Timg_7477his fall, the California Department of Water Resources (DWR) formally recognized a new Atascadero Groundwater Basin as a separate and distinct basin from the Paso Robles Groundwater Basin. The decision was a huge win for two GSI clients: Templeton Community Services District and Atascadero Mutual Water Company.

“This is truly a momentous decision by DWR,” said GSI’s Paul Sorensen, who along with Tim Nicely has been working with the two agencies on this boundary modification for almost 4 years. “It will allow the agencies to continue to successfully manage the groundwater resource within a definable boundary—an area over which they have control.”

A Landmark Decision


Under California’s Sustainable Groundwater Management Act (SGMA), public water purveyors had an opportunity to submit a request to modify the boundary of a groundwater basin, as previously defined by DWR, on either a jurisdictional or scientific basis. The approval of the modification of the Paso Robles Basin to form the Atascadero Basin was one of the few scientific modifications approved by DWR, and was a landmark decision that had been closely followed throughout California.

“This is the result of a long, collaborative effort,” said Paul. “I’ve really got to hand it to our clients for being persistent and steadfast in their commitment to it. A lot of agencies would’ve given up by now.”

In 2002, Paul led the hydrogeologic team that first proposed that the Atascadero Subbasin was hydrogeologically distinct from the Paso Robles Basin. This finding was the basis of the case to DWR to separate the two basins. After DWR initially denied the application, Paul joined his clients and their attorneys in a multi-day meeting in Sacramento this past August to appeal the decision and re-review the data. In September, DWR made the surprising reversal to approve the new basin.

Why the Decision Matters

The newly established Atascadero Basin is not in overdraft, unlike the Paso Robles Basin. The designation of the Paso Robles Basin by DWR as “critically overdrafted” triggered a series of required actions under SGMA. Now that the Atascadero Basin is considered a separate entity, Templeton Community Services District and Atascadero Mutual Water Company will have more direct control over how they will manage their groundwater resource.

“I can’t emphasize it enough how significant this decision really is,” Paul said.