Point source water pollution comes from discrete conveyances and alters the chemical, biological, and physical characteristics of water. In the United States, it is largely regulated by the Clean Water Act (CWA).United States. Federal Water Pollution Control Act Amendments of 1972. . Approved October 18, 1972. Among other things, the Act requires dischargers to obtain a National Pollutant Discharge Elimination System (NPDES) permit to legally discharge pollutants into a water body. However, point source pollution remains an issue in some water bodies, due to some limitations of the Act. Consequently, other regulatory approaches have emerged, such as water quality trading and voluntary community-level efforts.

Introduction

Definition Water pollution is the contamination of natural water bodies by chemical, physical, radioactive or pathogenic microbial substances. Point sources of water pollution are described by the CWA as "any discernible, confined, and discrete conveyance from which pollutants are or may be discharged." These include pipes or man-made ditches from stationary locations such as sewage treatment plants, factories, industrial wastewater treatment facilities, septic systems, ships, and other sources that are clearly discharging pollutants into water sources.

Relevant science The input of pollutants into a water body may impact the water's ability to deliver ecological, recreational, educational, and economic services. While the impacts of water pollution vary considerably based on a variety of site-specific factors, they may be either direct or indirect. Pollutants that are directly toxic pose a threat to organisms that may come into contact with contaminated water. These include persistent organic pollutants used as pesticides and toxic byproducts of industrial activity (such as cyanide). Other pollutants may indirectly impact ecosystem services by causing a change in water conditions that allows for a harmful activity to take place. This includes sediment (loose soil) inputs that decrease the amount of light that can penetrate through the water, reducing plant growth and diminishing oxygen availability for other aquatic organisms.

There are a variety of water quality parameters that may be affected by point source water pollution. They include: dissolved oxygen and biochemical oxygen demand (BOD), temperature, pH, turbidity, phosphorus, nitrates, total suspended solids, conductivity, alkalinity, and fecal coliform. BOD is perhaps the most widely used metric to assess water quality.

Water quality is also closely linked with water quantity issues. Water shortages from natural and anthropogenic activity reduce the dilutive properties of water and may concentrate water pollution. Conversely, during flooding events, water pollution may spread to previously uncontaminated waters through surface overflow or the failure of man-made barriers.

Nature of the problem/context Water pollution incidents and public response Before the CWA was enacted, companies indiscriminately discharged their effluents into water bodies. One such water body was the Cuyahoga River located in north-east Ohio. The river was thrust into the national limelight in 1969 when it caught fire, although the river had been plagued by fires since 1936. Pollution of the river had become prevalent in the early 1800s as contaminants from municipal and industrial discharges, bank erosion, commercial/residential development, atmospheric deposition, hazardous waste disposal sites, urban storm water runoff, combined sewer overflows (CSOs) and wastewater treatment plant bypasses were discharged into the river. Time magazine described the Cuyahoga as the river that "oozes rather than flows" and in which a person "does not drown but decays." The 1969 river fire, and the 1969 Santa Barbara oil spill in California—the largest such spill in U.S. history at that time—drew significant public attention to the state of the nation's waterways. Although Congress had been holding hearings and considering additional pollution control legislation in the late 1960s, these widely publicized incidents increased the pressure on Congress to act, which they eventually did with the 1972 Clean Water Act, the establishment of the Environmental Protection Agency (EPA) and later the Oil Pollution Act of 1990.

Regulatory framework History of regulation The Rivers and Harbors Act of 1899 contained provisions that made discharging refuse matter into navigable waters of the United States illegal without a permit issued by the U.S. Army Corps of Engineers.United States. Rivers and Harbors Act of 1899, Ch. 425, Sec. 9, 30 Stat. 1151. . March 3, 1899 The focus of the law was controlling obstructions to navigation, such as dumping refuse into rivers, and discharging oil from ships and boats. Most legal analysts have concluded that the 1899 law did not address environmental impacts from pollution, such as sewage or industrial discharges. However, there were several pollution enforcement cases in the 1960s and 1970s where the law was cited for broader pollution control objectives, prior to passage of the 1972 Clean Water Act.

By the mid-20th century, water pollution laws in the United States began to include health- and use-based standards to protect environmental and economic interests. In 1948 Congress passed the Federal Water Pollution Control Act (FWPCA).United States. Federal Water Pollution Control Act. Approved June 30, 1948. The law authorized the Surgeon General and the Public Health Service to develop programs to combat pollution that was harming surface and underground water sources, but did not create any new regulatory or enforcement authority for pollution control. The FWPCA also authorized cooperation between federal and state agencies to construct municipal sewage treatment plants.

