Approved Determination of the Revised Groundwater Sustainability Plan Submitted for the San Joaquin Valley – Merced Subbasin

California Department of Water Resources (DWR) | August 4th, 2023

Artes: An Integrated Model of Water Supply in L.A. County

University of California, Los Angeles (UCLA) | May 1st, 2017

Los Angeles faces a future with less imported water. Infrastructure and institutions will have to adapt. Understanding emerging policy and investment needs requires anal

Los Angeles faces a future with less imported water. Infrastructure and institutions will have to adapt. Understanding emerging policy and investment needs requires analysis across systems, a typically elusive goal within the diverse and disparately managed water systems of L.A. A more comprehensive analysis of water resources in Los Angeles requires an understanding of people, pipes, and plants. It could also be flexible to incorporate the fast-changing landscape of models, data, and analysis that the active agencies of the region continue to develop. With these goals in mind, we developed a water supply model for the metropolitan L.A. County region (Artes) to understand the potential for enhancing local water use across scenarios of demand and supply. The basic approach combines knowledge from engineering, hydrology, ecology, and sociology. The model is intentionally lightweight. Flexible and adaptive modeling can address many questions at multiple geographic scales, while also being able to incorporate new tools, data, and other models that are released. This model was developed to: * Determine how local groundwater, recycling and stormwater capture supplies could maximally meet water demands across L.A. County, based on current knowledge of hydrology and hydrogeology * Analyze tradeoffs in per capita water demand and available imported water supplies * Investigate system-wide effects of increased conservation * Minimize assumptions regarding data gaps * Use modeling to highlight to key gaps in scientific understanding, while creatively addressing the shortfalls in a precautionary manner. For instance, we compare modeled and historic groundwater pumping and managed aquifer recharge to assess the potential for groundwater overdraft. This manual describes important information for understanding model operations, assumptions, inputs, and outputs. The manual version (3.7) was written after development of 3 versions code for different research studies, which are in press or under review.

Assessing the Effects of Climate Change on Middle Rio Grande Surface Water Supplies Using a Simple Water Balance Reservoir Model

American Meteorological Society (AMS) | August 12th, 2022

The middle Rio Grande is a vital source of water for irrigation in the region. Climate change is impacting regional hydrology and is likely to put additional stress on a

The middle Rio Grande is a vital source of water for irrigation in the region. Climate change is impacting regional hydrology and is likely to put additional stress on a water supply that is already stretched thin. To gain insight on the hydrologic effects of climate change on reservoir storage, a simple water balance model was used to simulate the Elephant Butte–Caballo Reservoir system (southern New Mexico). The water balance model was forced by hydrologic inputs generated by 97 climate simulations derived from CMIP5 global climate models, coupled to a surface hydrologic model. Results suggest that the percentage of years that reservoir releases satisfy agricultural water rights allocations over the next 50 years (2021–70) will decrease relative to the past 50 years (1971–2020). The modeling also projects an increase in multiyear drought events that hinder reservoir management strategies to maintain high storage levels. In most cases, changes in reservoir inflows from distant upstream snowmelt is projected to have a greater influence on reservoir storage and water availability downstream of the reservoirs than will changes in local evaporation and precipitation from the reservoir surfaces.

Asymmetric emergence of low-to-no snow in the midlatitudes of the American Cordillera

Nature Portfolio (Springer Nature) | November 14th, 2022

Societies and ecosystems within and downstream of mountains rely on seasonal snowmelt to satisfy their water demands. Anthropogenic climate change has reduced mountain sn

Societies and ecosystems within and downstream of mountains rely on seasonal snowmelt to satisfy their water demands. Anthropogenic climate change has reduced mountain snowpacks worldwide, altering snowmelt magnitude and timing. Here the global warming level leading to widespread and persistent mountain snowpack decline, termed low-to-no snow, is estimated for the world’s most latitudinally contiguous mountain range, the American Cordillera. We show that a combination of dynamical, thermodynamical and hypsometric factors results in an asymmetric emergence of low-to-no-snow conditions within the midlatitudes of the American Cordillera. Low-to-no-snow emergence occurs approximately 20 years earlier in the southern hemisphere, at a third of the local warming level, and coincides with runoff efficiency declines (8% average) in both dry and wet years. The prevention of a low-to-no-snow future in either hemisphere requires the level of global warming to be held to, at most, +2.5 °C.

At Risk: Public Supply Well Vulnerability Under California’s Sustainable Groundwater Management Act

Pacific Institute | June 1st, 2021

Base of fresh ground water (approximately 3,000 micromhos) in the San Joaquin Valley, California

U.S. Geological Survey (USGS) | June 30th, 1971

Widespread pumping of groundwater in the San Joaquin Valley began about 1900, and since 1940 pumpage has increased at an accelerated rate. In response to the heavy withdr

Widespread pumping of groundwater in the San Joaquin Valley began about 1900, and since 1940 pumpage has increased at an accelerated rate. In response to the heavy withdrawal of groundwater, water levels have declined rapidly beneath extensive areas of the valley. Consequently, it becomes necessary to delineate the base of fresh groundwater so that changes in thickness of the fresh-water zone can be monitored, and limited depths of water wells can be determined. In turn, those data will be useful in determining favorable areas for groundwater storage, and areas and depths for waste-water disposal wells. Because other agencies and the U.S. Geological Survey have collected a vast amount of well log and other data, most of the information in this report was assembled from existing files. However, for areas where data were scanty, a few hundred additional electrical logs were collected to supplement the available information.

Bulletin 118 - California's Groundwater Update 2013

California Department of Water Resources (DWR) | April 15th, 2015

California’s Groundwater Update 2013 compiles and analyzes readily available groundwater information to characterize California’s groundwater basins, aquifers, and we

California’s Groundwater Update 2013 compiles and analyzes readily available groundwater information to characterize California’s groundwater basins, aquifers, and well infrastructure. It also presents data and analysis related to groundwater monitoring efforts, aquifer conditions in response to extraction, groundwater management practices, and conjunctive management programs. It expands and enhances baseline groundwater information on a regional scale, identifies challenges associated with sustainable groundwater management, and helps guide implementation of diverse resource management strategies. The set of data, information, and analysis developed can help local and regional groundwater managers, as well as individual well owners, better understand California’s hidden and commonly misunderstood resource. This Bulletin has been uploaded in the following separate files reflecting hydrologic regions and appendices. Chapter One / Introduction  Chapter Two / State-wide Update  Chapter Three / North Coast Chapter Four / San Francisco Bay Chapter Five / Central Coast Chapter Six / South Coast  Chapter Seven / Sacramento River Chapter Eight / San Joaquin River Chapter Nine / Tulare Lake Chapter Ten / North Lahontan Chapter Eleven / South Lahontan Chapter Twelve / Colorado River Appendix A: Methods and Assumptions Appendix B: CASGEM Basin Prioritization Appendix C: Groundwater Use Data 2010-2015 Appendix D: Conjunctive Management Survey Appendix E: Change in Groundwater in Storage Appendix F: Subsidence

Bulletin 17-00, Dams within Jurisdiction of the State of California

California Department of Water Resources (DWR) | July 31st, 2000

Bulletin 17-88, Dams within Jurisdiction of the State of California

California Department of Water Resources (DWR) | October 31st, 1988

Bulletin 17-93, Dams within Jurisdiction of the State of California

California Department of Water Resources (DWR) | June 30th, 1993