UC groundwater research: A survey

California Agriculture (UCANR) | March 13th, 2018

As California implements the Sustainable Groundwater Management Act (SGMA), UC research is building knowledge and supporting innovation in groundwater recharge, groundwat

As California implements the Sustainable Groundwater Management Act (SGMA), UC research is building knowledge and supporting innovation in groundwater recharge, groundwater accounting, groundwater quality, groundwater governance and more. Here's a sample of work from across the UC system: whole watershed accounting; water availability for recharge; precision data on snowmelt; spatial data on well vulnerability; large scale groundwater recharge and agricultural systems; groundwater-surface water interactions; groundwater quality and salinity; water supply, land use and rural communities; data on water use and water rights; managed aquifer recharge on farmland; soil suitability for recharge; distributed stormwater collection; net metering for groundwater; geophysical imaging; groundwater governance; lessons on groundwater permitting from around the West; supporting Groundwater Sustainability Plan development; the economics of sustainable groundwater management; and considerations for groundwater markets.

Ukiah Valley Groundwater Sustainability Plan

Ukiah Valley Groundwater Sustainability Agency (UVGSA) | January 12th, 2022

The Sustainable Groundwater Management Act (SGMA), passed by the California legislature in 2014, requires local entities to jointly assess groundwater conditions in thei

The Sustainable Groundwater Management Act (SGMA), passed by the California legislature in 2014, requires local entities to jointly assess groundwater conditions in their local areas and to develop a Groundwater Sustainability Plan (GSP) by a specified deadline to ensure that sustainable conditions are achieved within 20 years of GSP adoption. An effective and efficient groundwater management plan is critical for the local economy and the health and welfare of the people, the environment, and all other beneficial uses and users of groundwater in a local area. The Ukiah Valley Basin (Basin) is a medium-priority groundwater basin located in Mendocino County. The sole Groundwater Sustainability Agency for the Basin is the Ukiah Valley Groundwater Sustainability Agency (UVBGSA or GSA). The GSA consists of the following local agencies: the County of Mendocino (County), the City of Ukiah (City), the Upper Russian River Water Agency (URRWA), and the Russian River Flood Control and Water Conservation and Improvement District (RRFC). The GSA applied for and was awarded Proposition 1 and Proposition 68 grant funds to develop the GSP and meet the SGMA-mandated schedule for submitting a GSA-approved GSP to the California Department of Water Resources (DWR) by January 31, 2022. GSA will be funded through member agency contributions during the first 5-year implementation period until a fee structure is implemented to support and fund GSA activities. Additional funding opportunities will continue to be explored, including grants. In late-2022, DWR will open round 2 solicitations under the SGMA Grant Program, which will provide approximately $204 million to high and medium priority subbasins to implement the GSP and its projects and management actions. A variety of local interests are represented by the GSA and served on the technical advisory committee (TAC), including municipal-residential water users, agricultural water users, public water systems, local land use planning agencies, environmental users, surface water users, tribal governments, disadvantaged communities, groundwater monitoring and reporting entities, holders of overlying groundwater rights, adjacent Basins, industrial users, commercial users, remediation pumpers, natural ecosystems, and the general public. Many of these local entities have a long history with groundwater and surface water management in the Basin and are well equipped to perform SGMA-required planning functions. The GSA, TAC members, and the public have undertaken a thorough and timely review of past, current, and projected future water resources needs and groundwater conditions to meet SGMA requirements for GSP development. Throughout the development of the GSP, regular communication and engagement activities were conducted to inform and receive input from local stakeholders and the public. The GSP includes a comprehensive groundwater basin description, which was used to develop a regional integrated hydrological model that quantifies current water budgets and projects future conditions of the Basin. The GSP also includes an assessment of the impacts of predicted future groundwater levels on beneficial users, including groundwater-dependent ecosystems, shallow wells, and interconnected surface water using the best available data and science available. Importantly, these assessments are used to develop measurable sustainable management criteria that avoid significant and unreasonable impacts to these beneficial users, and that can be monitored and adjusted throughout plan implementation. The key finding of the GSP, based on a thorough analysis of the best available information, is that the Basin will be sustainable over the next twenty years if planned projects and management actions (PMAs) are implemented as needed with respect to climate change and changes in the water system. These PMAs will help maintain groundwater levels and storage volumes and protect ecosystems, interconnected surface water, and shallow wells. Potential climate change impacts are not fully understood at this stage due to data gaps and the need for additional modeling and data collection. The GSP will implement a more comprehensive data collection that improves modeling capabilities and can provide a better assessment of climate change impacts in the future. The proposed PMAs will promote adaptive management practices and long-term resiliency to varying climatic conditions, such as more frequent, longer-lasting, and more intense droughts and less frequent and wetter winters. As described in Chapter 2, the sustainable yield for the entire Basin is estimated to be at least 6,500 acre-feet, based on historical, average groundwater pumping. The sustainable yield of the Basin is defined based on avoidance of undesirable results. Because the Basin is not overdrafted and the historical pumping average may not represent the actual sustainability yield of the Basin. A groundwater monitoring network comprised of selected wells will be used to track groundwater levels and groundwater quality. Sustainable management criteria set at representative monitoring wells in the network will be implemented to gage these conditions over time and ensure that groundwater levels and quality remain within a range that avoids significant and unreasonable impacts to beneficial uses and users of groundwater. Streamflow measurements are added to the monitoring network to measure surface water depletion due to groundwater pumping in combination with groundwater level measurements and integrated hydrological modeling simulations. Monitoring and data collection efforts will continue through the first five years of GSP implementation to further identify and prioritize project and management actions. Once approved by the GSA, the activities identified throughout the GSP development process will be implemented, including: • Ongoing monitoring and annual reporting on conditions in the Basin; • Ongoing public engagement and outreach; • Coordination within the watershed and with neighboring basins and water management entities; • Development and implementation of a shallow well protection and monitoring program; • Coordination with land use agencies and water supply agencies to promote consistency with the GSP; • Coordination with regional agencies in the development of updated climate change projections; • Implementing PMAs as deemed needed by the GSA to maintain and promote sustainability of the Basin; and, • Preparation of five-year updates to the GSP starting in 2027. Due to file size, the GSP is divided into separate files. Part 1, Part 2, Part 3, Part 4, Part 5, Part 6  

