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2017 Salinas Valley Groundwater Level Contours & Seawater Intrusion Maps
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2017 Salinas Valley Groundwater Level Contours & Seawater Intrusion Maps
Monterey County Water Resources Agency (MCWRA) | April 24, 2018...
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A conceptual model for floodplains in the Sacramento-San Joaquin Delta

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A conceptual model for floodplains in the Sacramento-San Joaquin Delta
San Francisco Estuary and Watershed Science | October 3, 2012...
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Floodplains are among the most biologically productive and diverse ecosystems on Earth and they provide significant benefits to society such as attenuation of...
Floodplains are among the most biologically productive and diverse ecosystems on Earth and they provide significant benefits to society such as attenuation of floodwaters, groundwater recharge, filtration of nutrients and sediments, carbon sequestration, fisheries productivity and recreation. However, floodplains are also among the most converted and threatened ecosystems. Floodplain habitats in the Sacramento-San Joaquin Delta, and throughout California’s Central Valley, have been greatly reduced from their historic extent and key processes that create and maintain floodplains, such as flood flows and meander migration, have been greatly altered. These widespread alterations to habitats and processes have lead to declines in many species’ populations in California’s Central Valley and Delta, creating challenges for both environmental and water management. To address these challenges numerous entities and programs are now focused on restoring floodplains and other Delta habitats. This paper provides a conceptual model for floodplains that characterizes the key features and identifies the critical processes, drivers, and linkages that allow floodplains to produce a variety of functional outputs of management importance. These outputs include: (1) the floodplain habitat mosaic, including riparian vegetation and its associated wildlife; (2) spawning and rearing habitat for native fish; and (3) food-web productivity that can support native fish on the floodplain as well as be exported to downstream ecosystems. The model emphasizes that the production of these outputs from floodplains requires vertical and lateral hydrological connectivity across a broad range of flow conditions. For example, long-duration flooding in the spring promotes native fish spawning and food-web productivity that benefits native species.

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A Guide for Using the Transient Ground-Water Flow Model of the Death Valley Regional Ground-Water Flow System, Nevada and California
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A Guide for Using the Transient Ground-Water Flow Model of the Death Valley Regional Ground-Water Flow System, Nevada and California
U.S. Geological Survey (USGS), U.S. Department of Energy Office of Environmental Management | November 4, 2006...
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This report is a guide for executing numerical simulations with the transient ground-water flow model of the Death Valley regional ground-water flow system,...
This report is a guide for executing numerical simulations with the transient ground-water flow model of the Death Valley regional ground-water flow system, Nevada and California using the U.S. Geological Survey modular finite-difference ground-water flow model, MODFLOW-2000. Model inputs, including observations of hydraulic head, discharge, and boundary flows, are summarized. Modification of the DVRFS transient ground-water model is discussed for two common uses of the Death Valley regional ground-water flow system model: predictive pumping scenarios that extend beyond the end of the model simulation period (1998), and model simulations with only steady-state conditions.

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A hybrid machine learning model to predict and visualize nitrate concentration throughout the Central Valley aquifer, California, USA
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A hybrid machine learning model to predict and visualize nitrate concentration throughout the Central Valley aquifer, California, USA
Science of the Total Environment | June 9, 2017...
Summary
Intense demand forwater in the Central Valley of California and related increases in groundwater nitrate concentration threaten the sustainability of the groundwater resource....
Intense demand forwater in the Central Valley of California and related increases in groundwater nitrate concentration threaten the sustainability of the groundwater resource. To assess contamination risk in the region, we developed a hybrid, non-linear, machine learning model within a statistical learning framework to predict nitrate contamination of groundwater to depths of approximately 500m below ground surface.

A database of 145 predictor variables representing well characteristics, historical and current field and landscape-scale nitrogen mass balances, historical and current land use, oxidation/reduction conditions, groundwater flow, climate, soil characteristics, depth to groundwater, and groundwater age were assigned to over 6000 private supply and public supply wells measured previously for nitrate and located throughout the study area. The boosted regression tree (BRT) method was used to screen and rank variables to predict nitrate concentration at the depths of domestic and public well supplies.

