The Clean Water Act

The Clean Water Act (CWA) is the primary federal statute governing water pollution in the United States. Its objective is to restore and maintain the chemical, physical, and biological integrity of the nation's waters.

Scope and Coverage

The CWA regulates the discharge of pollutants into navigable waters of the United States. The scope of "navigable waters" (defined as "waters of the United States") has been the subject of extensive litigation and regulatory interpretation, with the Supreme Court addressing the issue in Rapanos v. United States (2006) and Sackett v. EPA (2023).

The NPDES Permit System

The National Pollutant Discharge Elimination System (NPDES) is the backbone of CWA regulation. Any facility that discharges pollutants from a point source (a discrete conveyance like a pipe, ditch, or outfall) into navigable waters must obtain an NPDES permit.

Permits specify:

Effluent limitations — maximum pollutant levels that may be discharged

Monitoring and reporting requirements

Best management practices

Compliance schedules

Technology-Based and Water Quality-Based Standards

The CWA uses a two-tier approach:

Technology-based standards — require application of treatment technologies regardless of the receiving water's condition (e.g., Best Available Technology — BAT)

Water quality-based standards — additional limits applied when technology-based standards alone are insufficient to meet water quality standards for a particular water body

Nonpoint Source Pollution

Nonpoint source pollution — from agricultural runoff, stormwater, and other diffuse sources — is addressed primarily through state planning and voluntary programs under Section 319, rather than the permit system.

Wetlands Protection

Section 404 of the CWA regulates the discharge of dredged or fill material into wetlands and other waters. The Army Corps of Engineers issues Section 404 permits, with EPA oversight. Developers must often demonstrate that no practicable alternatives exist and must provide compensatory mitigation (creating or restoring wetlands elsewhere).

Enforcement and Citizen Suits

The CWA provides for civil penalties, criminal prosecution (for negligent or knowing violations), and citizen suits allowing any person to sue alleged violators or the EPA for failure to enforce.

The Clean Water Act