The City of Arcata Wastewater Division is responsible for the monitoring, reporting, testing and treatment of all wastewater for the City of Arcata.  The Arcata Wastewater Treatment Plant (AWWTP) uses mechanical and biological processes to treat wastewater to a quality that is acceptable for discharge into Humboldt Bay.

The City’s National Pollutant Discharge Elimination System (NPDES) permit prohibits excessive discharge of pollutants into Humboldt Bay.  AWWTP can efficiently remove organic materials from the waste stream; however it is very difficult to remove some (inorganic) pollutants. 

In order to prevent pollution the U.S. EPA and the State Water Resources Control Board require in the NPDES permit that the City have a Pretreatment Program for all industrial users that discharge wastewater to the City collection system.

Pretreatment Program

The Pretreatment Program is designed to prevent businesses from discharging pollutants to the collection (sewer) system.  This makes it easier for the AWWTP to treat wastewater and reduces the risk of discharging pollutants into Humboldt Bay.

There are many pollutants that the City does not want in the waste stream.  They range from grease produced at restaurants, to chemicals used at manufacturing facilities, to heavy metals from dental offices. 

Each category of industrial users must meet different requirements to keep pollutants from the waste stream.  The City currently has the following categories in its Pretreatment Program:

Check back with us in the future, we will be extending our program to

  • Hospitals and Medical Facilities
  • Jewelry Making
  • Auto shops
  • And more

Fats, oils & grease from food service establishments

A food service establishment (FSE) is defined as a place where food is manufactured, prepared, processed, or packaged with the intention of individual service and includes the site at which the food is served, whether consumption occurs on or off the premises, and whether the product is offered with or without charge. 

FSEs submit a Wastewater Survey to the City that details what type and how much food is served or prepared.  Depending on the activities at your facility you may be required to install equipment that removes FOG from the waste stream before it is discharged to the City's collection system.  Please mail or deliver your completed survey to the Environmental Services Department, City of Arcata, 736 F Street, Arcata, CA  95521, by fax to (707) 825-2116 or email to

All FSEs are subject to Fats, Oils, and Grease (FOG) inspections.  FSEs that are found to produce FOG are inspected twice a year to make sure that they are disposing of FOG in an appropriate manner.   

FOG produced at FSEs can have a significant detrimental impact on the City’s collection system and the AWWTP.  Most notable, FOG build up in sewer pipes can cause sanitary sewer overflows, which can lead to raw sewage in local creeks and the bay.  The Arcata Municipal Code prohibits excessive FOG discharges. 

Significant industrial users 

Many manufacturing businesses are categorized as Significant Industrial Users (SIU) either because they are classified as a categorical industrial user by the US EPA or because the nature of their discharge can significantly impact the Publically Owned Treatment Works (POTW).  If your business is classified as a Significant Industrial User then your business must be permitted by the City for wastewater discharge.

The permitting process involves submitting operational information such as what chemicals are used on site and what contaminants might be in your wastewater. 

Facilities that are permitted are required to monitor their wastewater for certain contaminants and to submit regular reports to the City of Arcata Environmental Compliance Office.   To receive a SIU Wastewater Discharge Permit Application, please contact the Environmental Compliance office of the Environmental Services Department, City of Arcata, 736 F Street, Arcata, CA  95521, by phone at (707) 822-8184 or email at

Dental offices

Dental offices are required to submit a survey to the Environmental Compliance Office.  The survey asks questions about the use and disposal of X-ray development chemicals and amalgam. Please mail or deliver your completed survey to the Environmental Services Department, City of Arcata, 736 F Street, Arcata, CA  95521, by fax to (707) 825-2116 or email to

The Pretreatment Program is committed to helping dental offices find appropriate ways to dispose of their wastes.  We also encourage dental offices to invest in digital X-ray equipment and to consider the use of composite filling material rather than mercury based amalgam.


Laboratories often have hazardous waste to dispose of.  The City of Arcata Pretreatment Program surveys laboratories to ensure that they are disposing of hazardous wastes in an environmentally safe manner. 

If you have questions about the proper way to dispose of your laboratory waste call the City of Arcata Environmental Services Department for more information.