Commentary: How the SFPUC Flooded Stern Grove – the Untold Story

By Nancy Wuerfel

Westside Observer, Aug. 31, 2021. (Reprinted with permission from the author.)

Well, THAT was not supposed to happen! The San Francisco Public Utilities Commission (SFPUC) should be really embarrassed to allow a commonplace air release valve, essential for controlling pressures in every pipeline and pump station, to fail thereby causing the pipeline to rupture. Proper valve maintenance and recommended periodic valve replacement could have avoided this event, especially since this new pipeline was just completed in 2012.

Then to exacerbate this unfortunate situation, the SFPUC decided to hastily dump 700,000 gallons of drinking water out of the pipeline so they could begin repairs of the faulty valve, but with no regard for the repercussions on Stern Grove and the neighborhoods.

Photo courtesy of

It must be noted that there is nothing ordinary about this particular pipeline, and it is not like the usual old pipelines that have leaks. This is the big San Andreas Pipeline No. 3 that brings treated Hetch Hetchy water from the peninsula into Merced Manor Reservoir to go on to fill Sunset Reservoir. It is the seismically reinforced, 36 inches wide, 4.4 miles long, replacement pipeline paid for by the $4.8 billion Water System Improvement Program (WSIP) bond, and somehow it developed a faulty air valve.

It must also be noted that there is nothing ordinary about the reservoir that receives the water. The Merced Manor Reservoir is one of the three “terminal reservoirs” inside the City that receives and stores treated water from Hetch Hetchy. These terminal reservoirs are also co-owned with the peninsula customers. By law, in an emergency such as an earthquake, we must share this water equitably with the peninsula cities. This means that 79% of all locally available water can be apportioned without knowing how much the City will get. The City does have free access to the 21% balance of water in the remaining reservoirs.

How the SFPUC Keeps Us in the Dark

However, there are two actions by the SFPUC that are ordinary and customary in the way they mishandle the public:

First, the SFPUC does not want to be transparent about its service problems. It never mentioned that the pipeline shutdown was the big San Andreas Pipeline No. 3 that feeds into Merced Manor Reservoir and the Central Pump Station. The public was only told through news media that the “problematic pipeline was in the area of Sloat Boulevard and 22nd Avenue.” Any future serious event such as this, especially requiring a massive 700,000-gallon release of water, must be acknowledged with details by a press release from the SFPUC.

Second, a Tweet from a nameless SFPUC person stating “We apologize for any inconvenience this may have caused” is insulting in the Tweet delivery and the actual message. Trashing Stern Grove by flooding it with uncontrolled volumes of water destroying trees, paths, the performance venue, sending mud into Pine Lake, etc. is not just an “inconvenience.” SFPUC caused serious harm to our 64-acre park and canceled the final performance of the summer festival. Such a major disruption to the use of public space deserves a sincere apology from the General Manager and a hearing at the Public Utilities Commission, and some compensation for the damage done.

Another SFPUC Do-over

By the way, some people may recall that the Merced Manor Reservoir was upgraded in 2004 to seismically strengthen and repair the roof structure and foundations. However, after the completion of the upgrade, spalling of concrete (breaking off in fragments) at various locations on the roof structure was observed over the years due to the changes in expansion and contraction that affected the temperature gradient experienced in the roof structure. So, the reservoir must, once again, undergo modification of the roof structure and repair of the spalled concrete because the first design of the seismic retrofit was done “without the benefit of the lessons learned from later roof retrofits and construction at Sunset North Basin and University Mound North Basin.”  Perhaps with proper engineering, this second repair will be final. The WSIP bond will again finance the repair scheduled to begin in 2022 and be completed by 2031. 

Let us ask the Public Utilities Commission and the SFPUC senior staff 1) to examine the events outlined in this article as just a small sample of the unspoken problems the Water Enterprise is facing but is not telling the public about, and 2) to provide the leadership necessary to greatly improve the transparency and accountability of departmental actions to the public.

Nancy Wuerfel is a government fiscal analyst and served as a member of the Park, Recreation, Open Space Advisory Committee (PROSAC) for nine years.

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