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Continuation of Program Overview

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Statutory Authority

In 1972, under the authority of Public Law 92-500, the Federal Water Pollution Control Act, EPA created the NPDES. This was intended to control discharges to the Nation's waters from industrial, commercial, and municipal point sources; these discharges presented a threat to water quality and public health. Initial efforts focused on traditional pollutant discharges from industrial manufacturing processes and municipal Wastewater Treatment Plants.

Later amended to become the CWA, this law provides broad authority for EPA or States (authorized by EPA) to issue NPDES permits. Specific reporting requirements are established in the permits to require monitoring and reporting of discharges. The CWA establishes two types of standards for conditions in NPDES permits: technology-based standards and water quality-based standards. These standards are used to develop effluent limitations and special conditions in NPDES permits. Numeric effluent limitations establish pollutant concentration limits for effluents at the point of discharge. Section 402(a)(1) authorizes the inclusion of other types of conditions that are determined to be necessary, known as special conditions, in NPDES permits. Special conditions can include requirements for best management practices (BMPs) to control WWFs.

Since the implementation of the CWA requirements, EPA has begun to address nontraditional sources of pollution, such as those that result from WWF. The NPDES program currently requires permits for pointsources, but not for NPSs.

EPA's CSO Control Policy

EPA issued a National Combined Sewer Overflow Control Strategy on August 10, 1989 (EPA, 1989). This strategy reaffirmed that CSOs are point-source discharges subject to NPDES permit and the CWA requirements. The strategy recommended that all CSOs be identified and categorized according to their status of compliance with these requirements. It also set forth three objectives: ensure that if CSOs occur, they are only as a result of wet weather; bring all weather CSO discharge points (wet weather and dry weather) into compliance with the technology-based and water quality-based requirements of the CWA; and minimize the impacts of CSO on water quality, aquatic biota, and human health. In addition, the CSO Strategy charged all states to develop permitting strategies designed to reduce, eliminate, or control CSO.

Although the CSO Strategy was successful in focusing increased attention on CSO, it fell short in resolving many fundamental issues. In mid-1991, EPA initiated a process to accelerate implementation of the Strategy. The process included negotiations with representatives of the regulated community, State regulatory agencies, and environmental groups. The initiative resulted in a CSO Control Policy which: provides guidance to NPDES permitting and enforcement authorities, State water quality standard (WQS) authorities, and NPDES permittees with CSO; ensures coordination among the appropriate parties in planning, selecting, designing, and implementing CSO management practices and controls to meet the requirements of the CWA; and ensures public involvement during the decision making process.

The CSO Control Policy contains provisions for developing appropriate, site-specific NPDES permit requirements for all combined-sewer systems that overflow due to wet-weather events. It also announces an enforcement initiative that requires the immediate elimination of overflows occurring during dry weather and ensures compliance with the remaining CWA requirements as soon as possible.

The CSO Control Policy contains the following four key principles to ensure that CSO controls are cost effective and meet the requirements of the CWA:

NPDES Permitting Program for Stormwater

Responding to the need for comprehensive NPDES requirements for stormwater point-source discharges, Congress amended the CWA in 1987 to require the EPA to establish phased NPDES requirements for stormwater discharges. These comprehensive requirements address permit applications, regulatory guidance, and management and treatment requirements. To implement these requirements, EPA published the initial Phase I Stormwater program permit application requirements to address certain categories of stormwater discharges associated with industrial activity and discharges from larger stormsewer systems (located in 842 municipalities with populations of 100,000 or more) on November 16, 1990 (EPA, 1990).

One-hundred thirty thousand facilities have been identified as having stormwater discharge associated with industrial activity.

These include all stormwater discharges associated with industrial activity whether they discharge through municipal stormwater systems (whether they be small or large) or directly into waters of the United States. Discharges of stormwater to a sanitary-sewer system or to a Wastewater Treatment Plant are excluded.

Facilities with stormwater discharges associated with industrial activity include: manufacturing facilities; construction operations disturbing five or more acres; hazardous waste treatment, storage, or disposal facilities; landfills; certain sewage treatment plants; recycling facilities; power plants; mining operations; some oil and gas operations; airports, and certain other transportation facilities. Government-owned facilities must also comply. Stormwater discharge permits will provide a mechanism for monitoring the discharge of pollutants to waters of the United States and for establishing appropriate controls.

The Phase II Stormwater program potentially applies to smaller municipalities and is estimated to include as many as 1.1 million commercial, institutional, and retail sources, and 5,700 municipalities (urbanized areas of populations between 50,000 and 100,000). This is about ten times the number of facilities identified in Phase I. In 1995, EPA submitted a Report to Congress providing data, facts, and other information on sources to be considered under a Phase II Stormwater program.

Legal Framework for Controlling SSOs

The CWA prohibits point-source discharges of pollutants to waters of the United States unless authorized by NPDES permit. Thus, unpermitted discharges from sanitary-sewer systems, e.g., SSOs, violate the CWA. This is true whether the discharge is directly to surface waters or indirectly through groundwater hydrologically connected to surface waters. Similarly, SSOs that drain through streets or other areas into storm sewers and then into waters of the United States violate the CWA, unless authorized by NPDES permit. Finally, even SSOs that do not discharge to waters of the United States may be associated with NPDES permit violations. For example, 40 CFR 122.41(e) requires that NPDES permits include a provision for proper operation and maintenance of all treatment facilities and systems and controls installed or used by the permittee to comply with permit conditions. Poor operation and maintenance practices that result in SSO would violate such permit provisions.

SSOs may be specifically identified as subject to NPDES monitoring and reporting requirements. Operators of systems with SSOs that are not authorized by NPDES permit must either eliminate the discharge or submit a permit application (see 40 CFR 122.21(a)).

The CWA does not specify whether the technology-based standard for permits for SSO would be either: (1) the standard for publicly owned treatment works (POTW) or (2) the standard for all point-source discharge except those from POTW.

For POTW, the CWA requires secondary treatment. For all other point-source discharges, the CWA has different requirements for different categories of pollutants: (1) best available technology economically achievable for toxic pollutants and nonconventional pollutants, and (2) best conventional pollutant control technology for conventional pollutants. Conveyances (e.g.,sewers, pump stations) which transport wastewater to the Wastewater Treatment Plant are included in the regulatory definition of POTW. SSOs discharge from these types of conveyances. Therefore, one interpretation of the legal framework for controlling SSOs is that the POTW secondary treatment standard applies. For combined sewer systems, EPA decided bypasses occur only from the process areas on the plant side of the headworks. Therefore, in the CSO context, secondary treatment requirements are only applicable to discharges from the Wastewater Treatment Plant, not discharges from CSO outfalls that occur before reaching the headworks of the treatment works. This interpretation was upheld by the court in Montgomery Environmental Coalition v. Costle, (1980). EPA has not clarified whether SSOs should be addressed in a similar or different manner than CSOs.

A Federal Advisory Committee Act Urban WWFs Advisory Committee subcommittee was formed to provide recommendations on how to address issues associated with SSOs including deciding between sewer rehabilitation and treatment options to control SSO pollution.

NPS Requirements

Section 319 of the CWA requires States to develop NPS assessment and management programs. During FY96, EPA began to implement changes designed to strengthen the framework for State and national NPS management programs. The two primary areas of change will be establishing clear benchmarks for upgraded State NPS management programs and streamlining NPS grants administration for grant eligibility.

The specific NPS management program requirements to be implemented during FY96 are:

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