The Gulf's "Dead Zone" Is Not Dead Yet - and Probably Won't Be Anytime Soon
The dead zone in the Gulf of Mexico grabs the media's attention every summer when scientists funded by the National Oceanic and Atmospheric Administration (NOAA) boat around the Gulf, taking its annual measurement. This year, it was bigger than expected at 6,474 square miles - roughly the size of Connecticut and Rhode Island combined.
But despite the alarming name, "dead zone," dead fish rarely wash up on shore.
“No, no, it doesn't kill fish!” said an exasperated Mark David, a professor at the University of Illinois who corrected me during an interview this year. “Most fish swim away. If a billion fish washed up on the shore of Louisiana and Mississippi every summer, yes, that would get people's attention.”
The Dead Zone, an oxygen-deficient area of water, does lead to toxic algae blooms and the death of bottom-dwelling organisms, like benthic worms. Fish can be negatively impacted because they depend on some of these organisms for food. The dead zone is created annually by excess nitrogen, phosphorus and other chemical fertilizers leaching through soil, or running off the top, and flowing into streams and rivers that end up in the gulf. While some of this fertilizer is seeping off lawns and golf courses, most of the pollution is flowing from farms in the Mississippi River watershed, according to the EPA.
Federal and state agencies have been aware of the impact farm runoff has on the Gulf for at least two decades. In 2008, the Environmental Protection Agency (EPA) set a goal to cut the size of the dead zone nearly in half by 2015. Despite this ambitious goal, there’s been little on-the-ground action to address the problem. Earlier this year, in fact,the EPA pushed their 45% reduction goal back two decades, to 2035.
There’s been some good news. In the past few years, some of the world’s biggest food companies, in partnership with state governments and nonprofit organizations, have begun helping farmers pay for conservation practices, as I reported earlier this year. The government and industry are focusing on “in-field practices,” encouraging farmers to correctly apply fertilizer and plant cover crops which can sequester excess nutrients and prevent erosion. But the acres involved in such programs are few and far between, and the impact they’ll have on the dead zone probably won’t be noticeable.
In a new study issued last week, the Environmental Defense Fund (EDF) is calling for more aggressive action. In order to reduce the size of the dead zone, the study suggests farmers need to plant perennial crops, like alfalfa, change how they drain excess water from their fields, and reintroduce wetlands. In the past few years, several states in the Mississippi River watershed have published plans for reducing runoff that also include these suggestions.
As I read the EDF’s report, I felt both encouraged and cautiously skeptical. On the one hand, the report found a few specific watersheds that are most vulnerable to nitrogen loss. This knowledge could allow federal and state agencies to more directly target limited conservation dollars on the places that will have the biggest impact on the Gulf.
On the other hand, the conservation methods the report suggests - even if they are targeted to specific, vulnerable acreage - could be unrealistic. As David told me, farmers are unlikely to make aggressive changes, like planting perennial biofuel crops, because there’s no economic incentive, or regulatory requirement, to do so.
“A lot of these things just cost money,” he said. “They don’t improve yields.”
Currently, there’s no market for perennial crops and reintroducing wetlands would take valuable cropland out of production. Changing drainage practices - farmers in states like Illinois and Iowa typically rely on tiles, a system that dates back generations - would be an upfront cost that might not pay off in the long run, he said.
In a state like Illinois, David estimates significantly reducing runoff will cost the agricultural sector $16 billion over the next 20 years. “To meet the [EPA’s] 45 percent reduction goal,” he said, “It will take pretty much somebody doing something different on every acre of cropland.”
Meanwhile, the need for aggressive action is likely to become more pronounced. The size of the Dead Zone is linked to the amount of rain, and the severity of the storms, that fall on the Mississippi River watershed in the spring. As a result of climate change, scientists have documented a steady increase in spring rainfall in many of these states.
So despite all the attention on shrinking it, the Dead Zone could stay stubbornly large in the future.