How is California’s landmark groundwater law impacting Sonoma County?
The drought is intensifying efforts to conserve all of Sonoma County’s water resources, including a supply that has eluded oversight until recently: groundwater. But even as plans for groundwater monitoring and sustainable use proceed, tensions are building over its management.
The authority to evaluate and regulate groundwater comes from a 2014 law crafted in the middle of the state’s last drought. It authorized government regulation for certain groundwater basins through the establishment of local agencies, with the goal of “sustainable” management – that is, no significant drop in groundwater tables year-to-year – by 2042.
Three of Sonoma County’s 14 groundwater basins are subject to such oversight: Sonoma Valley, the Santa Rosa Plain and Petaluma Valley. The location of these basins corresponds to both high population density and major groundwater demands.
“There are three levels of county stakeholders most affected by groundwater management,” said Ann DuBay, administrator for the Petaluma Valley and Sonoma Valley Groundwater Sustainability Agencies. “First are homeowners – mostly rural homeowners – who are on well water. Next is agriculture, which is a lynchpin of our economy. And finally, there’s the environment, including the streams and rivers that get at least some recharge from groundwater.”
Andy Rodgers, administrator for the Santa Rosa Plain agency, likens a groundwater basin to a subterranean bathtub: the volume of water the tub holds fluctuates depending on season and demand. Shallower basin aquifers may be connected to surface water such as streams, while deeper aquifers typically are not connected to surface flows.
Under the 2014 state law, the Sustainable Groundwater Management Act (SGMA), “local agencies are authorized for each medium to high priority basin, and a board and advisory committee are formed,” said Rodgers. “Once an agency is in place, the goal is the development of a groundwater plan that’s sustainable long-term.”
As an example, Rodgers cited the Santa Rosa Plain basin, which is now in a “slight water budget deficit.” Over time, said Rodgers, more water is extracted than replenished.
“During the next 20 years our job is to remove that budget deficit, or even achieve a net positive,” said Rodgers. “That’s the whole point of SGMA.”
The new drought is the first time California has had such regulation in place. And while the state law generally favors a soft approach that emphasizes groundwater quantification, monitoring and incentives for conservation, it isn’t toothless.
“We do have the authority to investigate, and if there are problems and clear lines of evidence, we do have the authority to take action,” said Rodgers.
Investigating ways to recharge local basins
Two of the county’s basins – the Santa Rosa Plain and the Petaluma Valley – are in relatively good shape, said DuBay.
“There has been recognition for some time that the Sonoma Valley has issues, specifically in deep aquifer declines,” said DuBay. “There are a couple of hot spots where this is particularly problematic – El Verano and the region around Eighth Street East come immediately to mind.”
Groundwater management is not wholly about monitoring and regulation – it’s also about replenishment, and the county is investigating several avenues for recharging local basins, said Jay Jasperse, the chief engineer and groundwater manager for Sonoma Water, the county agency.
“You get some profound benefits from recharging shallower aquifers that feed streams,” said Jasperse. “You enhance water supplies, of course, but you also get significant environmental benefits by maintaining stream flows.”
One approach to groundwater recharge is known by a wonky acronym: flood-MAR, short for Managed Aquifer Recharge. During high water river flows, water can be directed to nearby agricultural lands – vineyards along the Russian River are a good example. The standing water subsequently percolates down to underlying aquifers.
“Certain crops aren’t harmed by standing water, and research conducted in the Central Valley indicates (dormant) grapevines are in that category,” said Jasperse.
For deeper county aquifers, managers can direct Russian River winter flows through existing pipelines to established agricultural and municipal wells.
“We did a pilot study with a well in the Sonoma Valley, and it was successful,” Jasperse said. “Typically, there’s a SGMA process for implementing new data into the sustainability plans, but the drought is accelerating our responses in general. We’re looking to get one or more wells expedited for this approach in the near future.”