SFPUC reports brief blending of untreated water into treated supply; agency says no public-health emergency

The San Francisco Public Utilities Commission (SFPUC) reported that on March 3 a pipeline configuration in Sonoma Valley briefly allowed a limited volume of untreated water to mix with treated water in the SFPUC system. Staff worked with wholesale customers to isolate the flow and discharged the blended water to Crystal Springs Reservoir, where it will be treated through normal plant operations.

Dave Briggs of the Water Enterprise, who summarized the operational response to the commission, said "it was not a public health emergency" and described coordinated customer actions to isolate the flow and limit the affected area. Briggs said the raw water traveled east to west across Alameda and Santa Clara counties and that the SFPUC and its regional customers isolated the flow and discharged the water to Crystal Springs for treatment.

The General Manager’s office reported staff monitored water quality around the clock, shut valves to isolate the affected pipeline segment and worked with wholesale customers to limit impacts. The SFPUC said it will continue to coordinate with the State Water Resources Control Board and with wholesale customers on any required public notifications; staffing indicated a follow-up meeting with the state was scheduled the day of the commission meeting.

Commissioners and staff emphasized there is a formal administrative process under the agency’s permit for customer notification; the Water Enterprise said outreach (direct mail and newspaper ads) could occur as part of that process if the State Water Board or internal review requires it. The commission did not take formal regulatory action at this meeting beyond receiving the report.

Next steps: SFPUC staff will meet with the State Water Resources Control Board and affected wholesale customers to complete the administrative review and to determine whether and how additional public notification will be issued.