The National Oceanic and Atmospheric Administration expects a so-called “dead zone” roughly the size of New Jersey to develop in the Gulf of Mexico this summer.
Also known as a hypoxic zone, a reference to the low-oxygen conditions that kill fish and marine life, this year’s measurement is expected to cover more than 7,000 square miles. Although that forecast falls below the record size of nearly 8,800 square miles in 2017, it is higher than the four-decade average of just over 5,200 square miles.
“The trend has been one of growth mostly since they started measuring it,” said Doug Daigle, a research associate at Louisiana State University and the coordinator of the Louisiana Hypoxia Working Group, a group of researchers, government agencies and other stakeholders focused on the issue.
As a researcher with years of experience working on the Gulf’s dead zone, Daigle said it's important to focus on the overall goal to reduce the size of the dead zone.
“We don't get too hung up on any particular year because what we're interested in is affecting the trend over time,” Daigle said.
That’s a goal shared by the Environmental Protection Agency’s Mississippi River/Gulf of America Hypoxia Task Force, a cooperative of federal, state and tribal agencies. Currently, the group is working to shrink the deadzone to 1,900 square miles — or 5,000 square kilometers — by the year 2035.
The annual dead zone forms due to an overabundance of nutrient pollution, such as nitrates and phosphorus, that is caused primarily by agricultural industries and urban areas throughout the Mississippi and Atchafalaya rivers. This excess in nutrients then causes algae to overgrow, die, decompose and then deplete oxygen in the surrounding waters.
With little to no oxygen, fish populations in the Gulf sharply decline, along with those of shellfish, coral and aquatic plants. As a result, both the seafood and tourism industries have suffered critical losses.
“So it not only has ecological and environmental impacts, it has economic impacts as well,” said Kelly McGinnis, the executive director of One Mississippi, a national nonprofit that works on conserving and restoring the river.
But along with the levels of discharge, Daigle said each year’s measurements can be affected by climate conditions such as drought, flooding or rainfall. If the forecast is high, he said that usually means there’s been rain or flooding upstream.
“And then when you have the dry periods, it's less, but a lot of those nutrients will get flushed out later,” Daigle said.
While changing weather can affect the annual results, the work towards reducing the size of the dead zone appears to be progressing, Mike Naig, the secretary of agriculture for Iowa and co-chair of the Mississippi River/Gulf of America Hypoxia Task Force, said in a mid-June press release. The task force announced then that it had achieved its interim goal of reducing pollution from the Mississippi and Atchafalaya rivers into the Gulf by 20%.
According to the group, that’s likely a result of states in the basin — such as Missouri, Illinois and Wisconsin — implementing their own nutrient reduction programs.
“State-driven, science-based strategies and local partnerships are critical to continue scaling up conservation practices, accelerating implementation and delivering measurable results,” said Naig in the press release.
Each year, NOAA uses multiple models and datasets, such as the U.S. Geological Survey’s, to track nutrient levels, which help to inform its hypoxia forecast model and identify sources. In turn, the members of the task force use the data to support their states’ nutrient reduction strategies and the overall goal for the Mississippi River and the Gulf of Mexico. Meanwhile, researchers have also conducted a cruise survey for over four decades to compare dead zone predictions in the Gulf.
Despite the many years of collaborative efforts, Daigle does not expect the dead zone to disappear completely. Yet, he is concerned about the future of hypoxia reduction programs both in the Mississippi River and in the Gulf downstream.
“What a lot of folks don't realize is that it's never really gotten the resources adequate to reverse the trend,” he said.
As such, Daigle’s Louisiana Hypoxia Working Group — along with 62 other organizations in agriculture and conservation — signed a letter last December to ask Congress to support their efforts. Previously, lawmakers authorized funding for fiscal years 2022 through 2026 for the EPA to implement its hypoxia program in the Gulf. Without future funding secured, advocates like McGinnis said the reduction goal for 2035 seems “highly unattainable.”
“I want the federal government to be successful in reaching that goal,” she said, “but it is hard to see the pathways that will lead to it.”
This story is a product of the Mississippi River Basin Ag & Water Desk, an independent reporting network based at the University of Missouri in partnership with Report for America, with major funding from the Walton Family Foundation.