NPDES Permits

EPA or an authorized state agency issues two basic types of NPDES permits to ensure protection of the receiving water from direct or indirect discharges:

  • Individual Permit. A permit specifically tailored to an individual facility.

  • General Permit (40 CFR 122.28). A permitting authority develops and issues a general permit to cover multiple facilities in a specific category of discharges or of sludge use or disposal practices.

The permitting process is different depending on whether the facility is applying for an individual permit or a general permit.

For individual permits:

  • The permit application must be received 180 days prior to expiration of the existing permit (or prior to the planned discharge).

  • The permit writer determines that the application is complete, and drafts the permit and develops the fact sheet (using all available information).

  • The draft permit (and fact sheet) is then sent to the applicant and publicly-noticed for comments.

  • Once the public comment period ends, the permit writer responds to the comments and revises the permit as necessary. If substantive changes are made, then the permit will be publicly-noticed again.

  • Once the permit is finalized, the permit writer compiles the permit Administrative Record to document the information that was used to develop the final permit.

  • Finally, the permit is issued and becomes effective.

  • Permits are effective for up to 5 years, however, coverage may be administratively extended if the permittee has submitted a timely permit application.

The permitting agency can determine there is a need for a General Permit. For example, if there are several hundred facilities with similar industrial activities, similar discharges, and the permit conditions for each of these industrial activities are the same.

For General Permits:

  • Instead of issuing individual permits to each facility, the permitting authority may develop a single general permit and fact sheet to cover a large number of facilities; publicly notice the proposed permit; receive comments and develop a responses to comments; develop the administrative record; and finalize the permit (which means another notice to indicate the permit is available).

  • Then, facilities that meet the criteria for coverage under the general permit submit a notice of intent (NOI) to be covered by the permit (the state may or may not call this application an NOI). Note: A facility may instead apply for coverage under an individual permit and it may be granted by the permitting agency, if justified.

  • At this point, the permitting authority can accept the NOI, or, determine that the facility is not eligible for the general permit, and require the facility to apply for an individual permit.

NPDES permits protect waters of the United States by placing effluent limitations on discharges. These limitations come in two forms:

The intent of technology-based effluent limits in NPDES permits is to require a level of treatment of pollutants for point source discharges based on available treatment technologies, while allowing the discharger to use any available control technique to meet the limits. For industrial (and other non-municipal) facilities, technology-based effluent limits are derived by:

  • Using national effluent limitations guidelines and standards established by EPA, or

  • Using best professional judgment (BPJ) on a case-by-case basis in the absence of national guidelines and standards.

Water quality based standards are the foundation of the water quality-based control program mandated by the Clean Water Act. Water quality standards define the goals for a waterbody by designating its uses, setting criteria to protect those uses, and establishing provisions to protect water quality from pollutants. A water quality standard consists of four basic elements:

  • designated uses of the water body (e.g., recreation, water supply, aquatic life, agriculture),

  • water quality criteria to protect designated uses (numeric pollutant concentrations and narrative requirements),

  • an antidegradation policy to maintain and protect existing uses and high quality waters, and

  • general policies addressing implementation issues (e.g., low flows, variances, mixing zones).

If a NPDES permit writer determines that technology-based effluent limits are not sufficient to ensure that water quality standards, designed to protect the water quality, will be attained in the receiving water, they must develop water quality-based effluent limits designed to ensure that water quality standards will be attained.

In addition, under CWA ยง402(o), EPA permit writers cannot allow water quality backsliding; NPDES permits cannot be reissued with effluent limits that are less stringent than current permit limits.




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