Gulf Of Mexico's 2017 'Dead Zone' Predicted To Be Third Largest In 32 Years

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Gulf of Mexico's 2017 'dead zone' predicted to be third largest in 32 years

Posted on June 20, 2017 at 5:23 PM

By Mark Schleifstein

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NOLA.com | The Times-Picayune

The 2017 summertime low-oxygen "dead zone" in the Gulf of Mexico along the Louisiana and Texas shore could be the third largest ever measured, according to federally sponsored research results announced Tuesday (June 20). The prediction is based on modeling of the nutrients that are carried into the gulf by the Mississippi and Atchafalaya rivers.

Three different sets of predictions were released by the National Oceanic and Atmospheric Administration and two groups of scientists working with the agency. Each prediction carried slightly different estimates of the size of the dead zone, where bottom waters contain 2 parts per million or less of oxygen, a condition known as hypoxia.

    A team of researchers from the University of Michigan and North Carolina State University estimated the low-oxygen area this year would be 7,722 square miles, larger than the state of Connecticut.

    The official estimate by the National Oceanic and Atmospheric Administration and the U.S. Geological Survey, a blend of modeling results from all the scientists, estimated the area would be 8,185 square miles, about the size of New Jersey, and the third largest since dead zone tracking begin in 1985.

    However, a team of LSU and Louisiana Universities Marine Consortium researchers, which also works with the research project, estimated the 2017 zone at 10,089 square miles, larger than the state of Vermont. If that estimate is accurate, this year's hypoxia zone could be the largest ever.

The average, based on 32 years of monitoring, is 5,309 square miles.

The latest size predictions will be measured against the results of a week-long cruise along the shelf areas of Louisiana and Mississippi. It is scheduled July 24-31, to be led by Nancy Rabalais, a researcher with LSU and the marine consortium and co-author of that team's estimate.

'Dead zone' map cruise canceled; first time in 27 years

Scientific expedition was to determine whether June forecast of 6,824-square-mile low-oxygen zone is accurate

Last year's cruise was cancelled after a National Oceanic and Atmospheric Administration research ship developed mechanical troubles. This year, the monitoring will be conducted aboard the state-owned Pelican, which is operated by the marine consortium.

The dead zone got its name from the effects of low oxygen on wildlife and fisheries: Fish and shrimp tend to swim away to areas with higher oxygen, while bottom-loving organisms that are unable to move suffocate and die. Research earlier this year blamed hypoxia along Louisiana's coast for price spikes for jumbo shrimp.

Price spikes for jumbo shrimp blamed on Gulf dead zone

And price for smaller shrimp falls during low-oxygen periods along Louisiana coast

The nutrients carried by freshwater exiting the Mississippi and Atchafalaya rivers cause huge blooms of algae in the fresh, surface layer of the gulf along the coast. As the algae die, they sink to the bottom and decompose, using up oxygen in the deeper, saltier layer. Until the surface freshwater, higher in oxygen content, is mixed with the deeper salty water, the low-oxygen effects persist.

Tropical Storm Cindy, which was expected to stir coastal waters over the next few days, might reduce the size of the low-oxygen areas. But Rabalais and LSU researcher Eugene Turner said the storm's effects will result in only a 30 percent reduction of the predicted size of the dead zone. That would drop the estimate of the hypoxic area to 6,600 square miles, still larger than Connecticut.

The nutrients triggering the algae blooms result from fertilizer runoff from Midwest farmland and releases of sewer system and other septic wastewater within the Mississippi River watershed, which drains all or part of 31 states and two Canadian provinces.

"This year's predicted large size is due mainly to heavy May stream flows, which were about 34 percent above the long-term average and had higher-than-average nutrient loads," the National Oceanic and Atmospheric Administration said in a news release. The Geological Survey "estimates that 165,000 metric tons of nitrate -- about 2,800 train cars of fertilizer -- and 22,600 metric tons of phosphorus flowed down the Mississippi and Atchafalaya rivers into the Gulf of Mexico in May."

In 2014, the Mississippi River/Gulf of Mexico Watershed Nutrient Task Force, made up of federal agencies and states that border the Mississippi and the gulf, set a goal of reducing nitrogen and phosphorus pollution enough to lower the size of the dead zone to 1,930 square miles by 2035. An interim target of a 20 percent reduction was set for 2025.

However, that same goal was set by the task force in 2001, three years after the group was formed, when it said it expected the goal to be met by 2015.

The task force's voluntary goal program has been criticized by environmental groups as doing little to reduce the size of the low-oxygen area. These groups want the federal Environmental Protection Agency to set limits on so-called "non-point source" emissions -- nutrients in rainfall runoff -- from farms.

In December, however, a federal judge in New Orleans ruled that the federal government need not impose such mandatory restrictions. That ruling reversed an earlier one by the same judge who had ordered EPA to conduct a "necessity determination," the first step towards adopting more stringent rules.

Judge Jay Zainey's original ruling was overturned by the 5th U.S. Circuit Court of Appeals in 2015. The appeals court said Zainey must consider whether EPA violated the federal Administrative Procedures Act in deciding not to conduct the determination. It told Zainey that his new review was to be "extremely limited and deferential to EPA's decisionmaking authority.

The original suit was filed by a number of environmental groups active along the Mississippi and its tributaries, including the New Orleans-based Gulf Restoration Network. They were represented by the Tulane Environmental Law Clinic.

No appeal was made of that decision.

EPA and farm state officials contend that a number of voluntary programs are beginning to show promise in reducing nutrients. These programs include federal grants to farmers to turn marginal farmland back into wetlands that absorb nutrients, and so-called precision farming that uses global positioning system technology to guide the amount of fertilizer delivered to crops by tractors.