'Dead Zone' smaller than expected, but bigger than desired
The so-called dead zone where the Mississippi River dumps into the Gulf of Mexico, an area of low oxygen that cannot sustain life, clocked in at 3,275 square miles this year. The National Oceanic and Atmospheric Administration (NOAA) announced the size Wednesday, noting that it is below the recent average and smaller than what the agency had previously predicted, but almost twice the target goal set by 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.
The reduction in this year’s dead zone, which is caused by nutrient runoff throughout the Mississippi River Basin, was due largely to reduced river flow, Nancy Rabalais, professor at Louisiana State University’s Department of Oceanography & Coastal Sciences, said. She said the decrease in size had little to do with efforts to reduce runoff, which largely comes from farms.
“Human action did not really contribute anything to the lower size,” Rabalais said on a press call 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 is still 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 of Mexico, thereby 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.
“Our measurements and analyses can empower communities to take action to protect their coasts and contribute to the region’s economic sustainability.”
The nitrogen and phosphorus nutrient pollution that lands in the Gulf of Mexico 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.
The dead zone tends to stretch from the mouth of the Mississippi River in Louisiana westward and can reach as far as the Texas border and beyond.
This year, the zone didn’t extend further west than near the Atchafalaya River delta, Rabalais, who led the research team, said. She helped record the hypoxic zone on the Pelican research vessel this summer, where her team provides a one-time snapshot of the zone on an annual basis.
Billions of dollars in damage
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 the year 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, Louisiana, 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 these days than ever and that many fishing boats aren’t equipped with cabins and aren’t designed for extended excursions.
The increased use of fuel, and other expenses, also cut into his bottom line.
“We’re dealing with the way the economy is nowadays: the price of shrimp, the price of fuel and the equipment – everything's sky high,” Cooper said. “So that ends up coming out of your pocket” he said, adding that fishermen are often unable to work in the wintertime and rely on profits made during the warmer months to survive.
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 of Healthy Gulf said. States 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, and little financial incentive to opt in.
Many of the agricultural practices that are the main culprits behind the nutrient pollution are exempt from regulatory oversight under the federal Clean Water Act, he said.
Still, according to a report the EPA 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 towards reducing such pollution.
Mike Naig, Iowa’s Secretary of Agriculture, 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 said on the press call Wednesday.
Meanwhile, 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 U.S. would need to invest annually to reach the 1,930 square mile goal. And a study from 2019 concluded that reductions in nitrogen loading that reaches the Gulf have been minimal.
Cooper, for his part, plans to continue communicating the threat that nutrient pollution poses to him and his industry.
Referring to states upstream, he said, “They need to be aware of what they’re letting run off, and what goes into the rivers and streams that winds up at the mouth of the river – that's the whole creation of the dead zone.”
More funding from the federal government to reduce that runoff wouldn’t hurt either, Cooper said.
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 and funded by the Walton Family Foundation.