Groundwater Discharge by Evapotranspiration, Dixie Valley, West-Central Nevada, March 2009–September 2011

U.S. Geological Survey (USGS) | April 30th, 2015

Groundwater Dynamics in the Colorado River Limitrophe

Pacific Institute | May 23rd, 2013

The Colorado River, diverted and channelized and intensively managed, only rarely has enough water to flow even 20 miles past Morelos Dam, the last dam on the river, near

The Colorado River, diverted and channelized and intensively managed, only rarely has enough water to flow even 20 miles past Morelos Dam, the last dam on the river, near the California/Arizona/Baja California border. The river’s limitrophe reach – the roughly 22.5 mile stretch from Andrade to San Luis that separates Baja California from Arizona – is generally considered the uppermost extent of the remnant Colorado River delta, with some of the most extensive stands of native cottonwoods and willows left on the lower Colorado River and one of the few areas where the river still occasionally has enough water to exceed its banks and reach its floodplain. Because of this, there has been intense restoration interest in the limitrophe reach for more than a decade. In recent years, however, concern has grown that deteriorating groundwater conditions in the lower portion of the limitrophe will limit the success of restoration efforts. Groundwater Dynamics in the Colorado River Limitrophe describes and explains the changing groundwater conditions in and adjacent to the Colorado River’s limitrophe reach, and analyzes the impact of groundwater pumping on these overdraft conditions. The key question underlying this study asks how changing groundwater conditions in the limitrophe could affect the sustainability of planned habitat restoration projects. This study indicates that, even after the exceptionally dry period of 2005-2009, when surface flows failed to reach the gage at the downstream end of the limitrophe on 90 percent of days, more than a third of the channel through the limitrophe still exhibited connectivity with the water table, and roughly two-thirds of the limitrophe still had a water table that remained within the reach of the roots of cottonwoods and willows. The plunging water table at the downstream end of the limitrophe suggests that the final five miles of the river within the limitrophe may not respond to efforts to restore riparian habitat, at least not without a long-term commitment to supplemental irrigation, but areas upstream appear well-insulated from the recent drawdown and would benefit from restoration activity, such as that proposed by the recent Minute 319.

Groundwater Exchange Pools and Urban Water Supply Sustainability: Modeling Directed and Undirected Networks

American Society of Civil Engineers (ASCE) | August 1st, 2018

Groundwater basins are important sources of water supply and storage for many cities. Groundwater exchange pools offer additional opportunities for utilizing these

Groundwater basins are important sources of water supply and storage for many cities. Groundwater exchange pools offer additional opportunities for utilizing these common pool resources, but their potential role in urban water management is not clear, and modeling such exchanges can be challenging. This paper presents an analysis of the potential for groundwater basin exchange pools to contribute to urban water supply sustainability. Building on an existing model of urban water management in Los Angeles, the analysis assesses the potential for groundwater exchange pools to reduce scarcity and demonstrates a method for modeling two-way (undirected) flows within a directed-network model using linear programming. Results indicate that exchange pools can help alleviate shortages from operational changes (reduced imported water) in Los Angeles, but providing more parties with access to storage improves their effectiveness. Exchange pools could potentially provide 6–12% of total supplies and reduce shortages as much as 86%. Considerations for organizing exchange pools are discussed to explore policy implications for managing common pool resources. The analytical method for embedding undirected network flows within a larger directed-network model has wide applicability for water resource systems analysis applications, including modeling water markets and interbasin transfers. * U.C. Davis hosts a discussion of the content by the authors at California Water Blog. 

Groundwater Flow Model of the East and South Las Posas Sub-Basins – Preliminary Draft Report

Calleguas Municipal Water District (CMWD) | ?

