Delano Earlimart Irrigation District Groundwater Sustainability Plan

Delano Earlimart Irrigation District | January 27th, 2020

Delineation of ground‐water flow systems in the southern Great Basin using aqueous rare earth element distributions

National Groundwater Association (NGWA) | January 1st, 1997

The rare earth element (REE) signature of ground waters from both felsic volcanic rocks on the Nevada Test Site and from the regional Paleozoic carbonate aquifer of south

The rare earth element (REE) signature of ground waters from both felsic volcanic rocks on the Nevada Test Site and from the regional Paleozoic carbonate aquifer of southern Nevada resemble the REE signature of the rocks through which they flow. Moreover, the REE signatures of Ash Meadows ground waters are similar to those of springs in the Furnace Creek region of Death Valley but different from shallow ground waters from predominantly tuffaceous alluvial deposits in the Amargosa Desert, perched ground waters from felsic volcanic rocks, and ground waters that have only flowed through the regional Paleozoic carbonate aquifer. The similar REE patterns of Ash Meadows and Furnace Creek ground waters support previous investigations that suggested ground waters discharging from the Furnace Creek springs are similar to the ground waters emerging from the Ash Meadows springs. The REE patterns indicate that the contribution of ground water from the Amargosa Desert to the Furnace Creek springs is of minor importance. Our REE analyses along with previous stable isotope, ground‐water potentiometric surface relationships, and geologic structure analyses support ground‐water flow from east to west in the fractured and faulted carbonate rocks beneath Ash Meadows, the Amargosa Desert, and the southern end of the Funeral Mountains. Our observations are contrary to some previous investigations that identified shallow ground waters from the central and northwestern Amargosa Desert as a substantial component of the ground water that discharges from the Furnace Creek springs.

Delineation of Spatial Extent, Depth, Thickness, and Potential Volume of Aquifers Used for Domestic and Public Water-Supply in the Central Valley, California

U.S. Geological Survey (USGS) | September 5th, 2019

Identification of the groundwater resources used for drinking-water supplies is essential for the design of strategies to manage those resources. In this study, t

Identification of the groundwater resources used for drinking-water supplies is essential for the design of strategies to manage those resources. In this study, the spatial extent, depths, thicknesses, and volumes of groundwater aquifers used for domestic and public drinking-water supply were estimated from locations and well-construction data from 11,725 domestic-supply wells and 2,376 public-supply wells in the Central Valley, California. The data were compiled as part of the U.S. Geological Survey National Water Quality Assessment Project and California State Water Resources Control Board Groundwater Ambient Monitoring and Assessment Program Priority Basin Project. The spatial distributions of the depth to top and bottom of well screens were interpolated using Empirical Bayesian Kriging across buffer areas surrounding domestic- and public-supply wells. These surfaces provide a measure of the likely maximum horizontal and vertical extent of the aquifer volume accessed for drinking water in the Central Valley during the past century. Well depth generally increased from north to south, and over time from 1905 to 2010. Well-construction depths were generally more consistent in the Sacramento Valley than in the San Joaquin Valley. The total potential aquifer volume accessed for public supply was calculated to be greater than domestic-supply access, even though the estimated spatial extent of domestic-supply wells was 1.5 times larger than the spatial extent of public-supply wells. Public-supply wells commonly have screen lengths greater than 51 meters, whereas domestic-supply wells typically have shorter screen lengths (overall median of 6 meters). Consequently, the accessed thickness and volume of the aquifer is on average 1.8 and 1.4 times greater for public-supply wells than domestic- supply wells, respectively. Results are presented as maps of areal extent, depth, and thickness of zones in the Central Valley aquifer system used for domestic and public drinking- water supplies.