Unanswered questions for implementation of the Sustainable Groundwater Management Act

California Agriculture (UCANR) | August 24th, 2016

California is grappling with the implications of the Sustainable Groundwater Management Act (SGMA), a visionary and potentially revolutionary law that could profoundly ch

California is grappling with the implications of the Sustainable Groundwater Management Act (SGMA), a visionary and potentially revolutionary law that could profoundly change the way water is managed in the state. The nature of the revolution, however, is not yet clear. Whether and how SGMA achieves its goals hinges on open questions about its implementation.  

Unprecedented continental drying, shrinking freshwater availability, and increasing land contributions to sea level rise

American Association for the Advancement of Science (AAAS) | July 25th, 2025

Changes in terrestrial water storage (TWS) are a critical indicator of freshwater availability. We use NASA GRACE/GRACE- FO data to show that the continents have undergon

Changes in terrestrial water storage (TWS) are a critical indicator of freshwater availability. We use NASA GRACE/GRACE- FO data to show that the continents have undergone unprecedented TWS loss since 2002. Areas experiencing drying increased by twice the size of California annually, creating “mega-drying” regions across the Northern Hemisphere. While most of the world’s dry/wet areas continue to get drier/wetter, dry areas are now drying faster than wet areas are wetting. Changes in TWS are driven by high-latitude water losses, intense Central American/European droughts, and groundwater depletion, which accounts for 68% of TWS loss over non-glaciated continental regions. “Continental drying” is having profound global impacts. Since 2002, 75% of the population lives in 101 countries that have been losing freshwater water. Furthermore, the continents now contribute more freshwater to sea level rise than the ice sheets, and drying regions now contribute more than land glaciers and ice caps. Urgent action is required to prepare for the major impacts of results presented

Unwatering the Comstock Lode

Scientific American | November 4th, 1899

AN operation of immense interest to miners and mining generally has been in progress for the past five months in Nevada, in the district embracing the well known Comsto

