Before discharging pollutants into Waters of the United States under federal law, which of the following describes the permit requirement?

• A. A permit under the NPDES program is required, along with any applicable state water quality certification.
• B. No permit is required for any discharge.
• C. A permit is required only for discharges to groundwater.
• D. A permit under a federal program is required only for interstate waters.

Answer: (D)

Discharging pollutants into Waters of the United States requires an NPDES permit under the Clean Water Act, and, where applicable, a state water quality certification under §401. Waters of the United States include navigable waters and intrastate waters that could affect interstate commerce, as well as connected wetlands. Because of that broad scope, the permit requirement is not limited to interstate waters. The idea that a federal permit is needed only for interstate waters is therefore incorrect. In practice, you obtain an NPDES permit before discharging to surface waters, and you may also need a §401 certification from the state confirming that the discharge meets state water quality standards.