Scientists are predicting a "dead zone" near the Gulf of Mexico, where water contains little oxygen to sustain marine life.
"An important contributing factor to the large dead zone this year is the abnormally high amount of spring rains in many parts of the Mississippi River basin," the National Oceanic and Atmospheric Administration said in a statement Monday. This has led to record quantities of water carrying large amounts of fertilizer and other nutrients downstream, he said.
Nutrients feed algae, which die and decompose on the seabed, using oxygen from the bottom up in an area along the coasts of Louisiana and Texas.
The area of low oxygen or hypoxia will likely cover about 20,200 square kilometers – roughly the size of Slovenia or the entire land in Massachusetts, NOAA said. A Louisiana team estimated that the dead zone would be 22,560 square kilometers.
It will be measured during an annual July cruise by Nancy Rabalais of the Louisiana Universities Marine Consortium.
The record set in 2017 is 8,776 square miles (22,700 square kilometers).
Scientists have previously said that widespread flooding has made likely a large dead zone this year.
A federal, tribal and state agency task force from 12 of the 31 states that make up the Mississippi River Basin has set a goal for nearly two decades to reduce the dead zone from an average of about 15,000 square miles to an average of 1,900 4,900).
"Although this year's area is larger than normal due to flooding, the long-term trend is still not changing," said Don Scavia, a University of Michigan aquatic ecologist, Emeritus Professor at the School of Environment and Sustainability. "What is important is that we will never achieve the 1,900 square mile dead zone reduction goal until more serious action is taken to reduce the loss of West Midwest fertilizer in the Mississippi River system."
Rabalais has measured the hypoxic zone since 1985.
Storms prior to the last year's mapping cruise have reduced this hypoxic zone to about 7,040 square kilometers, about 40 percent of the average size predicted and among the lowest recorded.
This story clarifies that the NOAA forecast is an area roughly the size of the land in Massachusetts and removes the incorrect reference to the size of Turkey.