Selected Techniques for Monitoring Water Movement Through Unsaturated Alluvium During Managed Aquifer Recharge

U.S. Geological Survey (USGS) | October 21st, 2016

Managed aquifer recharge is used to augment natural recharge to aquifers. It can be used to replenish aquifers depleted by pumping or to store water during wetter years f

Managed aquifer recharge is used to augment natural recharge to aquifers. It can be used to replenish aquifers depleted by pumping or to store water during wetter years for withdrawal during drier years. Infiltration from ponds is a commonly used, inexpensive approach for managed aquifer recharge. At some managed aquifer recharge sites, the time when infiltrated water arrives at the water table is not always clearly shown by water-level data (fig. 1). As part of site characterization and operation, it can be desirable to track downward movement of infiltrated water through the unsaturated zone to identify when it arrives at the water table.

Selected trace-elements in alluvium and rocks, western Mojave Desert, southern California

Journal of Geochemical Exploration (Elsevier) | September 3rd, 2018

Concentrations of twenty-seven elements, including naturally-occurring water-quality contaminants arsenic, chromium, and uranium, were measured in 217 samples of alluviu

Concentrations of twenty-seven elements, including naturally-occurring water-quality contaminants arsenic, chromium, and uranium, were measured in 217 samples of alluvium and rock from the western Mojave Desert, southern California, using portable (pXRF) and laboratory (LXRF) X-ray fluorescence. Comparison of measurements with NIST-traceable standards was good, although pXRF overestimated iron compared to LXRF. Results suggest pXRF survey data are sufficiently accurate to assess regional geochemical differences in geologic-source terrains. Principal component analysis showed rubidium and potassium were associated with alluvium eroded from felsic terrain, while iron, copper, chromium, and to a lesser extent titanium, manganese, and nickel were associated with alluvium eroded from mafic terrain. Zinc, vanadium, and arsenic were associated with alluvium eroded from hydrothermal terrain. Elemental assemblages associated with different source terrains were traced spatially to identify the source and composition of alluvium composing aquifers pumped for water supply. Changes in geologic source terrain to the Mojave River, associated with movement along the San Andreas Fault over the past one to five million years, reduced the mafic fraction and increased the felsic fraction of alluvium deposited to the regionally important floodplain aquifer along the Mojave River—lowering chromium concentrations in alluvium through geologic time. Comparison of pXRF and sequential extraction data from 40samples showed arsenic and uranium were more abundant on the surfaces of mineral grains, while chromium and vanadium remained mostly within unweathered mineral grains—suggesting arsenic and uranium may be more readily mobilized into groundwater with changes in pH, redox, or ionic strength than chromium or vanadium.

Sensing the ups and downs of Las Vegas: InSAR reveals structural control of land subsidence and aquifer-system deformation

Geological Society of America (GSA) | June 1st, 1999

Land subsidence in Las Vegas, Nevada, United States, between April 1992 and December 1997 was measured using spaceborne interferometric synthetic aperture radar. The deta

Land subsidence in Las Vegas, Nevada, United States, between April 1992 and December 1997 was measured using spaceborne interferometric synthetic aperture radar. The detailed deformation maps clearly show that the spatial extent of subsidence is controlled by geologic structures (faults) and sediment composition (clay thickness). The maximum detected subsidence during the 5.75 yr period is 19 cm. Comparison with leveling data indicates that the subsidence rates declined during the past decade as a result of rising ground-water levels brought about by a net reduction in ground-water extraction. Temporal analysis also detects seasonal subsidence and uplift patterns, which provide information about the elastic and inelastic properties of the aquifer system and their spatial variability.

Sensing the ups and downs of Las Vegas: InSAR reveals structuralcontrol of land subsidence and aquifer‐system deformation

Geological Society of America (GSA) | June 1st, 1999

Land subsidence in Las Vegas, Nevada, United States, between April 1992 and December 1997 was measured using spaceborne interferometric synthetic aperture radar. The deta

Land subsidence in Las Vegas, Nevada, United States, between April 1992 and December 1997 was measured using spaceborne interferometric synthetic aperture radar. The detailed deformation maps clearly show that the spatial extent of subsidence is controlled by geologic structures (faults) and sediment composition (clay thickness). The maximum detected subsidence during the 5.75 yr period is 19 cm. Comparison with leveling data indicates that the subsidence rates declined during the past decade as a result of rising ground-water levels brought about by a net reduction in ground-water extraction. Temporal analysis also detects seasonal subsidence and uplift patterns, which provide information about the elastic and inelastic properties of the aquifer system and their spatial variability.

SGMA Alternative Groundwater Sustainability Plan – Bridge Document for the Indio Subbasin

Coachella Valley Water District (CVWD) | December 15th, 2016

Decline in the Coachella Valley’s groundwater table was first noted in the 1910s. Concerned that their artesian wells were drying, local residents and farmers formed th

