In July, the National Oceanic and Atmospheric Administration announced that the Gulf of Mexico's toxic "dead zone" measures 5,840 square miles this year—about the size of Connecticut. But many small wetlands placed far upstream can help solve this very large problem.
The dead zone is formed every summer by the huge amount of nutrient pollution flowing down the Mississippi River into the Gulf, which causes rampant algal growth. When the algae sinks to the seabed and decomposes, it creates hypoxic (low-oxygen) conditions toxic to marine life. Researchers from the Louisiana Universities Marine Consortium have been mapping the extent of this zone since 1985. While this year's dead zone is smaller than originally predicted, it's still above the long-term average and above the average size for the last five years.
This map shows the extent of the 2013 dead zone in the Gulf of Mexico, with red indicating the areas of lowest dissolved oxygen. Map by LUMCON (Rabalais).
A major source of the nutrient pollution triggering the dead zone is fertilizer runoff from agricultural fields—and of all the states in the Mississippi River Basin, Illinois is the single largest contributor of that agricultural runoff.
This fact is one of the drivers behind the Wetlands Initiative's work in the heavily agricultural Big Bureau Creek Watershed in north-central Illinois to demonstrate how farm-based wetlands can help address the dead zone. Wetlands naturally remove excess nutrients, producing cleaner water along with many other benefits for the environment and communities.
TWI's research and modeling have found that many precisely positioned small wetlands along streams and drainage ditches would have a significant impact on nutrient runoff without taking large amounts of farmland out of production. Ultimately, farmers could be paid for providing this service as part of a market-based "water quality trading" system. Farmers who install wetlands would generate nutrient removal credits, which would then be bought by wastewater treatment plants to meet regulatory requirements without having to make much costlier upgrades to their facilities.
TWI's senior environmental engineer, Dr. Jill Kostel, is currently leading a targeted outreach effort in the watershed to find farmers willing to install a "demonstration wetland" to show their peers how they work and to demonstrate the potential for such a market. Replicating these farm-based wetlands across the Midwest could go a long way to shrinking the dead zone.
Alliance Pipeline, McKnight Foundation, and Siragusa Foundation are the major funders of this critical new phase of the project. To learn more, view TWI's fact sheet about our Big Bureau Creek work here.