The dead zone in the Gulf of Mexico, which is believed to have been around since the 1970’s, is now an estimated 6,474 square miles of water unable to support marine life.
Government and independent scientists believe nutrient runoff is the main cause of the dead zone. Pollutants such as nitrogen and phosphorus flow into the gulf of Mexico by way of the Mississippi River and its tributaries.
For many, the ethanol industry and the government’s 2005 Renewable Fuel Standard carry a lot of the blame. Since the governments introduction of the Renewable Fuel Standard in 2005, acreage of U.S. land to farm corn and soy beans has grown by 16.8 million and over 1.2 million acres of grassland has been lost.
Flooding in 2015 and earlier this year washed away tremendous amounts of pollutants that had accumulated on land during the prolonged drought. The sources of much of these nutrients were cornfields, 40% of which are dedicated to producing ethanol, which fuel companies are compelled by Congress to blend with gasoline.
NOAA officials estimate the Dead Zone costs the nation’s seafood and tourism industries $82 million a year. And it likely will get worse, scientists believe. The gulf produces about 40 percent of the nation’s seafood, which includes offshore species such as shrimp and red snapper. And Louisiana is second in seafood production to Alaska, according to The Nature Conservancy.
An estimated 9 to 10 percent of Wisconsin wells have tested over safe limits for nitrate.
Studies have estimated that 90% of nitrate in groundwater comes from spreading of synthetic fertilizers and dairy manure on farm fields, with most of the remainder from septic systems.
Nitrate behaves differently. Relatively little lingers near roots where it can be absorbed. Water washes it down into shallow groundwater that is the source of drinking water for one-quarter of Wisconsin residents.
Legumes and alfalfa, take up nitrogen before it can reach groundwater, but are not as profitable as corn. When prices rise for corn, which requires heavy applications of nitrogen-based fertilizer, farmers quickly convert acreage and boost spreading. Wisconsin farmers applied over 200 million pounds of nitrogen in excess of UW-Extension recommendations.
Not only does the fertilizer create toxic drinking water, but the phosphorus in fertilizer and manure contributes to abnormal algae growth in lakes and streams when it runs off the land with rain and snowmelt.
Drinking water contaminated with more than 10 milligrams per liter of nitrate poses acute risks to infants and women who are pregnant, a possible risk to fetuses in early stages of pregnancy, and a longer-term risk of serious disease in adults.