"Incomplete” Determination of the 2020 Groundwater Sustainability Plans Submitted for the San Joaquin Valley – Madera Subbasin

California Department of Water Resources (DWR) | September 22nd, 2022

The Department of Water Resources (Department) has evaluated the four groundwater sustainability plans (GSPs) submitted for the San Joaquin Valley – Madera Subbasin (Su

The Department of Water Resources (Department) has evaluated the four groundwater sustainability plans (GSPs) submitted for the San Joaquin Valley – Madera Subbasin (Subbasin), as well as the materials considered to be part of the required coordination agreement. Collectively, the four GSPs and the coordination agreement are referred to as the Plan for the Subbasin. The Department has determined that the Plan is “incomplete” pursuant to Section 355.2(e)(2) of the GSP Regulations. The Department based its incomplete determination on recommendations from the Staff Report, included as an enclosure to the attached Statement of Findings, which describes that the Subbasin’s Plan does not satisfy the objectives of the Sustainable Groundwater Management Act (SGMA) nor substantially comply with the GSP Regulations. The Staff Report also provides corrective actions which the Department recommends the Subbasin’s 7 groundwater sustainability agencies (GSAs) review while determining how and whether to address the deficiencies in a coordinated manner. The Subbasin’s GSAs have 180 days, the maximum allowed by the GSP Regulations, to address the identified deficiencies. Where addressing the deficiencies requires modification of the Plan, the GSAs must adopt those modifications into their respective GSPs and all applicable coordination agreement materials, or otherwise demonstrate that those modifications are part of the Plan before resubmitting it to the Department for evaluation no later than March 21, 2023.

A New Technique for Modeling Land Subsidence Facilitates Better Groundwater Management

Stanford University | December 1st, 2019

Land subsidence – the sudden sinking or gradual settling of Earth’s surface – can occur naturally or be triggered by human activity. One of the most comm

Land subsidence – the sudden sinking or gradual settling of Earth’s surface – can occur naturally or be triggered by human activity. One of the most common human-affected factors is groundwater pumping, a practice that has been steadily increasing due to prolonged periods of drought. Groundwater pumping is so prevalent in some areas that it is severely compromising the quantity and quality of the groundwater as well as the physical structure of the land and aquifer capacity beneath it. Large-scale initiatives for putting water back into the ground, or groundwater recharge, are being implemented in some regions. However, groundwater resource managers still need better information to determine where the land is at greatest risk of subsidence as well as where recharge efforts would be the most effective. Integrating two reliable data gathering sources – helicopter-deployed systems (airborne electromagnetic or AEM technology) that measure electromagnetic fields and satellite-deployed systems (interferometric synthetic aperture radar or InSAR) to measure deformations – offers groundwater managers an improved method for more accurately modeling changes in the land surface related to the pumping and recharge of groundwater. Additionally, the ability to more precisely detect subsidence may offer an early warning system for declining groundwater levels.

Abrupt transition to irreversible damage in the overdrafted Sacramento Valley aquifer system

National Academy of Sciences (NAS) | July 27th, 2026

Groundwater extraction can cause both reversible and irreversible ground deformation, with the latter leading to permanent land subsidence and loss of groundwater storage

Groundwater extraction can cause both reversible and irreversible ground deformation, with the latter leading to permanent land subsidence and loss of groundwater storage capacity. Satellite observations of land surface deformation reveal that large areas of the Sacramento Valley abruptly transitioned from reversible to irreversible compaction over the 2020–2022 California drought—a transition not anticipated from the groundwater monitoring network alone. Subsidence rates reaching several decimeters per year and not following groundwater levels indicate lasting damage to the aquifer system and underscore the need for more conservative groundwater management. By imaging this sharp transition at the regional scale, our analysis demonstrates the potential of space-based monitoring for early detection of groundwater overdraft and the resulting loss of aquifer storage capacity worldwide.

Achieving Groundwater Access for All: Why Groundwater Sustainability Plans are Failing Many Users

Groundwater Leadership Forum | July 3rd, 2023

California made a serious commitment to bring the most depleted groundwater basins back into balance when it passed the Sustainable Groundwater Management Act (SGMA) in 2

California made a serious commitment to bring the most depleted groundwater basins back into balance when it passed the Sustainable Groundwater Management Act (SGMA) in 2014. This commitment is being carried out at the local level through the formation of hundreds of new groundwater agencies, the launch of basin-level planning processes, and the creation of groundwater sustainability plans. This report summarizes the results of a scientific study published in Nature Communications. that analyzed the degree to which these groundwater plans equitably integrate and protect vulnerable groundwater users, and suggests course corrections in the ongoing SGMA process to ensure we are preparing our groundwater basins for a changed climate.

