Central Kings Groundwater Sustainability Agency Groundwater Sustainability Plan (Revised)

Central Kings Groundwater Sustainability Agency (CKGSA) | July 13th, 2022

Characterization of Groundwater Recharge and Flow in California's San Joaquin Valley From InSAR-Observed Surface Deformation

American Geophysical Union (AGU) | March 4th, 2021

Surface deformation in California's Central Valley (CV) has long been linked to changes in groundwater storage. Recent advances in remote sensing have enabled the mappin

Surface deformation in California's Central Valley (CV) has long been linked to changes in groundwater storage. Recent advances in remote sensing have enabled the mapping of CV deformation and associated changes in groundwater resources at increasingly higher spatiotemporal resolution. Here, we use interferometric synthetic aperture radar (InSAR) from the Sentinel-1 missions, augmented by continuous Global Positioning System (cGPS) positioning, to characterize the surface deformation of the San Joaquin Valley (SJV, southern two-thirds of the CV) for consecutive dry (2016) and wet (2017) water years. We separate trends and seasonal oscillations in deformation time series and interpret them in the context of surface and groundwater hydrology. We find that subsidence rates in 2016 (mean −42.0 mm/yr; peak −345 mm/yr) are twice that in 2017 (mean −20.4 mm/yr; peak −177 mm/yr), consistent with increased groundwater pumping in 2016 to offset the loss of surface-water deliveries. Locations of greatest subsidence migrated outwards from the valley axis in the wetter 2017 water year, possibly reflecting a surplus of surface-water supplies in the lowest portions of the SJV. Patterns in the amplitude of seasonal deformation and the timing of peak seasonal uplift reveal entry points and potential pathways for groundwater recharge into the SJV and subsequent groundwater flow within the aquifer. This study provides novel insight into the SJV aquifer system that can be used to constrain groundwater flow and subsidence models, which has relevance to groundwater management in the context of California's 2014 Sustainable Groundwater Management Act (SGMA).

Chino Basin Municipal Water District v. City of Chino et al

Superior Court of California, County of San Bernardino | August 25th, 2014

From "An Evaluation of California's Adjudicated Groundwater Basins" by Langridge et al: "Chino Basin is one of the largest groundwater basins in Southern California. It a

From "An Evaluation of California's Adjudicated Groundwater Basins" by Langridge et al: "Chino Basin is one of the largest groundwater basins in Southern California. It abuts Los Angeles County, Orange County, and Riverside County. Over the past few decades, the basin has experienced rapid growth. The southern area was once notable for containing the heaviest concentration of dairy farms in the United States. There is significant subsidence in areas of the basin due to overpumping. While it is often described as a basin with ongoing conflict, there were also significant collaborative efforts to address basin problems during and after the adjudication process. Three different stakeholder groups—overlying agricultural, overlying non-agricultural, and appropriators—negotiated a management plan prior to adjudication, and it was adopted in a 1978 stipulated judgment. Stakeholders agreed on water rights for each group of users. There were multiple additional amendments over the last twenty years adopted in a 2012 restated judgment." Click here for the Chino basin Department of Water Resources Adjudicated Basin Reporting page.

Chowchilla Subbasin Staff Assessment

California State Water Resources Control Board (SWRCB) | April 1st, 2025

The state intervention process for the Chowchilla Subbasin was triggered in March 2023 when DWR determined the subbasin’s 2022 GSP was inadequate and identified multipl

The state intervention process for the Chowchilla Subbasin was triggered in March 2023 when DWR determined the subbasin’s 2022 GSP was inadequate and identified multiple deficiencies in the GSP. DWR identified issues regarding the local agencies’ plans for managing for the chronic lowering of groundwater levels and land subsidence (land sinking due to groundwater pumping). State Water Board staff reviewed the 2022 GSP and determined that implementing the 2022 GSP would result in additional groundwater level declines, potential impacts to drinking water wells, and damage to subbasin infrastructure, such as canals and levees, through continued land subsidence. The GSAs released a revised draft GSP in August 2024, which they adopted with slight revisions in March 2025 (2025 GSP). State Water Board staff evaluated the 2025 GSP to determine if identified deficiencies were addressed. The GSAs made significant progress through the 2025 GSP and adequately addressed deficiencies. Through the 2025 GSP, the GSAs show a greater commitment to protecting drinking water users and improved groundwater management. State Water Board staff concludes the GSAs amended the GSP such that a probationary designation of the Chowchilla Subbasin is unnecessary and recommends the Board return the Subbasin to DWR’s jurisdiction for continued evaluation of local management under SGMA.

