Gulf Of Mexico

A barge sits in Missouri on the Mississippi River before it heads downstream to the Gulf of Mexico.
File: Abbie Fentress Swanson / Harvest Public Media

Chemical runoff from Midwest farm fields is contributing to the largest so-called ‘dead zone’ on record in the Gulf of Mexico.

Scientists have mapped the size of the oxygen-deprived region in the Gulf since 1985. This year’s is estimated at more than 8,700 square miles, which is about the size of New Jersey.

The amount and timing of rainfall contribute to the washing of chemicals from farm fields throughout the watershed into the Mississippi River and down to the Gulf.