GSA hears technical analysis showing slight long-term groundwater declines; staff to develop demand-management triggers

The Arroyo Seco Groundwater Sustainability Agency's general manager reported that a technical advisory group analysis found a multi-decade dry trend and a slight decline in groundwater elevations across parts of the basin, though recent years have not shown broad, acute threshold violations.

"Over the last few decades, we've had kind of a dry trend," the general manager said, summarizing the technical group's review. The GM said the analysis, led by the group's chair, "Gus," examined distributions of wells, time sequences and elevation changes and found clusters of wells on the bench showing faster declines.

The GM told the board that the analysis did not find a direct statistical relationship between pumping volumes and the observed elevation changes in the data set. That suggests that demand-management triggers may need to be tied to recharge conditions and recent water-year forecasts rather than to pumping alone.

"If it rains and we get adequate recharge, I think we're going to remain sustainable," the GM said, while warning that continued dry conditions over decades could require actions to reduce pumping if minimum thresholds are at risk.

Board members asked whether earlier data collection and faster delivery from the Monterey County Water Resources Agency would improve review timing for the annual report; the GM said collecting data sooner should help in future years but did not change this year's review schedule.

Next steps: staff will bring the technical advisory group's analysis to the implementation and advisory committees for local review and adapt demand-management criteria that reflect recharge conditions and recent forecasts.