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Water pollution in the United States is regulated through a number of statutes and regulations and overseen by a combination of federal agencies and states. The Federal Water Pollution Control Act (now commonly known as the Clean Water Act), first passed in 1948, was substantially amended in 1972, 1977, and 1987. It puts forward a system to regulate direct and indirect discharges of pollutants in the “waters of the United States” and intends to “restore and maintain the chemical, physical, and biological integrity of the Nation’s waters.” The Safe Drinking Water Act regulates public water systems and sets national drinking water regulations. Water use —the supply of water, its ownership and allocation among various users—is largely governed by the states.

Listen to and download materials from the ELI Summer School Seminar on Clean Water for a general overview of how water regulations work. For a discussion on current topics in the Clean Water Act, listen to the Clean Water Act at 40 seminar co-sponsored with George Washington Law School.

For a thorough overview of the Clean Water Act, see Ann Powers, Introduction to Environmental Law: Cases & Materials on Water Pollution Control.

Clean Water Act

The Clean Water Act was substantially amended in 1972 to create the regulatory system that is known today. It regulates the discharge of pollutants through two permitting systems, the National Pollutant Discharge Elimination System (NPDES) program and the Section 404 wetlands program, through effluent limitations applicable to types of direct discharges to water, and by setting standards for water quality known as water quality standards and total maximum daily loads.

Over the years, there has been a question over the scope of federal jurisdiction under the Clean Water Act. In Solid Waste Agency of Northern Cook County v. Corps of Engineers and Rapanos v. United States, the Supreme Court found that not all wetlands and waters in the United States fall under the jurisdiction of the Clean Water Act, resulting in significant uncertainly as to just how far federal power extends over water pollution.

For a discussion of the uncertainty around the scope of federal water jurisdiction, download the ELI Research Report Clean Water Act Jurisdictional Handbook, 2d ed. ELI members may listen to and download materials from the ELI Seminar Assessing Jurisdiction under the New Clean Water Act Guidance. See also the ELR article, Jon Devine, The Intended Scope of Clean Water Act Jurisdiction.

Water Quality Standards

The Clean Water Act requires that water quality standards be established by EPA or states, territories or tribes authorized by EPA to implement the program. To determine what the water quality standards should be, the waterbody must be given a “designated use.” This depends on how the public uses the waterbody, such as drinking water, water-based recreation, or fishing. Water quality criteria, which can be numeric or narrative, are then assigned to protect that designated use.

Authorized states, territories and tribes monitor waterbodies to determine whether they meet the water quality standards. If the WQS are met, then antidegradation policies are employed so that the water quality is kept at an acceptable level. If the WQS are not met, the most common tool to use is to establish total maximum daily loads (TMDL), which are the pollutant load the water can withstand and be in compliance with the water quality standards.

For a thorough discussion of the TMDL program, see Oliver Houck, Clean Water Act TMDL Program: Law, Policy, and Implementation and The Clean Water Act Returns (Again): Part I, TMDLs and the Chesapeake Bay. See materials from the ELI-lead State TMDL conferences here.

NPDES Program

Section 402 of CWA creates the National Pollution Discharge Elimination System (NPDES) program, which authorizes permits for point sources that are going to discharge into surface waters. A “point source” is “any discernible, confined and discrete conveyance, including but not limited to any pipe, ditch, channel, tunnel, conduit, well, discrete fissure, container, rolling stock, concentrated animal feeding operation, or vessel or other floating craft, from which pollutants are or may be discharged.” The permit puts a limit on the amount that a point source may discharge. Most states and some territories and tribes have been authorized by EPA to issue NPDES permits; EPA remains the permitting authority in non-authorized states.

For a discussion of the requirement to get an NPDES permit for application of pesticides, ELI members may listen to the ELI Seminar The Clean Water Act, the Endangered Species Act, and the Federal Insecticide, Fungicide, and Rodenticide Act Collide, But With What Result?

The NPDES program is structured to either provide permits by developing a unique permit for each discharger (individual permits) or by developing a single permit that covers a large number of similar dischargers (general permits). The individual permit sets specific limits on the amount of pollutants that can be discharged from the facility. The limits can be either technology-based or water quality-based.

The effluent limits on pollutants are performance standards, meaning that the discharging facility can use a combination of processes to meet the permit limits. EPA also sets effluent limitation standards that apply to types of industrial discharge sources that are then applied in individual permits.

For an ELR article on effluent limitation standards, see Melissa Thorme, “Antibacksliding: Understanding One of the Most Misunderstood Provision in the Clean Water Act.

The NPDES program also covers discharges of stormwater from construction or industrial activity and from municipal separate storm sewers. Stormwater is rain or snowmelt that flows over the ground or impervious surfaces, like roads and parking lots, that may collect contaminants and debris harmful to water quality if discharged. Most stormwater permits require best management plans and occasional testing.

EPA also allows watershed-based permitting, in which NPDES permits are issued in order to achieve watershed-wide water quality standards. Such programs may incorporate water quality trading, where various sources trade the ability to pollute because some may be able to reduce discharges more cost-effectively.

Find resources and further information at Background Information on Water Quality Trading and Wetland Mitigation Banking.

