Mississippi's Water Pollution: What's The Main Culprit?

The Mississippi River, the second-longest river in the United States, has faced significant water pollution, largely due to human activities along its course and within its watershed. The river, which serves as a critical drainage basin for over 40% of the country, has been a site for extensive commercial use since the 19th century, with engineering projects aimed at enhancing navigability and preventing flooding, severely degrading its ecosystems. The introduction of pollutants from industrial activities, agricultural runoff, and waste disposal has led to a decline in water quality and the loss of biodiversity along its banks. While legislative efforts and environmental initiatives have improved water quality in certain areas, challenges such as nonpoint source pollution and habitat loss persist, requiring continued attention from environmental advocates and policymakers.

Commercial use and engineering projects

The river has been home to thousands of life forms, including several endangered species, hundreds of species of birds and mammals, and the largest wetlands area and hardwood forest in the US. However, engineering projects aimed at enhancing navigability and preventing flooding have severely degraded these ecosystems.

The US Army Corps of Engineers has been undertaking projects to optimize the river's value for commerce since 1879. After a disastrous flood in 1927, they constructed a series of 27 locks and dams to create a continuous nine-foot shipping lane from Minneapolis to St. Louis, Missouri, facilitating barge traffic. While these projects improved navigability, they altered the river's natural movement of sediment, leading to sedimentation, which is one of the river's most serious problems.

Sedimentation fills in the main pools and backwaters of the river with silt and sand particles, destroying important habitats for fish and wildlife and covering up spawning grounds. This sediment also transports pollutants like PCBs, heavy metals, and phosphorus, which can lead to problems with algae blooms. The Upper Mississippi River is particularly vulnerable to sedimentation due to its vast drainage area and the altered natural movement of sediment caused by the lock and dam system.

In addition to engineering projects, commercial enterprises such as agriculture and industrial activities have directly introduced pollutants into the river, further degrading water quality and leading to the disappearance of various species. The construction of levees and dams has also altered natural flood patterns, creating areas of hypoxia or "dead zones" at the river's mouth.

Industrial activities and agricultural runoff

The Mississippi River and its tributaries carry excessively high levels of nutrients, leading to a biological dead zone at the river mouth in the Gulf of Mexico. This dead zone, also known as hypoxia, has very low oxygen levels in the water. The hypoxic zone in the Gulf of Mexico forms annually due to excess nutrients from the Mississippi River and the seasonal stratification of the waters in the Gulf.

Industrial Activities

Industrial waste discharges are a significant contributor to water pollution in the Mississippi River. Various human activities, including navigation, dredging, construction, wetland development, and increased recreational use, negatively impact the river's water quality.

Agricultural Runoff

Agricultural practices are a leading cause of water pollution in the United States, and the Mississippi River is no exception. Agricultural runoff from farms carries excess nutrients, such as fertilizers and animal waste, into the river system, contributing to eutrophication and hypoxia. Corn (maize), the number one crop in the United States, is sensitive to nutrient-poor soil, leading to over-fertilization by farmers to ensure high crop yields. This excess fertilizer, along with animal waste, is carried into the Mississippi River and its tributaries by rainfall or snowmelt, a process known as runoff.

Nitrogen and phosphorus are the most common agricultural pollutants found in the public waters of the Mississippi River Basin. These chemicals contribute to harmful algae growth, fish kills, and animal deaths. They also play a significant role in the formation of the Dead Zone in the Gulf of Mexico, an area devoid of life that forms each summer due to low oxygen levels.

The MRC Agriculture Group works to reduce nitrogen and phosphorus pollution in the Basin's rivers, lakes, and streams. They provide recommendations for cropland and livestock operations to reduce nutrient pollution and develop science-based policies to protect the Mississippi River basin watersheds from agricultural pollution.

Sedimentation and silt

Sedimentation has also helped to bury some of the pollutants that once flowed downstream from the Twin Cities Metropolitan area. These contaminated sediments settled in Lake Pepin and were covered by silt carried by the river, improving the water quality downstream. The Mississippi River Delta was formed over the last 7,000 years as the river deposited sediment at the mouth of the river, along what is now Louisiana's coastline. When enough sediment accumulates underwater, plant communities begin to thrive and develop, encouraging new sediment to accumulate until new land is formed.