Delta Adapts: Creating a Climate Resilient Future

Delta Stewardship Council (Delta Council) | June 25th, 2021

The time to act is now. Climate change is already altering the physical environment of the Sacramento–San Joaquin Delta and Suisun Marsh (Delta), and we will continue t

The time to act is now. Climate change is already altering the physical environment of the Sacramento–San Joaquin Delta and Suisun Marsh (Delta), and we will continue to experience its effects through hotter temperatures, more severe wildfires, and prolonged droughts. Over the long term, climate change in the Delta is expected to harm human health and safety, disrupt the economy, diminish water supply availability and usability, shift ecosystem function, compromise sensitive habitats, and increase the challenges of providing basic services. Many of these impacts will disproportionately affect vulnerable communities. Although the exact extent and timing of these impacts is uncertain, this climate change vulnerability assessment phase of Delta Adapts will help the Delta Stewardship Council (Council) understand specific regional climate risks and vulnerabilities. Regional, collaborative adaptation strategies rooted in science are more critical than ever. The next phase of Delta Adapts, preparing an adaptation strategy, will identify ways to address the risks and vulnerabilities.

Delta Adapts: Creating a Climate Resilient Future

Delta Stewardship Council (DSC) | June 25th, 2025

The Delta Stewardship Council (Council) was established, in part, to provide sustainable management for the Delta ecosystem, and climate adaptation is a critical consider

The Delta Stewardship Council (Council) was established, in part, to provide sustainable management for the Delta ecosystem, and climate adaptation is a critical consideration to achieve that mission in future decades. To respond to the challenge of climate adaptation,the Council developed this initiative, Delta Adapts: Creating a Climate Resilient Future (Delta Adapts). Climate change must be considered to attain the state’s coequal goals, as established by the 2009 Delta Reform Act: securing a reliable water supply for California, protecting and restoring the ecosystem and wildlife it supports, and enhancing the Delta as a unique place, with its community, tribal, and agricultural heritage. The Council adopted the Delta Plan, which has regulatory policies that protect land for restoration and agriculture, help manage flood risk, and improve water supply reliability. The Delta Plan directs the Council to guide and regulate actions of the 200+ state and local agencies in the Delta to ensure they support statewide water supply reliability and Delta ecosystem restoration.

Delta Adapts: Creating a Climate Resilient Future Sacramento-San Joaquin Delta Climate Change Adaptation Plan (Draft)

Delta Stewardship Council (Delta Council) | November 1st, 2024

Initiated in 2018 by the Council, Delta Adapts began with a Climate Change Vulnerability Assessment (CCVA) to understand how regional climate impacts will affect the Delt

Initiated in 2018 by the Council, Delta Adapts began with a Climate Change Vulnerability Assessment (CCVA) to understand how regional climate impacts will affect the Delta’s ecosystems, water supply, infrastructure, agriculture, and communities, including socially vulnerable communities (defined in Chapter 1). Now, this Adaptation Plan builds upon the CCVA and proposes strategies to address how Delta communities, infrastructure, and ecosystems can adapt to climate change in a manner consistent with the Council’s resilience goals.

Delta Aquatic Resources Inventory Factsheet

San Francisco Estuary Institute (SFEI) | July 1st, 2019

 DARI is the Delta Aquatic Resources Inventory of surface waters, wetlands and other aquatic resources in the Sacramento-San Joaquin Delta (Delta). The goal of the DARI

 DARI is the Delta Aquatic Resources Inventory of surface waters, wetlands and other aquatic resources in the Sacramento-San Joaquin Delta (Delta). The goal of the DARI project is to develop a geospatial inventory of aquatic resources that will be used as a common base map for the Delta. A similar mapping approach used to create the California Aquatic Resource Inventory (CARI; www. sfei.org/cari) will be applied to provide a map of the aquatic resources and their associated attributes. The final map will be incorporated into CARI and made publicly available through EcoAtlas (ecoatlas.org) and similar platforms. 

