Scientists have released their 2023 forecast for the so-called "dead zone" in the Gulf of Mexico — predicting it will be about 4,100 square miles this summer. That's much bigger than last year, but still smaller than average.
The dead zone is a hypoxic area where low oxygen can kill fish and other marine life. It's caused by excessive nutrient runoff, largely from fertilizer used on farm fields in the Midwest, which ends up in the Mississippi River and flows south to the Gulf.
The National Oceanic and Atmospheric Administration uses models and data from the U.S. Geological Survey to forecast the size of the dead zone each year. Data from river and stream gauges showed that nitrate and phosphorus discharges were below average in the Mississippi River and Atchafalaya River, which splits off in south Louisiana.
While some see this season's forecast as good news, it is still well above the federal Hypoxia Task Force's goal of shrinking the dead zone to 1,900 square miles or smaller by 2035. The area's five-year average size is 4,280 square miles, more than double that target, and has trended mostly larger over time.
Don Scavia, an emeritus professor at the University of Michigan, leads one of several research teams partnering with the federal government on the annual forecast.
"Lack of a downward trend in the dead zone illustrates that current efforts to reduce those loads have not been effective," he said. "Clearly, the federal and state agencies and Congress continue to prioritize industrial agriculture over water quality."
A NOAA press release said the results were due to lower river flow rates. Despite lots of rain and flooding in the upper Midwest early this spring, discharge in May in the Mississippi and Atchafalaya rivers was about 33% below the long-term average.
Lauren Salvato, policy and program director at the Upper Mississippi River Basin Association, said she's hopeful about the projections. "It's certainly positive," she said. "Our states are working hard and they want to meet their nutrient reduction goals."