The main federal environmental laws in the United States are the Clean Air Act, the Clean Water Act, and the Comprehensive Environmental Response, Compensation, and Liability Act, better known as CERCLA or Superfund. Each targets a different problem. The Clean Air Act controls pollutants released into the air. The Clean Water Act controls what can be discharged into rivers, lakes, and wetlands. CERCLA forces the cleanup of land contaminated by hazardous waste and decides who pays for it. Together they give the Environmental Protection Agency and other federal agencies the authority to set pollution limits, issue permits, and hold polluters financially responsible.
The Clean Air Act
The Clean Air Act gives the EPA authority to regulate harmful pollutants released from factories, power plants, vehicles, and other sources. Its central mechanism is the National Ambient Air Quality Standards (NAAQS), which set maximum allowable concentrations for common pollutants: ozone, particulate matter, carbon monoxide, sulfur dioxide, nitrogen dioxide, and lead. The EPA sets two levels for each. Primary standards protect public health with a margin of safety. Secondary standards protect the environment, crops, buildings, and visibility.1Office of the Law Revision Counsel. 42 USC 7409 – National Primary and Secondary Ambient Air Quality Standards
How States Carry the Standards Out
Once the EPA publishes a standard, the real work falls to the states. Each state must develop a State Implementation Plan showing exactly how it will meet and maintain the standard within its borders, and must submit that plan within three years of a new standard’s issuance.2Office of the Law Revision Counsel. 42 USC 7410 – State Implementation Plans for National Primary and Secondary Ambient Air Quality Standards If a plan falls short or a state fails to submit one, the EPA can impose a federal plan.
Hazardous Air Pollutants
Beyond the six common pollutants covered by NAAQS, the Act separately targets hazardous air pollutants, chemicals known or suspected to cause cancer, birth defects, or other serious health effects. For industrial sources that emit them, the EPA sets technology-based emission limits, meaning facilities must install the best available control equipment rather than simply meeting an ambient concentration target.3Office of the Law Revision Counsel. 42 USC 7412 – Hazardous Air Pollutants
Vehicles
The Act also regulates vehicle emissions, though this area has changed. In February 2026, the EPA finalized a rule repealing all federal greenhouse gas emission standards for new motor vehicles. Vehicle emission controls for conventional pollutants like carbon monoxide and nitrogen oxides remain in place under other provisions.
The Clean Water Act
The Clean Water Act’s stated goal is to restore and maintain the chemical, physical, and biological integrity of the nation’s waters.4Office of the Law Revision Counsel. 33 USC 1251 – Congressional Declaration of Goals and Policy In practice, it makes discharging any pollutant from a pipe, ditch, or other identifiable source into navigable waters illegal unless you hold a permit.
The NPDES Permit Program
The permit system at the heart of the Act is the National Pollutant Discharge Elimination System (NPDES). Any industrial facility, municipal wastewater treatment plant, or other operation that sends pollutants directly into surface waters needs an NPDES permit. Permits set specific discharge limits, require monitoring and reporting, and run for fixed terms of up to five years before renewal.5Office of the Law Revision Counsel. 33 USC 1342 – National Pollutant Discharge Elimination System States can administer their own NPDES programs with EPA approval, and most do.
Wetlands After Sackett
Section 404 of the Act protects wetlands by requiring a permit from the U.S. Army Corps of Engineers before anyone can discharge dredged or fill material into navigable waters. Building on wetlands, filling marshes for development, and large-scale land-clearing all fall within it. Routine farming, ranching, and maintenance of existing structures are generally exempt.6Office of the Law Revision Counsel. 33 USC 1344 – Permits for Dredged or Fill Material
The scope of these protections narrowed significantly after the Supreme Court’s 2023 decision in Sackett v. Environmental Protection Agency. The Court held that the Act covers only relatively permanent bodies of water that qualify as traditional navigable waters in ordinary language, and that wetlands fall under federal jurisdiction only when they have a continuous surface connection to such a water body, making it hard to tell where the water ends and the wetland begins.7Supreme Court of the United States. Sackett v. Environmental Protection Agency The broader “significant nexus” test was eliminated.
The regulatory picture remains unsettled. The EPA issued a conforming rule in September 2023, then proposed another updated definition of “waters of the United States” in November 2025. As of early 2026, different definitions apply in different parts of the country: 24 states plus D.C. and U.S. territories operate under the amended 2023 rule, while 26 states follow the pre-2015 regulatory framework as interpreted through Sackett.8US EPA. Definition of Waters of the United States – Rule Status and Litigation Update If you are planning a project that might affect wetlands or waterways, checking which definition applies in your state is the essential first step.
