Understanding Epa's Big Three Water Pollutants

Water pollution is a pressing issue, with our rivers, reservoirs, lakes, and seas being inundated with chemicals, waste, plastic, and other pollutants. The US Environmental Protection Agency (EPA) plays a crucial role in addressing this problem by regulating point source and nonpoint source pollution. Point source pollution, which originates from a single source such as a wastewater treatment facility or an oil refinery, is regulated by the EPA through the establishment of limits on the discharge of pollutants into bodies of water. Nonpoint source pollution, on the other hand, comes from diffuse sources like agricultural or stormwater runoff, and while it is the leading cause of water pollution in US waters, it is challenging to regulate due to the lack of a specific culprit. The EPA also maintains lists of toxic and priority pollutants to help manage water contamination. These lists were developed in the 1970s and are used as a starting point for creating regulations, water quality criteria, and standards. The Priority Pollutant List, in particular, focuses on specific chemical pollutants and provides practical guidance for water testing and regulatory purposes.

Point-source pollution

The United States Environmental Protection Agency (EPA) identifies two broad categories of pollution: point-source pollution and non-point-source pollution. Point-source pollution is defined by the EPA as "any single identifiable source of pollution from which pollutants are discharged, such as a pipe, ditch, ship, or factory smokestack". In other words, it is pollution that comes from a single, identifiable place. This is in contrast to non-point-source pollution, which comes from multiple places at once and is therefore harder to identify and address.

Air pollution from industrial sources is also considered a point-source of pollution. Smokestacks from factories and power plants may emit carbon monoxide, heavy metals, sulfur dioxide, nitrogen dioxide, or particulate matter (small particles) into the air. These airborne pollutants are major contributors to acid rain, which is considered non-point-source pollution as it results from the long-range movement of pollutants from multiple factories and power plants.

To control point-source discharges, the Clean Water Act established the National Pollutant Discharge Elimination System (NPDES). Under the NPDES program, point sources such as factories, sewage treatment plants, and farms must obtain a permit from the state and EPA before discharging their waste or effluents into any body of water. These point sources are required to use the latest technologies to treat their effluents and reduce the level of pollutants before discharge.

Nonpoint-source pollution

Nonpoint-source (NPS) pollution is the single largest source of water contamination today. NPS pollution is caused by rainfall or snowmelt moving over and through the ground, picking up and carrying natural and human-made pollutants, and depositing them into lakes, rivers, wetlands, coastal waters, and groundwater. NPS pollution is distinct from pollution from industrial and sewage treatment plants in that it comes from many diffuse sources.

The term "nonpoint source" refers to any source of water pollution that does not meet the legal definition of "point source" in the Clean Water Act. Point sources are defined as discernible, confined, and discrete conveyances from which pollutants are or may be discharged, such as pipes, ditches, tunnels, or containers. NPS pollution, on the other hand, includes runoff from farm fields, livestock facilities, construction sites, lawns and gardens, city streets and parking lots, surface coal mines, and forestry.

The major sources of NPS pollution can be grouped into two categories: agricultural and urban. Agricultural NPS pollution includes runoff from fertilizers, pesticides, herbicides, and animal waste, which can contain nutrients and sediments that harm aquatic life and reduce water quality. Urban NPS pollution includes runoff from roads, sidewalks, driveways, and other developed areas, which can carry oil, pet waste, road salt, bacteria, and other contaminants into water bodies.

NPS pollution has been identified as the leading cause of water quality problems in many states. It can damage aquatic habitats, harm aquatic life, and reduce the capacity of water resources to be used for drinking water and recreation. Sediment, a common type of NPS pollutant, can make the water cloudy, hindering the ability of aquatic organisms to see and feed properly. It can also damage fish gills and the breathing of aquatic insects, cover fish spawning habitats, and reduce sunlight penetration, affecting plant growth. Additionally, sediments can carry other pollutants such as metals and toxic chemicals.

There are federal programs in place, such as the Nonpoint Source Management Program, that address NPS pollution and its impact on coastal areas. There are also fact sheets and guides available that provide information on how the public can help control and reduce NPS pollution.

