Smaller ‘dead zone’ still bigger than desired

The “dead zone” where the Mississippi River dumps into the Gulf of Mexico — an area of low oxygen that cannot sustain life, fueled by pollution running the length of the river — clocked in at 3,275 square miles this year, less that recent averages but still twice the size of predictions made by a task force trying to reduce the zone.

The National Oceanic and Atmospheric Administration this week announced the size, noting it was smaller than what the agency predicted. But the reduction, which is caused by nutrient runoff throughout the Mississippi River Basin, was due largely to reduced river flow, said Nancy Rabalais, professor at Louisiana State University’s Department of Oceanography & Coastal Sciences.

She said the decrease in size had little to do with efforts to reduce runoff, which largely comes from farms. The Gulf of Mexico Hypoxia Task Force, a partnership formed in the late 1990s with the goal of reducing the size and severity of the hypoxic zone, currently is co-chaired by Iowa Agriculture Secretary Mike Naig.

“Human action did not really contribute anything to the lower size,” Rabalais said on a call with reporters co-hosted by NOAA. “But instead it's weather, possibly climate change, that led to the drought in the Mississippi River Basin, especially after the end of May,” she said, which tempered the river’s flow.

This year’s hypoxic zone is the ninth-smallest recorded size since scientists began measuring the phenomenon in 1985. In July, NOAA predicted that the size of the zone would total approximately 5,364 square miles.

But it still is well above the Hypoxia Task Force’s reduction goal of 1,930 square miles or smaller by 2035. And the five-year average is 4,280 square miles, more than double the target.

The hypoxic zone occurs seasonally when the Mississippi and Atchafalaya rivers carry nutrients into the Gulf, creating algal blooms. Bacteria feed on the algae once they die, depleting oxygen levels in subsurface waters during the decomposition process.

Bottom-dwelling sea creatures move away to escape the dead zone, while animals and other organisms that are not as mobile can perish in large numbers.

“While some hypoxia is natural, the size and scale of what we’ve seen here in the last several decades is unusually large and detrimental,” Nicole LeBoeuf, director of NOAA’s National Ocean Service said in a statement.

The nitrogen and phosphorus nutrient pollution that lands in the Gulf is caused by a variety of human activities — which include agricultural runoff, the burning of fossil fuels and wastewater treatment discharge. Agricultural activities, however, are the main driver of the pollution.

Since the Louisiana Universities Marine Consortium, an organization supported by NOAA, began annual monitoring during the Reagan administration, the size of the dead zone has ranged from an anomalously small 15 square miles in 1988 to a record high 8,776 square miles in 2017.

The Hypoxia Task Force was formed in 1997. The dead zone size satisfied the target goal just once during that period, in 2000.

“Since the Hypoxia Task Force started — the best you could say is that the size of the dead zone has kind of plateaued,” Matt Rota, senior policy director at the environmental advocacy group Healthy Gulf, told The Lens. “But we definitely haven't been seeing reductions of anything within the (targeted) level.”

The dead zone has wreaked serious damage on the Gulf’s ecosystems and fisheries. A study released by the Union of Concerned Scientists in 2020 concluded that, since 1980, nitrogen pollution has caused up to $2.4 billion annually in damage to the Gulf’s marine habitat and fisheries.

As a result of the dead zone, fishermen like shrimper Acy Cooper of Venice, La., are forced to travel further into open water to earn their livelihoods, which can prove both hazardous and expensive.

“Any time you have to move further away from home, it's that much more dangerous,” Cooper said, noting that storms in the Gulf are more severe than ever.

Federal government has little authority

One of the issues the Hypoxia Task Force has encountered in its efforts to mitigate nutrient pollution is that it’s forced to rely on voluntary mechanisms to encourage states to act, Rota said. States including Iowa can encourage farmers to opt in to reduction programs that reduce fertilizer runoff, like cover crops and planting buffer zones, but there is no penalty if they don’t.

Many of the agricultural practices behind the nutrient pollution are exempt from regulatory oversight under the federal Clean Water Act, Rota said. Still, according to a report the Environmental Protection Agency submitted to Congress in March, efforts are being made across the basin to reduce the nutrient pollution.

For example, states have reported that approximately $37 million in grant funding provided by the EPA is going toward reducing such pollution. Naig said that work should be recognized.

“I hope we take away from this is that there are a lot of variables and a lot of factors that go into the size of the hypoxic zone each year,” he told reporters.

The Infrastructure Investment and Jobs Act includes $60 million in funding over five years for the Hypoxia Task Force to reduce nutrient pollution. But that level of funding is a far cry from the $2.7 billion that researchers concluded the United States would need to invest annually to reach the 1,930 square mile goal.

This story is a product of the Mississippi River Basin Ag & Water Desk, an editorially independent reporting network based at the University of Missouri School of Journalism in partnership with Report For America, which includes The Gazette, and funded by the Walton Family Foundation. The Lens covers the Gulf Coast.