Summer is for grilling, swimming, and estimating the size of the Gulf of Mexico Dead Zone.
Last year, it was the size of Connecticut. In 2017, it set a record at the size of New Jersey. This year, scientists believe the polluted Mississippi River will create a Dead Zone the size of Massachussetts.
The Mississippi River's watershed drains more than 1.2 million square miles, including all or parts of 31 U.S. States and two Candadian provinces. There, cities and farms dump all kinds of pollutants — think sewage, pesticides, and industrial waste — into the river. It was made worse this year with heavy spring rains and high river flows.
- U.S. Geological Survey
- The Mississippi River watershed is more than 1.2 million square miles.
All of those pollutants flow into the Gulf of Mexico. When they get there, algae gobble up nutrients from the waste, expand, eventually die, sink, and decompose in the water. This process sucks much of the oxygen from the water, enough to kill most marine life there.
This Dead Zone this year is forecast to swallow 7,829 square miles of the Gulf, according to scientists with the U.S. Geological Survey (USGS). That agency operates more than 3,000 real-time stream gauges, 50 real-time nitrate sensors, and 35 long-term monitoring sites throughout the Mississippi-Atchafalaya watershed.
"Long-term monitoring of the country's streams and rivers by the USGS has shown that while nitrogen loading into some other coastal estuaries has been decreasing, that is not the case in the Gulf of Mexico," said Don Cline, associate director for the USGS Water Resources Mission Area.
The effects of the Dead Zone are real, experts say. It can consume about a quarter of the environment for brown shrimp, driving up seafood costs. Cities that use the river as a drinking-water source have to pay more to filter the water. Toxic algae blooms have killed dogs, birds, fish, and made humans ill. On-river marinas and boat dealers have closed.
The Environmental Protection Agency (EPA) formed a task force to combat the issue in 1997. In 2001, an action plan sought to curtail nutrients in the river to identify heavy polluters and tighten up state and federal laws on runoff.
The task force's goal is to curtail the zone's size to about 1,930 square miles by 2035, getting at least 20 percent of the way there by 2025. But in its 2017 report to Congress, the task force reported nutrient levels well above its target range.
Last year, mayors with the Mississippi River Cities and Towns Initiative signed an agreement with the feds for a water quality program to detect nutrients in about 75 percent of the river's main stem. With it, water-quality monitors will be deployed on barges from St. Paul to New Orleans and report in real time.
"This added security feature for our source water is paramount to sustaining our freshwater economy of $300 billion in annual revenue," said Baton Rouge Mayor Sharon Weston. "It will also be able to tell us if the hundreds of millions of dollars going into conservation work to reduce nutrient loading is actually making a difference."