The novel approach included as predictor variables outputs from existing physically based models of the Central Valley. The top five most important predictor variables included two oxidation/reduction variables (probability of manganese concentration to exceed 50 ppb and probability of dissolved oxygen concentration to be below 0.5 ppm), field-scale adjusted unsaturated zone nitrogen input for the 1975 time period, average difference between precipitation and evapotranspiration during the years 1971–2000, and 1992 total landscape nitrogen input.

Twenty-five variables were selected for the final model for log-transformed nitrate. In general, increasing probability of anoxic conditions and increasing precipitation relative to potential evapotranspiration had a corresponding decrease in nitrate concentration predictions.

Conversely, increasing 1975 unsaturated zone nitrogen leaching flux and 1992 total landscape nitrogen input had an increasing relative impact on nitrate predictions.

Three-dimensional visualization indicates that nitrate predictions depend on the probability of anoxic conditions and other factors, and that nitrate predictions generally decreased with increasing groundwater age.

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A Water Resources Data Network Evaluation for Monterey County, California; Phase 1; South County
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A Water Resources Data Network Evaluation for Monterey County, California; Phase 1; South County
U..S. Geological Survey (USGS), Monterey County Flood Control and Water Conservation District | July 12, 1986...
Summary
An evaluation made of rainfall, surface water, groundwater, and water quality monitoring networks in Salinas River basin in southern Monterey County, California, proposed...
An evaluation made of rainfall, surface water, groundwater, and water quality monitoring networks in Salinas River basin in southern Monterey County, California, proposed all long-term rain gages be continued for extending short-term records and suggested the installation of two additional recording gages. Eight new storage rain gages were suggested at midaltitudes of east and west sides of Salinas Valley where few data are available. The evaluation revealed some short-term gaging stations could be discontinued because of good regression relations between them and the long-term stations Arroyo Seco near Soledad.

Of 16 stations selected for the proposed network, 4 are new recording stations, 6 are new nonrecording streamflow and water quality sampling sites, 5 are existing stations, and the last is a station operated from 1969 to 1976; also included are water quality sampling stations on Lakes Nacimiento and San Antonio. The proposed groundwater network was developed from information on geology, geohydrology, and groundwater quality, high priority objectives for groundwater network, and consideration for providing good areal coverage of levels and water quality. Of 145 sites selected, 86 are existing monitoring wells.

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A Water Resources Data Network Evaluation for Monterey County, California; Phase 3, Northern Salinas River Drainage Basin
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A Water Resources Data Network Evaluation for Monterey County, California; Phase 3, Northern Salinas River Drainage Basin
U.S. Geological Survey, Monterey County Flood Control and Water Conservation District | December 13, 1990...
Summary
Continuing data collection and analysis are vital to efficient development and management of water resources. To insure that water managers have adequate information...
Continuing data collection and analysis are vital to efficient development and management of water resources. To insure that water managers have adequate information on conditions and trends, data-collection programs must be evaluated and updated periodically. Changes in population, land use, and agricultural practices may increase the demand for water, so that effective water management and supporting data collection become even more critical. Consideration of cost effectiveness, however, means that every site must count, and redundancy must be minimized. Water resources management and monitoring are ever-changing, and periodic reevaluation is a necessary part of this process. This report presents an evaluation of precipitation, surface-water, and ground-water monitoring networks in the northern Salinas River drainage basin of Monterey County, California. This report is third in a series of reports prepared in cooperation with the Monterey County Flood Control and Water Conservation District (MCFCWCD). The phase 1 report (Showalter and Hoffard, 1986) covers the southern Salinas River drainage basin, the phase 2 report covers the north county and coastal areas of Monterey County (W.E. Templin, P.E. Smith, and R.C. Schluter, U.S. Geological Survey, written commun., 1989), and this report (phase 3) covers the northern Salinas River drainage basin.

