Cleaning Up the Mississippi River
LSU Boyd Professor tracks 100-year history
BATON ROUGE – LSU College of the Coast & Environment Boyd Professor R. Eugene Turner
reconstructed a 100-year record chronicling water quality trends in the lower Mississippi
River by compiling water quality data collected from 1901 to 2019 by federal and state
agencies as well as the New Orleans Sewerage and Water Board. The Mississippi River
is the largest river in North America with about 30 million people living within its
watershed. Turner focused on data that tracked the water’s acidity through pH levels
and concentrations of bacteria, oxygen, lead and sulphate in this study published in Ambio, a journal of the Royal Swedish Academy of Sciences.
Rivers have historically been used as disposal sites worldwide. From the polluted
Cuyahoga River in Cleveland, Ohio that caught fire to the Mississippi River where
sewage was dumped resulting in increases in lead and decreases in oxygen, rivers were
environmentally hazardous until the passage of the U.S. Clean Water Act in 1972. The
Clean Water Act as well as the Clean Air Act, the Toxic Substances Control Act and
others established a federal structure to reduce pollutant discharges into the environment
and gave the Environmental Protection Agency the authority to restrict the amounts
and uses of certain toxic chemicals such as lead. Turner’s study assesses changes
in water quality before and after the Clean Water Act and Clean Air Act went into
effect. The water quality data he compiled were collected from four locations on the
southern end of the Mississippi River at St. Francisville, Plaquemine, two locations
in New Orleans and at Belle Chasse, Louisiana.
His research found that after these environmental policies were put into place, bacterial
concentrations decreased by about 3 orders of magnitude, oxygen content increased,
lead concentrations decreased and sulphate concentrations declined less dramatically.
His research also found that as sulfur dioxide emissions peaked in 1965, the river’s
pH dropped to a low of 5.8. In the U.S., natural water falls between 6.5 and 8.5 with
7.0 being neutral. However, as sulfur dioxide emissions declined in 2019, the pH of
the river was restored to an average of 8.2.
“The promulgation and acceptance of the Clean Water Act and Clean Air Act demonstrates
how public policy can change for the better and help everyone who is demonstrably
‘downstream’ in a world of cycling pollutants,” Turner said.
Consistent vigilance and monitoring are necessary to ensure water quality in the Mississippi
River and northern Gulf of Mexico. Plastics fill oceans, pharmaceuticals are distributed
in sewage and COVID-19 virus and other viruses spread in partially treated sewerage
wastes from aging septic tanks, unconstrained wetland treatment systems with insufficient
hydrologic controls and overloaded treatment systems.
New pollutants are added to the river each year, which will require monitoring and
testing. Unfortunately, lead monitoring has stopped, but decades of sustained and
effective efforts at a national scale created water quality improvements and are an
example for addressing new and existing water quality challenges, Turner said.
Additional Link:
Declining bacteria, lead, and sulphate, and rising pH and oxygen in the lower Mississippi
River, Ambio: https://link.springer.com/article/10.1007/s13280-020-01499-2
Contact Alison Satake
LSU Media Relations
510-816-8161
asatake@lsu.edu