This year's Gulf of Mexico dead zone could be one of the biggest ever, NOAA says

A summertime Gulf of Mexico dead zone fueled by pollution flowing out of the Mississippi River watershed could be among the largest on record this year.

In a seasonal forecast issued this week, the National Oceanic and Atmospheric Administration said heavy spring rain over the watershed, which drains 37 states - or about 41 percent of the U.S. - was expected to flush large amounts of nitrogen and phosphorus into the northern Gulf. That could create a dead zone covering more than 7,800 square miles.

It's too early to tell what influence the zone might have on seasonal red tides that form off the Florida shelf. Following a 2017 record-setting dead zone, a toxic red tide started in October that lasted for more than a year, littering southwest Florida beaches with dead marine life and eventually sweeping up the Atlantic coast.

"This is an atypical year given the really high discharges, so it would be something to keep an eye on," said NOAA oceanographer David Schuerer.