NPDES Permits: What are they and what do you need to know

Mike Milius, Civil Engineer

November 21, 2017


The National Pollution Discharge Elimination System (NPDES) is the permitting system used to monitor the location and establish discharge requirements for most of the treated water that is released into our environment every day. An NPDES permit is typically considered a license for a facility to discharge a specific amount of a pollutant into a receiving water under certain conditions.

Over the years, I have been highly involved with the review, evaluation, and negotiations associated with these permits. This process has a number of areas a permitee needs to be concerned with. The goal of this article is to provide a brief overview of the program and explain key elements of the permit review process.

History of the Program

The NPDES program started in 1972 as part of the Clean Water Act (CWA). The permit is based on two levels of control: technology-based limits and water quality based limits, if technology-based limits are not sufficient to protect the water body.

In 1977, Congress amended the CWA to enhance the NPDES program, causing the permitting program to become more complex. This amendment shifted the focus from controlling conventual pollutants to controlling toxic dischargers.

The program was updated in 1987, when Congress also passed the Water Quality Act. This legislation called for increased monitoring and accessing water bodies to ensure that water quality standards were being upheld in the nation’s waters. The program continues to be updated, typically every two to three years.

Permitting / Enforcement

The CWA authorizes the Environmental Protection Agency (EPA) to allow the NPDES program to be run by states, tribal, and territorial governments. It enables these entities to perform the permitting and any administrative or enforcement aspects of the program. In states authorized to implement CWA programs, EPA retains oversight responsibilities. Currently 46 states and one territory are authorized to implement the NPDES program.

Permit Types 

Two types of permits are issued in the NPDES program: individual permits and general permits.

Individual Permit

An individual permit is a permit specifically tailored to an individual facility. Once a facility submits the appropriate applications, the permitting authority develops the permit for the specific facility based on the information contained in the permit application, such as type of activity, nature of discharge, receiving stream, water quality, etc. The authority then issues the permit to the facility for a specific time frame. Permits may also authorize facilities to process, incinerate, or beneficially use sewage sludge as in landfills.

The maximum length of a permit is 5 years, and you must reapply before the permit expires. Typically, each permitting authority has some notification and public advertisement requirements they follow before issuing a new, revised, or renewed permit.

General Permit

A general permit covers a group of discharges with similar qualities within a given geographical area. General permits offer a cost-effective option for permitting agencies because many facilities can be covered under one permit. Some examples of this include Storm Water Discharge Permits and Water Treatment Plant Discharge Permits. The type and number of general permits vary dramatically from state to state. These permits are renewed at the agency level.

Permit Requirements

For all discharges that are under an NPDES permit program (both individual and general), there are a number of water quality testing, flow, and reporting requirements. This information is reported back to the regulatory agency on a monthly Discharge Monitoring Report (DMR).

Permit Key Items

As noted above for the individual permits, permits can be complicated and can have major implications for the facility. Below are some key items to look for when reviewing a new or renewed permit.

New Permit

The key items to look at for a new permit include the discharge and testing requirements. These requirements are key items that will control the design of the treatment facility. These limits are established using a large amount of data regarding the receiving stream and the anticipated discharge. This data should be reviewed for accuracy since it can have a major impact on the proposed limits. Additionally, the testing requirements also need to be fully understood, since this testing will be completed and reported for the life of the permit.

Permit Renewals

For the renewal of permits, make sure you submit the renewal application by the required dates. This is typically 180 days before the current permit expires, but verify this.

Once the renewal data is received, the agency will typically provide you with a draft of the proposed permit for your review. It is recommended that your operational staff and your engineering staff / consultant also be included in this review. We recommend you review the following:

-       Any changes from the current permit to the new permit, including changes to the required sampling

-       Additions to the permit (both contaminate testing and other permit requirements)

-       Whether your treatment facility meets the revised limits (if they are changed)

This is the key time to ask the issuing agency any questions and share concerns. We also recommend reviewing the data being used to establish the new permit limits. The revised permit will include a compliance schedule if the existing facility cannot meet the revised requirements. Review this schedule and make sure you are comfortable with it. Typically, the compliance schedule cannot exceed the length of the permit, but there are exceptions. Also, in some states the cost of the compliance is included so the financial impacts to rate payers can be evaluated.

Current and Future Trends

As you are aware, the regulations continue to get more stringent and the NPDES program is no different. As we look out across our service area, every state has new regulations that are being evaluated and implemented, and legal challenges are being decided. So, the landscape is always changing in the NPDES world. The current trends are targeted around providing more protection for aquatic life and the minimization of nutrients (nitrogen and phosphorus) in the water.

Future requirements are being discussed and a number of these requirements may deal with pharmaceuticals in the water. This is being driven by the effects of medicines passing through our bodies and through our treatment systems and the adverse effect they cause on aquatic life. This will be a major step in compliance efforts since this treatment cannot be addressed by our current typical treatment systems.

The NPDES can be a complicated and ever-changing system. It will continue to be used to implement current and new regulations for discharging water into our environment. The key is to stay abreast of trends and changes in the program and to try and plan for the future. If you need assistance in this area, please contact me at 816.442.6013 or I can help you understand the process and details for your specific situation.

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