Food and the Future Environment

Managing Runoff to Reduce the Dead Zone


Managing Runoff to Reduce the Dead Zone

What can be done to reduce the size of the dead zone?

The dead zone in the Gulf of Mexico is primarily a result of runoff of nutrients from fertilizers and manure applied to agricultural land in the Mississippi River basin. Runoff from farms carries nutrients with the water as it drains to the Mississippi River, which ultimately flows to the Gulf of Mexico. If a number of nutrients reaching the Gulf of Mexico can be reduced, then the dead zone will begin the shrink.

Since 2008, the Hypoxia Task Force, led by the U.S. Environmental Protection Agency and consisting of five federal agencies and 12 states, has been working to implement policies and regulations with the aim of reducing the size of the dead zone in the Gulf of Mexico. Many of the strategies for reducing nutrient loading target agricultural practices including (USEPA, The Sources and Solutions: Agriculture).

  • Nutrient management: The application of fertilizers can vary in amount, timing, and method with varying impacts on water quality. Better management of nutrient application can reduce nutrient runoff to streams.
  • Cover Crops: Planting of certain grasses, grains, or clovers, called cover crops can recycle excess nutrients and reduce soil erosion, keeping nutrients out of surface waterways.
  • Buffers: Planting trees, shrubs, and grass around fields, especially those that border water bodies, can help by absorbing or filtering out nutrients before they reach a water body.
  • Conservation tillage: Reducing how often fields are tilled reduces erosion and soil compaction, builds soil organic matter, and reduces runoff.
  • Managing livestock waste: Keeping animals and their waste out of streams, rivers, and lakes keep nitrogen and phosphorus out of the water and restores stream banks.
  • Drainage water management: Reducing nutrient loadings that drain from agricultural fields helps prevent degradation of the water in local streams and lakes.

Watch the following video from the US Department of Agriculture about strategies to reduce nutrient loading into the Mississippi River:

Video: Preventing Runoff Into The Mississippi River (1:44)

Click for a transcript of the Preventing Runoff into the Mississippi River.
A US Department of Agriculture initiative is helping Missouri farmers keep farm field runoff from reaching the Mississippi River. USDA's Natural Resources Conservation Service is working with producers through the Mississippi River Basin healthy watersheds initiative, or MRBI. The focus of the MRBI project is to hopefully cut down on sediment, nutrients, and pesticides that are moving down the Mississippi River to the Gulf of Mexico. USDA NRCS and initiative partners are working with farmers to determine which conservation practices and which conservation systems work best on their farms to keep runoff from reaching the Mississippi. What we're trying to do is identify what conservation practices will have the biggest impact in the reduction of nutrient transport to the Mississippi River, which eventually makes it to the Gulf of Mexico. One such conservation practice is terracing. By building the terraces it controls erosion, which then reduce the sediment. By reducing sediment we're also going to be reducing the hypoxia issue in the Gulf. We wanted to then monitor what effects we could have on reductions by putting out monitoring stations, such as this one so we could be able to determine that what benefits we were having with the cost share dollars we were putting on the land. Landowners interested in learning more about how to protect their soil and reduce runoff should contact their local NRCS office. I'm Bob Ellison for the US Department of Agriculture.

EPA website about nutrient pollution and some solutions to nutrient pollution: The Sources and Solutions: Agriculture

Activate Your Learning

Review the graphs below and answer the questions that follow. Figure 4.2.11 presents the size of the hypoxic zone in the Gulf of Mexico from 1985 to 2014. The U.S. Environmental Production Agency led a task force in 2008 that identified a goal to reduce the five-year average of the size of the dead zone to less than 2,000 square miles by 2015.

Graph of size of the Gulf of Mexico hypoxic zone in mid-summer.
Figure 4.2.11. Size of the Gulf of Mexico hypoxic zone in mid-summer.
Credit: Data source: Nancy N. Rabalais, LUMCON, and R. Eugene Turner, LSU. Funding sources: NOAA Center for Sponsored Coastal Ocean Research and U.S. EPA Gulf of Mexico Program. From Gulf of Mexico Ecosystems & Hypoxia Assessment (NGOMEX).
Graph of Annual Total Nitrogen loads to the Gulf of Mexico
Figure 4.2.12. Annual Total Nitrogen loads to the Gulf of Mexico
graph of annual total phosphorus loads to the Gulf of Mexico
Figure 4.2.13. Annual total phosphorus loads to the Gulf of Mexico