NPDES stands for National Pollutant Discharge Elimination System, which is the compliance system for the Clean Water Act. The NPDES permit requires municipalities, like Aiken County, that discharge storm water to the waters of the United States meet minimum federal water quality requirements trough the implementation of six minimum control measures. The six minimum control measures that Aiken County must adhere to are outlined below.
1.   Public Education and Outreach
Distribute educational materials and perform outreach to inform citizens about the impacts polluted stormwater runoff discharges can have on water quality.
2.   Public Participation/Involvement
Provide opportunities for citizens to participate in program development and implementation.
3.   Illicit Discharge Detection and Elimination
Develop, implement, and enforce a program to detect and eliminate illicit discharges to the storm sewer system (includes developing a system map and informing the community about hazards associated with illegal discharges and improper disposal of waste).
4.   Construction Site Runoff Control
Develop, implement, and enforce an erosion and sediment control program for construction activities.
5.   Post-Construction Runoff Control
Develop, implement, and enforce a program to address discharges of post-construction stormwater runoff from new development and redevelopment areas.
6.   Pollution Prevention/Good Housekeeping
Develop and implement a program with the goal of preventing or reducing pollutant runoff from municipal operations. The program must include municipal staff training on pollution prevention measures and techniques (e.g., regular street sweeping, reduction in the use of pesticides, or frequent catch-basin cleaning).