INTERA Incorporated (INTERA) was retained by the Calleguas Municipal Water District (CMWD) to develop a numerical groundwater model of the East Las Posas Management Area

INTERA Incorporated (INTERA) was retained by the Calleguas Municipal Water District (CMWD) to develop a numerical groundwater model of the East Las Posas Management Area (ELPMA), which includes the locally-recognized east and south sub-basins of the Las Posas Valley Basin (LPVB). Groundwater in the ELPMA is found in a multiple-aquifer system characterized by intense faulting and folding, which is known to exert structural controls on groundwater flow and movement. The ELPMA is known to receive recharge from surface water flows in Arroyo Las Posas/Simi that runs east to west along the southern edge of the basin. Flows in the Arroyo have become perennial as a result of discharges from wastewater treatment plants and dewatering wells within and upstream of the ELPMA. Hence, understanding and modeling the surface-water/groundwater interaction along the Arroyo is an important component of the numerical model development. CMWD also owns and operates the Las Posas Basin Aquifer Storage and Recovery (ASR) Project, consisting of eighteen high capacity ASR wells and associated facilities located in the ELPMA that are used to inject and recover potable water purchased from Metropolitan Water District of Southern California (Metropolitan). Basin response to injection/extractions at the ASR well fields and the evaluation of storage capacity of the ASR well field are key considerations for this modeling project. 

Groundwater Geology and Hydrology of Death Valley National Park, California and Nevada

U.S. Department of the Interior (DOI) | December 3rd, 2012

Groundwater in California

Public Policy Institute of California (PPIC) | June 6th, 2024

Groundwater Level Monitoring and the Importance of Long-Term Water-Level Data

U.S. Geological Survey (USGS) | December 18th, 2001

Ground water is among the Nation’s most precious natural resources. Measurements of water levels in wells provide the most fundamental indicator of the status of this r

Ground water is among the Nation’s most precious natural resources. Measurements of water levels in wells provide the most fundamental indicator of the status of this resource and are critical to meaningful evaluations of the quantity and quality of ground water and its interaction with surface water. Water-level measurements are made by many Federal, State, and local agencies. It is the intent of this report to highlight the importance of measurements of ground-water levels and to foster a more comprehensive and systematic approach to the long-term collection of these essential data. Through such mutual efforts, the Nation will be better positioned in coming decades to make wise use of its extensive groundwater resources.

Groundwater level observations in 250,000 coastal US wells reveal scope of potential seawater intrusion

Nature Portfolio (Springer Nature) | June 26th, 2020

Seawater intrusion into coastal aquifers can increase groundwater salinity beyond potable levels, endangering access to freshwater for millions of people. Seawater intrus

Seawater intrusion into coastal aquifers can increase groundwater salinity beyond potable levels, endangering access to freshwater for millions of people. Seawater intrusion is particularly likely where water tables lie below sea level, but can also arise from groundwater pumping in some coastal aquifers with water tables above sea level. Nevertheless, no nation-wide, observation-based assessment of the scope of potential seawater intrusion exists. Here we compile and analyze ~250,000 coastal groundwater-level observations made since the year 2000 in the contiguous United States. We show that the majority of observed groundwater levels lie below sea level along more than 15% of the contiguous coastline. We conclude that landward hydraulic gradients characterize a substantial fraction of the East Coast (>18%) and Gulf Coast (>17%), and also parts of the West Coast where groundwater pumping is high. Sea level rise, coastal land subsidence, and increasing water demands will exacerbate the threat of seawater intrusion.

Groundwater Management and Safe Drinking Water in the San Joaquin Valley

Water Foundation | June 2nd, 2020

Groundwater Management Plan Goleta Groundwater Basin

Goleta Water District (GWD) | May 11th, 2010

Goleta Water District (“GWD”) and La Cumbre Mutual Water Company (“La Cumbre”), the purveyors of groundwater in the Goleta Groundwater Basin, joined in developing

Goleta Water District (“GWD”) and La Cumbre Mutual Water Company (“La Cumbre”), the purveyors of groundwater in the Goleta Groundwater Basin, joined in developing a Groundwater Management Plan (“Plan”) for the basin. This Plan reiterates current adjudication and voter-passed components of groundwater management, addresses groundwater issues, adopts Basin Management Objectives, outlines management strategies for the basin, and recommends future tasks and timelines associated with these tasks.