Locations ››

Navigating the NPDES Permitting Program and Phosphorus Regulations

The Problem

The Gulf of Mexico is slowly dying! At least certain “dead spots” are forming in the northern Gulf, adjacent to the Mississippi River. These effects are causing regulations to be ramped up to control the amount of nutrients like Phosphorus and Nitrogen being discharged into the Mississippi River from Wisconsin, Illinois, Iowa, and other states in the Midwest.

The Cause

The main cause for these “dead spots” is an environmental phenomenon called Hypoxia. Hypoxia, or low oxygen, is the decrease of the concentration of dissolved oxygen in the water column to a level that can no longer support living aquatic organisms. Hypoxic areas, or "dead zones," have become more frequent and long-lasting around the globe since the 1970s. The largest hypoxic zone currently affecting the United States, and the second largest hypoxic zone worldwide, is the northern Gulf of Mexico adjacent to the Mississippi River. This animation from the Louisiana Universities Marine Consortium shows how these “dead zones” are created and cause marine life to cease.

Another issue created by excess nutrients is eutrophication, or the proliferation of algae. This is caused by the excess nutrients creating a very friendly environment for algae growth which lead to algal blooms, a coating of algae over a water body that blocks sunlight, and the corresponding normal photosynthesis of aquatic plants. This lack of sunlight keeps the plants from producing oxygen, disrupting the delicate aquatic ecosystem. The introduction of nutrients from households, industry, and agriculture can cause the excess of nutrients into the water systems. In response to the issues caused by excess nutrients, regulations have been instituted to lower the introduction of these excess nutrients into the creeks, rivers, lakes, and eventually the Gulf of Mexico. 

About the NPDES Permit ProgramDiagram of basins draining into Gulf of Mexico

The United States passed the Clean Water Act (CWA) in 1972 in an effort to ensure that the water being discharged was meeting a standard that did not compromise the integrity of the nation’s waters. The CWA was the foundation for the United States Environmental Protection Agency (USEPA) developing the National Pollutant Discharge Elimination System (NPDES) permit program; to protect water quality and public health from the negative impacts of polluted stormwater and wastewater discharge. As authorized by the CWA, the NPDES permit program controls water pollution by regulating point sources that discharge pollutants into waters of the United States. Stormwater and wastewater must meet certain minimum standards before it can be released back into the watershed. For the purpose of this article, we will focus on the wastewater NPDES permits and new phosphorus requirements.

Municipalities and industries throughout the United States that discharge water into surface water bodies typically need to comply with an NPDES permit. The USEPA works in partnership with state agencies, local governments, tribes, the private sector, and non-governmental organizations to regulate the entities that discharge to surface waters. The EPA’s Office of Wastewater Management oversees the regulatory and voluntary programs that help manage our nation’s wastewater. The USEPA describes the NPDES permit in this way, “The permit contains limits on what you can discharge, monitoring and reporting requirements, and other provisions to ensure that the discharge does not hurt water quality or people's health.”

Entities that discharge wastewater directly to surface waters must obtain an NPDES wastewater permit and may be required to provide treatment prior to discharge. Typically, NPDES permits are issued for a five-year term, with the renewal dates dependent on the original issue date.

About Phosphorus Limits

One of the nutrients causing negative impacts to the watershed throughout the Midwest is phosphorus (P). Although naturally occurring, an over-enrichment of P can cause algal blooms, deplete oxygen levels in rivers and lakes, endanger fish and other aquatic life, and cause a number of ailments for humans. This excess P is often attributable to human activity and can come from both “point” and “non-point” sources. Wastewater is considered a “point source”. To address the P contributed by wastewater dischargers, certain states are including P effluent limits in NPDES permits. Some states such as Wisconsin have been on the leading edge of addressing P “point source” levels, having effluent P limits of approximately 1 milligram per liter (mg/L) since 1992. Since implementation of the P limits, publicly owned treatment works (POTWs) in Wisconsin have reduced P discharges by 80 to 90% or more. In 2010, Wisconsin created water quality standards for P in surface waters which resulted in proposed P effluent limits as low as 0.03 mg/L for some dischargers.Graphic showing how stormwater and wastewater runoff cause hypoxia and eutrophication

In recent years, other Midwestern states have also started to develop strategies for reducing overall levels of P in the watersheds. In response to the 2008 Gulf Hypoxia Action Plan, Iowa and Illinois have both developed nutrient reduction strategies to reduce nutrient loading to surface waters and the Gulf of Mexico. The “Iowa Nutrient Reduction Strategy” was first released in 2012 and includes reduction strategies for both point and non-point sources. The “Illinois Nutrient Loss Reduction Strategy” was released for public comment in 2014 and also includes strategies for reducing nutrient loadings from point and non-point sources. For P loadings from wastewater facilities, both Iowa and Illinois are generally focusing on larger dischargers (greater than 1 million gallons per day) and targeting an effluent P limit of around 1 mg/L.

