Watershed Regulatory

Pretreatment Program

The National Pretreatment Program was established in the early 1970s as part of the Clean Water Act (CWA) to address the discharge of harmful pollutants into municipal wastewater treatment plants. Its primary purpose is to reduce the amount of pollutants that are released into the environment by controlling the discharges from industrial and commercial sources before they reach municipal sewage treatment facilities. The program aims to prevent the introduction of pollutants that could interfere with the operation of these treatment plants, contaminate sewage sludge, or pass through the treatment process untreated, thereby protecting water quality and ensuring the safety of water bodies.

The authority for implementing the National Pretreatment Program is shared between the State Water Resources Control Board (State Water Board) and the nine Regional Water Quality Control Boards (RWQCBs). California received primacy, or the authority to implement the program, from the U.S. EPA in 1989. The State Water Board provides overall guidance, policy direction, and coordination for the pretreatment program statewide, ensuring consistency with federal and state regulations. The Los Angeles Water Board is tasked with overseeing the control authorities’ (dischargers’) pretreatment program implementation and enforcing the pretreatment program within this region. The Los Angeles Water Board works closely with local municipalities to oversee industrial dischargers, review and approve pretreatment programs, review and approve local limits, conduct pretreatment compliance inspections and pretreatment compliance audits, and ensure compliance with discharge limits and monitoring requirements.