Groundwater management workshops:

Sonoma Valley

Wednesday, March 14, 5:30-7:30 p.m. Sonoma Veterans Memorial Building, 126 1st St. W., Sonoma Santa Rosa Plain Wednesday, March 21, 5:30-7:30 p.m. Finley Community Center, 2060 W. College Ave., Santa Rosa Petaluma Valley

Thursday, March 29, 5:30-7:30 p.m.

Petaluma Community Center, 320 N. McDowell Blvd., Petaluma

More information:

Sonoma County is launching a public outreach campaign this week to gather input on its nascent groundwater regulatory system that could eventually levy new costs on thousands of residents throughout the region. The county has a trio of new groundwater management agencies — one each for the Santa Rosa Plain, the Sonoma Valley and the Petaluma Valley — that will over the coming weeks hold community workshops focused on the funding mechanisms they might implement moving forward.

First up is the Sonoma Valley meeting Wednesday at the Sonoma Veterans Memorial Building, with the Santa Rosa Plain workshop following March 21 at the Finley Community Center and the Petaluma Valley workshop concluding the series March 29 at the Petaluma Community Center.

“For the most part, residents and businesses have used groundwater as a source of free water,” said Supervisor Susan Gorin, who chairs the Sonoma Valley agency. “The introduction of the groundwater sustainability agencies means we have to look at water in totality. Surface water and groundwater are interconnected, and we have a finite supply.”

The agencies’ creation last year was prompted by a landmark California law designed to protect local groundwater supplies, which were previously unregulated, unlike in other western states. The new law took effect in 2015, when the state was in the throes of a historic drought that strained communities’ water resources.

Sonoma County’s three groundwater agencies have each been recommended to receive $1 million in state grant funding. But officials say they need additional funds to support their development of plans that will study the amount of groundwater available in each basin and lay out measures to ensure their sustainability for the next two decades.

The agencies also have additional day-to-day costs and reserve goals intended to help finance major projects in the future. Those costs are estimated between $350,000 to $400,000 annually for each agency, according to Ann DuBay, a spokeswoman for the Sonoma County Water Agency.

Funding options under consideration include charges on groundwater use or wells, as well as potential new levies by parcel or acreage, DuBay said.

“We want to get people’s input on all of these different options and also their thoughts on does it make sense to have a combination of options,” DuBay said. “It could be all of the above. But the goal is to keep the cost of the agency and doing the groundwater sustainability plan as low and efficient as possible so that we can keep the rates and fees as low as possible.”

The vast majority of parcels in the three basins are supplied by water systems — namely cities and water districts — but many of those systems also use groundwater, DuBay said.

Nearly 6,300 wells are estimated across all the basins, though the real number is likely far higher because the county didn’t begin registering wells until after 1970, according to DuBay.

Residents can visit for more information, including the boundaries of the three groundwater basins.