Clean Water Act (CWA) Compliance Monitoring

EPA works with its federal, state and tribal regulatory partners to monitor and ensure compliance with clean water laws and regulations in order to protect human health and the environment. The Clean Water Act is the primary federal law governing water pollution.

On this page:

Wastewater Management

The CWA’s National Pollutant Discharge Elimination System (NPDES) Program regulates point sources that discharge pollutants into waters of the United States. Compliance monitoring under the NPDES Program encompasses a range of techniques, from Discharge Monitoring Report reviews, to on-site compliance evaluation as well as providing assistance to enhance compliance with NPDES permits.  The objective is to address the most significant problems and to promote compliance among the regulated community. The NPDES Compliance Inspection Manual provides information on how compliance inspections are conducted.

Compliance monitoring under the NPDES Program takes place largely at the state level.  EPA has authorized all but four states to implement their own NDPES programs to control water pollution.  EPA oversees authorized state programs and has direct implementation responsibilities for the unauthorized states (ID, NM, MA and NH) as well as federal facilities and in Indian Country.

The CWA NPDES Compliance Monitoring Strategy provides implementation guidance to EPA regions and authorized states by describing EPA’s inspection frequency goals.  

NPDES permits are issued to any facility that discharges directly into waters of the US. Regulated entities include industrial and municipal facilities and include the following types of discharges:

  • Municipal Wastewater Overflows and Stormwater Management
    Boom captures litter and other debris carried by stormwater
    Boom captures litter and other debris carried by stormwater

    Overflows of raw sewage and inadequately controlled stormwater discharges from municipal sewer systems can end up in waterways or backup into city streets or basements of homes threatening water quality, human health and the environment. EPA conducts inspections of Publicly Owned Treatment Works (POTWs) including combined sewer systems and sanitary sewer systems. 

    EPA inspections for combined sewer systems involve:

    • reviewing the NPDES permit and any enforcement orders
    • verifying the permittee is in compliance with the permit
    • verifying that the permittee is preventing combined sewer overflows (CSOs) during dry weather
    • reviewing compliance with the nine minimum CSO controls
    • verifying that the permittee is adhering to a schedule in the long term control plan
    • implementing a monitoring program
    • eliminating overflows in sensitive areas
    • minimizing industrial discharges during overflow events

    EPA inspections for sanitary sewer systems involve:

    • reviewing the NPDES permit and any enforcement orders
    • verifying that the permittee is in compliance with the NPDES standard permit conditions to mitigate and institute proper operation and maintenance
    • determining if there are any unpermitted discharges such as sanitary sewer overflows (SSOs)
  • Pretreatment

    EPA implements the National Pretreatment Program to ensure that industrial and commercial facilities (e.g., dry cleaners, gas stations, and food service establishments) discharging to publicly-owned treatment works (POTWs) do not discharge pollutants that pass through POTWs untreated or interfere with a POTW’s wastewater treatment processes and sewage sludge use or disposal. Pollutants including metals, oil and grease, and other pollutants, may interfere with the operation of POTWs leading to the discharge of untreated or inadequately treated pollutants into waterways. As part of the National Pretreatment Program, EPA may approve states and local POTWs to implement an approved pretreatment program.

    EPA conducts both inspections and audits of POTWs to assess the effectiveness of their pretreatment program. Pretreatment audits are designed as a comprehensive review of all facets of the POTW's pretreatment program. The audit addresses all of the items covered in a pretreatment inspection, but in greater detail. 

    Pretreatment inspections involve:

    • reviewing the approved program, annual reports, NPDES compliance status, previous inspection reports, pretreatment files, citizen complaints
    • interviewing officials knowledgeable of the program
    • inspecting various industrial user operations, if appropriate

    Additional information on the National Pretreatment Program.

  • Stormwater

    Stormwater pollution occurs when debris, chemicals, sediment or other pollutants are washed into storm drains and flows into water bodies.  The CWA, and its implementing regulations, requires that certain industrial facilities, construction sites, and municipal separate storm sewer systems (MS4) obtain coverage for their stormwater discharges under an NPDES permit, develop a Stormwater Pollution Prevention Plan (SWPPP) or Stormwater Management Plan (SWMP) and put measures in place to prevent discharges of pollutants in stormwater runoff.  

    EPA conducts inspections of three types of facility operations subject to the storm water regulations:

    These inspections involve:

    • reviewing the storm water permit, the SWPPP or SWMP, and stormwater records and reports
    • interviewing personnel knowledgeable of the SWPPP or SWMP and facility operations
    • reviewing and observing best management practices and control measures in place, and
    • sampling stormwater discharges if appropriate.

