Human Impact: Water Pollution Sources

Water pollution is a pressing issue that poses a threat to human health, the environment, and the economy. It is caused by a range of human activities and natural sources, with the leading cause being nonpoint source pollution from agricultural runoff. This includes toxic chemicals, pesticides, fertilizers, and waste from farms and livestock operations that contaminate waterways, leading to harmful algal blooms and water degradation. Industrial sites and factories also contribute significantly to water pollution, releasing untreated toxic waste and chemicals into freshwater systems. Other sources include oil spills, sewage, and stormwater runoff carrying debris, oils, and chemicals into water bodies. Climate change further exacerbates water pollution by altering weather patterns and causing droughts and floods, which impact water availability and quality.

Industrial waste

The types of industrial waste generated include cafeteria garbage, dirt and gravel, masonry and concrete, scrap metals, trash, oil, solvents, chemicals, weed grass and trees, wood and scrap lumber, and similar wastes. Industrial waste is one of the main sources of water pollution, with 80% of ocean pollution originating on land. Contaminants such as chemicals, nutrients, and heavy metals are carried from factories and cities by streams and rivers into bays and estuaries and eventually out to sea.

Mining and smelting operations, for example, are responsible for contaminating water with heavy metals in almost every state in the US. In addition, shale gas extraction produces large volumes of wastewater that can contain high concentrations of dissolved solids, radionuclides, metals, and other pollutants.

The effects of water pollution from industrial waste are devastating to people, animals, fish, and birds. Polluted water is unsuitable for drinking, recreation, agriculture, and industry. It also destroys aquatic life and reduces its reproductive ability. According to the World Health Organization (WHO), polluted water is water whose composition has been changed to the extent that it is unusable, and it causes diseases like diarrhoea, cholera, dysentery, typhoid, and poliomyelitis that kill more than 500,000 people worldwide every year.

While some industries have treatment facilities for industrial effluents, this is not the case with small-scale industries, which cannot afford the necessary investments in pollution control equipment. Technologies have been developed to address solid waste and other environmental and recycling problems, but there is still a failure of federal and state policy to keep people safe from industrial pollution in their drinking water.

Agricultural pollution

Agriculture is a leading cause of water pollution, and the biggest consumer of global freshwater resources. Farms discharge large quantities of agrochemicals, organic matter, drug residues, sediments, and saline drainage into water bodies.

Agricultural contaminants can impair the quality of surface water and groundwater. Fertilizers and pesticides don't remain in the soil where they are applied; instead, they are transported into local streams, rivers, and groundwater through runoff and infiltration. When land is converted to agricultural use, it is modified to be optimized for agricultural production, and these modifications can have unintended environmental impacts on the water and their ecosystems, including changes in water quality and quantity.

In the United States, agricultural pollution is the top source of contamination in rivers and streams, the second-biggest source in wetlands, and the third main source in lakes. About a half million tons of pesticides, 12 million tons of nitrogen, and 4 million tons of phosphorus fertilizer are applied annually to crops in the continental United States. Soil erosion, nutrient loss, bacteria from livestock manure, and pesticides constitute the primary stressors to water quality.

In addition to pesticides, fertilizers, and manure, a new class of agricultural pollutants has emerged in the form of veterinary medicines (antibiotics, vaccines, and growth promoters). These medicines move from farms through water to ecosystems and drinking water sources.

Sewage and wastewater treatment

Wastewater treatment facilities play a crucial role in addressing this issue. In the United States, these facilities process approximately 34 billion gallons of wastewater daily, removing pollutants such as nitrogen and phosphorus from human waste, food, soaps, and detergents. However, the effectiveness of treatment varies among plants, and some struggle to meet nutrient reduction goals. Additionally, septic systems, which locally treat wastewater for approximately 20% of US homes, can become a source of nutrient pollution if not properly maintained.

