NOAA expects very large 'dead zone' in Gulf of Mexico

By: Tyler Sebree

Posted: Jun 11, 2019 8:52 PM EDT

The latest forecast for this year's Gulf of Mexico 'dead zone' has been issued by the National Oceanic and Atmospheric Administration. According to the press release, scientists are forecasting this summer’s Gulf of Mexico ‘dead zone’ to be approximately 7,829 square miles in size, which isn't far from the record size of 8,776 square miles. That record was achieved just two years ago in 2017.

A general illustration of how runoff from both farms and cities drain into the Mississippi River before entering the Gulf of Mexico. That runoff fuels the yearly hypoxic zone ('dead zone'). NOAA

But what is this so-called 'dead zone'? Also referred to as the Gulf of Mexico's hypoxic zone, the 'dead zone' is the area in the Gulf of Mexico that forms as a result of excess nutrient pollution from human activities like urbanization and agriculture entering the Mississippi River watershed, and eventually the Gulf of Mexico.

Once in the Gulf of Mexico, the nutrients cause an overgrowth of algae. According to NOAA, these algae "eventually die, then sink and decompose in the water. The resulting low oxygen levels near the bottom [of the Gulf] are insufficient to support most marine life and have long-term impacts."

This so-called 'dead zone' occurs annually, but varies in size and exact location. This year's prediction of 7,829 square miles is well above the 5-year average of 5,770 square miles. NOAA says the reasoning behind the forecast is the excessive amount of spring rainfall that fell in and near the Mississippi River watershed.