Industrial Pretreatment, Wastewater Treatment, and the Environment

The Industrial Pretreatment Program for Clackamas County Water Environment Services (WES) began in 1983 when it was approved by the Oregon Department of Environmental Quality (DEQ). We administer the Industrial Pretreatment Program as a way to control and reduce the discharge of  pollutants from industrial and commercial sources into the municipal sewer systems. Our efforts — together with some 1,500 similar programs nationwide — make up the National Pretreatment Program.

Congress created this national program in 1972 as part of the Clean Water Act to protect the nation's wastewater treatment plants and waterways from discharges of toxins and other pollutants. The term "industrial pretreatment" refers to the requirement that industries discharging excessive pollutants treat their wastewaters before releasing to municipal sewer systems.

The objectives of the National Pretreatment Program are:

  • To protect municipal wastewater treatment systems (also known as publicly owned treatment works, or POTWs) from interference caused by industrial wastes.
  • To protect the nation's waters from industrial pollutants that pass through POTWs untreated.
  • To provide for the beneficial use of POTWs wastewater biosolids (the solid materials resulting from wastewater treatment) as soil conditioners and fertilizers.

Industrial User Responsibilities

All businesses — including industrial, commercial and governmental establishments — that discharge other than normal sanitary wastewater are subject to the requirements of the General Pretreatment Regulations. For most businesses, this simply means that they must not discharge anything that will adversely affect the sewage system or its workers, or the sewage plant biosolids or effluent.

For businesses discharging significant amounts of toxic pollutants, or other pollutants in amounts which may be detrimental to the POTW operations, additional regulation is required. These businesses, classified as Significant Industrial Users (SIUs), are required to obtain industrial wastewater discharge permits from WES in order to discharge to the sewer system. Each permit contains specific limits on industrial pollutants that can be present in an industry's discharge. Permits also contain monitoring and reporting requirements with which the industry must comply if it is to continue discharging to the municipal sewer system.

Which businesses are SIUs? All businesses engaged in operations identified as "categorical" processes by the Environmental Protection Agency (EPA) are automatically considered SIUs. These categorical processes include electroplating, metal finishing, nonferrous metals forming, battery manufacturing and a number of other activities. The EPA has established "categorical standards" for these processes, which limit the quantities of various pollutants that can be discharged to the sewer. Categorical standards are national standards, and all businesses in the U.S. engaged in the same categorical processes are subject to the same standards.

Bbusinesses are considered SIUs if they:

  • Discharge 25,000 gallons per day or more of process wastewater 
  • Contribute 5% or more of the dry weather hydraulic or organic capacity of the treatment plant are also considered SIUs.

Any business, regardless of size, whose discharge has the potential to adversely affect the operations of the POTW, is considered to be an SIU.

Where necessary to meet applicable pretreatment standards, SIUs are required to install facilities to treat their wastewaters prior to discharge into the municipal sewer system. SIUs must periodically sample and analyze their discharges to determine compliance, and must report the results to the POTW. SIUs who fail to comply with pretreatment standards face the possibility of serious enforcement actions, including monetary penalties and termination of sewer service.

WES Source Control Division Programs

In addition to the federal and state-mandated Industrial Pretreatment Program, our Industrial Permits Division also administers other programs associated with the discharge of non-residential wastewater to the sanitary sewer. These other programs include:

  • Septage receiving
  • Extra-strength billing
  • Restaurant fats, oils and grease (FOG) reduction
  • Illicit discharge investigation
  • Industrial surface water sampling
  • Temperature monitoring
  • Mercury minimization activities


If you are a business within the WES service area and have questions about discharge requirements, please contact:

Ron Wierenga
Environmental Services Manager


40 Code of Federal Regulations Part 403


150 Beavercreek Road #430, Oregon City, OR 97045

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