Discharges to waterways in the US are regulated by the National Pollutant Discharge Elimination System (NPDES), which was created by the Clean Water Act. The Endangered Species Act further regulates activities affecting critical habitat for threatened or endangered species, such as some species of fish. How do these work, and what does it mean for water treatment?
What is the Clean Water Act?
The Clean Water Act is a law in the United States that helps protect rivers, lakes, and oceans from pollution. It was passed in 1972 in response to growing concerns about serious water pollution across the United States. At the time, many rivers and lakes were so polluted with industrial waste and sewage that they were unsafe for fishing, swimming, or even touching. One famous example was the Cuyahoga River in Ohio, which was so contaminated that it actually caught fire multiple times.
The goal of the Clean Water Act was to restore and maintain the integrity of the nation's waters. It gave the federal government, through the Environmental Protection Agency (EPA), the authority to regulate pollution by setting standards and requiring permits for anyone discharging pollutants into surface waters. The Act marked a major turning point in U.S. environmental policy and laid the foundation for modern water protection efforts.
What is the NPDES?
The National Pollutant Discharge Elimination System (NPDES) is a regulatory program established under the Clean Water Act to control water pollution by regulating point source discharges of pollutants into U.S. waters. Administered by the U.S. Environmental Protection Agency (EPA) or authorized state agencies, the NPDES program requires facilities such as industrial operations, municipal wastewater treatment plants, and construction sites to obtain permits before discharging wastewater or stormwater into surface waters. These permits set specific limits on the types and quantities of pollutants that can be released, along with monitoring, reporting, and best management practice requirements to protect water quality and public health. Through NPDES, the EPA ensures that discharges are managed in a way that meets environmental standards and supports the long-term health of rivers, lakes, and coastal waters.
What is the Endangered Species Act and how does it affect the NPDES?
The Endangered Species Act (ESA) passed in 1973 to protect animals and plants that are at risk of extinction, along with the habitats they need to survive. It is managed by the U.S. Fish and Wildlife Service and the National Marine Fisheries Service. The law makes it illegal to harm, kill, or damage the habitat of any species listed as endangered or threatened.
The ESA affects NPDES (National Pollutant Discharge Elimination System) permits by requiring that any water discharge allowed under the permit does not harm endangered species or their habitats. Before an NPDES permit can be issued, the permitting agency must evaluate whether the discharge could impact a protected species. If there’s a potential impact, the agency must consult with federal wildlife experts.
This process can lead to changes in the permit—such as limits on pollutants, special discharge conditions, or additional monitoring—to ensure the activity complies with the ESA. In some cases, a permit could even be denied to prevent harm to a species. This coordination ensures that protecting water quality also supports the protection of vulnerable wildlife.
Example: Endangered Species Act (ESA) Affecting an NPDES Permit
A good example is the case of Puget Sound Chinook salmon in Washington State. These salmon are listed as threatened under the Endangered Species Act. When a city or industrial facility in the Puget Sound region applies for an NPDES permit to discharge treated stormwater or wastewater into local rivers or directly into the Sound, the permitting agency (like the Washington Department of Ecology or EPA) must evaluate whether the discharge could affect the salmon or their spawning habitat.
If the discharge contains pollutants like copper or zinc, which are known to interfere with salmon’s ability to navigate and survive, the ESA requires that this risk be addressed. This often results in:
- Stricter pollutant limits in the permit
- Use of advanced treatment technologies like biofiltration or enhanced media filters
- Monitoring requirements to track pollutant levels and protect spawning seasons
In this way, the ESA can significantly shape the conditions of an NPDES permit to prevent harm to a protected species, ensuring both clean water and species protection goals are met.
