Definition
A federal permit program established under the Clean Water Act that regulates the discharge of pollutants from point sources into waters of the United States. Airports and aviation facilities that discharge stormwater or wastewater (for example, runoff from ramps, fuel storage areas, deicing operations, or aircraft washing) are typically required to hold an NPDES permit and meet specific limits on what may enter local waterways.
Plain English
A government permit system that controls what airports and other facilities are allowed to let flow into rivers, lakes, and streams. If an airport's water runoff could carry fuel, deicing fluid, or other contaminants, the airport needs an NPDES permit and must follow rules on cleanliness.
Context Anchor
You may see NPDES in airport operations, construction, fueling, washing, stormwater, or environmental compliance documents rather than in cockpit flying procedures.
Derivation
The name describes the purpose: 'eliminate' the discharge of pollutants into national waters. It comes from the 1972 Clean Water Act, which set up this permit system as the main legal tool for controlling water pollution in the United States.
Why Pilots Care
Pilots and operators handling fuel, deicing fluid, or aircraft washing on airport property are working inside an NPDES-regulated environment. Spills, careless rinsing, or improper disposal can trigger reportable violations for the airport and the operator, with real legal and financial consequences.
Grounding Statement
If water leaving an airport can carry fuel, oil, chemicals, or dirt into public waterways, NPDES may control how that water must be handled.
Intuition Check
NPDES is not an aircraft system or navigation procedure. It is an environmental permit program that applies to water pollution from facilities, including some airport activities.
Example Sentence 1
The airport's NPDES permit requires that deicing runoff be collected and treated before it reaches the storm drain.
Example Sentence 2
Construction plans near the taxiway included NPDES drainage controls to avoid runoff violations.