California's Groundwater Basins Show Mixed Progress as State Braces for El Niño
vendredi 16 octobre 2026
California's Department of Water Resources released its Fall 2026 semi-annual update on the state's groundwater conditions this week, offering a mixed picture of progress under the state's decade-old Sustainable Groundwater Management Act even as officials look ahead to a potential El Niño winter.
The report, covering Water Year 2026, found continued local progress in many of the state's high- and medium-priority groundwater basins, while flagging persistent challenges in preparing the infrastructure and inter-agency agreements needed to capture water during future recharge opportunities. DWR deputy director Paul Gosselin, writing alongside the update, argued that the state's groundwater strategy has to work in both directions at once: "Managing our groundwater resources requires planning for both drought and floods." He pointed to strong El Niño forecasts for the coming months as both a risk of flooding and an opportunity to replenish aquifers that have been drawn down over decades of overpumping, if the right capture infrastructure is in place in time.
The update landed the same week a Kings County judge is weighing whether to extend a preliminary injunction blocking the State Water Resources Control Board's pumping fees on farmers in the Tulare Lake subbasin, following hearings held 6 and 7 October. The judge is also due to decide whether the underlying lawsuit — which challenges the state's authority to levy fees on growers in groundwater basins placed under state probationary status — proceeds to trial or is dismissed outright. The case has become a closely watched test of how far the state can go in enforcing the Sustainable Groundwater Management Act against local resistance from agricultural water users.
The California report comes against a wider backdrop of groundwater stress across the American West. Separate research out of Virginia Tech, using satellite gravity data, has found that groundwater losses across the Colorado River Basin have accelerated in recent years, with the Upper Basin — historically seen as more resilient than the drought-stressed Lower Basin — now showing disproportionately large declines. The basin, which supplies water to seven US states and part of Mexico, has faced more than two decades of below-average flows on the Colorado River itself, pushing farmers and cities alike to lean more heavily on groundwater as a backup supply, a shift researchers say is now showing up clearly in long-term satellite measurements of the land's gravitational signature.
Together, the California update and the basin-wide research underscore a central tension facing western water managers heading into winter: the same storms that could begin to refill depleted aquifers also carry flood risk, and the infrastructure, legal authority and political will needed to manage both at once remain very much under construction.