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Addressing Regional Surface Water Depletions in California: A Proposed Approach for Compliance with The Sustainable Groundwater Management Act

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Addressing Regional Surface Water Depletions in California: A Proposed Approach for Compliance with The Sustainable Groundwater Management Act
Environmental Defense Fund (EDF) | August 15, 2018...
Summary
Successful implementation of the Sustainable Groundwater Management Act (SGMA), including its provision to avoid significant and unreasonable depletion of interconnected surface water, is a high priority...
Successful implementation of the Sustainable Groundwater Management Act (SGMA), including its provision to avoid significant and unreasonable depletion of interconnected surface water, is a high priority for the Environmental Defense Fund (EDF). The lack of established mechanisms for addressing depletions of interconnected surface water makes the implementation of this aspect of SGMA especially challenging. Accordingly, EDF offers recommendations to address the requirements of the law related to depletion of interconnected surface water, commonly referred to as “Undesirable Result No. 6” (UR #6). We propose an approach that we believe provides a reasonable balance among the conflicting factors of rigor, cost, uncertainty, and enforceability that weigh on the implementation of this requirement.

Our goal is to offer a pathway to achieve the fundamental and critical objective of UR#6, which aims to prevent significant impacts to water users and ecosystems that depend on streams and rivers that may be depleted by groundwater withdrawals, in a way that is not unreasonably costly or unproductively burdensome on the Groundwater Sustainability Agencies (GSAs), water users, and state agencies who will bear most of the burden of complying with—or ensuring compliance with—SGMA.

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Alamitos Barrier Project: Annual Report on the Control of Seawater Intrusion 2016-2017
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Alamitos Barrier Project: Annual Report on the Control of Seawater Intrusion 2016-2017
Los Angeles County Department of Public Works (LACDPW) | June 30, 2017...
Summary
The Alamitos Barrier Project (ABP) was designed and constructed to protect the groundwater supplies of the Central/Orange County Basin of the Coastal Plain...

The Alamitos Barrier Project (ABP) was designed and constructed to protect the groundwater supplies of the Central/Orange County Basin of the Coastal Plain from the intrusion of seawater through the Alamitos Gap area. The project facilities are located near the Los Angeles-Orange County border about two miles inland from the terminus of the San Gabriel River. The original facilities included injection wells to form a freshwater pressure ridge and extraction wells to form a saltwater trough. The freshwater pressure ridge has proven to be historically effective, whereas the saltwater trough has not. As a result, the extraction wells are currently not in operation. A map showing the supply pipeline, injection wells, extraction wells, and observation wells is shown on page A-12.1. The County of Los Angeles Department of Public Works (Public Works) operates and maintains the ABP and its associated facilities under the direction and approval of the Joint Management Committee (JMC), acting on behalf of the Los Angeles County Flood Control District (LACFCD) and the Orange County Water District (OCWD). This report summarizes design and construction issues, operation and maintenance activities, hydrogeologic effects, chloride concentrations, and project costs for Fiscal Year (FY) 2016-17 (i.e., July 1, 2016 through June 30, 2017).

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Aliso Water District Groundwater Sustainability Plan

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Aliso Water District Groundwater Sustainability Plan
Aliso Water District Groundwater Sustainability Agency | January 17, 2020...
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An Update of the Death Valley Regional Groundwater Flow System Transient Model, Nevada and California

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An Update of the Death Valley Regional Groundwater Flow System Transient Model, Nevada and California
U.S. Geological Survey (USGS) | October 31, 2016...
Summary
The U.S. Geological Survey (USGS) has revised the regional-scale Death Valley regional groundwater flow system (DVRFS) numerical model with new data and interpretations...
The U.S. Geological Survey (USGS) has revised the regional-scale Death Valley regional groundwater flow system (DVRFS) numerical model with new data and interpretations since the original numerical flow model was published in 2004 (Belcher (2004); re-published as Belcher and Sweetkind [2010]). Since the original publication of the DVRFS flow model, additional data have been collected and interpretations have been made. Cooperators such as the Bureau of Land Management, National Park Service, U.S. Fish and Wildlife Service, the Department of Energy, and Nye County, Nevada, recognized a need to update the existing regional numerical flow model to maintain its viability as a groundwater management tool for regional stakeholders. For the purposes of this report, the version of the DVRFS numerical flow model documented in Belcher and Sweetkind (2010) and Faunt, Blainey, and others (2010) is designated as DVRFS v. 1.0. The updated version, as presented in this report, is referred to as DVRFS v. 2.0.

