The Clean Water Program is a comprehensive plan to upgrade San Mateo’s wastewater collection system and wastewater treatment plant to provide reliable service for years to come. The wastewater treatment plant is owned by the Cities of San Mateo and Foster City/Estero Municipal Improvement District. The wastewater treatment plant also serves Crystal Springs County Sanitation District, a portion of unincorporated San Mateo County, and the southern portion of the Town of Hillsborough. Those services are paid for by partner agency reimbursements.

The Clean Water Program is intended to meet the following goals:

• To replace aging pipes and facilities. Sewer pipes have an average lifespan of 50-60 years, and most of San Mateo’s sewer pipes were constructed between 1900 and 1960. The wastewater treatment plant has many components that are over 75 years old, and nearly half of the system is reaching the end of its useful life. Although it has been maintained and upgraded over the years, improvements to meet current and future operating requirements are needed.
• To meet current and future regulatory requirements and increase system capacity during heavy rains. The regulatory environment that protects our community continues to change. We are responding to the current direction of regulators (the Regional   Water Quality Control Board) that require specific corrective actions to prevent sewer overflows during heavy rains, while planning for future regulations related to the quality of our treated wastewater.
• To align with long-term sustainability goals. Improvements to the wastewater treatment plant and sewer collection system will protect public health and the health of San Francisco Bay. The higher-quality water will become a source of recycled water that can be reused for landscaping and other uses. Additionally, the solid waste can be turned into an alternative fuel source for City vehicles.

In San Mateo, wastewater from homes and businesses is collected via a system of pipes (sewer laterals and mains) and pump stations. The collection system includes about 234 miles of pipelines, more than 5,500 manholes, and 26 pump stations. The collection system transports the wastewater to the treatment plant. There, it undergoes a series of biological and physical treatment processes so that it is suitable for discharge into the San Francisco Bay. The plant treats an average of 12 million gallons per day during summer months; during heavy rains, the plant can receive up to 8 times greater than the average normal flows.

Because the system does not have the capacity to treat the extra wastewater during heavy rains, sometimes sanitary sewer overflows (SSOs) occur. An SSO is the result of high volumes of rainwater mixing with sewage and exceeding the system’s capacity to transport and treat it. The Regional Water Quality Control Board has issued the City with a Cease and Desist Order for SSOs.

Read Wastewater: The Basics to learn more about San Mateo’s sewer collection system and Wastewater Treatment Plant!

Failure to meet our permit obligations (i.e., treating the discharged water to an acceptable quality) and Regional Water Quality Control Board requirements (e.g., preventing sewer overflows) by mandated deadlines could result in large fines that will be passed on to ratepayers.

The program is funded by sewer use fees paid by all properties that tie into the sewer collection system. The City is seeking grants and low-interest loans to finance the capital improvements needed, while minimizing the impacts on sewer rates.

Several communication channels are used to inform the public of new information and upcoming meetings. These channels include mailing of community meeting invitations, sending invitations to City Council and Boards/Commissions, and updating the City’s events calendar and Clean Water Program website. Additionally, the City emails residents, Homeowners Associations, and other community groups; posts to social media sites, such as NextDoor, Facebook, Twitter, and YouTube; and distributes press releases to various media contacts. The Program will continue to send community information through these channels, and the City encourages the public to subscribe to the email list and to NextDoor.com to stay up to date with City and Program activities.