Earth Wise

A look at our changing environment.

You are here: Home / Archives for mississippi river

mississippi river

Mississippi River Running Dry | Earth Wise

By Leave a Comment

Water levels in the lower Mississippi River are running very low.  During September, the readings in Memphis, Tennessee were within inches of the all-time low.  The situation is causing real problems for the grain export industry.

The water levels of the lower Mississippi are determined by the amount of rainfall in the upper Midwest.  At the point where the Ohio and Mississippi Rivers come together, about 90% of the water headed for the lower Mississippi has been accumulated.

Almost 400 miles of the Mississippi have experienced water levels at or below critical levels for shipping.  During September, parts of the Mississippi have been closed to ship traffic more than 20 times.  At least 36 vessels were reported to have run aground.

The low water levels on the river have caused shippers of soybean and corn exports to lighten their loads to keep the vessels from running aground.  They have also reduced how many barges they pull at once in order to be able to navigate shipping channels that have narrowed because of the reduced water levels.

Fall is the busiest grain export season for the region.  About 60% of grain exports from the Midwest leave the U.S. through terminals on the Gulf Coast.  The low levels of the Mississippi River threaten gridlock for this vital industry.  It has caused freight costs to be the highest since historic river lows last year caused U.S. grain to be less competitive globally.

Unfortunately, October is not normally a strong precipitation month, but the hope is that the El Niño now underway may lead to increased precipitation in the Southern U.S.

**********

Web Links

Mississippi River Nears Historic Lows, Putting Grain Exports at Risk

Photo, posted March 8, 2023, courtesy of Errol Sandler via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Too Many Bison | Earth Wise

By Leave a Comment

In the northern part of Yellowstone National Park, an historically large bison herd is hampering the comeback of quaking aspen trees, whose numbers were greatly diminished by decades of over-browsing by elk.  Restoring the balance of ecosystems at Yellowstone is proving to be a complicated matter.

Long ago, the bison population in the Great Plains was as much as 30 million.  The population sharply decreased in the 1800s.  By the 1830s, there were no bison east of the Mississippi River.  Fifty years later, the Plains bison was nearly extinct.  Several small herds lived near Yellowstone Park when it was established in 1872, but poachers killed off nearly of them by the turn of the century.  Protective measures were taken and by 1925, Yellowstone’s Lamar Valley herd had grown to more than 750.  After that, occasional culling took place for over 40 years. 

When gray wolves and cougars were removed from the park, elk populations boomed, and the elk gradually decimated the growth of quaking aspen, cottonwood, willow, and berry-producing shrubs.  Both elk and bison were regularly culled until 1968 when public and congressional outcry intervened.

The return of wolves and cougars to the park made some progress in restoring ecosystem balance, particularly with respect to the elk population which has dropped from 20,000 to 5,000.  But bison numbers have grown to over 4,000 over past 20 years and the damage once caused by elk is now continuing from bison.

Park administrators are faced with complex management decisions about how to best preserve the ecosystems at Yellowstone National Park.

**********

Web Links

Bison in northern Yellowstone proving to be too much of a good thing

Photo, posted October 6, 2016, courtesy of Christian Collins via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

A Below-Average Dead Zone In The Gulf of Mexico | Earth Wise

By Leave a Comment

The Gulf of Mexico dead zone, or hypoxic area, is an area of low oxygen content that can kill fish and other marine life.  It occurs every summer and is mostly a result of excess nutrient pollution from human activities in cities and farms throughout the Mississippi River watershed.  The nutrients carried by the river into the gulf stimulate an overgrowth of algae, which eventually die and decompose, which depletes oxygen in the water as the algae sink to the bottom.

The resultant low oxygen levels near the bottom of the gulf cannot support most marine life.  Fish and shrimp often leave the area seeking better places to be.  Animals that can’t swim away – like mussels and crabs – can be stressed by the low oxygen level or even killed.

The National Oceanic and Atmospheric Administration produces a dead zone forecast each year based on a suite of models developed by NOAA and partners at multiple universities. 