CERCLA (Superfund)
CERCLA deals with the problem of contaminated land. When hazardous waste has been dumped, spilled, or abandoned at a site, the Act gives the EPA authority to identify who is responsible and force them to clean it up or pay for the cleanup.9Office of the Law Revision Counsel. 42 USC 9607 – Liability
Who Pays for Cleanup
CERCLA casts a wide net. Four categories of people can be held liable for contamination at a site:
- Current owners or operators of the contaminated property, even if they did not cause the contamination
- Past owners or operators who owned or ran the site when hazardous substances were disposed of there
- Generators who arranged for their hazardous waste to be sent to the site
- Transporters who hauled hazardous substances to the site
Liability under CERCLA is strict, so the government does not have to prove anyone was careless or intended to cause harm. It is also joint and several in most cases, meaning any single responsible party can be forced to pay the entire cleanup cost, not just their proportional share. The EPA can then recover those costs from other responsible parties.9Office of the Law Revision Counsel. 42 USC 9607 – Liability A company that contributed five percent of the waste at a site can end up footing the whole bill if the other responsible parties are bankrupt or cannot be found.
The National Priorities List
The EPA ranks the country’s most seriously contaminated sites on the National Priorities List (NPL). Placement is based on danger to public health, the hazard potential of the substances involved, risk to drinking water supplies, potential for direct human contact, and damage to ecosystems.10Office of the Law Revision Counsel. 42 USC 9605 – National Contingency Plan NPL sites get priority for long-term remediation. When responsible parties cannot be found or cannot pay, the Superfund trust fund, financed through excise taxes on certain chemicals and petroleum along with cost recoveries and penalties, covers the cost.11Office of the Law Revision Counsel. 26 USC 9507 – Hazardous Substance Superfund
The Innocent Landowner Defense
Buying property that turns out to be contaminated is one of the biggest financial risks in real estate, precisely because CERCLA can hold current owners liable regardless of fault. The law offers a defense for innocent landowners, but the requirements are demanding. You must show that you had no reason to know about the contamination when you bought the property, and you can only do that by proving you conducted “all appropriate inquiries” into the property’s history before closing.12Office of the Law Revision Counsel. 42 USC 9601 – Definitions
In practice, that means hiring an environmental professional to perform a Phase I Environmental Site Assessment before you purchase. The review examines past uses, ownership history, government records, and physical conditions to flag potential contamination. If contamination is later discovered and you skipped this step, the innocent landowner defense is off the table.13US EPA. Third Party Defenses/Innocent Landowners Even with a completed assessment, you must cooperate fully with any cleanup effort and comply with land-use restrictions tied to the remediation.
Reporting Hazardous Releases
CERCLA also imposes an immediate reporting obligation on anyone in charge of a facility or vessel where a hazardous substance release occurs. If the amount released equals or exceeds the reportable quantity for that substance, you must notify the National Response Center right away.14Office of the Law Revision Counsel. 42 USC 9603 – Notification Requirements Respecting Released Substances The default reportable quantity is one pound for listed hazardous substances, though the EPA has adjusted the threshold for many individual chemicals.15US EPA. Hazardous Substance Designations and Release Notifications Failing to report is itself a violation that can result in penalties.
Penalties for Violations
All three laws carry serious consequences for noncompliance, including civil fines and criminal prosecution. Under the Clean Water Act, criminal penalties scale with the violator’s mental state. A first negligent violation carries fines of $2,500 to $25,000 per day and up to one year in prison. A first knowing violation carries fines of $5,000 to $50,000 per day and up to three years, with penalties doubling for repeat offenses.16Office of the Law Revision Counsel. 33 USC 1319 – Enforcement Civil penalties, which do not require a criminal conviction, are adjusted for inflation and can exceed $68,000 per day per violation at current levels.
Knowing violations of Clean Air Act requirements, including emission standards, permit conditions, and inspection rules, carry up to five years in prison for a first offense, doubling for a second conviction. Falsifying monitoring data or failing to file required reports carries up to two years, also doubled for repeat offenses.17Office of the Law Revision Counsel. 42 USC 7413 – Federal Enforcement Knowingly releasing hazardous air pollutants under circumstances that place someone in imminent danger of death or serious injury triggers the harshest penalties under the Act.
CERCLA’s penalty structure is different because its primary enforcement mechanism is liability for cleanup costs rather than fines per day of violation. A single Superfund cleanup can cost tens of millions of dollars, and any responsible party can be forced to bear that entire cost. The Act also authorizes civil penalties for failure to report a release and criminal penalties for knowingly providing false information during a cleanup.
Citizen Suits
One powerful feature shared by all three laws is the citizen suit provision, which lets ordinary people and organizations enforce them directly in federal court. You do not need to be a government agency to hold a polluter accountable.
Under the Clean Air Act, any person can sue someone alleged to be violating an emission standard, permit condition, or EPA order. You can also sue the EPA itself for failing to perform a mandatory duty.18GovInfo. 42 USC 7604 – Citizen Suits The Clean Water Act contains a nearly identical provision for effluent standards and discharge permits.19Office of the Law Revision Counsel. 33 USC 1365 – Citizen Suits
Both laws require the same procedural step before filing: you must give 60 days’ written notice to the EPA, the relevant state agency, and the alleged violator. If the EPA or the state begins and actively pursues a case against the violator during that period, the citizen suit is generally blocked, though you can intervene in the government’s case as a matter of right.19Office of the Law Revision Counsel. 33 USC 1365 – Citizen Suits To have standing, you need to show a concrete injury connected to the alleged violation, not just a general interest in seeing the law enforced. Environmental organizations typically establish standing through members who live, work, or recreate near the polluting facility and can show they are personally affected.