Average Gulf of Mexico 'Dead Zone' Predicted This Summer
NEW ORLEANS (AP) — Federal scientists expect an average oxygen-starved "dead zone" off Louisiana's coast this summer, an area of nearly 5,500 square miles, or about the size of Connecticut.
The National Oceanic and Atmospheric Administration said that for the first time, it's combining four models to make its predictions. Those estimates range from 4,344 to 5,985 square miles. Previously, forecasts were released separately.
"The dead zone in the Gulf of Mexico affects nationally important commercial and recreational fisheries and threatens the region's economy," the statement said.
Scientists say the area is created because the Mississippi River carries nutrients from farm runoff, sewage and other sources into the Gulf. They feed algae blooms, which feed microscopic animals. Algae and animals die, fall and decompose, using oxygen from the bottom up.
The forecast is based on nutrient runoff and river stream data from the United States Geological Survey, which operates more than 3,000 stream gauges, 50 real-time nitrate sensors, and collects water quality data at long-term stations throughout the Mississippi River basin to track how nutrient loads are changing over time.
The Geological Survey estimates that 104,000 metric tons of nitrate and 19,300 metric tons of phosphorus flowed down the Mississippi and Atchafalaya rivers into the Gulf of Mexico in May. This is about 21 percent below the 1980-2014 average for nitrogen, and 16 percent above the long-term average for phosphorus.
"The size of the annual Gulf of Mexico dead zone varies from year to year in response to changing weather patterns, primarily in the Corn Belt," said University of Michigan aquatic ecologist Don Scavia, director of the Graham Sustainability Institute and one of the scientists who worked on the forecasts. "But the bottom line is that we will never reach the action plan's goal of 1,950 square miles until more serious actions are taken to reduce the loss of Midwest fertilizers into the Mississippi River system, regardless of the weather."
A lawsuit asking for federal limits on those nutrients is before U.S. District Judge Jay Zainey in New Orleans. He ordered the Environmental Protection Agency in 2013 to set limits on phosphorus and nitrogen in U.S. waterways, but the 5th U.S. Circuit Court of Appeals asked him to take another look at the case.
The 5th Circuit said Zainey was wrong to rule that the EPA could not simply decide against studying whether to set the standards for all U.S. waterways. The judges ordered Zainey to decide whether the EPA gave adequate reasons, based on the Clean Water Act, for its original refusal to do so.
The four dead zone forecast models used were developed by NOAA-sponsored teams and researchers at the University of Michigan, Louisiana State University, Louisiana Universities Marine Consortium, Virginia Institute of Marine Sciences/College of William and Mary, Texas A&M University, North Carolina State University and the Geological Survey.
"NOAA, along with our partners, continues to improve our capability to generate environmental data that can help mitigate and manage this threat to Gulf fisheries and economies," said NOAA administrator Kathryn D. Sullivan. "We are adding models to increase the accuracy of our dead zone forecast."