Wastewater Permitting - NPDES

Iowa was delegated authority to administer the NPDES program by the EPA in 1978. Under Iowa's NPDES program, all facilities that discharge pollutants from any point source into waters of the United States or waters of the state are required to obtain an NPDES or operation permit, respectively. These permits require compliance with all federal and state standards and may require additional controls based on local conditions.

The term pollutant includes any type of industrial, municipal, and agricultural waste discharged into water. Pollutants can enter waters from a variety of sources, and the sources are categorized as either point sources or non-point sources. Point source discharges include those from publicly owned treatment works (POTWs), from industrial facilities, and from urban runoff. While some provisions of the NPDES program address certain agricultural activities, most agricultural facilities are defined as non-point sources and are exempt from NPDES regulation.

Pollutant contributions may come from both direct and indirect sources.  Direct sources discharge wastewater directly into a waterbody, whereas indirect sources discharge wastewater to a POTW, which in turn discharges into a waterbody.

Because POTWs are direct dischargers, they must obtain and comply with an NPDES permit. If the concentration of pollutants leaving a POTW is too high, or if a POTW's discharges endanger public health or the environment, the facility can violate its permit and can be fined and/or required to upgrade. A POTW may have trouble complying with its NPDES permit if the pollutant amounts in the wastewater flowing into the treatment plant (influent wastewater) are too high. Pollutants in influent wastewater can often be reduced by pretreatment. Some larger cities in Iowa have accepted responsibility for administering local pretreatment programs that regulate industrial discharges in their community.

Industries that are direct dischargers to surface waters must also obtain and comply with an NPDES permit. Industries who discharge wastewater directly to a municipal sewer system may be required to have a treatment agreement. The NPDES Section reviews treatment agreements for conformance to federal and state pretreatment requirements. 

An NPDES permit is a license for a facility to discharge a specified amount of pollutants into a receiving water under certain conditions. A permit limits the amount of pollutants a wastewater treatment plant may discharge. The two basic types of NPDES permits are individual and general permits. 

An individual permit is specifically tailored to an individual facility. Once a facility submits the appropriate permit application(s) (available on the NPDES Permit Application Forms webpage), the DNR develops a specific permit based on the application and issues the permit to the facility for a specific time period (usually five years) with a requirement that the facility reapply prior to the expiration date.

A general permit covers multiple facilities within a specific category. NPDES General Permits are a cost-effective option because a large number of facilities that can be covered under a single permit. General permits may cover categories of point sources having common elements, such as:

• Facilities that involve the same or substantially similar types of operations;
• Facilities that discharge the same types of wastes;
• Facilities that require the same effluent limits or operating conditions; and
• Facilities that require the same or similar monitoring.

General permits allow the DNR to allocate resources in a more efficient manner and provide more timely permit coverage. For example, a large number of facilities with common elements may be covered under a general permit without expending the time and money necessary to issue many individual permits. In addition, using a general permit ensures consistency of permit conditions for similar facilities.

All NPDES permits, at a minimum, consist of five general sections:

1. Cover Pages - Contains the permittee's name and location, a statement authorizing the discharge, and the specific discharge locations that are authorized.
2. Effluent Limits - Primary means of controlling pollutant discharges. Permit writers spend a majority of their time deriving appropriate effluent limits based on applicable technology-based and water quality-based standards.
3. Monitoring and Reporting - Used to characterize waste streams and receiving waters, evaluate treatment efficiency, and determine permit compliance.
4. Special Conditions - Conditions developed to supplement effluent limits, such as best management practices (BMPs) and additional monitoring.
5. Standard Conditions - Preestablished conditions that apply to all NPDES permits and delineate the legal, administrative, and procedural requirements.

The NPDES permitting process begins when a facility owner (permittee) submits an application. After receiving an application and making a decision to proceed with the permit, a permit writer reviews the application for accuracy. When an application is complete, a permit writer develops a draft permit and the justification for the permit conditions (referred to as a permit rationale).

The first major step in the permit development process is deriving technology-based effluent limits (TBELs) based on federal standards. Next a permit writer derives effluent limits that are protective of state water quality standards (i.e., water quality-based effluent limits or WQBELs). The permit writer then compares the TBELs and WQBELs and places the more stringent limits in the permit. The decision-making process for deriving limits is documented in the permit rationale. A permit may have TBELs for some parameters and WQBELs for others.

Following the development of effluent limits, a permit writer develops appropriate monitoring and reporting conditions, facility-specific special conditions, and includes the standard permit conditions. After a draft permit is complete, it is sent to the facility. A public notice announces that a draft permit is available for review, and interested parties may submit comments regarding the draft permit. The public can sign up for email notifications for new draft individual permits on the Wastewater Permit Information Exchange (WWPIE) system. After the comment period ends, the permit writer considers any comments, develops a final permit, documents the decisions for the record, and issues the final permit to the facility. All final individual NPDES and operation permits can be viewed on WWPIE, and a list is available on the Current Permits webpage.