Delta Chromium-53/52 isotopic composition of native and contaminated groundwater, Mojave Desert, USA

Applied Geochemistry (Elsevier) | April 20th, 2012

Chromium(VI) concentrations in groundwater sampled from three contaminant plumes in aquifers in the Mojave Desert near Hinkley, Topock and El Mirage, California, USA, wer

Chromium(VI) concentrations in groundwater sampled from three contaminant plumes in aquifers in the Mojave Desert near Hinkley, Topock and El Mirage, California, USA, were as high as 2600, 5800 and 330 μg/L, respectively. δ53/52Cr compositions from more than 50 samples collected within these plumes ranged from near 0‰ to almost 4‰ near the plume margins. Assuming only reductive fractionation of Cr(VI) to Cr(III) within the plume, apparent fractionation factors for δ53/52Cr isotopes ranged from εapp = 0.3 to 0.4 within the Hinkley and Topock plumes, respectively, and only the El Mirage plume had a fractionation factor similar to the laboratory derived value of ε = 3.5. One possible explanation for the difference between field and laboratory fractionation factors at the Hinkley and Topock sites is localized reductive fractionation of Cr(VI) to Cr(III), with subsequent advective mixing of native and contaminated water near the plume margin. Chromium(VI) concentrations and δ53/52Cr isotopic compositions did not uniquely define the source of Cr near the plume margin, or the extent of reductive fractionation within the plume. However, Cr(VI) and δ53/52Cr data contribute to understanding of the interaction between reductive and mixing processes that occur within and near the margins of Cr contamination plumes. Reductive fractionation of Cr(VI) predominates in plumes having higher εapp, these plumes may be suitable for monitored natural attenuation. In contrast, advective mixing predominates in plumes having lower εapp, the highly dispersed margins of these plumes may be difficult to define and manage.

Delta Conservation Adaptive Management Action Strategy

Delta Stewardship Council (Delta Council) | April 11th, 2019

Various efforts are ongoing to restore and enhance ecosystems in the Sacramento-San Joaquin Delta, Yolo Bypass, and Suisun Marsh (hereafter the Delta) that require suppor

Various efforts are ongoing to restore and enhance ecosystems in the Sacramento-San Joaquin Delta, Yolo Bypass, and Suisun Marsh (hereafter the Delta) that require support for adaptive management. Adaptive management is a science-based, structured approach to environmental decision making under uncertain conditions. Adaptive management emphasizes acquisition and use of new knowledge in natural resource management, leading to continuous iterative improvements in project planning, implementation, monitoring, and follow-up. Adaptive management is required for compliance with multiple regulatory processes, such as consistency with the Delta Plan and the Suisun Marsh Plan, but recent reviews have found that a full adaptive management cycle is rarely completed at either the project- or system-level in the Delta (Delta Independent Science Board 2016; Nagarkar and Raulund-Rasmussen 2016). To address this issue, the Delta Science Program initiated an effort to work with agency and stakeholder partners in the Delta to develop a comprehensive, science-based adaptive management approach to support achievement of Delta conservation goals. Conservation, as defined in the Delta Conservation Framework (Sloop et al. 2018), consists of efforts to protect, restore, and enhance ecosystems in the Delta. The Delta Conservation Adaptive Management Action Strategy is based on the Adaptive Management Framework outlined in the Delta Plan (Figure 1, Delta Stewardship Council 2013). 

Delta Conveyance Environmental Review Notice of Preparation Overview

California Department of Water Resources (DWR) | January 15th, 2020

The Department of Water Resources (DWR) is pursuing an environmental review process to evaluate a single tunnel option to modernize Delta conveyance under the California

The Department of Water Resources (DWR) is pursuing an environmental review process to evaluate a single tunnel option to modernize Delta conveyance under the California Environmental Quality Act (CEQA). The first step in this process is release of a Notice of Preparation (NOP). The NOP informs agencies and the public about the preparation of the Environmental Impact Report (EIR) and solicits input on the scope and content of the EIR, including information needs, potential project effects and mitigation measures, and possible alternatives to the proposed project. Modernizing Delta conveyance is part of the state’s Water Resilience Portfolio, which describes the framework to address California’s water challenges and support long-term water resilience and ecosystem health.