San Joaquin River

Population exposure to pre-emptive de-energization aimed at averting wildfires in Northern California

Environmental Research Letters (IOP) | August 26th, 2020

Recent extreme fire seasons in California have prompted utilities such as Pacific Gas and Electric to pre-emptively de-energize portions of the electrical grid during per

Recent extreme fire seasons in California have prompted utilities such as Pacific Gas and Electric to pre-emptively de-energize portions of the electrical grid during periods of extreme fire weather to reduce the risk of powerline-related fire ignitions. The policy was deployed in 2019, resulting in 12 million person-days of power outages and widespread societal disruption. Retrospective weather and vegetation moisture data highlight hotspots of historical risk across northern California. We estimate an average of 1.6 million person-days of de-energization per year, based on recent historical climate conditions and assuming publicly stated utility de-energization thresholds. We further estimate an additional 70% increase in the population affected by de-energization when vegetation remains abnormally dry later into autumn—suggesting that climate change will likely increase population vulnerable to de-energization. Adaptation efforts to curtail fire risk can be beneficial, but efforts to prepare affected populations, modernize the grid, and refine decision-making surrounding such policies have high potential to reduce the magnitude of negative externalities experienced during the 2019 de-energization events.

Post-Drought Groundwater Storage Recovery in California's Central Valley

American Geophysical Union (AGU) | October 5th, 2021

California's Central Valley has experienced chronic groundwater depletion over the past few decades, the rate of which was amplified by droughts in 2007–2009 and 2012â€

California's Central Valley has experienced chronic groundwater depletion over the past few decades, the rate of which was amplified by droughts in 2007–2009 and 2012–2016. There is limited knowledge as to how much of the drought-caused groundwater depletion has recovered during post-drought years and how climate and water management affect overdraft recovery times. We address these issues by estimating groundwater storage changes using four methods and conducting numerical experiments with varying climatic conditions and water management options. We find that less than one-third of the groundwater overdraft from the most recent droughts was recovered during post-drought years. Projected overdraft recovery times vary greatly depending on the climate scenarios and water management strategies, and future droughts are likely to cause overdrafts from which recovery is unlikely given the current level of groundwater extractions. However, management measures such as capping groundwater pumping could reduce recovery times by a factor of two or more depending on the groundwater extraction cap and post-drought climate.

Post-fire evapotranspiration estimates in ground truth limited environments

Elsevier | June 16th, 2025

Wildfires are catastrophic events with increasing incidence and severity, especially in Mediterranean climates like California. Wildfires can drastically change the hydro

Wildfires are catastrophic events with increasing incidence and severity, especially in Mediterranean climates like California. Wildfires can drastically change the hydrologic components of a watershed and require consistent and reliable data to monitor recovery. With the upcoming retirement of the Moderate Resolution Imaging Spectroradiometer (MODIS), a reliable evapotranspiration (ET) product at the subcatchment scale is necessary to monitor longitudinal ET, particularly post-fire. We evaluate NASA JPL's ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS), MODIS, and the North American Land Data Assimilation System phase 2 (NLDAS-2) to assess performance in longitudinal evapotranspiration (ET) estimates and post-fire ET change detection using correlation analysis and linear regression for twelve subwatersheds located within the August Complex Fire (August 2020) in Trinity County, the Delta Fire (September 2018) in Shasta and Trinity Counties, and the Creek Fire (September 2020) in Fresno County for a four-year period. We found that MODIS and ECOSTRESS showed the strongest correlation in daily ET estimates (mean r = 0.56), while correlations between ECOSTRESS-NLDAS-2 (r = 0.06) and MODIS-NLDAS-2 (r = 0.30) were notably weaker. However, ECOSTRESS data availability constrained post-fire change detection and annual ET sum assessments. Its higher spatial resolution and correlation with MODIS have potential for finer-scale model parameterization of post-fire landcover changes, particularly vegetation loss in place of MODIS. NLDAS-2 can be useful in monthly and annual patterns at larger scales. By comparing ECOSTRESS with established platforms of ET estimation, we validate ECOSTRESS as a tool for post-fire ET monitoring, especially in areas where ground truth data is unavailable. These findings can allow for more informed and effective land management decisions, particularly in wildfire and vegetation monitoring.

Postfire Sediment Mobilization and its Downstream Implications Across California, 1984–2021

American Geophysical Union (AGU) | August 27th, 2024

Potential Impacts of Future Geological Storage of CO2 on the Groundwater Reservoirs in California's Central Valley

California Energy Commission (CEC) | May 1st, 2013

This study assessed the history of oil production and pressure changes in the southern portion of the San Joaquin Basin in California’s Central Valley as a reverse anal

This study assessed the history of oil production and pressure changes in the southern portion of the San Joaquin Basin in California’s Central Valley as a reverse analog for understanding the pressure response to potential geologic carbon sequestration. Sequestration involves injecting carbon dioxide into permeable strata such as those that trap oil. This results in pressure increases in the existing fluid in the subsurface that can provide a motive force for brines at those depths to migrate into groundwater, affecting its quality. The pressure can also cause differential ground surface uplift that can affect surface water flow, particularly in engineered water conveyances such as canals. The strata underlying the Central Valley have been assessed as having considerable capacity to store carbon dioxide, but the area also contains urban areas and extensive agriculture that rely on engineered surface water delivery systems and groundwater supplies. The Stevens Sand, Temblor Formation and Vedder Formation were identified as having the largest cumulative net production from typical geologic carbon sequestration depths. Two oil pools were identified in each of these stratigraphic units for more detailed analysis, which included converting fluid level data to pressure at the pool scale. Data were collected that allowed an assessment of the hydraulic connectivity of each unit. The results indicated that the Vedder was hydraulically connected at the near basin scale, the Stevens was hydraulically connected at the pool scale and was disconnected between pools and the Temblor was disconnected within pools. Researchers used these results to analyze possible brine leakage driven by geologic carbon sequestration. They also reviewed over 200 articles on historic groundwater contamination. They concluded that no instance of contamination due to upward leakage of brine in the Central Valley was reported.

