Is Paso basin tapped? 

There are still plenty of uncertainties about the Paso Robles groundwater basin. But while the details of a 13-year basin study are fuzzy in some areas, the one thing experts agree on is that the basin is in trouble and has effectively reached its cap.

“No matter how you change the assumptions, outflows are going to be equaling inflows now, or in the very near future,” San Luis Obispo County Senior Planner James Caruso said during a Nov. 9 joint-session of the county Board of Supervisors and Planning Commission.

In effect, the massive North County water basin is approaching its limit. The dwindling water supply, which is particularly low in a roughly 200-foot-deep central cone of depression county officials are calling the “Estrella/Creston Area of Concern,” has county planners recommending a “level of severity three” distinction for the basin.

In what could have been seen as a ploy to lull the crowd to sleep, Paul Sorensen, a hyrdrogeologist with Fugro West, outlined the basin study ongoing in various forms since 1998. Regardless of changing assumptions in the data collected, he said, “I think what you need to look at [is] that water levels are declining over a large part in the central part of the basin.”

The basin, which stretches from Highway 101 to the San Andreas Fault and from Santa Margarita to the Monterey County line, has been heavily pumped year after year. In 1997, for example, 74,061 acre-feet per year were pumped, 49,683 of which was for agriculture; last year 93,907 acre-feet per year were pumped, 63,077 of it for agriculture.

Though local officials can’t regulate who takes water out of the ground, what they can do is regulate land use to control water pumping in the area. Officials also warned that conservation and relying on outside sources of supplemental water from the state and Nacimiento Water Project wouldn’t be enough to solve the problem.

Some land developers and agriculturalists (mostly represented by the Paso Robles Wine Country Alliance) worried that county officials were laying the groundwork to make drastic and restrictive land-use policies without adequate community input and based on incomplete data.

“I think we need to take a look at the economic benefits as you approach the very critical decision of determining the level of severity for this,” said Alliance Executive Director Stacie Jacob.

No decision was made at the hearing. Planning commissioners will hold a formal hearing on Dec. 9. The item will then go to county supervisors, likely early next year.