AN operation of immense interest to miners and mining generally has been in progress for the past five months in Nevada, in the district embracing the well known Comstock mines. The remarkable circumstances connected with the discovery and development of the wonderful lode upon which these famous mines are located is a matter of comparatively recent history—too recent to require more than a passing reference. The wild speculation, which followed their discovery, forms one of the most thrilling pages of the annals of the Far West. It is estimated that up to the year 1886 the assay value of the gold and silver extracted from these mines amounted to $500.000,000. It was during this period of greatest production that the race of California multi-millionaires arose. Up to 1886 the exploration of all the territory embraced in the Comstock lode was industriously pursued, one shaft reaching a depth of 3,300 feet, but the exhaustion of ore bodies of high grade and the large expense attending milling and mining together with the heavy tax necessary in controlling the enormous volumes of water which every where flowed from the ground caused an abandonment of all mining below the 1,600-foot level. Another element of difficulty was the high temperatures experienced on the deeper levels, which increased as the shafts were lowered until miners were able only to work in shifts of a few moments in length. In a few months the water arose to within 1,640 feet of the surface opening of the Consolidated California and Virginia shaft, and at that level it has remained for nearly thirteen years. Above this level mining has been prosecuted with some success since the lower levels were flooded, and it is now believed that all pay ore bodies above the 1,600-foot level are practically exhausted.

Update on an Analysis of a Potential Groundwater Storage and Recovery Program in the Carpinteria Groundwater Basin

Montecito Water District (MWD) | March 11th, 2025

Updated Groundwater Sustainability Plan, San Joaquin Valley – Tule, Alpaugh Groundwater Sustainability Agency

Alpaugh Groundwater Sustainability Agency | July 27th, 2022

Alpaugh GSA is part of the Tule Subbasin and was formed in May 2016 for the purpose of complying with the SGMA. This updated GSP complies with the SGMA by addressing the

Alpaugh GSA is part of the Tule Subbasin and was formed in May 2016 for the purpose of complying with the SGMA. This updated GSP complies with the SGMA by addressing the DWR GSP Emergency Regulations in § 354.2 through 354.10. The GSP is the result of a collaborative process between local water agencies, technical experts, environmental managers, and community members with a mutual goal of sustainably managing the groundwater basin. Alpaugh GSA is one of seven participating GSAs in the Tule Subbasin, which organize their activities through the updated Tule Subbasin Coordination Agreement (Coordination Agreement). Due to size this file has been divided. Part 1, Part 2, Part 3, Part 4, Part 5

Updated Study Reporting Levels (SRLs) for Trace-Element Data Collected for the California Groundwater Ambient Monitoring and Assessment (GAMA) Program Priority Basin Project, October 2009–October 2018

U.S. Geological Survey (USGS) | April 16th, 2020

Groundwater samples have been collected in California as part of statewide investigations of groundwater quality conducted by the U.S. Geological Survey for the Groundwat

