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One situation occurs every summer off the coast of Louisiana. It’s known as the “Dead Zone.” This scientific term is a hypoxia zone, an area depleted of dissolved oxygen which suffocates marine life.

“The hypoxic zone off the Mississippi can reach to about 7,000 square miles in size each year and it can have a direct effect on Texas, but we also have hypoxic zones that have formed off of Galveston, off of Corpus and in different bay systems because of the same thing and that is too many nutrients,” Dr. Larry McKinney, executive director of the Harte Research Institute, said.

These nutrients come from a variety of sources. One is fertilizer routinely applied to crops.

When rain falls, excess fertilizer washes off the fields and drains into the surrounding watershed. Cities and towns contribute their share, especially from fertilized suburban lawns. As the river approaches the coast, it is charged with the combined nutrient load from the human activity upstream.

“Basically it’s like a garden hose," McKinney said. "It just sprays those nutrients out right in near shore waters. And when the conditions are right, during the summer, you get these tremendous algal blooms and they begin the process of dying off, decomposing and using up the oxygen and creating these hypoxic zones. Of course, these creatures can’t really get away very easily.”

Forty-one percent of the continental United States eventually drains into the main body of the Mississippi River. Twelve million people also live in urban areas throughout the drainage area. Most of this land is the heart of America’s agriculture industry.

The channel of the Mississippi has been lined with levees to control flooding. These levees keep water and the nutrients flowing straight into the Gulf. Each summer, the hypoxia zone off the Mississippi River is bigger than the summer before.

“If that zone continues to expand as it seems to be doing, it doesn’t expand like a balloon, it expands toward Texas, and so imagine if you would, the entire upper Texas coast from Galveston to Sabine Pass having water with no oxygen in it for all of the summer," McKinney said. "That’s a real possibility. That’s why we all have a stake in what happens in this country in the Midwest and so forth to try to deal with that nutrient over-enrichment.”

You can watch the entire hour of “The State of the Gulf-America’s Sea” online through streaming video at TexasTheStateOfWater.org as well as read the latest Texas Parks and Wildlife magazine focused on the drought, titled “Every Drop Counts.”