This summer, the "dead zone" in the Gulf of Mexico was about the size of Connecticut. Almost nothing can stay alive in this swath of sea because the water has become so low in dissolved oxygen. The dead zone is caused by an excess of fertilizers washing into the Mississippi watershed, where it feeds algae, which in turn uses up water's oxygen.
The major source of these fertilizers is agricultural runoff, although raw sewage overflow can also be a contributor. Globally, dead zones have grown in size since the 1960s. In 2008, a study from Louisiana State University fingered the rapid expansion of corn as the contributor to a then-record-breaking dead zone. Corn is a particularly fertilizer-intense crop. In the U.S., about a third of the corn crop is made into ethanol.
Biologist and science writer Kristopher Hite points out that the Energy Independence and Security Act of 2007, which requires the U.S. to produce 36 billion gallons of biofuels by 2022, is seemingly at odds with efforts to decrease the Gulf Coast dead zone. Hite first wrote about the issue in 2009, and today followed up with the most recent developments with the Environmental Protection Agency's action plan:
"If agriculture is going to keep escalating in order to meet world food demand AND keep up with the EISA mandate how can we hope to reign in the Dead Zone?
Nine environmental groups including the Natural Resources Defense Council, the Gulf Restoration Network, the Sierra Club and the Prairie Rivers Network have come together to force the EPA to set up run-off ground-rules. In a ruling handed down Friday September 20th, 2013, U.S. District Judge Jay Zainey in New Orleans gave the EPA six months to decide whether to set standards for nitrogen and phosphorous in U.S. waterways. If the EPA says no the judge has stipulated that they at least have to explain why such regulation is not needed."
A number of actions can be taken to reduce runoff, such as crop diversity and land management. While we wait for the EPA to take action, Hite suggests algae biofuels made from the blooms that lead to dead zones.