The Environmental Protection Agency (EPA) is a United States federal regulatory agency responsible for developing and enforcing environmental law, conducting environmental research, and administering federal grants for environmental programs. Established by executive reorganization under President Richard Nixon, the EPA began operations on 2 December 1970 following passage of the National Environmental Policy Act of 1969. The agency operates under the executive branch and is headed by an Administrator appointed by the President and confirmed by the Senate. Its jurisdiction spans air quality, water quality, land contamination, toxic substances, pesticide regulation, and radiation protection, among other areas.

The EPA administers a body of federal environmental statutes, including the Clean Air Act, the Clean Water Act, the Resource Conservation and Recovery Act, the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA, commonly known as Superfund), and the Toxic Substances Control Act. The agency sets national standards, issues permits, monitors compliance, and brings enforcement actions against violators. It also funds and conducts scientific research through its Office of Research and Development and maintains a network of laboratories and monitoring stations across the country. The EPA's regulatory actions carry the force of law and are subject to judicial review; regulated industries, states, environmental groups, and individuals have all challenged EPA rules in federal court.

The agency operates through ten regional offices, each responsible for implementing federal environmental programs within a defined geographic area. States may seek authorization to administer certain federal environmental programs within their borders, subject to EPA oversight. This federal-state relationship is a recurring subject of policy debate, with ongoing disagreement about the appropriate division of authority. For an account of the agency's founding, the evolution of its statutory authority, and shifts in enforcement priorities across administrations, see Environmental Protection Agency - History.

The EPA's regulatory authority derives from statutes enacted by Congress; the agency does not possess inherent rulemaking power. Significant EPA actions include setting National Ambient Air Quality Standards (NAAQS), establishing maximum contaminant levels for drinking water, listing and prioritizing contaminated sites for remediation under Superfund, and registering or restricting pesticides and industrial chemicals. In 2007, the U.S. Supreme Court held in Massachusetts v. EPA that greenhouse gases are air pollutants subject to regulation under the Clean Air Act if the agency determines they endanger public health or welfare; the EPA issued such an endangerment finding in 2009. The scope of that authority, and whether subsequent regulatory actions exceeded it, has been contested in litigation and in Congress. In 2022, the Supreme Court's decision in West Virginia v. EPA curtailed the agency's ability to mandate broad shifts in the electricity sector's generation mix, invoking the major questions doctrine.

The agency's budget, staffing levels, and enforcement priorities vary across presidential administrations, producing significant variation in regulatory aggressiveness and rulemaking activity over time.

There is broad scientific consensus, reflected in EPA assessments and peer-reviewed literature, on a range of factual questions the agency addresses - including the health effects of criteria air pollutants, the toxicity of certain chemicals, and the role of anthropogenic greenhouse gas emissions in climate change. For scientific consensus positions relevant to EPA's regulatory domain, see Climate Science - Consensus and Air Quality Health Effects - Consensus. Whether and how that scientific consensus should translate into specific regulatory requirements, economic trade-offs, or the appropriate scope of federal authority are separate questions, addressed under Viewpoints and Debates below.

For extended treatment of contested questions surrounding the EPA's authority, effectiveness, and appropriate scope, see Environmental Protection Agency - Debate.

• Expansive federal regulation justified - Some argue that environmental problems are inherently interstate and intergenerational, that market actors will not internalize pollution costs without regulatory compulsion, and that a strong federal agency is necessary to prevent what proponents describe as a race to the bottom among states competing to attract industry by relaxing environmental standards. See EPA - Expansive Federal Regulation Viewpoint-viewpoint.

• Regulatory overreach and economic harm - Critics contend that the EPA has exceeded its statutory authority, imposes costs on industry and consumers disproportionate to environmental benefits, and substitutes agency judgment for legislative and democratic deliberation. See EPA - Regulatory Overreach Viewpoint-viewpoint.

• State primacy and federalism - A federalist position holds that environmental regulation is best handled at the state and local level, where regulators are more accountable to affected communities and better positioned to weigh local conditions. See EPA - State Primacy Viewpoint-viewpoint.

• Environmental justice framework - Some analysts and advocates argue that EPA enforcement and standard-setting have systematically underprotected communities of color and low-income communities, and that the agency should explicitly incorporate distributional equity into its regulatory criteria. See EPA - Environmental Justice Viewpoint-viewpoint.

• Agency capture and industry influence - A distinct critique, advanced from varying political directions, holds that the EPA has at times been captured by the industries it regulates or by political interests, undermining the scientific integrity of its decisions. See EPA - Regulatory Capture Viewpoint-viewpoint.

• Environmental Protection Agency - History
• Environmental Protection Agency - Debate
• EPA - Expansive Federal Regulation Viewpoint-viewpoint
• EPA - Regulatory Overreach Viewpoint-viewpoint
• EPA - State Primacy Viewpoint-viewpoint
• EPA - Environmental Justice Viewpoint-viewpoint
• EPA - Regulatory Capture Viewpoint-viewpoint
• Clean Air Act
• Clean Water Act
• Superfund (CERCLA)
• Climate Science - Consensus
• Administrative State
• Federalism and Environmental Regulation

1. Nixon, Richard M. “Reorganization Plan No. 3 of 1970.” 9 July 1970. Established the EPA effective 2 December 1970.
2. National Environmental Policy Act of 1969, Pub. L. 91-190, 83 Stat. 852 (1 January 1970).
3. Massachusetts v. Environmental Protection Agency, 549 U.S. 497 (2007).
4. EPA. “Endangerment and Cause or Contribute Findings for Greenhouse Gases Under Section 202(a) of the Clean Air Act.” 74 Fed. Reg. 66,496 (7 December 2009).
5. West Virginia v. Environmental Protection Agency, 597 U.S. 697 (2022).
6. EPA. “Our Mission and What We Do.” U.S. Environmental Protection Agency. https://www.epa.gov/aboutepa/our-mission-and-what-we-do (accessed 15 June 2026).