    For MS4 operators, EPA also conducts audits designed to provide a comprehensive review of primary facets of the stormwater management program, namely:

    • control of illicit discharges,
    • discharges from construction sites (active and post construction),
    • discharges from industrial facilities (typically only for the largest MS4s),
    • implementation of pollution prevention/good housekeeping practices, and
    • involvement of and outreach to the public.
  • Discharges from Concentrated Animal Feeding Operations (CAFOs)
    Beef cattle operation
    Beef cattle operation

    Under the Clean Water Act, Concentrated Animal Feeding Operations (CAFOs) are defined as point source dischargers.

    EPA's revised NPDES CAFO regulation prohibits discharges from a CAFO to waters of the U.S. without an NPDES permit. The NPDES regulation describes which operations qualify as CAFOs and sets forth the basic requirements that will be included in all CAFOs' permits.

    For information to help determine if your operation is a CAFO and if you require a NPDES permit, EPA has prepared a NPDES Permit Writers' Manual for Concentrated Animal Feeding Operations.

    EPA and state permitting authorities use several approaches to monitor compliance with environmental regulations.

    • Inspections - EPA and state permitting authorities may periodically inspect facilities subject to these regulations. Inspections may be in response to a citizen complaint or tip, a result of a random selection, or targeting based on a state's targeting method. EPA and state permitting authorities conduct two main types of inspections at CAFOs:
      1. Inspections that help to decide whether a facility is a CAFO and if it has discharged or is discharging pollutants to a water of the U.S. without a permit.
      2. Inspections to determine whether a permitted CAFO is in compliance with its NPDES permit.
    • Permits, Records, and Reports - For permitted CAFOs, the permitting authority will monitor all information submitted, including the annual report and the nutrient management plan.
    • Self-audit and self-disclosure - Permittees are responsible for ensuring that a CAFO is always in compliance with the conditions in the NPDES permit. EPA encourages the use of its Audit Policy or Small Business Policy if a facility self-discovers it is in non-compliance.

    EPA has put together a series of answers to commonly asked questions to help livestock and poultry operation owners and operators understand what to expect from EPA National Pollutant Discharge Elimination System (NPDES) inspections.

  • Biosolids

    When sewage sludge from municipal wastewater treatment works is properly treated and processed, it becomes biosolids that can be applied as fertilizer, recycled or disposed.

    EPA conducts inspections of Publicly Owned Treatment Works (POTW) and other industrial facilities that generate, store, transport and dispose of biosolids. EPA inspections involve:

    • reviewing the NPDES permit
    • reviewing sludge self-monitoring records and reports
    • interviewing facility personnel knowledgeable of the facility
    • inspecting the sludge treatment and storage units
    • sampling sludge
    • reviewing how samples are collected and analyzed by the laboratory

Top of Page

CWA Section 404

Section 404 of the CWA regulates the placement of dredged or fill material into wetlands, lakes, streams rivers, estuaries and certain other types of waters. The goal of Section 404 is to avoid and minimize losses to wetlands and other waters and to compensate for unavoidable loss through mitigation and restoration.  Section 404 is jointly implemented by EPA and the U.S. Army Corps of Engineers (Corps).  The Corps issues Section 404 permits and monitors compliance with the issued permits. 

Both the Corps and EPA are responsible for on-site investigations and enforcement of unpermitted discharges under CWA Section 404.  The joint implementation of the Section 404 enforcement program is outlined in a 1989 Memorandum of Agreement (MOA) between the agencies.

The Section 404 Permitting web page contains more detailed information.

Top of Page

Oil Spills and Spill Prevention

The CWA prohibits the discharge of oil or hazardous substances to waters of the U.S. or their adjoining shorelines in quantities that may be harmful to the public health or welfare or the environment.  EPA Oil Pollution Prevention regulations further require owners and operators of non-transportation-related oil facilities to make and implement plans to prevent oil discharges. EPA regional personnel periodically conduct inspections which may be either announced, or unannounced, to ensure compliance with these regulations. Facilities inspected are randomly chosen or:

  • based on risk factors such as facility proximity to drinking water intakes or environmentally sensitive areas, or the age of facility infrastructure (tanks, piping, etc.)
  • as a follow up to an oil spill, or
  • based on citizen complaints or tips

During inspections, EPA inspectors generally:

  • request and review the Spill Prevention Control and Countermeasures (SPCC) Plan
  • interview facility personnel and conduct a walk-through inspection of the facility to ensure the facility is implementing its SPCC Plan
  • interview personnel and conduct a walk-through inspection of the facility to ensure that the facility is implementing its Facility Response Plan (FRP), if applicable; and/or
  • conduct a government-initiated unannounced exercise at FRP facilities to ensure implementation of the Plan

EPA guidance on the SPCC program:

Top of Page