The Gulf of America hypoxia zone was measured at approximately 4,402 miles last week, 21% smaller than estimates from early June and the 15th smallest measurement on record, according to the National Oceanic and Atmospheric Administration (NOAA). The hypoxia zone, also known as the “dead zone,” is an area of low to no oxygen that can kill fish and marine life. 

This year’s zone is 30% smaller than last year, which officials say is an encouraging sign and a testament to the effectiveness of collaborative efforts supporting marine ecosystems. 

The annual measurement informs the work of the Mississippi River/Gulf of America Hypoxia Task Force, which has a long-term goal of reducing the five-year average dead zone area to fewer than 1,900 square miles by 2035. In June, NOAA predicted a dead zone size of 5,574 square miles, based on Mississippi River discharge and nutrient runoff data from the U.S. Geological Survey.