Wastewater Division

The Wastewater Division serves as the first line of defense in protecting the Monterey Bay's precious water quality. The Watsonville Wastewater Treatment Facility first constructed during the 1920s, has seen its mission grow from servicing a small agricultural community to treating wastewater for thousands of residents, commercial and industrial discharges. More than 170 miles of pipeline are used to transport wastewater to the facility for treatment that processes an average of 6.7 million gallons of wastewater every day.

The wastewater is treated to the advanced secondary treatment level for ocean discharge and, advanced tertiary treatment for direct food crop irrigation. Both levels of treatment undergo extensive monitoring and testing to insure compliance with all Local, State and Federal pollution prevention laws prior to being discharged to the Monterey Bay over a mile off shore, or to approximately 2000 acres of row crops.

Wastewater treatment monitoring, drinking water and landfill analysis are performed at the Public Works and Utilities Laboratory located at the Water Resource Center to insure compliance with all applicable State and Federal Laws.

Wastewater Treatment Facility Facts

Service Area

  • 21 Square miles
  • Composed of City of Watsonville, Pajaro, Freedom, and Salsipuedes sanitary districts consisting of a population of 55,000


  • 1 Facility Manager
  • 8 Operators
  • 5 Mechanics
  • 4 Laboratory Personnel
  • 1 Source Control Manager
  • 1 Administrative Assistant
  • 4 Collection System Operators

Average Carbonaceous Biological Oxygen Demand

  • Influent: 387 milligrams/liter
  • Effluent: 10.8 milligrams/liter

Average Suspended Solids

  • Influent: 347 milligrams/liter
  • Effluent: 9 milligrams/liter

Plant Capacity

  • 12.1 million gallons per day, secondary
  • 7.7 million gallons per day, tertiary

Bio-Solids Removed From Facility Each Year

  • 3200 Wet Tons

Average Daily Flow

  • 6.7 million gallons per day