Study estimates cost of reducing Gulf “dead zone”

A group of national researchers, including Todd Campbell, Philip Gassman, Adriana Valcu, and Catherine Kling from the Center for Agricultural and Rural Development, as well as others from across the country, has quantified the cost of reducing the Gulf of Mexico hypoxic “dead” zone, an area of low oxygen that can’t support marine life. To meet the national policy goal of reducing the hypoxic zone to 5,000 km2, a goal set by the national Gulf of Mexico Task Force, the US would need to invest about $2.7 billion annually, researchers found. The research is detailed in an article published in the Proceedings of the National Academy of Sciences, available at

The cost of reducing the hypoxic zone was achieved by studying more than 550 agricultural subwatersheds that generate nutrient runoff from agricultural practices into the gulf. The study allowed researchers to determine which subwatersheds would be the most cost-effective to target for conservation investments and determine the actual cost of making the investments.

Currently the hypoxic zone is about 15,000 km2, and can vary in size from year to year. “The size of the zone has varied significantly over the last 20 years, but it has largely been on a steady or upward trend,” said Catherine Kling. “Weather has a large influence on the annual size—drought years create smaller zones and heavy rainfall years produce larger zones as nutrients are carried by the watersheds into the gulf.”

Kling, an environmental economist, has been studying the Gulf of Mexico hypoxic zone for several years. “I was first struck by how small actions in thousands of agricultural fields could collectively contribute to such a large problem area,” she said. “The more I learned the more I realized that this is the end result of a problem affecting streams, rivers, and lakes throughout the Midwest, and that the tools of my trade could help frame some of the issues for policymakers and the general public.”

While the researchers were able to put the $2.7 billion annual price tag on achieving the action plan goal, the study didn’t look into where that money would come from. “There are a number of policies that could be implemented to achieve the reduction in the hypoxic zone. If the policies subsidize conservation practices, then the cost is largely borne by taxpayers. If, on the other hand, the policies require a change in farming practices without compensation, then the cost is initially covered by farmers, but could be passed on through higher food and fuel prices,” Kling said. The cost of the reduction, Kling said, is scalable—the same policies could be implemented on a smaller scale for less money, but with a smaller reduction in the hypoxic zone. “This is an important decision for society to make, and we hope our work will help people consider the tradeoffs between cost and the environment,” Kling said. Lastly, Kling said, the any changes in policy that affect the hypoxic zone will happen over the course of many years. “Realistically, change is not likely to occur very quickly—if it takes decades for land-use change to occur, it will take that long for significant changes in the hypoxic zone,” she said.

(Released January 2015)