Flint River Pollution: Understanding The Science Behind It

The Flint River has been the site of a public health crisis, prompting a federal state of emergency declaration by President Obama. The water crisis in Flint, Michigan, began on April 25, 2014, when the city switched its drinking water supply from Detroit’s system to the Flint River to save costs. The river has been an unofficial waste disposal site for decades, receiving industrial and human waste, agricultural and urban runoff, and toxins from landfills. This has resulted in high levels of bacteria and organic matter, as well as a wide range of other contaminants, in the water. Inadequate treatment and testing of the water resulted in major water quality and health issues for Flint residents, including skin rashes, hair loss, and itchy skin. Studies have also shown a link between elevated blood lead levels in children and the use of the Flint River as a water source.

Industrial dumping

The Flint River has been used as an unofficial waste disposal site for over a century. Various local industries, including carriage and car factories, meatpacking plants, and paper mills, have dumped treated and untreated refuse into the river. This includes sewage, chemicals, and road salt.

In addition to direct industrial dumping, there have been several significant pollution events caused by accidental dumping into the river. In 1999, a subcontractor digging near the Flint River accidentally opened a gash in an unmarked pipe, causing untreated water to flow directly into the river. In another instance, a furniture salesman was convicted of dumping drums of chemicals onto his property along the riverbank.

The automotive industry, particularly General Motors, has played a significant role in polluting the Flint River. At its peak in the early 1980s, the company employed 80,000 workers in factories along the river. The company's operations and those of its suppliers resulted in the pollution of the river with lead and other toxic chemicals.

While environmental regulations have prevented direct dumping into the river, illegal and accidental dumping have been common. The river's history of pollution, including industrial dumping, has contributed to its reputation as an exceptionally polluted water source.

Agricultural runoff

The Flint River has long been used as an unofficial waste disposal site for local industries, agricultural and urban runoff, and toxic landfill leaching. The river has been polluted by agricultural fields, construction sites, parking lots, roads, and septic seepage. This nonpoint source pollution (pollution that cannot be traced to a specific source) is the most significant factor in the degradation of water quality in the Flint River watershed.

The heavy use of fertilizers in rural areas upstream of the city has also polluted the river. A 1975 EPA study of the Holloway Reservoir upstream showed that phosphates from fertilizers and detergents had stimulated algae growth. As a result, the water's oxygen levels collapsed, turning it cloudy and brown.

The Flint River has also received untreated waste from local industries, including carriage and car factories, meatpacking plants, and lumber and paper mills. This has further contributed to the high levels of bacteria and organic matter in the river, as well as introducing a wide range of other potential contaminants, whether natural or human-made.

Untreated waste

The pollution of the Flint River in Michigan has been ongoing for over a century. The river has served as an unofficial waste disposal site for both treated and untreated refuse from local industries, including factories, meatpacking plants, and paper mills.

The river has also been contaminated by untreated waste that has been intentionally or accidentally dumped into it. This includes raw sewage from the city's waste treatment plant, as well as agricultural and urban runoff, and toxins from leaching landfills. In 1999, a subcontractor accidentally diverted 22 million gallons of raw human, industrial, residential, and commercial waste into the river, resulting in a swimming and fishing ban that lasted 14 months.

The heavy use of fertilizers in rural areas upstream has also contributed to the pollution of the river. A 1975 EPA study showed that phosphates from fertilizers and detergents stimulated algae growth, causing oxygen levels to collapse, turning the water cloudy and brown.

The river's pollution has been further exacerbated by contaminants washed into the river by rain or snow. In 2019, heavy rain caused the wastewater treatment plant to overflow, resulting in 2 million gallons of untreated sewage being discharged into the river.

The inadequate treatment and testing of the water, as well as the dismissal of residents' complaints about the water quality, led to a series of major health issues for Flint residents, including skin rashes, hair loss, and itchy skin.

Inadequate water treatment

The Flint River has been an unofficial waste disposal site for over a century. It has received treated and untreated industrial and human waste, as well as agricultural and urban runoff, and toxins from landfills. The river water was also treated with additional chlorine due to high levels of bacteria, which made the water more acidic and corrosive to pipes.

In April 2014, during a financial crisis, the city of Flint changed its drinking water source from Detroit's system (sourced from Lake Huron) to the Flint River in a cost-saving move. This switch was made without the necessary corrosion control treatment to prevent lead release from pipes and plumbing.

The water from the Flint River was not treated properly, and this inadequate treatment resulted in a series of major water quality and health issues for residents. The water was foul-smelling, discoloured, and off-tasting, and caused skin rashes, hair loss, and itchy skin. The river water's higher chloride concentration made it more corrosive than lake water, causing lead to leach from aging pipes.

The inadequate treatment of the Flint River water resulted in elevated lead levels in the blood of children and adults, with studies showing a doubling or tripling of cases. This lead exposure can have serious health consequences, including damage to children's brains and nervous systems, slow growth and development, and learning, behaviour, hearing, and speech problems.

The crisis was a result of multiple factors, including financial decline, mismanagement, and systemic racism. It was ultimately the relentless efforts of the Flint community, supported by doctors, scientists, journalists, and activists, that brought attention to the issue and forced a reckoning.

Increased river temperature

The Flint River has been a site for the disposal of treated and untreated industrial and human waste, as well as agricultural runoff, for over a century. The river is also warmer than Lake Huron, and its flow is less constant, particularly in the summer.

The temperature of the river water is important to consider as it is a factor that influences the levels of bacteria and organic matter in the water. Warmer water has lower oxygen levels, which is detrimental to plants and animals. Warmer water temperatures also promote the spread of bacterial and viral infections, as well as pathogens that have relatively high-temperature thresholds.

There are several factors that contribute to the increase in river water temperature. One factor is climate change, which has led to a projected increase in Tw (thermal water temperature) of 0.03°C per year in the UK, 0.001–0.08°C per year in the USA, and 0.03–0.05°C per year in China. Another factor is anthropogenic heat emission, which has further increased river water temperatures. Additionally, warmer runoff from urban surfaces, altered snowmelt timing, and thermally modified effluent from power stations, industrial units, and wastewater treatment plants can also impact river thermal regimes.

The construction of dams and weirs has also contributed to the increase in river water temperature. These structures can cause reduced flow velocities and increase the exposure time of surface water to solar radiation, leading to warming.

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