I have studied the “dead zone” in the Gulf of Mexico.This page focuses on what it is, its history, the causes and what conditions contribute to the situation, how it affects our lives and the lives of animals, and how we can possibly rectify the situation.
Agriculture is one of the most important parts of the US economy. In order for the land to produce what we have come to expect it to produce requires constant monitoring and testing, as well as the use of fertilizers to stimulate and encourage plant growth. These fertilizers are used in large quantities over many thousands of acres in the Mississippi Valley. Rain causes the fertilizers to be flushed down the Mississippi River and be dumped into the Gulf of Mexico. 
This Nitrogen-rich fertilizer is one of the main causes of the dead zone in the Gulf.
The dead zone is a region of oxygen-deprived water located where the Mississippi River dumps its water into the Gulf.
Gulf of Mexico Dead Zone