Decline in the Coachella Valley’s groundwater table was first noted in the 1910s. Concerned that their artesian wells were drying, local residents and farmers formed the Coachella Valley Water District (CVWD) in 1918. CVWD took steps to secure water supplies from the Colorado River that led to the completion of the Coachella Branch of the All-American Canal in 1949. CVWD and Desert Water Agency (DWA) contracted with the State of California for water from the State Water Project (SWP) in the early 1960s with the first deliveries in 1973. At that time, CVWD and DWA implemented groundwater replenishment programs and collected replenishment assessment from groundwater producers. However, continued growth in the Valley resulted in groundwater level declines and overdraft. Twenty years before the adoption of SGMA, CVWD began development of the initial Water Management Plan in 1994 after recognizing the need to sustainably manage the Coachella Valley Groundwater Basin. CVWD adopted the Coachella Valley Water Management Plan in 2002 (2002 WMP) to eliminate groundwater overdraft in the Basin. The 2002 WMP was updated in 2010 (2010 WMP Update) and adopted in 2012. This plan covers the Indio Subbasin of the Coachella Valley Groundwater Basin. CVWD, along with DWA and Mission Springs Water District also prepared the Mission Creek-Garnet Hill Water Management Plan (MCGH WMP) that covers the Mission Creek Subbasin and the Garnet Hill Subarea of the Indio Subbasin. As of 2016, plan implementation is showing positive results with stabilizing water levels throughout much of the Valley. Continued implementation is expected to eliminate water level declines by about 2025.

SGMA Alternative Groundwater Sustainability Plan Bridge Document for the Indio Subbasin

Coachella Valley Water District (CVWD) | December 29th, 2016

SGMA Alternative Groundwater Sustainability Plan Bridge Document for the Mission Creek Subbasin

Coachella Valley Water District (CVWD) | December 29th, 2016

SGMA and Underrepresented Farmers

Clean Water Action | May 31st, 2022

Groundwater resources play a vital role in maintaining environmental sustainability in California. During a typical year, approximately 40 percent of the state’s total

Groundwater resources play a vital role in maintaining environmental sustainability in California. During a typical year, approximately 40 percent of the state’s total water supply comes from groundwater. During dry years, groundwater contributes 60 percent (or more) of the state’s total supply, and serves as a critical buffer against the impacts of drought and climate change. This paper responds to concerns expressed by groundwater sustainability advocates that underrepresented farmers have not been included in the development and implementation of Groundwater SustainabilityPlans (GSPs) under the Sustainable Groundwater Management Act (SGMA) of 2014. It contains results from the evaluation of 14 Groundwater Sustainability Plans (12 from the San Joaquin Valley and 2 from the Central Coast) with a focus on stakeholder engagement and projected impacts of groundwater decline on underrepresented farmers.

SGMA Best Management Practice: Groundwater Monitoring Protocols, Standards, and Sites

California Department of Water Resources (DWR) | December 23rd, 2016

The objective of this Best Management Practice (BMP) is to assist in the development of Monitoring Protocols. The California Department of Water Resources (the Department

The objective of this Best Management Practice (BMP) is to assist in the development of Monitoring Protocols. The California Department of Water Resources (the Department or DWR) has developed this document as part of the obligation in the Technical Assistance chapter (Chapter 7) of the Sustainable Groundwater Management Act (SGMA) to support the long-term sustainability of California’s groundwater basins. Information provided in this BMP provides technical assistance to Groundwater Sustainability Agencies (GSAs) and other stakeholders to aid in the establishment of consistent data collection processes and procedures. In addition, this BMP can be used by GSAs to adopt a set of sampling and measuring procedures that will yield similar data regardless of the monitoring personnel. Finally, this BMP identifies available resources to support the development of monitoring protocols. This BMP includes the following sections: Objective. A brief description of how and where monitoring protocols are required under SGMA and the overall objective of this BMP. Use and Limitations. A brief description of the use and limitations of this BMP. Monitoring Protocol Fundamentals. A description of the general approach and background of groundwater monitoring protocols. Relationship of Monitoring Protocols to other BMPs. A description of how this BMP is connected with other BMPS. Technical Assistance. Technical content providing guidance for regulatory sections. Key Definitions. Descriptions of definitions identified in the GSP Regulations or SGMA. Related Materials. References and other materials that provide supporting information related to the development of Groundwater Monitoring Protocols.

SGMA Best Management Practice: Hydrogeologic Conceptual Model

California Department of Water Resources (DWR) | December 23rd, 2016

The objective of this Best Management Practice (BMP) is to assist in the use and development of hydrogeologic conceptual models (HCM). The California Department of Water

The objective of this Best Management Practice (BMP) is to assist in the use and development of hydrogeologic conceptual models (HCM). The California Department of Water Resources (the Department or DWR) has developed this document as part of the obligation in the Technical Assistance Chapter (Chapter 7) of the Sustainable Groundwater Management Act (SGMA) to support the long-term sustainability of California’s groundwater basins. Information provided in this BMP is meant to provide support to Groundwater Sustainability Agencies (GSAs) when developing a HCM in accordance with the Groundwater Sustainability Plan (GSP) Emergency Regulations (GSP Regulations). This BMP identifies available resources to support development of HCMs. This BMP includes the following sections: Objective. The objective and brief description of the contents of this BMP. Use and Limitations. A brief description of the use and limitations of this BMP. HCM Fundamentals. A description of HCM fundamental concepts. Relationship of HCM to other BMPs. A description of how the HCM relates to other BMPs and is the basis for development of other GSP requirements. Technical Assistance. A description of technical assistance to support the development of a HCM and potential sources of information and relevant datasets that can be used to further define each component. Key Definitions. Definitions relevant for this BMP as provided in the GSP and Basin Boundary Regulations and in SGMA. Related Materials. References and other materials that provide supporting information related to the development of HCMs.