The economic and environmental costs of inadequate wastewater treatment are significant. In developing countries, the lack of proper sewage collection services and the illegal dumping of human waste into water bodies contribute to unsafe water-related health issues. For example, in Haiti, only 40% of the population uses latrines and septic tanks, and much of the untreated solid waste is dumped into rivers and seas, leading to pathogenic microorganisms and toxins from algal blooms.

To address these challenges, organizations like The Nature Conservancy (TNC) are working on innovative solutions. In Florida, TNC has helped craft legislation banning the discharge of treated wastewater into the coastal zone by 2025, encouraging the reuse of wastewater. Similarly, pilot projects in Saint Lucia, Jamaica, and Tobago aim to develop national planning mechanisms to control marine pollution from domestic sewage and improve infrastructure for sewage and wastewater management.

Overall, effective sewage and wastewater treatment are essential for protecting aquatic ecosystems and public health. By implementing treatment options that better protect ecosystems, investing in innovative practices, and promoting the reuse of treated wastewater, we can make significant strides in tackling water pollution and its associated impacts on climate change and human well-being.

Oil spills and leaks

The transportation and storage of oil are subject to leaks and spills that pollute water resources. The more transfers that occur between ocean tankers, pipelines, trains, and trucks, the higher the risk of oil spills. For example, a city of five million people can discharge as much oil into the water through pavement runoff as a large oil tanker spill. Additionally, individual tanks within ships are limited in size, so a leak in one compartment may be minimized, but it can still cause significant damage.

Oil spills can harm sea creatures, ruin beaches, and make seafood unsafe to eat. Oil can coat a bird's wings, making it unable to fly, or strip away the insulating properties of a sea otter's fur, putting it at risk of hypothermia. These are examples of "fouling or oiling," which occurs when oil physically harms a plant or animal.

Oil spills can also have economic impacts. For instance, the president of the World Bank, David Malpass, has warned that deteriorating water quality due to pollution is stalling economic growth and exacerbating poverty in many countries. When biological oxygen demand—an indicator of organic pollution in water—increases, the growth in the Gross Domestic Product (GDP) of the affected regions is reduced by a third.

Oil spills have been a catalyst for change in pollution control and environmental activism. For example, the 1969 blowout and oil spill off the coast of Santa Barbara, California, accelerated the advancement of federal government policies and changed how the US government managed environmental pollution. In the years following this incident, Congress passed laws such as the National Environmental Policy Act and the Clean Water Act.

Climate change

One of the primary ways climate change contributes to water pollution is through the alteration of precipitation patterns. As temperatures rise, more water evaporates from oceans, lakes, soil, and plants, leading to increased moisture in the air. This results in heavier rainstorms, which, in turn, increase surface runoff—the water that flows over the ground after a storm. This runoff water can pick up pollutants, dirt, and other contaminants, flushing them into nearby bodies of water and compromising water quality.

The impact of climate change on water pollution is evident in the melting of glaciers and ice sheets. As they melt, they contribute to rising sea levels, jeopardizing coastal properties and ecosystems. Additionally, the loss of glacial meltwater reduces water availability during warm and dry periods for regions supplied by major mountain ranges, affecting both human populations and ecosystems.

The built environment is another concern. During construction, sediment pollution increases significantly. While direct sedimentation slows down once construction is complete, precipitation continues to be a problem. Its unpredictable nature and increased intensity due to climate change can lead to rapid discharges of polluted water from the built environment, such as roads, bridges, and sewers, further contributing to water pollution.

To address these challenges, various adaptation strategies and sustainable practices are being explored. These include implementing green infrastructure, such as extended detention wetlands, blue roofs, and permeable pavements, to manage stormwater runoff and improve water quality. Additionally, adopting climate-smart agriculture, improving water efficiency, and exploring unconventional water sources, such as regulated treated wastewater, are crucial steps in mitigating the impacts of climate change on water pollution and ensuring water security for a growing global population.

Frequently asked questions