Outfall Rehabilitation Projects
Overview
The San Francisco Public Utilities Commission is upgrading and rehabilitating several combined sewage discharge outfall structures around the City. Read more about the projects in planning, design, and construction below under the Outfall Rehabilitation Projects section.
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Project Background
What is a Combined Sewer Discharge (CSD)?
San Francisco is the only coastal city in California with a combined sewer system that collects and treats both sewage and stormwater in the same network of pipes and treatment facilities. This combined system means San Francisco treats stormwater runoff when other coastal cities in California would have stormwater - and the debris and pollutants it picks up - flow untreated into nearby bodies of water.
In San Francisco, the debris and pollutants in stormwater runoff are treated to the same high standards that the SFPUC uses to treat sewage from buildings before being discharged into the San Francisco Bay or Pacific Ocean. However, during intense storms the transport/storage boxes, huge underground rectangular tanks that surround the City, can reach capacity. When this occurs, it is necessary to discharge partially treated wastewater through outfall structures around the City.
Generally, only during the most prolonged intense rainstorms do the storage boxes completely fill up. Instead of allowing the excess water to backup through the sewers into homes and streets, water is discharged into either the Bay or Ocean through one of 36 discharge points. Studies have shown that discharges are 94 percent stormwater. On average, only 10 discharges happen each year. Before the storage/transport boxes were constructed, discharges happened more than 80 times a year without any treatment.
These discharge events are monitored and reported in a timely manner. Learn more about our Beach Monitoring Program and see the interactive map of outfall structures.
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Outfall Rehabilitation Projects
Laguna, Howard, and Mission Creek Outfall Rehabilitation Project
The Laguna, Howard, and Mission Creek Outfall Rehabilitation Project will rehabilitate the existing outfall structures, repair the baffles, and repair riprap located around the outfall structures. The work will not impact the discharge capability or any sewer operations.
Status: In construction
Schedule: Spring 2026 - Spring 2027
Construction Update:
- Howard Street Outfall
- Nov. 9 to Nov. 14: Installation of hydraulic actuator, concrete repair.
- Nov. 23 to Nov. 24: Tentatively scheduled final punchlist walkthroughs.
- Laguna Street Outfall (Laguna Street & Marina Boulvard)
- Construction has been completed at this location.
- 6th Street Outfall
- No construction activities scheduled at this time.
- 3rd Street Outfall (3rd Street & Berry Street)
- No construction activities scheduled at this time.
- 4th Street Outfall (4th Street & Berry Street)
- No construction activities scheduled at this time.
- 4th Street Outfall (4th Street & Channel Street)
- No construction activities scheduled at this time.
For updates related to the Laguna Street Outfall Rehabilitation Project location specifically, please visit our webpage here.
Evans and Mariposa Outfall Improvement Project
The Evans and Mariposa Outfall Improvement Project will rehabilitate the existing outfall structures. The work will not impact the discharge capability or sewer operations.
Status: In construction
Schedule: Spring 2026 - Winter 2026
Construction Update:
- Evans Avenue Outfall:
- Oct. 26 - Oct. 30: Spray mortar installation, final video inspection.
- Nov. 2: Bulkhead removal, demobilization.
- Mariposa Outfall:
- Nov. 2 - Nov. 4: Final video inspection, final walkthrough.
Brannan Street and Sansome Street Outfalls Improvement Project
The Brannan Street and Sansome Street Outfalls Improvement Project will rehabilitate the existing outfall structures. The work will not impact discharge capability or sewer operations.
Status: In Construction
Schedule: Spring 2026 - Fall 2026
- Howard Street Outfall
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Project Materials
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