Tulare Lake

Making Water Conservation a California Way of Life: Primer of 2018 Legislation on Water Conservation and Drought Planning Senate Bill 606 (Hertzberg) and Assembly Bill 1668 (Friedman)

California State Water Resources Control Board (SWRCB) | November 30th, 2018

In 2018, the California State Legislature (Legislature) enacted two policy bills, (Senate Bill (SB) 606 (Hertzberg) and Assembly Bill (AB) 1668 (Friedman)), to establish

In 2018, the California State Legislature (Legislature) enacted two policy bills, (Senate Bill (SB) 606 (Hertzberg) and Assembly Bill (AB) 1668 (Friedman)), to establish a new foundation for long-term improvements in water conservation and drought planning to adapt to climate change and the resulting longer and more intense droughts in California. These two bills amend existing law to provide expanded and new authorities and requirements to enable permanent changes and actions for those purposes, improving the state's water future for generations to come.

Maladaptation to drought: a case report from California, USA

Sustainability Science (Springer) | October 15th, 2015

The interactions between natural water availability and societal water demand and management are complex. In response to gaps in empirical research of the adaptive capaci

The interactions between natural water availability and societal water demand and management are complex. In response to gaps in empirical research of the adaptive capacity of social and environmental systems to climate stresses, we provide an assessment of responses to water scarcity during a multi-year drought in California. In particular, we use Barnett and O’Neill’s (Global Environ Change 20:211–213, 2010) criteria for maladaptation to examine responses in the agricultural and energy sectors to a multi-year (2007–2009) California drought. We conclude that despite evidence in both sectors of resiliency to the impacts of the drought, some of the coping strategies adopted increased the vulnerability of other systems. These other systems include California’s aquatic ecosystems and social groups that rely on those ecosystems for their health or employment; future generations whose resources were drawn down in the near-term, where otherwise those resources would have been available at a later time; and current and future generations who were, or will be, exposed to the effects of increased greenhouse gas emissions. This case study demonstrates that California’s current strategies for dealing with long or severe droughts are less successful than previously thought when short- and long-term impacts are evaluated together. This finding is particularly relevant given projections of more frequent and severe water shortages in the future due to climate change. This study recommends a shift from crisis-driven responses to the development and enactment of long-term mitigation measures that are anticipatory and focus on comprehensive risk reduction.

Managed Aquifer Recharge in California: Four Examples of Managed Groundwater Replenishment Across the State

American Geosciences Institute (AGI) | September 29th, 2017

In California, surface water from rainfall, snowmelt, and distant rivers rarely meets the state’s urban and agricultural water needs. Groundwater is an essentia

In California, surface water from rainfall, snowmelt, and distant rivers rarely meets the state’s urban and agricultural water needs. Groundwater is an essential water source, providing 35% of the fresh water used in California. However, when groundwater is used more rapidly than it is naturally replenished, groundwater management becomes necessary. One of the tools used by groundwater managers is managed aquifer recharge (MAR). Aquifers, the porous rocks and sediments that hold and transmit groundwater, are naturally replenished by surface water that seeps into the ground. MAR enhances the recharge rate by creating artificial streams and ponds where water trickles into the ground, or by using wells to directly inject water underground. MAR can also be used to improve groundwater quality and prevent some of the negative consequences of groundwater depletion, like ground sinking (subsidence) or the intrusion of salty groundwater from the oceans into coastal freshwater aquifers. Because of its arid climate and large population, California is home to some of the oldest and largest MAR projects in the United States. This case study highlights four of these projects, covering almost a century of MAR and water security in California.

Managing Water Scarcity: A Framework For Fair And Effective Water Right Curtailment In California

Berkeley Law Center for Law, Energy, & the Environment | April 15th, 2023

The report describes the legal context for water right curtailments in California, summarizes the history of curtailment practices in the state, and recommends actions Ca

The report describes the legal context for water right curtailments in California, summarizes the history of curtailment practices in the state, and recommends actions California can take to build an effective framework for curtailment.

Mapping aquifer salinity gradients and effects of oil field produced water disposal using geophysical logs: Elk Hills, Buena Vista and Coles Levee Oil Fields, San Joaquin Valley, California

PLOS | March 28th, 2022

The effects of oil and gas production on adjacent groundwater quality are becoming a concern in many areas of the United States. As a result, it has become increasingly i

The effects of oil and gas production on adjacent groundwater quality are becoming a concern in many areas of the United States. As a result, it has become increasingly important to identify which aquifers require monitoring and protection. In this study, we map the extent of groundwater with less than 10,000 mg/L TDS both laterally and vertically near the Elk Hills, Buena Vista and Coles Levee Oil Fields in the San Joaquin Valley, California and note evidence of effects of produced water disposal on salinity within the Tulare aquifer. Subsurface maps showing the depth at which groundwater salinity is less than 10,000 mg/L (or Base 10K) in the Tulare aquifer are generated using geophysical logs and verified by comparison to water sample analyses. The depth to Base 10K ranges from 240 m (800 ft) in Elk Hills to 800 m (2650 ft) in the adjacent Buena Vista syncline and is 670 m (2,200 ft) deep in the Coles Levee area to the east. Log-calculated salinities show a relatively smooth increase with depth prior to disposal activities whereas salinities calculated from logs collected near and after disposal activities show a more variable salinity profile with depth. The effect of produced water injection is represented by log resistivity profiles that change from low resistivity at the base of the sand to higher resistivity near the top due to density differences between the saline produced water and the brackish groundwater within each sand. Continued post-disposal logging in new wells in the 18G disposal area on the south flank of Elk Hills shows that injected water has migrated approximately 1,200 m (4,000 ft) downdip (south) over a period of 20 years since the inception of disposal activity.