Chowchilla Subbasin Sustainable Groundwater Management Act (SGMA) Groundwater Sustainability Plan (3rd Revision)

Madera County | January 3rd, 2025

In 2024-2025, the GSAs revised the Subbasin GSP to:  Amend the Domestic Well Mitigation Program Refine the Groundwater Level Representative Monitoring Sites (RMS

In 2024-2025, the GSAs revised the Subbasin GSP to:  Amend the Domestic Well Mitigation Program Refine the Groundwater Level Representative Monitoring Sites (RMS) Network Refine Groundwater Level Sustainable Management Criteria (SMC)  Backstop Projects and Management Actions Refine Subsidence SMC and Provide for Subsidence Mitigation

Chowchilla Subbasin Sustainable Groundwater Management Act (SGMA) Groundwater Sustainablity Plan

Chowchilla Subbasin GSP Advisory Committee | January 1st, 2020

City of Barstow, et al v. City of Adelanto, el al (Mojave Basin Area cases)

Superior Court of California, County of Riverside | December 5th, 2002

From An Evaluation of California’s Adjudicated Groundwater Basins, Langridge et al, UC Davis (2016): "The Mojave Basin adjudication was initiated by a lawsuit filed

From An Evaluation of California’s Adjudicated Groundwater Basins, Langridge et al, UC Davis (2016): "The Mojave Basin adjudication was initiated by a lawsuit filed May 30, 1990, by the City of Barstow and the Southern California Water Company. The complaint alleged that the cumulative increase in water use in the upper part of the Mojave Basin caused or threatened to cause a reduction in the natural flow of water to the central part of the Mojave Basin. Water users included downstream agriculture (many alfalfa farms), aquaculture, recreational lakes, homeowner associations, and upstream burgeoning municipalities. In the center of the basin is the smaller, low-income town of Barstow, which was concerned about its water supply. A 1993 Stipulated Judgment set forth a proposed physical solution that did not apportion production rights on the basis of preexisting legal water rights, and parties representing over 80 percent of verified water production in the basin agreed to its terms. However, some farmers with overlying rights chose not to stipulate to the judgment. On appeal, the court stated that in considering a stipulated physical solution involving equitable apportionment, the water rights of parties that did not join the stipulation must also be considered. The adjudication set out a complex system to reduce production a producer’s free production allowance (FPA) over time, but withdrawals remain significant in three out of the five subareas. The judgment also contained unique provisions for assuring that the water needs of endangered and other species and their habitat would be protected. One outcome of the adjudication was that many farmers in the western Alto Subarea sold or leased their base annual production (BAP) rights or leased their FPA to municipalities, and population in the Alto Subarea almost doubled. The Barstow Marine Corps Logistics Base east of Barstow is a federal Superfund site."

City of San Bernardino vs. Fontana Water Co. et al.

Superior Court of California, County of San Bernardino | January 28th, 1924

Community Perspectives and Environmental Justice in California's San Joaquin Valley

University of California, Merced | December 1st, 2022

Critical Aquifer Overdraft Accelerates Degradation of Groundwater Quality in California's Central Valley During Drought

American Geophysical Union (AGU) | September 1st, 2021

It has been established that wells are at risk to run dry when groundwater levels decline during drought, but associated impacts to water quality are poorly understood. 

It has been established that wells are at risk to run dry when groundwater levels decline during drought, but associated impacts to water quality are poorly understood. This study examined 30 yr of data from California's Central Valley to find dramatic groundwater-level declines during drought were associated with worsening groundwater quality. This likely happens because increased pumping during drought can draw shallow, contaminated groundwater to depths commonly tapped by public drinking water wells. This is the first study of its kind to show direct linkages between drought and groundwater quality at such a broad spatial scale