Groundwater samples have been collected in California as part of statewide investigations of groundwater quality conducted by the U.S. Geological Survey for the Groundwater Ambient Monitoring and Assessment (GAMA) Priority Basin Project (PBP) since 2004. The GAMA-PBP is being conducted in cooperation with the California State Water Resources Control Board to assess and monitor the quality of groundwater resources used for public and domestic drinking-water supply and to improve public knowledge of groundwater quality in California. Quality-control samples (including but not limited to field, equipment, and source-solution blanks) were collected to evaluate and quantify the quality of the groundwater sample results. The GAMA-PBP previously determined study reporting levels (SRLs) for trace-element results based primarily on field blanks collected in California from May 2004 through March 2013. SRLs are raised reporting levels used to reduce the likelihood of reporting false detections attributable to contamination bias. The purpose of this report is to identify any changes in the pattern or magnitude of concentrations or detections in field blanks since the last evaluation that would require changing or ending the use of SRLs implemented in October 2009. Constituents analyzed were aluminum, antimony, arsenic, barium, beryllium, boron, cadmium, chromium, hexavalent chromium, cobalt, copper, iron, lead, lithium, manganese, molybdenum, nickel, selenium, silver, strontium, thallium, uranium, vanadium, and zinc. For this review, data from 167 field blanks collected from October 2009 through October 2018 by the GAMA-PBP for trace elements were compiled. Based on a consistent pattern of decreasing cobalt and manganese concentrations in field blanks from 2009 to 2013, the GAMA-PBP decided to reevaluate all trace-element SRLs, effectively setting an end date for previously defined SRLs. Beginning October 2013, SRLs would be determined from field-blank data collected through October 2018. The detection frequency and upper limit of potential contamination bias (BD-90/90) were determined from field blanks for each trace element. The BD-90/90, that is, the upper 90-percent confidence limit of the 90th percentile concentration of potential extrinsic contamination, was calculated by assuming the binomial probability distribution. These results were compared to each constituent’s detection limit to determine whether an SRL was necessary to minimize the potential for detections in the groundwater samples, attributed principally to contamination bias. Results of the evaluation were used to set SRLs for trace-element data collected by the GAMA-PBP between October 2013 and October 2018. Trace elements prescribed an SRL based on this review were hexavalent chromium, cobalt, copper, lead, and zinc. This review also resulted in the removal of SRLs from iron, manganese, molybdenum, and nickel. Although an SRL for hexavalent chromium could not be evaluated in the earlier reviews because the data were not collected regularly until 2015, one was established herein as 0.34 micrograms per liter (μg/L). The SRL for cobalt, as previously implemented, had been to reject all results; it was changed to 0.16 μg/L following a reduction in cobalt field-blank detection frequency resulting from mitigation steps, starting in 2014, aimed at reducing contamination bias introduced by high-capacity capsule filters used during sample collection. The SRL for copper did not change, and the SRL for lead changed very little based on this review. Lastly, the SRL for zinc was lowered from 6.2 μg/L to 3.9 μg/L.

Updating the CALVIN Hydro-Economic Optimization Model of California: Central Valley Groundwater

University of California, Davis (UC Davis) | July 11th, 2012

Updates are being made to Central Valley groundwater in CALVIN, a hydro-economic model of California’s intertied water supply and delivery system. These updates reflect

Updates are being made to Central Valley groundwater in CALVIN, a hydro-economic model of California’s intertied water supply and delivery system. These updates reflect better estimates of water demands, groundwater availability, and local water management opportunities. This poster focuses on updating CALVIN groundwater parameters based on California Department of Water Resources’ (DWR) California Central Valley Groundwater-Surface Water Simulation Model (C2VSIM) and the United States Geological Survey (USGS) Central Valley Hydrologic Model (CVHM) model inputs and results. Two CALVIN update projects, using the DWR and USGS groundwater models, are underway to improve groundwater representation including basin inflows, reuse, return flows, capacities, and pumping costs. These sub-projects will result in a CALVIN model with updated groundwater representation based on C2VSIM and CVHM. This poster shows a preliminary comparison of these sub-projects and a summary comparison between the DWR and USGS models.

Uplift and seismicity driven by groundwater depletion in central California

Nature Portfolio (Springer Nature) | May 14th, 2014

Groundwater use in California’s San Joaquin Valley exceeds replenishment of the aquifer, leading to substantial diminution of this resource and rapid subsidence of the

Groundwater use in California’s San Joaquin Valley exceeds replenishment of the aquifer, leading to substantial diminution of this resource and rapid subsidence of the valley floor. The volume of groundwater lost over the past century and a half also represents a substantial reduction in mass and a large-scale unburdening of the lithosphere, with significant but unexplored potential impacts on crustal deformation and seismicity. Here we use vertical global positioning system measurements to show that a broad zone of rock uplift of up to 1–3 mm per year surrounds the southern San Joaquin Valley. The observed uplift matches well with predicted flexure from a simple elastic model of current rates of water-storage loss, most of which is caused by groundwater depletion. The height of the adjacent central Coast Ranges and the Sierra Nevada is strongly seasonal and peaks during the dry late summer and autumn, out of phase with uplift of the valley floor during wetter months. Our results suggest that long-term and late-summer flexural uplift of the Coast Ranges reduce the effective normal stress resolved on the San Andreas Fault. This process brings the fault closer to failure, thereby providing a viable mechanism for observed seasonality in microseismicity at Parkfield and potentially affecting long-term seismicity rates for fault systems adjacent to the valley. We also infer that the observed contemporary uplift of the southern Sierra Nevada previously attributed to tectonic or mantle-derived forces is partly a consequence of human-caused groundwater depletion.