NPDES / Wastewater Permitting

NPDES Wastewater Permitting

NPDES Program Basics

The NPDES Section of the Iowa Department of Natural Resources issues discharge permits under delegation of the federal program known as the NPDES (National Pollutant Discharge Elimination System) permit program. The NPDES program regulates the direct discharge of wastewater to surface waters. The authority to issue NPDES permits rests either with a state or with the U.S. Environmental Protection Agency (EPA). States can gain approval to administer the NPDES program by demonstrating their program meets the federal requirements. Iowa was delegated authority to administer the NPDES program by EPA in 1978.

Under Iowa's NPDES program, all facilities that discharge pollutants from any point source into surface waters are required to obtain an NPDES or operation permit from the Iowa DNR. The permits require compliance with all federal standards, state rules, and state administrative code.

The term pollutant includes any type of industrial, municipal, and agricultural waste discharged into water. Pollutants can enter waters from a variety of pathways including agricultural, domestic, and industrial sources. These sources are generally categorized as either point sources or non-point sources.

Typical point source discharges include discharges from publicly owned treatment works (POTWs), discharges from industrial facilities, and discharges of urban runoff. While provisions of the NPDES Program do address certain specific agricultural activities, the majority of agricultural facilities are defined as non-point sources and are exempt from NPDES regulation.

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

Because POTWs are direct dischargers, they must obtain an NPDES permit. If the amount of pollutants leaving a POTW is too high, or the discharge endangers public health or the environment, the facility violates its permit and can be fined and/or required to upgrade. A POTW may have trouble meeting its NPDES permit conditions if there are too many pollutants in the wastewater flowing into the treatment plant. One way to reduce the amounts of pollutants in influent wastewater is to require pretreatment. Thus, the conditions of a POTW's permit might dictate the need for pretreatment. Some larger cities in Iowa have accepted responsibility for administering local pretreatment programs that regulate industrial discharges in their community.

Industries, businesses, and other privately-owned facilities that discharge directly to surface waters must also obtain an NPDES permit. Industries who discharge wastewater to a POTW may be required to have a treatment agreement with the POTW. The NPDES Section reviews treatment agreements for conformance to federal and state pretreatment requirements.

To read more about wastewater, please view the following article from the Iowa Conservationist: Down the Drain: What Happens to Our Wastewater?

Types of NPDES Permits

An NPDES permit is a license for a facility to discharge a specified amount of a pollutants into a waterbody under certain conditions. The 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 a permit specifically tailored to an individual facility. Once a facility submits an application, a permit writer develops a permit for that particular facility based on the application and issues the permit for a specific time period (generally five years) with a requirement that the facility reapply prior to the expiration date.

A general permit covers multiple facilities within a specific category. General permits offer a cost-effective option because many facilities can be covered under a single permit. General permits may be written to cover categories of point sources having common elements, such as:

Facilities with the same or similar types of operations;
Facilities discharging the same type of waste;
Facilities that require the same effluent limits or operating conditions; and
Facilities that require similar monitoring.

By issuing general permits, the DNR can allocate resources more efficiently and can provide more timely permit coverage. In addition, using a general permit ensures consistency of permit conditions for similar facilities. For more information on Iowa’s general NPDES permits, see the NPDES General Permits page.

Major Components of an NPDES Permit

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

Cover Page - Contains the name and location of the permittee, a statement authorizing the discharge, and the location of the authorized discharge.
Effluent Limits - The primary mechanism to control discharges of pollutants. Permit writers spend a majority of their time deriving effluent limits based on applicable technology and water quality standards.
Monitoring and Reporting Requirements - Used to characterize waste streams and receiving waters, evaluate wastewater treatment efficiency, and determine compliance with permit conditions.
Special Conditions - Conditions developed to supplement effluent limits. Examples include best management practices (BMPs) and additional monitoring.
Standard Conditions - Pre-established conditions that apply to all NPDES permits that outline the legal, administrative, and procedural permit requirements.

Development of an Individual NPDES Permit

The NPDES permitting process begins when the owner of a facility (permittee) submits an application. A permit writer in the NPDES section will review the application and contact the applicant if needed. When the application is complete, a permit writer develops a draft permit and justification for the permit conditions (referred to as the permit rationale).

To develop a permit, a permit writer will first derive technology-based effluent limits (often from federal regulations). Next, the permit writer will derive effluent limits to protect state water quality standards (water quality-based effluent limits). The technology and water quality -based effluent limits are then compared, and the more stringent limits are applied in the permit. The decision-making process for deriving limits is documented in the permit rationale. A permit may have both technology-based and water quality-based permit limits.

Following the development of effluent limits, the permit writer sets monitoring and reporting conditions and facility-specific special conditions, and includes the standard permit conditions. Once the draft permit is complete, the public can submit comments. A public notice announces the draft permit, the due date for comments, and the means for submitting comments. After the comment period, the permit writer develops the final permit, responds to any comments, documents decisions on the final permit, and issues the final permit.

For more information about Iowa's NPDES permits and permit program, please use the links in the left navigation bar.