Outfall Rehabilitation Projects
Overview
The San Francisco Public Utilities 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: Pre-construction
Schedule: Spring 2026 - Spring 2027
Construction Update February 2026
This project recently awarded the Notice-to-Proceed to the contractor and is in early discussions coordinating the overall workplan and schedule. This contract includes three locations for outfall upgrades or rehabilitation - Laguna, Howard, and Mission Creek. Once the schedule and duration of work at each site is confirmed, updates will be posted here and shared to our contact lists. To be added to our email update list, please contact us at ssip@sfwater.org.
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: Pre-construction
Schedule: Spring 2026 - Winter 2026
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: Pre-construction
Schedule: Spring 2026 - Fall 2027
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