The National Pollutant Discharge Elimination System (NPDES) prohibits the discharge of pollutants into U.S. waters unless a permit is issued by

The National Pollutant Discharge Elimination System (NPDES) is a crucial part of the Clean Water Act that regulates discharges of pollutants into U.S. waters. Under this system, a permit is required for any discharge of pollutants to ensure that water quality standards are maintained and protected.

The correct answer indicates that a permit can be issued either by the Environmental Protection Agency (EPA) or by a state agency that has been authorized to administer the NPDES program. This flexibility accommodates federal and state governance of water quality protection, allowing states to have more localized control and responsiveness to their specific environmental conditions while still adhering to federal standards.

It's important to recognize that the EPA is the default permitting authority at the federal level, but many states have demonstrated the capability and have been authorized to issue NPDES permits on their own. This dual approach provides a framework that promotes cooperation between federal and state agencies in protecting water resources.

In summary, the option that encompasses both the EPA and state agencies as entities that can issue permits reflects the collaborative regulatory structure established under the NPDES, which is vital for maintaining the integrity of U.S. waters.