Compliance Strategies

There are a number of different strategies that can be utilized to comply with existing or upcoming P NPDES permit limits.  Depending on current discharge levels, current treatment system, and budget, an effective strategy can be determined. With new P requirements, many industrial and municipal wastewater treatment plants are reviewing their systems to improve their ability to meet these new requirements to avoid regulatory implications. As noted above, regulations vary state to state, so it is important to be aware of your state’s requirements. The financial penalties for not being compliant with an NPDES permit limit are dependent on the infraction, but most of the regulating bodies have set up a system to assist in becoming compliant. A compliance schedule is typically used to effectively phase-in the changes. For new P limits, the regulating agency will often encourage the discharger to determine what the current P levels are and then assess the removal effectiveness and capabilities of the existing system. Next, the schedule typically allows for an evaluation of alternatives for how the permittee will ultimately comply with the new regulations.

The different strategies to meet P limits vary in complexity and budget. For example, wastewater dischargers that are targeting an effluent P concentration of 1 mg/L (Iowa and Illinois) will likely be evaluating Chemical Phosphorus Removal (CPR) or Biological Phosphorus Removal (BPR). However, dischargers that are targeting an effluent P concentration of 0.1 mg/L or less (Wisconsin) will likely be coupling CPR or BPR with an additional treatment process or strategy. Some examples of advanced treatment processes to achieve an effluent P concentration of less than 0.1 mg/L include reactive sand filters, cloth media filters, ballasted settling, and membrane filtration.

Several states also provide watershed-based strategies that can be used by wastewater dischargers to comply with P limits. Water Quality Trading (WQT) is an option being used in Wisconsin and a few other states to meet the new P requirements. In general, WQT allows for an NPDES permittee to work with a non-point source (e.g., farmers) or another point source in the same watershed to reduce P loadings. The permittee would arrange to buy credits for any reductions made by the trade partner. The USEPA has established two main criteria for water quality trading: (1) trades should not result in violations of water quality criteria; and (2) trades must result in an overall improvement of water quality, not just maintain the status quo.

A similar alternative being implemented in Wisconsin is Adaptive Management (AM). Similar to WQT, AM is a compliance strategy built on partnerships between point source facilities and other landowners, municipalities, private, and public entities. The main difference between AM and WQT is that AM focuses on the compliance of P criteria (in-stream concentrations). In other words, the permittee must work with watershed partners to reduce the P concentration in the receiving stream to below the established P criteria for the stream.

Another option that a permittee may choose to evaluate is a regulatory variance. The availability and types of variances differ from state to state. Some states have variances for economic hardship or disadvantaged communities and others have variances for certain types of treatment (e.g., lagoons). In Wisconsin, a multi-discharger variance was authorized by the state’s legislature in 2014. The variance extends the timeline for complying with the proposed low-level P limits and allows permittees to proceed with step-wise reductions in P while also helping to reduce non-point P loadings. The variance is currently being reviewed by the state and will likely be submitted to USEPA for review and approval.


Overall, in order to protect the U.S. waters, there are a number of ways to comply with the requirements. It is important to reach out to experts to help navigate through the complicated options and various regulations. The new NPDES permit P limits are here to stay and Fehr Graham has a number of experts that can help by answering questions and working with you to create a solution. In addition to our wastewater experts, we also have experienced funding specialists to work with you and explore the different options available for paying for the planned programs.


USEPA FAQs -   http://water.epa.gov/polwaste/npdes/stormwater/Stormwater-FAQs.cfm#5 
USEPA Memo    http://water.epa.gov/scitech/swguidance/standards/criteria/nutrients/upload/memo_nitrogen_framework.pdf
Illinois EPA -      http://www.epa.illinois.gov/topics/forms/water-permits/index
Iowa DNR -         http://www.iowadnr.gov/InsideDNR/RegulatoryWater/NPDESStormWater.aspx
Wisconsin DNR - http://dnr.wi.gov/topic/wastewater/generalpermits.html
Adaptive Management Fact Sheet - http://dnr.wi.gov/topic/surfacewater/documents/2012am_factsheet.pdf


Our mission is to improve the quality of life
for our clients in the communities where they live and work by providing
collaborative, insightful, results-driven solutions.