A Legacy of Innovation and Sustainability

SLO Water Plus improves the WRRF’s ability to recover resources traditionally classified as waste. The upgrade will improve the plant’s efficiency while helping reduce our dependency on reservoir and groundwater supplies long into the future. It will deliver significant long-term benefits to water quality, the environment, resiliency and community education.​


Upgrades Support Comprehensive Resource Recovery

The City of San Luis Obispo’s Water Resource Recovery Facility (WRRF) is responsible for treating all of the wastewater within the City, Cal Poly and the County airport. The facility treats 4.5 million gallons of wastewater daily, twenty four hours a day, 365 days a year. Staffing of operators, laboratory analysts and maintenance technicians ensure the WRRF is operated and maintained in the most efficient manner possible and complies with federal state and local discharge requirements. A comprehensive upgrade to the facility—called SLO Water Plus—is now underway and will support improved resource recovery.

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Upgrade details, shown on map:


1. New solids thickening equipment will increase plant efficiency by lowering the plant’s energy demand.

2. New digesters will replace equipment that has reached the end of its service life. The digesters will increase onsite biogas production for future conversion to electricity and heat.

3. An odor control system will improve air quality for our neighbors.

4. An upgraded electrical system, including provisions for future onsite solar, will provide greater protection for workers and improve plant reliability.

5. An expanded equalization pond will improve the plant’s capacity to treat storm flows.

6. A new membrane bioreactor (MBR) system, the heart of the upgrade, will remove solids from the water and dramatically improve water quality. 

7. A new ultraviolet (UV) disinfection system will destroy pathogens, remove the need for chemical disinfection and eliminate production of disinfection by-products.

Facility-wide improvements, not shown on map:

•  Flood protection improvements will protect critical infrastructure from a 100-year storm event.

•  Increased treatment capacity will accommodate population growth consistent with Major City Goals and increase reliability during storm events.

•  Instrumentation and controls will provide plant operators more information and greater flexibility to optimize plant operations.

•  A redundant treatment train for key processes will increase the plant’s resilience.

The City is committed to water research and community education. We offer learning opportunities that explore the water cycle, as well as water resource recovery innovations and operations.


Project Timeline


Project Team


WSC is serving as the Program Manager for the project in partnership with HDR.  WSC is providing program controls, risk management, permitting support, funding and financing support and public and stakeholder outreach services. 


Jacobs (formerly CH2M) designed the facility upgrades and will provide engineering services during construction.


In partnership with WSC, HDR is providing Program Management services for the project. HDR led development of the Facilities Plan and will assist the City and PCL with commissioning and start-up of the facility.


Carollo is providing construction management services for the project and is responsible for contract administration and quality assurance.


Rincon Consultants prepared the project Environmental Impact Report and will provide environmental support services during construction. 


PCL Construction is the general contractor for the project and is primarily responsible for constructing the facility improvements.