen concentration is so low it chokes out marine life -- could reach a near-record size.

Amanda Kooser
Freelance writer Amanda C. Kooser covers gadgets and tech news with a twist for CNET. When not wallowing in weird gear and iPad apps for cats, she can be found tinkering with her 1956 DeSoto.
Amanda Kooser
2 min read

NASA's Aqua satellite captured this look at the sediment-laden Gulf of Mexico after flooding in spring 2011.

NASA/MODIS Rapid Response Team/Goddard Space Flight Center

It's an annual event nobody looks forward to. The Gulf of Mexico hosts a human-caused "dead zone" every summer that kills off marine life, and 2019 could be a doozy.

The US National Oceanic and Atmospheric Administration released its forecast for the year's hypoxic zone on Monday. Scientists estimate it could cover 7,829 square miles (20,277 square kilometers), roughly the size of the state of Massachusetts or the country of Slovenia.

A hypoxic zone is an area where oxygen concentration is so low it chokes out marine life. The Gulf of Mexico's dead zone is primarily human-caused, a result of nutrient pollution, including nitrogen and phosphorus from urban environments and farms, traveling through the Mississippi River watershed and into the gulf. 


This map shows how pollution from cities and farms flows down into the Gulf of Mexico.


The nutrients feed an explosion of algae, which then die, sink and decompose. This creates the dead zone. 

A rush of spring rain feeding into the Mississippi is what's expected to push 2019's zone to a near-record size. NOAA calculated the record-setting 2017 dead zone reached an area of 8,776 square miles, while the five-year average is 5,770 square miles. 

NOAA drew a direct line between the dead zone and the price of shrimp in 2017. 

NOAA's forecast assumes normal weather conditions, but large storms could impact the ultimate area of the dead zone. NOAA will help launch a monitoring survey in August to confirm the size and see if it matches the forecast.

Researchers at Louisiana State University also issued a dead-zone forecast today, with a higher estimate of 8,717 square miles by late July. The scientists warn of impacts to resources living there, including fish, shrimp and crabs.

The Environmental Protection Agency's Hypoxia Task Force set a target goal of reducing the five-year average size of the dead zone down to 1,900 square miles, but that figure is far from today's reality.   

"Low oxygen conditions started to appear 50 years ago when agricultural practices intensified in the Midwest," LSU reported. "No reductions in the nitrate loading from the Mississippi River to the Gulf of Mexico have occurred in the last few decades." That's grim news for the gulf. 

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