Grand Jury report raises alarms about water security following an earthquake
First the electrical grid, now the water supply is being identified as one of the necessities of modern life that may be at risk in case of disaster.
The 2018-2019 Sonoma County Grand Jury report, issued in July, addresses several areas of concern that county residents and governments should be aware of, and prepare for. One of them is found in the “water report,” a 17-page document that poses the question, “Will there be water after an earthquake?”
Though it’s a generalized concern, for engineers in the water industry – including those at the Valley of the Moon Water District – it’s a hair-on-fire worry, especially in light of the unexpected recent closure of a water treatment plant at the Sonoma Development Center by the state’s Department of General Services.
“I’m pretty upset by it,” said Alan Gardner, general manager of the Valley of the Moon Water District since April. “If they were thinking of closing the (SDC) plant, they could have told us, ‘You guys better have a backup plan.’” But Gardner says a backup plan to the water that the SDC plan could supply would mean developing two or three wells, a project that could take up to three years and a million dollars each.
“If they could have given us three years notice, or even two, we would have been fine.” Instead, Gardner worries every day that in case of an accident, earthquake or other disaster, his agency won’t be able to deliver the water his 17,000 customers need for much longer than a day.
Danger of earthquake
It’s taken as a given that in case of a major earthquake, the county water supply “will probably be disrupted,” the grand jury reports. Water throughout most of the county, including to Sonoma Valley, is delivered by Sonoma Water, aka the Sonoma County Water Agency. They manage the distribution of Russian River water through a network of pumps, aqueducts and storage reservoirs to 600,000 customers, both residential and business.
While the agency projects that a minor earthquake of 5 or less would not impair water supply or services, a major earthquake of magnitude 7 or higher very likely will, producing from three days to two weeks of disrupted service depending on what facilities are damaged. As the City of Sonoma is at the end of the aqueduct servicing the Sonoma Valley, it is especially vulnerable to damage sustained upstream.
“It will put the Valley at additional risk if the aqueduct from the Russian River fails, as it did during the 2017 firestorm or if it were to sever in an earthquake,” said Chris Petlock, secretary of the VOMWD board of directors. He said that could leave the entire Valley with “little to no drinking and sanitation water while the aqueduct is down,” including the City of Sonoma.
Preparing for such an eventuality, Petlock said, “goes a little further than residents just having a few days of water on hand.” In case of such a major earthquake, pumps would keep the several reservoirs in the Valley topped off with groundwater to maintain water pressure, but that’s a short-term solution, perhaps as short as two or three days.
Sonoma Water’s assurances that it can return to full function in a three-day period is regarded skeptically by the jury. “Three days is an optimistic estimate,” reads the Grand Jury report. “Other factors and experience point to more extended water outages” of up to two to three weeks, the report continues.