Over the past week, Stanford students have fretted about the low level of snowfall in the Tahoe area in anticipation of dorm ski trips during the coming weekends. What students have not realized is that beyond inconveniencing skiers and snowboarders, this low snowfall could potentially have a future impact on California’s water supply.
The amount of water in the snow of the Sierra Nevada Mountains is currently 83 percent below its Jan. 3 average and could impact the San Francisco water system, which currently gets about 85 percent of its water from the Sierra Nevadas.
The system, which serves about half of the Bay Area, including San Francisco, the Peninsula and parts of Santa Clara and Alameda County, provides water from the Hetch Hetchy water system, which is fed by Sierra runoff.
Although the decreased snowfall in the Sierra may sound alarming, especially considering its link to the Bay Area and Stanford water supplies, there is little reason to be too concerned, according to Steve Ritchie, assistant general manager at the San Francisco Public Utilities Commission (SFPUC).
“Basically, coming into this year, the Hetch Hetchy reservoir is full or as close to full as we can have it this time of year,” Ritchie said. “So right at the moment, we are not overly concerned; but we are certainly keeping an eye on the amount of snowfall up [in the Sierras].”
Tom Zigterman, Associate Director and Civil Infrastructure Manager for Stanford, who manages the water systems here on campus, cited heavy precipitation in the past few years as the main reason for this.
“It isn’t as alarming as it might seem that we haven’t had as much rainfall this rainy season to date because the reservoirs are quite full in the state from the prior two years of good rainfall,” Zigterman said. “It would take two to three years of rainfall below normal to start seriously impacting California’s water supply.”
This does not mean that a drought is entirely out of the question, but rather that if one did occur, Californians would not feel the effects of it for a few years.
“This could be the beginning of a drought,” Ritchie said. “Would we see the effects of it directly? No, because we still have lots of carry-over storage from last year, but that means we have to be extra cautious going into next year.”
Additionally, California has reason to remain optimistic about future rainfall.
“While December 2011 was dry, typically January through May account for about two-thirds of the water year precipitation,” wrote Margaret Laporte, associate director of Utilities for Water Resources and Environmental Quality for Stanford, in an email to The Daily. “In the past two years we have had rains past May into June. So while precipitation to date is lagging, there are a number of historically wet months ahead of us.”
Even if a dry winter were to occur, the Bay Area would be able to depend on the full reservoirs. Stanford, which receives a majority of its water from the SFPUC, also would not be affected by a dry winter.
The SFPUC is one of three water supplies for Stanford, making up 100 percent of the University’s potable water supply — water that is suitable for drinking. Stanford’s non-potable service water comes from creeks in the foothills, rainfall runoff and ground water, and is used for purposes such as irrigation and toilet-flush.
If a drought were actually declared in the future, customers of the SFPUC could be expected to decrease their water consumption, something that the Santa Clara Valley Water District has had to mandate in the past.
Water conservation is not new to Stanford. The University has already made immense strides in water conservation, even without a drought, decreasing average daily potable water use from 2.7 million gallons per day to below 2.2 million gallons per day, despite continued campus growth.
Additionally, Stanford is continuing to explore conservation measures such as retrofitting fixtures and converting irrigation from potable water to non-potable water supply.
Although Californians will most likely not experience any effects of a dry winter in the immediate future, the current dry spell does cast a light on California’s water systems.
According to Zigterman, “It continues to indicate that we need to plan long-term in the state and particularly in dry climates like we have in California and the West, to be careful about our water supplies and use them prudently.”
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