In the early 1970's, Congress passed the Clean Water Act and began to protect the nation's water quality by creating the National Pollution Discharge Elimination System (NPDES) program. The NPDES program issues permits to all identified point source dischargers to waters of the United States.

Persigo Wastewater Treatment Plant is a permitted point source or "direct discharger" to the Colorado River, and as such, maintains compliance with a variety of discharge requirements listed in their NPDES permit. The requirement for Persigo to develop and implement an Industrial Pretreatment (IP) Program is a condition of this NPDES permit. The Persigo IP program was approved by EPA in 1984, and has been successfully implemented since that time.

Pretreatment programs require municipal treatment plants to function as "control authorities" in addition to their more traditional role as service providers. Persigo operates the IP program as part of a cooperative federal, state, and local effort to reduce the level of pollutants discharged by industry and other non-domestic wastewater sources into the municipal sewer system. Industrial and other non-domestic dischargers to a municipal sewer system are considered to be "indirect dischargers".

As most municipal treatment plants, including Persigo, are primarily designed to treat domestic sewage, non-domestic wastewater has the potential to harm the biological treatment processes used at these treatment plants. To prevent upsets of the treatment plant, non-domestic dischargers are required to use treatment techniques and/or management practices to reduce or eliminate the discharge of harmful pollutants to the sewer system. The act of treating wastewater prior to discharge to the sewers is called "pretreatment".

The National Pretreatment Program, published in Title 40, Code of Federal Regulations (CFR), Part 403, provides the regulatory basis to require compliance with pretreatment standards and discharge limitations. State laws and local ordinances (for local limitations, see section 38-49 in this pdf [324KB]) supplement the national program. The objectives of this effort is to:

protect the integrity of the treatment plant and sewer collection system;
protect the health and safety of workers;
prevent non-compliance with NPDES permits;
prevent pollutant pass through or plant interference;
protect the receiving waters (Colorado River);
protect the quality of biosolids allowing for beneficial uses

In pursuit of these goals, the Persigo IP program monitors the discharge activities of 30 permitted industrial users and hundreds of commercial users such as restaurants, vehicle service facilities, photoprocessors, machine shops, and institutions. Program activities include inspections, permit writing and administration, sampling, maintaining an industrial waste survey, compliance and enforcement, program billing, program development and technical assistance. Other activities include involvement with Persigo compliance issues and the identification and reduction of pollutant sources to the City's storm water collection system.