The Northern California Water Association (NCWA) and water resources managers in the Sacramento Valley are watching the groundwater resources very closely during this dry period with an eye toward preserving the sustainability of our precious groundwater resources. With four consecutive dry years and only two wet years this century, there is tremendous stress on the groundwater resources in the Sacramento Valley.
Two new reports from the Department of Water Resources further illuminate the pressures on California’s groundwater resources and provide a more detailed picture of groundwater conditions.
In the Sacramento Valley, there are no critically overdrafted basins initially identified by DWR in its list published on August 19.
NASA has also provided DWR with a Progress Report: Subsidence in the Central Valley, California. For the Sacramento Valley, the report identifies small, localized, increments of subsidence (2 to 6 inches) near the towns of Yolo and Arbuckle. The groundwater issues in these two pockets have been recognized by previous reports and the local counties and the nearby water suppliers are aware of this dynamic and are undertaking various local efforts to better understand the groundwater situation, so they can be prepared to take efforts necessary for sustainability.
Last year, NCWA commissioned a detailed Sacramento Valley Groundwater Assessment, which provides an overview of the Sacramento Valley’s groundwater resources and the evolving efforts to better understand and actively manage the resources to provide sustainable benefits for the Sacramento Valley. The report summarizes long-term trends within the Sacramento Valley that affect the region’s groundwater resources. Although groundwater levels in the Sacramento Valley have been generally consistent–draw down during dry years and then recovery in wet years–we are starting to see certain areas, such as the two areas identified in the NASA report, where groundwater levels are not recovering as they have in the past. While we cannot yet distinguish between the impacts of the ongoing drought and what may be longer-term changes to the Sacramento Valley water balance and aquifer systems, the lack of surface supplies and the expanding and intensifying use of groundwater in the Sacramento Valley are clearly contributing to this dynamic.
The assessment also provides a discussion on the historical development of land and water resources; the ongoing efforts for sustainable groundwater management; the effects of increasing use of groundwater; and recommendations for the future. The assessment will help inform the development of the next generation of groundwater management plans in the region in accordance with new state legislation.
For additional information, please see the recent NCWA blog on DWR’s update of its groundwater information for the Sacramento Valley. This report highlights the importance of groundwater resources, with groundwater providing nearly 30% of the region’s water supplies, with this percentage greatly increasing during dry years and during sustained droughts. Importantly, the groundwater resources in the Sacramento Valley are being actively managed and monitored throughout the region.
