The Gulf “dead zone” off Louisiana’s coast was nearly the size of Connecticut this summer, researchers reported Thursday, while the Trump administration proposes cuts to some federal funding intended to help address the pollution that contributes to it.
Despite the gargantuan size of the low-oxygen zone, covering an area across nearly the entire Louisiana coast west of the Mississippi River, it was smaller than predicted and slightly below the long-term average. It remained, however, far larger than a 2035 goal to reduce it.
Federal officials said states have made progress on reducing certain types of nutrient pollution flowing down the Mississippi, which leads to what has become known as the “dead zone” each summer. But they acknowledged that President Donald Trump’s proposed budget for fiscal year 2026 defunds two types of federal grants that assist states in addressing and monitoring pollution.
Researchers are watching closely to see if other cuts could be on the way as the Trump administration pursues what it describes as policies to make government more efficient. The president’s budget proposal is not the final word, since Congress can move to add or subtract money throughout the budget process.
Amounts for the two categories of Environmental Protection Agency grants defunded in Trump’s budget proposal — known as sections 106 and 319 — have varied over the years. The EPA has granted about $18.5 million yearly in 106 grants, though Congress has also added additional money. The 319 grants amounted to $178 million in fiscal year 2022, the last year available on the EPA website.
Brian Frazer, director of the EPA’s office of wetlands, oceans and watersheds, noted however that other funds to address hypoxia — the scientific term for low-oxygen areas — were still being distributed.
“It does call for no 319 or 106 funds,” Frazer said during a news conference to announce the dead zone findings. “That can always change. But as I mentioned earlier, states soon will have been awarded final Gulf hypoxia program grants totaling $4.3 million.”
The area of low oxygen can cause fish, shrimp and other marine life to flee or die. It can also affect fish diets, reproduction and growth.
Beyond the implications on marine life in general, the dead zone also affects Louisiana fisheries, particularly the shrimping industry.
‘Most productive fisheries’
The nutrient pollution leads to algae growth. When the algae dies and decomposes, it uses up the water’s oxygen.
Measuring the dead zone was pioneered by scientists based at the Louisiana Universities Marine Consortium and LSU, and those institutions still play a lead role in the research.
Cassandra Glaspie, of both LSU and the consortium, which researches coastal and marine systems, on Thursday reported the findings from those organizations’ annual cruise survey from July 20-25 to measure the dead zone. This year, it measured 4,402 square miles, or about 90% the size of Connecticut and about seven times the size of Lake Pontchartrain.
Scientists with the Louisiana Universities Marine Consortium lower an instrument into the “dead zone” in the Gulf of Mexico to measure water quality in 2023. (Photo by Cassandra Glaspie, Louisiana State University)
It remains far above the 2035 goal of around 1,900 square miles.
Glaspie noted that the dead zone “makes the seafloor in that region uninhabitable for fish and shellfish. And then this, of course, impacts one of our nation’s most productive fisheries.”
Besides the dead zone west of the river, new research is beginning to understand a similar phenomenon east of the river, causing major concerns for the Mississippi Gulf Coast. Findings on the size of this year’s dead zone in that area are expected to be reported next week.
Much of the nutrients flowing down the Mississippi come from fertilizer and animal waste from farms in the country’s Midwest, though there are other sources as well, including sewage and storm runoff. A task force including the federal government and states along the Mississippi has been seeking to address the issue, and some farms have adopted measures to try to limit nutrient runoff into the river.
Those include conservation practices such as two-stage ditches that can function as wetlands that absorb nutrients and encouraging the use of cover crops.
‘Pretty shocking to us’
Gretchen Oelsner with the U.S. Geological Survey said preliminary data from May showed nitrogen in the Mississippi and Atchafalaya Rivers was 24% below the long-term average, though phosphorus was around 31% above. But R. Eugene Turner, another LSU scientist who has closely studied the dead zone, said those figures were a “misdirection.”
He said nitrogen in the Mississippi has declined by 4% at most since a hypoxia action plan was adopted in 2001. The number cited by USGS is anchored in a baseline set in the 1980s, he said.
Turner also argued the size of the dead zone being somewhat less than predicted for this year likely had more to do with the Gulf being particularly warm, and said the modeling used for the predictions may not have sufficiently accounted for it. The measured size did, however, fall within the range of uncertainty for such estimates.
Warmer waters can limit the size of certain types of plankton, which contribute to the dead zone.
Glaspie highlighted the especially warm waters in her presentation, saying that surface temperatures were “extremely high” at up to 97 degrees — around the temperature of the human body.
“So we basically had human body temperature water at some of those locations out in the Gulf,” she said. “That was pretty shocking to us.”
Studies have identified a combination of cyclical factors and climate change for the rapidly warming Gulf.
Nancy Rabalais, the LSU professor who began carrying out dead zone measuring cruises in 1985, noted the five-year dead zone average remained 4,440 square miles, which is more than twice the 2035 target.
Describing this year’s size, Rabalais called it “average, but still large.”
Environmental group Healthy Gulf also noted the warm waters and said the 2035 goal seemed virtually impossible to attain.
“It would take $2.7 billion annually to meet the task force goal, utilizing current conservation practices,” Matt Rota, the group’s senior policy director, said in a statement.
“We need to understand that unless we fundamentally change how we address this pollution, from farming practices to federal and state policies, there is no way we will meet the 2035 goal. If we don’t reach this goal, our fisherfolk, coastal communities and Gulf ecosystem will continue to suffer.”