Chemical contaminants

The US Environmental Protection Agency (EPA) has developed the Clean Water Act to regulate toxic pollutants in waterways. The Toxic Pollutant List, developed in 1976 and added to the Clean Water Act in 1977, contains broad categories of pollutants. To make the list more practical for water testing and regulatory purposes, the EPA developed the Priority Pollutant List in 1977, which includes specific chemical pollutants for which the EPA has published analytical test methods.

Inorganic Contaminants (IOCs) include nitrate and arsenic. Nitrate and nitrite are associated with an acute health risk called Methemoglobinemia or "blue baby syndrome". Arsenic is a known carcinogen, and in 2001, the EPA adopted a lower standard for arsenic in drinking water, reducing the maximum amount from 50 parts per billion (ppb) to 10 ppb.

Synthetic Organic Contaminants (SOCs) are also regulated by the EPA, and these apply to all public water systems. The type, size, and water source type of the public water system determine which contaminants require monitoring.

Radiological contaminants are chemical elements with an unbalanced number of protons and neutrons, resulting in unstable atoms that emit ionizing radiation.

Biological contaminants

According to the US Environmental Protection Agency (EPA), biological contaminants are organisms in water, also referred to as microbes or microbiological contaminants. They include bacteria, viruses, protozoa, and parasites. These contaminants can be harmful to human health if consumed at certain levels in drinking water, and the EPA has the authority to regulate and control their presence in public water systems.

The EPA's Safe Drinking Water Act (SDWA) defines a "contaminant" as any physical, chemical, biological, or radiological substance or matter in water, excluding water molecules. While the presence of contaminants does not necessarily indicate a health risk, certain contaminants can adversely affect public health if they occur at significant levels. To address this, the EPA has established drinking water standards as part of the SDWA's "multiple barrier" approach to drinking water protection. These standards include regulations, water monitoring schedules, and methods to measure and control the levels of contaminants in drinking water.

The EPA also maintains a Contaminant Candidate List (CCL), which serves as the first level of evaluation for unregulated drinking water contaminants. The CCL is a periodically published list of contaminants that are known or anticipated to occur in public water systems and may require regulation under the SDWA. The EPA uses the CCL to prioritize research and data collection efforts, make regulatory determinations, and decide whether to initiate the rule-making process to establish National Primary Drinking Water Regulations (NPDWRs) for specific contaminants.

NPDWRs, or primary standards, are legally enforceable standards that apply to public water systems to protect public health by limiting the levels of contaminants in drinking water. Secondary standards, or National Secondary Drinking Water Regulations (NSDWRs), are non-enforceable guidelines that regulate contaminants causing cosmetic or aesthetic effects, such as skin or tooth discoloration, taste, odor, or color changes in drinking water. While states can choose to adopt these standards as enforceable, the EPA only requires a special notice for the exceedance of the fluoride secondary standard.

Radiological contaminants

Examples of radiological contaminants include cesium, plutonium, and uranium. Uranium, for instance, is a natural radionuclide that can be found in small amounts in almost all rocks and soil and can dissolve in water. The EPA has issued standards for uranium under the Safe Drinking Water Act (SDWA) Amendments of 1986, setting a Maximum Contaminant Level (MCL) of 30 µg/L.

Radon is another example of a radiological contaminant. It is a radioactive gas created through the decay of radium, which can naturally occur in groundwater. If not removed, radon can be released into the air during activities such as showering or doing laundry.

To address these radiological contaminants, the EPA published the Radionuclides Final Rule in 2000, revising the radionuclides regulation that had been in effect since 1977. This new rule set monitoring requirements for community water systems (CWS) to ensure that customers receive water meeting the MCL for radionuclides. The EPA also provides resources and guidance for drinking water system owners and operators, as well as state and primacy agencies, to assist in addressing radionuclide contamination.

Public drinking water systems play a crucial role in testing and filtering out radionuclides to ensure the water they provide meets federal, state, and local drinking water standards. They use filters and other methods to remove radionuclides and other chemicals, regularly testing the water to ensure its safety for consumption.

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