Nonpoint source (NPS) water pollution regulations are environmental regulations that restrict or limit water pollution from diffuse or nonpoint effluent sources such as polluted runoff from agricultural areas in a river catchments or wind-borne debris blowing out to sea. In the United States, governments have taken a number of legal and regulatory approaches to controlling NPS effluent. Nonpoint water pollution sources include, for example, leakage from underground storage tanks, storm water runoff, atmospheric deposition of contaminants, and golf course, agricultural, and forestry runoff. Nonpoint sources are the most significant single source of water pollution in the United States, accounting for almost half of all water pollution, and agricultural runoff is the single largest source of nonpoint source water pollution. This water pollution has a number of detrimental effects on human health and the environment. Unlike point source pollution, nonpoint source pollution arises from numerous and diverse sources, making identification, monitoring, and regulation more complex.
Basis for controls and regulations The basis for nonpoint source pollution regulation is the negative direct and indirect effects on both human health and the environment caused by the pollutants in NPS effluent.
Human health Human health is most directly affected when polluted water is ingested into the body. Nonpoint source pollution can often have toxic contaminants and chemicals present in the water. Additionally, there can be both bacteria and viruses (aka pathogens) found in the water.
Toxic contaminants and chemicals Effluent from nonpoint sources may include toxic contaminates and chemical compounds including heavy metals like lead, mercury, zinc, and cadmium, organics like polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs), and other substances resistant to breakdown. There are many health effects associated with many of these toxic substances.
Lead – can cause damage to the nervous connections as well as blood and brain disorders. Specific diseases include nephropathy, colic-like abdominal pains, and anemia. Mercury – Studies have shown effects such as chronic effects including tremors, impaired cognitive skills, and sleep disturbances. Acute exposure has shown to cause chest pain, dyspnea, cough, hemoptysis, impairment of pulmonary function, and evidence of damage to the lung tissue. Zinc – The U.S. Food and Drug Administration (FDA) has stated that zinc damages nerve receptors in the nose, which can cause loss of the sense of smell. Additionally, zinc toxicosis can occur in high doses of zinc. Cadmium – Exposure to cadmium-containing substances can result initially in metal fume fever but can progress to chemical lung damage, pulmonary edema, and even death. PCBs – People exposed to high levels of PCBs can exhibit skin conditions, such as rashes and liver damage. Common symptoms include dermal and ocular lesions, irregular menstrual cycles and lowered immune responses. Other symptoms include fatigue, headaches, coughs, and unusual skin sores. PAHs – The U.S. Environmental Protection Agency (EPA) classified seven PAH compounds as probable human carcinogens: benz[a]anthracene, benzo[a]pyrene, benzo[b]fluoranthene, benzo[k]fluoranthene, chrysene, dibenz(a,h)anthracene, and indeno(1,2,3-cd)pyrene.
Pathogens Pathogens are bacteria and viruses that can be found in water and cause diseases in humans. Pathogens found in contaminated runoff may include:
Cryptosporidium parvum – Primary symptoms of C. parvum infection are diarrhoea. Other symptoms can include anorexia, nausea/vomiting and abdominal pain. Giardia lamblia – Symptoms of infection include diarrhea, malaise, excessive gas, steatorrhoea, epigastric pain, bloating, nausea, vomiting, diminished interest in food, and weight loss. Salmonella – Symptoms are usually gastrointestinal. This can include nausea, vomiting, abdominal cramps and bloody diarrhea with mucus, headache, and fatigue. Parasitic worms (helminths) – Conditions associated with intestinal helminth infection include intestinal obstruction, insomnia, vomiting, weakness, and stomach pains.
Environment The environment is impacted by nonpoint source pollution through the input of sediment and nutrients from multiple sources directly into the water system.
Toxic contaminants and chemicals Toxic chemicals and contaminants, like motor oil, fuel, and industrial facility waste can enter the water system by storm water runoff. These chemicals, many of which can contain heavy metals, can enter the water system and coat the species present in the water. This can lead to death of the aquatic organisms which can cause increases in the amount of nutrients in the system from the decaying animals.
Sediment Sediment or suspended sediment in the water is soil that would not normally be present in the water column. When the sediment is suspended up in the water column, it blocks out the sunlight which is needed by bottom dwelling plants. If these plants, called submerged aquatic vegetation, are deprived of sunlight for a significant amount of time, they will die. These plants are a significant source of food for many aquatic organisms as well as trap oxygen and sediment. When there is an excess of dying plants in an aquatic ecosystem, it can lead to eutophic or hypoxic conditions in the water body.
Nutrients The primary nutrients found in water due to nonpoint source pollution are nitrogen and phosphorus from fertilizers. An influx of these nutrients can lead to eutrophication within the water. This is when there is an excess of nutrients in water, thus leading to an explosion in the growth of algae. The algae can cover the lake and block sunlight from reaching the organisms below, typically killing them.
Legal framework Some aspects of NPS water pollution are regulated at the federal, state, and local level, but to a lesser extent than point sources. The pollution persists and remains a significant problem in many watersheds. NPS water pollution comes from numerous and diverse sources, and control measures are expensive to implement. State and local governments are generally responsible for implementing NPS regulations. Coordination among localities can be difficult, and, furthermore, localities often lack the incentive to rigorously enforce NPS regulations because their NPS pollution is exported downriver, where other towns and cities must deal with the consequences.
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