Local residents released a collective sigh of relief when the first significant rainstorm of the season arrived Oct. 24. While the resulting precipitation may have rivaled decades-old records in San Francisco, it did not yield nearly enough water where locals need it most – distant valleys and mountain ranges for eventual long-term storage, according to local experts.

More than 50% of Santa Clara County’s water is imported from the Sacramento-San Joaquin Delta and the Hetch Hetchy Regional Water System in Northern Yosemite Valley.

The recent deluge raised reservoirs in those areas by less than 1%, said Gary Kremen, Santa Clara Valley Water District board member, last week.

“It’s kind of like we went from 88% empty to 87% empty,” he said. “That is better than a sharp stick in the eye or getting hit with a car on El Camino, but we’ve got a long way to go.”

The San Francisco Public Utilities Commission (SFPUC) sells water from the Hetch Hetchy system to various Bay Area agencies, including the city of Mountain View and the Purissima Hills Water District (PHWD), which mostly serves Los Altos Hills residents.

Steve Jordan, PHWD vice president, summarized his takeaways from an Oct. 26 SFPUC precipitation update.

By the time the Oct. 24 storm’s runoff reaches Hetch Hetchy reservoirs, the water will raise their levels just 10%, Jordan said; to fully replenish the reservoirs, the valley needs seven additional “atmospheric river” events before the season ends, an unlikely outcome.

“Nobody expects this is the end of the current drought, although this really helped a lot of agencies,” he said. “We’re still pretty sure everybody will have to significantly reduce usage, because we’d have to be in March or April and see a bunch of these before they would say, ‘OK. All clear.’”

When the SFPUC convenes this month, it will likely ask water districts to conserve at least 15%, and those home to heavy users, including the PHWD, might have to save even more, Jordan said. In anticipation of the request, PHWD directors are prepared at their Nov. 10 meeting to declare a water emergency, to instruct customers to ramp up their conservation efforts and to impose restrictions such as limiting outdoor watering to two days a week.

Already other water agencies and government bodies have issued formal requests for conservation. On June 9, Kremen and his colleagues declared a water shortage emergency, asked local water districts to reduce water consumption by 15% compared to 2019 levels and called on the county Board of Supervisors to issue a similar proclamation, which it did June 22.

On Oct. 20, California Water Service requested the Los Altos District advance to Stage 2 of its Water Shortage Contingency Plan with the California Public Utilities Commission. Cal Water has scheduled a meeting Nov. 17 to educate the public about associated restrictions like irrigation and penalties for overuse.

For water conservation tips and more information, visit calwater.com, purissimawater.org and valleywater.org.