Knowledge of basin water balances and the magnitude of interbasin groundwater flow is the basis for regional groundwater management and water-resource planning in the Great Basin of Nevada (Scott and others, 1971). Rapid population growth, arid conditions, and increased water use have led to development of available groundwater resources. Groundwater use in some alluvial-fill basins has resulted in continued water-level declines and land subsidence. Adjacent bedrock aquifers are increasingly being targeted for additional development. Such groundwater development may potentially impact local and regional water quantity and quality, existing water rights, and wildlife habitats. An understanding of hydrogeologic processes that control the rate and direction of groundwater flow in southern Nevada is necessary to assess the potential effects of any proposed large-scale groundwater development. Potential water-resource conflicts exist because of disparate interests in the region, particularly with respect to the development of groundwater resources to meet agricultural, municipal, and industrial water demand and the need to protect habitat for endangered and threatened species. Water demands in the Amargosa Farms area from agricultural and suburban development, and rapidly urbanizing areas in Las Vegas and Pahrump Valleys place increasing pressure on existing groundwater resources.

In addition, several solar-energy facilities have been proposed within the Death Valley region; water demands for these facilities will vary. Natural groundwater discharge at springs and seeps sustains habitat for numerous species, many of which are threatened, endangered, or otherwise considered sensitive.

In 2004, the USGS documented a calibrated numerical flow model of the DVRFS (Belcher, 2004). The model, DVRFS v. 1.0, incorporated elements of several precursor numerical models but defined the boundaries of the regional flow system slightly different than in previous versions. The model simulates transient groundwater flow conditions in the DVRFS from 1913 through 1998. The report was subsequently revised and published as a USGS Professional Paper (Belcher and Sweetkind, 2010). Since release of DVRFS v. 1.0 in 2004, continued use of the model by cooperators, stakeholders, and interested parties in the region has demonstrated the need to improve specific aspects (such as the flow into northern Yucca Flat and parts of the Amargosa Desert), to update it with more recently acquired geologic and hydrologic data, and to extend the simulation period.

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2017 Salinas Valley Groundwater Level Contours & Seawater Intrusion Maps

2017 Salinas Valley Groundwater Level Contours & Seawater Intrusion Maps

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A conceptual model for floodplains in the Sacramento-San Joaquin Delta

A conceptual model for floodplains in the Sacramento-San Joaquin Delta

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A Guide for Using the Transient Ground-Water Flow Model of the Death Valley Regional Ground-Water Flow System, Nevada and California

A Guide for Using the Transient Ground-Water Flow Model of the Death Valley Regional Ground-Water Flow System, Nevada and California

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A hybrid machine learning model to predict and visualize nitrate concentration throughout the Central Valley aquifer, California, USA

A hybrid machine learning model to predict and visualize nitrate concentration throughout the Central Valley aquifer, California, USA

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A Water Resources Data Network Evaluation for Monterey County, California; Phase 1; South County

A Water Resources Data Network Evaluation for Monterey County, California; Phase 1; South County

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A Water Resources Data Network Evaluation for Monterey County, California; Phase 3, Northern Salinas River Drainage Basin

A Water Resources Data Network Evaluation for Monterey County, California; Phase 3, Northern Salinas River Drainage Basin

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Addressing Regional Surface Water Depletions in California: A Proposed Approach for Compliance with The Sustainable Groundwater Management Act

Addressing Regional Surface Water Depletions in California: A Proposed Approach for Compliance with The Sustainable Groundwater Management Act

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Alamitos Barrier Project: Annual Report on the Control of Seawater Intrusion 2016-2017

Alamitos Barrier Project: Annual Report on the Control of Seawater Intrusion 2016-2017

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Aliso Water District Groundwater Sustainability Plan

Aliso Water District Groundwater Sustainability Plan

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An Update of the Death Valley Regional Groundwater Flow System Transient Model, Nevada and California

An Update of the Death Valley Regional Groundwater Flow System Transient Model, Nevada and California

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