However, the leveeing of the Mississippi River disrupted this natural cycle, and now most of the sediment bypasses the marshes that need it. Louisiana's land loss crisis is due to several factors, but the leveeing of the river is a significant contributor. The river's reduced sediment load has impacted the ability to restore the Mississippi River Delta and Louisiana's coast. To restore and maintain the health of the delta and coastline, it is crucial to treat sediment as a precious resource and maximize its capture for coastal restoration.

The Upper Mississippi River is particularly vulnerable to sedimentation because it drains a vast land area, and the lock and dam system has altered the river's natural movement of sediment. The sand that accumulates in the main channel of the river also contributes to the high cost of dredging required to maintain the navigation channel. While sedimentation and silt have negative impacts on the river, they also provide benefits to certain habitats. Shorebirds, for instance, heavily utilize sandbars and mudflats created through sedimentation.

Water quality and human impact

Water quality in the Mississippi River is a significant environmental issue. The river is an essential source of drinking water for nearly a quarter of the United States, and it is also vital for inland commerce. However, human activities have severely impacted the river's water quality and the surrounding ecosystems.

The Mississippi River has been heavily used for commercial purposes since the 19th century. Engineering projects aimed at improving navigability and preventing floods have altered the river's natural flow and caused severe ecological degradation. The construction of levees and dams has disrupted natural flood patterns, creating areas of hypoxia (dead zones) at the river mouth in the Gulf of Mexico. This hypoxia is caused by the excess nutrients, such as phosphorus, carried by the river, and the layering of freshwater and saltwater in the Gulf.

Industrial activities, agricultural runoff, and waste disposal have introduced pollutants into the river, leading to a decline in water quality and a loss of biodiversity. These pollutants include toxic chemicals, heavy metals, and PCBs, which can accumulate in the food chain and negatively impact both aquatic life and human health. Sedimentation, the filling of the river and its backwaters with silt and sand, is another serious problem. While sedimentation can create valuable habitats for shorebirds, it can also bury important fish spawning grounds and transport pollutants downstream.

Despite these challenges, there have been improvements in water quality over the last few decades. Legislative changes, such as the Clean Water Act, and the efforts of organisations like the MWMO, have helped reduce certain types of pollutants. However, some pollutants persist, and new threats continue to emerge. The Mississippi River's health remains a critical concern, requiring ongoing efforts to balance economic interests with ecological preservation.

Policy changes and environmental initiatives

The Mississippi River, the second-longest river in the United States, has faced significant environmental issues due to its extensive use for commercial purposes since the 19th century. Engineering projects aimed at improving navigability and flood control have led to severe ecological degradation, altered natural flood patterns, and created areas of hypoxia or "dead zones". These challenges have resulted from the introduction of pollutants from industrial activities, agricultural runoff, and waste disposal, causing a decline in water quality and biodiversity.

To address these issues, various policy changes and environmental initiatives have been implemented or proposed:

• Clean Water Act: The Clean Water Act is a piece of legislation aimed at protecting natural resources and improving water quality. This act was passed due to increased awareness of the negative impacts of pollution on humans and the environment.
• Mississippi River Cities and Towns Initiative (MRCTI): Under MRCTI, mayors of the Mississippi River are partnering with the United Nations Environment Programme (UNEP) and the University of Georgia to combat plastic pollution. Thousands of community volunteers are collecting data on plastic pollution through a "'citizen science' approach" using the Debris Tracker mobile app. This initiative kicked off in April 2021 in Baton Rouge, St. Louis, and St. Paul, and has since expanded to other cities.
• Driftless Area Conservation Initiative (DALCI) 2.0: The Driftless Area, a 22,000-acre region in the Upper Mississippi River Basin, is vulnerable to climate change and invasive species. DALCI 2.0 aims to support regenerative agriculture, improve conservation infrastructure, expand outdoor recreation, reduce nutrient runoff from agricultural land, and enhance climate resilience.
• Great Lakes Restoration Initiative (GLRI): The successful GLRI served as a model for providing federal funding to states along the Mississippi River to address environmental concerns. This funding operates within the Environmental Protection Agency.
• Environmental Law & Policy Center (ELPC): ELPC is working to clean up old pollution, plan resilient infrastructure, and create jobs in the green economy. They advocate for increased funding for initiatives like DALCI 2.0 and support the transition to regenerative agriculture and conservation.

These initiatives demonstrate a commitment to improving the health of the Mississippi River and balancing economic interests with ecological preservation. By involving communities, policymakers, and organizations, these efforts aim to protect the river's water quality, biodiversity, and economic significance for the Midwest region.

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