Mapping Aquifer Systems with Airborne Electromagnetics in the Central Valley of California

National Groundwater Association (NGWA) | March 9th, 2018

The passage of the Sustainable Groundwater Management Act in California has highlighted a need for cost-effective ways to acquire the data used in building conceptual mo

The passage of the Sustainable Groundwater Management Act in California has highlighted a need for cost-effective ways to acquire the data used in building conceptual models of the aquifer systems in the Central Valley of California. One approach would be the regional implementation of the airborne electromagnetic (AEM) method. We acquired 104 line-kilometers of data in the Tulare Irrigation District, in the Central Valley, to determine the depth of investigation (DOI) of the AEM method, given the abundance of electrically conductive clays, and to assess the usefulness of the method for mapping the hydrostratigraphy. The data were high quality providing, through inversion of the data, models displaying the variation in electrical resistivity to a depth of approximately 500 m. In order to transform the resistivity models to interpreted sections displaying lithology, we established the relationship between resistivity and lithology using collocated lithology logs (from drillers’ logs) and AEM data. We modeled the AEM response and employed a bootstrapping approach to solve for the range of values in the resistivity model corresponding to sand and gravel, mixed coarse and fine, and clay in the unsaturated and saturated regions. The comparison between the resulting interpretation and an existing cross section demonstrates that AEM can be an effective method for mapping the large-scale hydrostratigraphy of aquifer systems in the Central Valley. The methods employed and developed in this study have widespread application in the use of the AEM method for groundwater management in similar geologic settings.

Maximizing ENSO as a source of western US hydroclimate predictability

Climate Dynamics (Springer) | October 16th, 2019

Until recently, the El Niño–Southern Oscillation (ENSO) was considered a reliable source of winter precipitation predictability in the western US, with a historically

Until recently, the El Niño–Southern Oscillation (ENSO) was considered a reliable source of winter precipitation predictability in the western US, with a historically strong link between extreme El Niño events and extremely wet seasons. However, the 2015–2016 El Niño challenged our understanding of the ENSO-precipitation relationship. California precipitation was near-average during the 2015–2016 El Niño, which was characterized by warm sea surface temperature (SST) anomalies of similar magnitude compared to the extreme 1997–1998 and 1982–1983 El Niño events. We demonstrate that this precipitation response can be explained by El Niño’s spatial pattern, rather than internal atmospheric variability. In addition, observations and large-ensembles of regional and global climate model simulations indicate that extremes in seasonal and daily precipitation during strong El Niño events are better explained using the ENSO Longitude Index (ELI), which captures the diversity of ENSO’s spatial patterns in a single metric, compared to the traditional Niño3.4 index, which measures SST anomalies in a fixed region and therefore fails to capture ENSO diversity. The physically-based ELI better explains western US precipitation variability because it tracks the zonal shifts in tropical Pacific deep convection that drive teleconnections through the response in the extratropical wave-train, integrated vapor transport, and atmospheric rivers. This research provides evidence that ELI improves the value of ENSO as a predictor of California’s seasonal hydroclimate extremes compared to traditional ENSO indices, especially during strong El Niño events.

McMullin Area Groundwater Sustainability Agency Groundwater Sustainability Plan

McMullin Area Groundwater Sustainability Agency (MAGSA) | November 6th, 2019

McMullin Area Groundwater Sustainability Agency Groundwater Sustainability Plan (Revised)

McMullin Area Groundwater Sustainability Agency (MAGSA) | July 6th, 2022

Mean and Extreme Climate Change Impacts on the State Water Project

California Department of Water Resources (DWR) | August 27th, 2018

Warming temperatures, shifting hydrology, and rising sea levels will challenge management of California’s water resources. This study quantifies climate change risks t

Warming temperatures, shifting hydrology, and rising sea levels will challenge management of California’s water resources. This study quantifies climate change risks to California’s State Water Project (SWP) and federal Central Valley Project (CVP). This study uses the California Department of Water Resources’ (DWR’s) newly developed water planning model, CalSim 3.0, as a risk assessment tool. Impacts were assessed for 20 climate change scenarios (10 global climate models and two emission scenarios, representative concentration pathway (RCP) 4.5 and RCP 8.5). Water supply and water quality metrics evaluated include Delta exports, North of Delta Carryover storage, reservoir dead storage (i.e. when reservoir levels fall below the lowest outlets), and Delta salinity. Results for the driest future scenario were also analyzed to examine future drought impacts. In addition, a series of sensitivity tests were implemented to assess individual impacts of four climate change factors: flow seasonal pattern shift, sea level rise, annual flow volume change, and water demand change on the State Water Project and Central Valley Project operations. It was found that flow seasonal pattern shift will become a major climate change factor and sea level rise a secondary factor, leading to a half million‐acre feet of Delta export reduction as well as a roughly 25% decrease of North‐of‐Delta carryover storage by around 2060. The results also indicate that the extra runoff from early snow melting and higher percentage of rain in the winter and early spring is not conserved in reservoirs and thus cannot be used to meet the higher summer demand in the current SWP/CVP system. This extra water is released as flood water in the winter and early spring to become Delta outflow.