<\/p>\n
Rice farmer Don Bransford walks in May 2022 past a dry ditch that usually brings water to his 1,800 acres of rice fields near Williams. He did not grow any rice that year because of the drought. <\/p>\n
PAUL KITAGAKI JR.<\/p>\n
Sacramento Bee file<\/p>\n
A new study shows heavy groundwater pumping during California\u2019s 2020 to 2022 drought caused the ground in the Sacramento Valley to sink faster than expected, reducing the aquifer\u2019s ability to hold water.<\/p>\n
Published last week in the Proceedings of the National Academy of Sciences, the study<\/a> found the damage to the aquifer is irreversible. One of the study\u2019s authors, Kristel Chanard, estimated the lost groundwater storage capacity is roughly equivalent to San Francisco\u2019s annual water consumption.<\/p>\n \u201cThere is still water, but it\u2019s a big loss,\u201d she said.<\/p>\n The resulting lost groundwater storage capacity is significant, Chanard said, because groundwater provides a buffer during dry periods. Groundwater provides nearly 30% of the region\u2019s water supply, and more during dry years, according to the NCWA.<\/p>\n Land subsidence occurs when large amounts of groundwater are withdrawn from rocks, according to<\/a> the U.S. Geological Survey. The rocks compact because the water is partly responsible for holding up the ground.<\/p>\n Chanard and her colleagues used high-resolution satellite measurements to track ground deformation and groundwater levels in the Sacramento Valley from 2016 to 2022. They found the land initially exhibited elastic deformation, allowing it to rebound. During the 2020 to 2022 drought, however, subsidence exceeded the normal rate by up to roughly one foot per year.<\/p>\n Chanard said the aquifer reached a tipping point in 2021, when the compaction abruptly transitioned to irreversible. She compared the aquifer to a sponge: squeeze out the water, and it compresses; soak it again, and it usually springs back. Once damage becomes irreversible, she explained, that flexibility is lost, and refilling the aquifer won\u2019t restore its lost groundwater storage capacity.<\/p>\n The study\u2019s author attributed this change to increased groundwater pumping during the drought, which the Northern California Water Association considers<\/a> the worst in the region\u2019s recorded history.<\/p>\n \u201cBy losing this aquifer storage capacity through compaction, we actually change how much water we can store underground, and so how much we can be resilient to future long drought episodes,\u201d Chanard said.<\/p>\n NCWA President David Guy called the study a \u201cwarning sign\u201d for water management officials in the region.<\/p>\n \u201cWe know that we have some work to do,\u201d he said. \u201cWe want to make sure that we try to address the subsidence before it gets any worse.\u201d<\/p>\n According to Guy, heavy groundwater pumping occurred during the 2020 to 2022 drought because the west side of the Sacramento Valley had little surface water. In 2022, he said, water suppliers on the Sacramento River received between 0 to 18% of their supplies, when their contract calls for 75% of supplies in critically dry years.<\/p>\n But Guy noted the study does not capture improvements in groundwater levels after 2023.<\/p>\n \u201cObviously this is very serious,\u201d he said of the study, \u201cbut also that is \u2026 a really rough snapshot in time for the Sacramento Valley.\u201d<\/p>\n Guy suggested the 2020 to 2022 drought was a \u201cfluke,\u201d and said he believes the likelihood of another one like it is \u201cpretty remote.\u201d But Chanard believes the event is part of a pattern. Climate forecasts, she explained, suggest California will experience increasingly severe and frequent droughts.<\/p>\n \u201cWe know \u2026 that this is going to continue, so making sure that we understand how this impacts our groundwater storage capacity and our aquifer resources is very important,\u201d she said.<\/p>\n Chanard and Guy pointed to two main ways to prevent future damage to the aquifer: groundwater recharge, which means redirecting excess surface water to fill and replenish aquifers, and demand management, which means limiting groundwater pumping.<\/p>\n Jordon Navarrot, deputy manager at Reclamation District No. 108 in Yolo and Colusa counties, said that he and other water management officials are working with local residents to implement these types of solutions. The goal, he said, is to achieve a sustainable balance between groundwater extraction and replenishment.<\/p>\n According to Navarrot, the primary approach of his district is in-lieu groundwater recharge, a practice where excess surface water is supplied to users instead of pumping groundwater. He added that many growers have annexed their land to the district for surface water services in a move away from groundwater reliance.<\/p>\n \u201cIn all of the troubled areas in the Sacramento Valley, there\u2019s real work being done to combat subsidence and adapt to sustainably balanced groundwater withdrawals with recharge,\u201d he said. \u201cI think we\u2019re on the right track.\u201d<\/p>\n This story was originally published August 2, 2026 at 7:00 AM.<\/p>\n Maps published with a new study of subsidence caused by groundwater pumping in the Sacramento Valley show that some of the most significant sinking occurred near Woodland and Davis in Yolo County. Proceedings of the National Academy of Sciences <\/p>\n
Gov. Gavin Newsom tours Brian and Elena Corral\u2019s 810 acres of Dunnigan farmland in March 2023 to observe how recycled collected water is being used to flood the property to recharge Yolo County\u2019s groundwater aquifer. Newsom announced an end to some of the water restrictions implemented during the drought of the previous years. PAUL KITAGAKI JR. Sacramento Bee file <\/p>\n
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