Facilities are in violation of the CWA if they discharge without a permit or discharge more than allowed by their permit. Facilities are also in violation if they do not comply with extensive monitoring and reporting requirements. States, territories, and tribes that are delegated authority to oversee the NPDES program are responsible for enforcing the NPDES permits. EPA will take action if necessary, but must first give notice to the authorized agency if it believes enforcement is necessary and must give the agency time to act. Enforcement actions include injunctions, fines, imprisonment if criminal violation, and supplemental environmental projects. Citizens can bring a suit against a violator if an agency is not pursuing a violation, but they must give 60-day notice to EPA and the authorized agency so that they have time to act against the violator instead.

Nonpoint Source Program

Because the NDPES program largely regulates only direct discharges from point sources, section 319, added in 1987, focuses on nonpoint sources, which are anything that is not a point source. Common nonpoint sources are runoff from precipitation over and through the ground and from atmospheric deposition. Section 319 implements a federal grant program that gives money to states, territories and tribes for the development and implementation of nonpoint source management programs. Each entity receiving funding must create and update a nonpoint source management plan and must identify waters that are impaired or threatened by nonpoint sources, develop goals for cleaning those waters and identify the best management practices that will be used to clean up the waters.

For a discussion of ways to address nonpoint source pollution, download the ELI Research Report Enforceable State Mechanisms for the Control of Nonpoint Source Water Pollution and investigate the various ELI research materials on nonpoint source issues here. See also John Carter, Control of Nonpoint Pollution Through Citizen Enforcement of Unpermitted Stormwater Discharges: A Proposal for Bottom-Up Litigation.


The Section 404 program regulates the placement of dredged or fill material into the “waters of the United States,” which includes wetlands. The 404 permit program is administered jointly by EPA and U.S. Army Corps of Engineers. The Corps handles the issuance of the permits and determines whether the area in question is a wetland subject to federal jurisdiction. The Corps also has primary responsibility for ensuring compliance. EPA issues guidelines and policies, and can veto a Corps-issued permit. EPA is responsible for deciding whether states, territories, or tribes should be authorized to implement the 404 program.

ELI has an extensive wetlands program with many reports and resources to draw upon. The National Wetlands Newsletter provides in-depth policy and science coverage of wetlands issues as well. For a general overview of wetlands issues, see Margaret Strand, Wetlands Deskbook, 3rd ed.

Safe Drinking Water Act

The Safe Drinking Water Act seeks to maintain the quality of public drinking water supplies largely by regulating public water systems. EPA publishes health-based levels of contaminants that can appear in drinking water. The maximum contaminant level goal (MCLG) is the level at which there are no known or anticipated adverse health effects on the health of persons and that allows an adequate margin of safety. The national primary drinking water regulations specify the maximum contaminant level (MCL) that is as close as feasible to the MCLG. The MCL does not specify a particular treatment technique, but EPA may, in lieu of setting an MCL, require the use of a treatment technique. Like most other environmental programs, EPA may give authority to states, territories and tribes to adopt and enforce these drinking water standards.

For an overview of the Safe Drinking Water Act and its 1986 revisions, see Kenneth Gray, The Safe Drinking Water Act Amendments of 1986: Now a Tougher Act to Follow and Steven Koorse, New Safe Drinking Water Act Liability for Corporate America.

Public water systems must notify their customers if they do not comply with any applicable MCLs, if they fail to monitor, if they have a variance exemption, or if they fail to comply with any exemption. The public water system must give each customer an annual report that includes the quality of the water and includes information on any violations or contaminants in the water.

The Safe Drinking Water Act also regulates the underground injection of substances for storage and disposal, including the subsurface injection of the greenhouse gas carbon dioxide for storage, enhancing oil production, or other purposes. The underground injection control program regulations mainly seek to prevent the contamination of underground drinking water supplies.

Water Use

Listen to and download materials from the ELI seminar Uncertainty and Risk in Securing Adequate Water Supplies: Challenges and Opportunities. See Hunton & Williams’ Water Policy Institute page for a helpful list of links and many discussions of current issues.

The legal framework for the provision of water, its ownership, its allocation to various users, and its use are different from water pollution law. In general, water ownership and use are governed by state law, which largely grew from judge-made common law. Issues around water quantity between states are largely managed by inter-state compacts and river management boards set up across states. The federal government mostly serves a referee role for allocation between and disputes among states.

For a discussion of how the prior appropriation doctrine can function with modern water demands, download the ELI Research Report, Western Water in the 21st Century Policies and Programs that Stretch Supplies in a Prior Appropriation World. See also Robert Abrams, Water, Climate Change, and the Law: Integrated Eastern States Water Management Founded on a New Cooperative Federalism.

Surface water ownership law follows various models, predominantly the riparian doctrine in the eastern United States and the prior appropriation doctrine in the western United States. Riparian rights generally allow a landowner whose land abuts a waterbody to use that water. This system often is used in areas where water is plentiful. The prior appropriation doctrine, in contrast, allows the first user of the water who puts it to beneficial use to have ownership of that water right, a system adopted in drier areas. Many states’ laws combine elements of both doctrines in practice. Ground water law also generally follows these doctrines and is implemented on a statewide basis.