Residents of Sebastopol may well escape the kind of defined water conservation targets that are being imposed on communities all around them, thanks to a groundwater supply that so far appears stable despite severe drought conditions, city officials said Tuesday night.
While most other cities are dependent on dwindling stores of surface water delivered by the Sonoma County Water Agency, Sebastopol's independent wells are in good shape and the underground reserves far more abundant than are needed, even if it doesn't rain anymore this year, City Councilman Michael Kyes, a member of the city's water subcommittee, said at Tuesday's regular council meeting.
But while reservoirs serving 600,000 residents in Sonoma and Marin counties are visibly running low, the groundwater that supplies Sebastopol lies below ground, unseen, and that's more difficult to measure, officials conceded.
Groundwater levels historically have risen and fallen seasonally, with rainfall levels. The current levels are about what they were a year ago and do not appear to reflect — yet, anyway — the absence of regular rainfall, public works director Rich Emig said.
Asked directly if he could foresee a problem ahead, Emig said, “I don't know; that's why it's so important to monitor those water levels.”
An annual analysis due later this year may provide more information, as will continuing work on a comprehensive groundwater master plan for all of the Santa Rosa Plain, Engineering Director Sue Kelly said.
In the absence of a clear ability to project future stores, regular monitoring of the wells should make clear if there's a substantive change in supply, Kelly said.
Even with the unknown, Kyes said, “We can sort of estimate if we're doing OK or not OK.”
A 2007 study completed in connection with city planning efforts indicated the aquifer on which the city relies may contain 100,000 to 200,000 acre-feet of water, though not all of it can be tapped. But the city uses a mere 1,500 or so acre-feet a year, Kyes said.