The Water Quality Act of 1965 required states to issue water quality standards for interstate waters, and authorized the newly created Federal Water Pollution Control Administration to set standards where states failed to do so. No mechanism for federal enforcement was established.United States. Water Quality Act of 1965. . Approved October 2, 1965.

The 1966 Clean Water Restoration Act authorized a study to determine the effects of pollution on wildlife, recreation, and water supplies. The Act also set forth guidelines for abatement of water that may flow into international territory and prohibited the dumping of oil into navigable waters of the United States.

The Water Quality Improvement Act of 1970 required the development of certain water quality standards and expanded federal authority in upholding the standards.United States. Water Quality Improvement Act of 1970. Approved April 3, 1970. The most substantial amendments to the FWPCA occurred in 1972 and became known as the Clean Water Act.

Clean Water Act Point source water pollution is largely regulated through the Clean Water Act, which gives the EPA the authority to set limits on the acceptable amount of pollutants that can be discharged into waters of the United States. The 1972 law also created federal authority for a permit system—NPDES—to enforce the pollution standards. The Act broadly defines a pollutant as any type of industrial, municipal, and agricultural waste discharged into water, such as: dredged soil, solid waste, incinerator residue, sewage, garbage, sewage sludge, munitions, chemical wastes, biological materials, radioactive materials, heat, wrecked or discarded equipment, rock, sand, cellar dirt and industrial, municipal, and agricultural waste. Point source water pollution is discharged into waters through both direct and indirect methods.

Direct dischargers

Direct discharges are pollutants that are discharged directly to a surface water body. To legally discharge pollutants directly into a waterbody, a facility—municipal, industrial, commercial or government-owned—must obtain a National Pollution Discharge Elimination System (NPDES) permit from EPA or a state agency.Clean Water Act, sec. 301, "Effluent limitations."

NPDES Permit Program The NPDES permit program sets limits on the amount of pollutants that can be discharged into a waterbody. Technology based effluent limits establish a minimum level of pollution controls for all point source discharges. If technology based limits are not sufficient to protect a particular water body, then water quality based effluent limits are developed for facilities discharging to that water body.

Permits Individual states are authorized by the EPA to issue permits when they have demonstrated that their program is at least as stringent as the EPA's program. States perform the day-to-day issuance of permits and oversight of the program while the EPA provides review and guidance to the states. All NPDES permits must contain effluent limitations. The permits (excluding most stormwater management permits) also specify procedures for collection of wastewater samples and the test methods that will be used to analyze the samples.

Types of permits Individual – A unique permit is issued for each discharger. General – A single permit that covers a large number of similar dischargers; in some cases, located in a specific geographic area. Examples include the EPA Vessels General Permit and industrial stormwater general permits.

Permitting process The authorized permit issuing body receives and reviews the permit application. The technology-based and water quality-based effluent limits are developed and then compared to determine which is the more stringent, which is then used as the effluent limit for the permit. Monitoring requirements, special conditions, and standard conditions for each pollutant are developed and the permit is then issued and its requirements are implemented.

Technology-based requirements: A minimum level of treatment based on available treatment technologies is required for discharged pollutants, however, a discharger may use any available treatment technologies to meet the limits. The effluent limits are derived from different standards for different discharges: Municipal discharges (POTW): National secondary treatment standards define limits of biological treatment standards based on biochemical oxygen demand (BOD), total suspended solids (TSS), and pH balance. Industrial and other non-municipal discharges: Limits for many industrial dischargers are based on national standards for issued for specific categories, such as chemical plants, paper mills, and electric power plants (see Effluent guidelines). EPA issues these limitations based on the performance of pollution control and prevention technologies. For existing dischargers, this level of treatment is equivalent to "Best Available Technology Economically Achievable" (BAT) and for new discharges, the treatment level is "New Source Performance Standards" (NSPS). If there is no applicable national standard (effluent guideline regulation) for a particular facility, the NPDES permit agency develops requirements on a case-by-case basis.EPA. "Criteria and Standards for the National Pollutant Discharge Elimination System." Technology-based treatment requirements in permits. Code of Federal Regulations, 40 CFR 125.3(d). Water quality-based requirements: Should technology-based standards not be stringent enough, Water Quality Based Effluent Limits (WQBEL) are developed to ensure that water quality standards are attained. WQBELs are based on ambient water quality standards.

Permit components

All NPDES permits must contain the following five components: Cover page – indicates authorization for discharging and its locations Effluent limits – limits used to control discharges through technology-based or water quality-based standards Monitoring and reporting requirements – used to determine permit compliance Special conditions – can be used to supplement effluent limits Standard conditions – pre-established conditions that apply to all NPDES permits.