What does an NPDES Permit regulate?

An NPDES Permit, or National Pollutant Discharge Elimination System Permit, primarily regulates the limits on discharges into U.S. waterways. This permit system is designed to control water pollution by regulating point sources that discharge pollutants into waters of the United States. It requires facilities that discharge any pollutants from a point source into navigable waters to obtain a permit, ensuring they adhere to specific limits and monitoring requirements to protect water quality.

This regulatory framework is crucial for maintaining the integrity of aquatic ecosystems and ensuring clean water for public use. The other options, while related to water management, do not specifically address the core function of the NPDES Permit, which is focused explicitly on controlling and monitoring discharges to protect water bodies.