Advancing Strategic Land Repurposing and Groundwater Sustainability in California

Environmental Defense Fund (EDF) | March 26th, 2021

For decades, California has been on a steady trajectory toward water scarcity, which is now exacerbated by climate change. More frequent and intense droughts and incre

For decades, California has been on a steady trajectory toward water scarcity, which is now exacerbated by climate change. More frequent and intense droughts and increased demands have affected the reliability of surface water supplies. As a result, many have looked to groundwater to fill the gap. Groundwater overpumping has resulted in adverse impacts such as reduction in groundwater storage, subsidence, water quality degradation, sea water intrusion, wells going dry and depletion of interconnected surface waters throughout many areas in California’s San Joaquin Valley. These impacts led to the passage of the Sustainable Groundwater Management Act (SGMA) by the state Legislature in 2014, which mandates sustainable use of groundwater by 2040 for the most critically overdrafted basins.

Aliso Water District Groundwater Sustainability Plan

Aliso Water District Groundwater Sustainability Agency | January 17th, 2020

Amargosa Desert Hydrographic Basin 14-230 Groundwater Pumpage Inventory Water Year 2015

State of Nevada | July 31st, 2015

An Integrated Surface Water-Groundwater Interaction Model for the Carmel River

California State University, Monterey Bay | April 30th, 2010

The Carmel River supplies fresh water to the residents of the Monterey Peninsula within the water district served by the California American Water company (Cal-Am). The S

The Carmel River supplies fresh water to the residents of the Monterey Peninsula within the water district served by the California American Water company (Cal-Am). The State Water Resources Control Board, in 1995, ordered that Cal-Am reduce their annual diversions from the Carmel River Watershed to within legal right (3,376 acre-feet per year). An alternative water source to the Carmel River has yet to be determined, and as a result, Cal-Am must continue to divert more water than their legal entitlement. The current magnitude of diversions has a negative impact on the spawning and migrating habitat of Steelhead (Oncorhynchus mykiss). Existing software in the Tarsier Environmental Modeling Framework was used to model the spatial distribution of surface water along the Carmel River. The model simulated the flow of water downstream from catchment area to the Pacific Ocean. The river channel was represented by a network data set comprised of links, representing individual reaches of the river, connected by nodes. Prior to my work, systematic error in the model was thought to be partially the result of the model lacking a simulation of the interactions between the surface water and the underlying aquifer. A groundwater sub-model was developed to correct for the systematic error. The groundwater sub-model simulated the movement of water between the river channel and the aquifer. Stock variables representing a shallow and deep aquifer were added to each link of the network data set. Simulated water in the surface water stock of each link percolates to these aquifer stocks until the groundwater reaches aquifer capacity, allowing surface water to continue flowing downstream. The model also allows the lateral flow of groundwater according to Darcy’s Law. Quantitative and qualitative analysis of model output compared to observed data showed an increase in model accuracy. Quantitatively, a Nash- Sutcliff Coefficient was improved from 0.88 to 0.97 with the addition of the groundwater model. Qualitatively, a visualization of the longitudinal profile of the river system showed the simulated aquifer controlling the surface flow. A hypothetical application of this model is presented where reducing the pumping rate from the aquifer allowed the wetted river channel to increase by 2.5 km. Future work on the model should include a reservoir sub-model and accounting for spatial variability in the precipitation throughout the catchment area. With these improvements it will be possible to improve predictions of the spatial distribution of surface water along the Carmel River given hypothetical scenarios such as the rate and spatial distribution of pumping from the Carmel Aquifer. Using these simulations to inform decisions of river management could benefit all stakeholders of the river.

Analysis of Potential Water-Supply Management Options, 2010-60, and Documentation of Revisions to the Model of the Irwin Basin Aquifer System, Fort Irwin National Training Center, California

U.S. Geological Survey (USGS) | October 31st, 2014

The Fort Irwin National Training Center is considering several alternatives to manage their limited water-supply sources in the Irwin Basin. An existing three-dimensional

The Fort Irwin National Training Center is considering several alternatives to manage their limited water-supply sources in the Irwin Basin. An existing three-dimensional, finite-difference groundwater-flow model—the U.S. Geological Survey’s MOD-FLOW—of the aquifer system in the basin was updated and the initial input dataset was supplemented with groundwater withdrawal data for the period 2000–10. The updated model was then used to simulate four combinations, or scenarios, of groundwater withdrawal and recharge over the next 50 years (January 2011 through December 2060). The scenarios included combinations of continuing withdrawals from currently active production wells, supplementing any increases in demand with withdrawals from an inactive production well, reducing withdrawal amounts and rates, and reducing the discharge of treated wastewater to infiltration ponds that provide a recharge source to the underlying aquifer. Results of the simulations indicated that, depending on the scenario implemented, groundwater levels would rise (over the next 50 years) from 40 feet to as much as 65 feet in the northwestern part of the Irwin Basin, and from 5 feet to 10 feet in the southeastern part.

Annual Owens Valley Operations Plan for the 2024-25 Runoff Year

Los Angeles Department of Water & Power (LADWP) | June 20th, 2024