To address pollution and protect water we need to understand where the pollution is coming from (point source or nonpoint source) and the type of water body its impacting (groundwater, surface water, or ocean water). Accidentally released or improperly disposed of contaminants threaten groundwater, surface water, and marine resources. Consider the decommissioned Hanford nuclear weapons production site in Washington, where the cleanup of 56 million gallons of radioactive waste is expected to cost more than $100 billion and last through 2060. Radioactive waste can persist in the environment for thousands of years, making disposal a major challenge. It’s generated by uranium mining, nuclear power plants, and the production and testing of military weapons, as well as by universities and hospitals that use radioactive materials for research and medicine. Radioactive waste is any pollution that emits radiation beyond what is naturally released by the environment. Oil is also naturally released from under the ocean floor through fractures known as seeps. At sea, tanker spills account for about 10 percent of the oil in waters around the world, while regular operations of the shipping industry-through both legal and illegal discharges-contribute about one-third. Moreover, nearly half of the estimated 1 million tons of oil that makes its way into marine environments each year comes not from tanker spills but from land-based sources such as factories, farms, and cities. Oil pollutionīig spills may dominate headlines, but consumers account for the vast majority of oil pollution in our seas, including oil and gasoline that drips from millions of cars and trucks every day. But according to EPA estimates, our nation’s aging and easily overwhelmed sewage treatment systems also release more than 850 billion gallons of untreated wastewater each year. These facilities reduce the amount of pollutants such as pathogens, phosphorus, and nitrogen in sewage, as well as heavy metals and toxic chemicals in industrial waste, before discharging the treated waters back into waterways. In the United States, wastewater treatment facilities process about 34 billion gallons of wastewater per day. More than 80 percent of the world’s wastewater flows back into the environment without being treated or reused, according to the United Nations in some least-developed countries, the figure tops 95 percent. The term also includes stormwater runoff, which occurs when rainfall carries road salts, oil, grease, chemicals, and debris from impermeable surfaces into our waterways It comes from our sinks, showers, and toilets (think sewage) and from commercial, industrial, and agricultural activities (think metals, solvents, and toxic sludge). Nutrient pollution, caused by excess nitrogen and phosphorus in water or air, is the number-one threat to water quality worldwide and can cause algal blooms, a toxic soup of blue-green algae that can be harmful to people and wildlife. Every time it rains, fertilizers, pesticides, and animal waste from farms and livestock operations wash nutrients and pathogens-such bacteria and viruses-into our waterways. It’s also a major contributor of contamination to estuaries and groundwater. 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. Around the world, agriculture is the leading cause of water degradation. Not only is the agricultural sector the biggest consumer of global freshwater resources, with farming and livestock production using about 70 percent of the earth’s surface water supplies, but it’s also a serious water polluter.
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