The latest forecast, completed in May, found that the discharge of nutrients in the rivers was about one-third below the long-term average between 1980 and 2022.  Nitrate loads were down 42% and phosphorous levels down 5%.

Based on these measurements, the scientists forecast a summer dead zone that will cover an estimated 4,155 square miles, which is 22% lower than the 36-year average of 5,364 square miles.  Ongoing efforts by the Interagency Mississippi River and Gulf of Mexico Hypoxia Task Force to reduce nutrient levels seem to be paying off.

**********

Web Links

NOAA forecasts below-average summer ‘dead zone’ in Gulf of Mexico

Photo, posted September 6, 2013, courtesy of NOAA Photo Library via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The Gulf Of Mexico Dead Zone | Earth Wise

By Leave a Comment

Every summer, a so-called dead zone forms in the Gulf of Mexico.  It is primarily caused by excess nutrient pollution from human activities in urban and agricultural areas throughout the Mississippi River watershed. 

When these excess nutrients reach the Gulf, they stimulate excess growth of algae, which eventually die and decompose, depleting oxygen as they sink to the bottom.  These low oxygen levels near the Gulf bottom cannot support most marine life.  Animals that are sufficiently mobile – such as fish, shrimp, and crabs – generally swim out of the area.  Those that can’t move away are stressed or killed by the low oxygen.

A team of scientists funded by the National Oceanic and Atmospheric Administration issues an annual forecast for the dead zone based upon a suite of models that incorporate river flow and nutrient data. 

The 2021 forecasted area is somewhat smaller than, but close to, the five-year measured average for the dead zone, which is 5,400 square miles, roughly the size of the state of Connecticut.   Each year, these forecasts are reported as comparisons to long-term averages, but the problem is that the long-term average is unacceptable.

The Interagency Mississippi River and Gulf of Mexico Hypoxia Task Force has set a goal of reducing the size of the dead zone to a five-year average of 1,900 square miles – about a third of the current average.

Large reductions in nutrient loads have been called for in federal and state action plans for nearly 20 years, but clearly these reductions have not yet been sufficient. The Interagency Task Force continues to provide information for managing nutrient loads in the Mississippi River Basin. 

**********

Web Links

Average-sized ‘dead zone’ forecast for Gulf of Mexico

Photo, posted October 6, 2020, courtesy of Christine Warner via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Forecasting A Massive Dead Zone

By Leave a Comment

The Gulf of Mexico dead zone occurs every summer, and is considered one of the largest dead zones in the world.  This cyclical event occurs where the Mississippi River empties into the Gulf of Mexico, just off the coast of Louisiana and Texas. 

This annual dead zone is primarily caused by excess nutrient pollution from human activities, such as urbanization and agriculture, occurring throughout the Mississippi River watershed.  Washed off the land by spring rains, these excess nutrients stimulate an overgrowth of algae once they reach the Gulf of Mexico.  The algae in the Gulf eventually die, and then sink and decompose in the water. The resulting area of the ocean ends up with a condition known as hypoxia, which is an insufficient amount of oxygen to support most marine life.  In hypoxic or dead zones, animals that can’t swim away will often suffocate and die. 

Scientists from the National Oceanic and Atmospheric Administration estimate that this year the dead zone in the Gulf of Mexico will be approximately 8,000 square miles, which is roughly the size of Massachusetts.  The research team uses U.S. Geological Survey river flow and nutrient data to make its forecast. 

According to NOAA, the abnormally high amount of spring rainfall is a major factor contributing to this year’s dead zone.  Last month, nitrate loads entering the Mississippi River watershed were 18% above the long-term average, and phosphorus loads were about 49% above the long-term average. 

While the 2019 forecast is slightly less than the record size of more than 8,700 square miles set in 2017, it’s still much larger than the five year average size of 5,700. 

**********

Web Links

Very large dead zone forecast for the Gulf of Mexico

Massive 8,000-mile ‘dead zone’ could be one of the gulf’s largest

Photo, posted May 22, 2009, courtesy of Michael McCarthy via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

WAMC Northeast Public Radio

WAMC/Northeast Public Radio is a regional public radio network serving parts of seven northeastern states (more...)