Potential Impacts of Future Geological Storage of CO2 on the Groundwater Resources in California’s Central Valley: Southern San Joaquin Basin Oil and Gas Production Analog for Geologic Carbon Storage

California Energy Commission (CEC) | May 1st, 2013

This study investigated the potential impacts of the injection and storage of large quantities of carbon dioxide on shallow water resources in California’s southern San

This study investigated the potential impacts of the injection and storage of large quantities of carbon dioxide on shallow water resources in California’s southern San Joaquin Basin, including the possibility that if such injection was properly planned it might help mitigate the land subsidence impacts related to over-pumping of groundwater. The project used simulation studies to investigate whether the basin-scale pressure changes and brine displacement caused by future carbon dioxide storage in the deep sediments could impact the groundwater-surface water systems in the area. Two simulation models were developed. The Deep Basin Reservoir Simulation Model was developed for accurately simulating the multiphase processes of carbon dioxide and brine flow occurring in deep sequestration reservoirs. The Shallow Water Resources Impact Simulation Model was developed for accurately predicting the impact of deep carbon dioxide sequestration on a stressed water system, including evaluation of carbon dioxide-related impacts in the context of the long-term groundwater and subsidence trends occurring in the area as a result of other water stresses such as pumping and irrigation. The Deep Basin Reservoir Simulation Model showed that the caprock and overlying geological units had sufficient barrier attributes to prevent pressure propagation from the injection layer to the shallow aquifers. The Shallow Water Resources Impact Simulation Model simulation results showed that deep carbon dioxide injection would create only minor head change and surface uplift in the shallow model layers. Overall the simulation results suggested that even large carbon dioxide storage projects should have minimal impact on shallow groundwater and surface water systems if thick layers of shales and sands separated the deep CO2 injection layers from shallow aquifers. Researchers believed this study justified devoting resources to evaluating the potential impact from localized pathways or from induced seismicity to more thoroughly investigate the feasibility of carbon dioxide storage in the southern San Joaquin Basin. 

PPIC Statewide Survey: Californians and the Environment

Public Policy Institute of California (PPIC) | July 28th, 2022

With California facing a severe drought and wildfire season, public awareness has risen of the impact of climate change as well as state policies to reduce greenhouse gas

With California facing a severe drought and wildfire season, public awareness has risen of the impact of climate change as well as state policies to reduce greenhouse gas emissions. A sharp increase in petroleum prices has led to discussions about expanding oil production and renewable energy sources. These are among the key findings of a statewide survey on environmental issues conducted by the Public Policy Institute of California from July 8 to 15, 2022.

PPIC Statewide Survey: Californians and the Environment

Public Policy Institute of California (PPIC) | August 8th, 2024

Californians have been facing a record heat wave and wildfires across the state this summer. The state’s multibillion-dollar budget deficit prompted spending cuts for

Californians have been facing a record heat wave and wildfires across the state this summer. The state’s multibillion-dollar budget deficit prompted spending cuts for climate and energy programs. In response, the legislature approved a $10 billion state bond for the November ballot that asks voters to approve more funding for drought, floods, wildfires, coastal resilience, and extreme heat mitigation. The deep partisan divide on climate and energy policies surfaced in the presidential debate on June 27. These are the key findings of the Californians and the Environment survey on local, state, and national issues and coastal and inland topics that was conducted June 24–July 2, 2024.

Predation on Fishes in the Sacramento–San Joaquin Delta: Current Knowledge and Future Directions

University of California, Davis (UC Davis) | July 1st, 2016

The Delta is a diverse, highly modified aquatic system. This paper reviews relevant predator–prey theory, describes data on predator–prey relationships of Delta fishe

The Delta is a diverse, highly modified aquatic system. This paper reviews relevant predator–prey theory, describes data on predator–prey relationships of Delta fishes, ranks predator consumption rates, and presents hypotheses for the effects of predation on native and invasive species. Thiry-two different predator categories and 41 different prey categories are identified. The analysis yielded few generalizations regarding predator–prey interactions for Delta fishes. The only evidence for predator specialization occurred in Prickly Sculpin which, when it consumed fishes, ate mostly native species. Data for reptilian, avian, and mammalian predators were sparse; however, these predators may be significant fish predators in altered habitats or when hatchery salmonids are released. The database for predators and their fish prey was not strong, and long-term dietary studies combined with prey availability and behavioral and experimental studies are needed. The behavioral effects of contaminants on prey species also warrant further examination. Although it has been suggested that a reduction in the Striped Bass population be implemented to reduce predation mortality of Chinook Salmon, the large number of salmon predators in the Delta make it unlikely that this effort will significantly affect salmon mortality.

Predicting California Water-Year Types Using Seasonal Climate Forecasts

American Meteorological Society (AMS) | August 1st, 2025