Zeno Levy, Ph.D.
I am a groundwater hydrologist and geochemist at the California Water Science Center specializing in drinking-water resources.
I work primarily on the California State Water Resources Control Board's Groundwater Ambient Monitoring and Assessment (GAMA) program. My research deals with understanding hydrologic and geochemical factors driving changes in groundwater-resource quality over time. To accomplish this, I develop novel research integrating basic hydrogeochemical methods with “big data” statistical learning techniques. I develop computational tools to query large, geochemical databases and characterize regional drivers of groundwater-quality trends. I am interested in identifying specific processes with broad transfer value that can help to forecast the fate drinking-water resources to extreme precipitation and drought.
Science and Products
Groundwater Ambient Monitoring & Assessment (GAMA)
The Groundwater Ambient Monitoring and Assessment Program’s Priority Basin Project (GAMA-PBP) was established by the California State Water Resources Control Board (SWRCB) in response to the Ground-Water Quality Monitoring Act of 2001 (Sections 10780-10782.3 of the California Water Code). The USGS is the technical lead for the GAMA-PBP and between 2004-2012 focused on characterizing the quality of...
Environmental chemistry from selected sites in Lakeport, Lake County, California (version 1.1, August 2023)
This data release documents chemical analyses of environmental samples collected by the U.S. Geological Survey (USGS) in Lakeport (Lake County, California) during July 11-12, 2022. Environmental samples were collected at selected sites to assess the effects of lead-based paint on soil chemistry. This sampling was made as part of a broader study to attribute sources of lead in soils in...
Compilation of Public-Supply Well Construction Depths in California
This data release is a compilation of construction depth information for 12,383 active and inactive public-supply wells (PSWs) in California from various data sources. Construction data from multiple sources were indexed by the California State Water Resources Control Board Division of Drinking Water (DDW) primary station code (PS Code). Five different data sources were compared with the...
Groundwater-quality data in the Modesto-Turlock-Merced Domestic-Supply Aquifer Study Unit, 2020-2021: Results from the California GAMA Priority Basin Project
The U.S. Geological Survey collected groundwater samples from 71 wells used for domestic and small system drinking water supplies in Stanislaus and Merced counties of California during 2020-2021. The wells were sampled for the Modesto-Turlock-Merced Domestic-Supply Aquifer Study Unit of the State Water Resources Control Board Groundwater Ambient Monitoring and Assessment (GAMA) Program...
Groundwater-quality data in the Northern San Joaquin Valley Domestic-Supply Aquifer Study Unit, 2019: Results from the California GAMA Priority Basin Project
The U.S. Geological Survey collected groundwater samples from 46 wells used for domestic and small system drinking water supplies in San Joaquin, Calaveras, and Stanislaus counties, California in 2019. The wells were sampled for the Northern San Joaquin Valley Domestic-Supply Aquifer Study Unit of the California State Water Resources Control Board Groundwater Ambient Monitoring and...
Grid Cells and Modeled Groundwater Levels to Characterize Hydrologic Conditions for Public-supply Aquifers in California's Central Valley, 1990-2020
This data release documents grid cells and modeled groundwater levels for hydrologic characterization of aquifer areas used for public drinking-water supply in California’s Central Valley from 1990 to 2020. Observations of spring groundwater level (median depth to groundwater measured from January through April) were calculated for selected wells from the California Department of Water...
Potential Explanatory Factors for Groundwater Quality in the Northern Sierra Nevada Foothills Domestic-Aquifer Assessment Study Units, 2015-2017: California GAMA Priority Basin Project
This data release codifies and attributes explanatory factors that could potentially impact groundwater quality at 142 groundwater sites (wells or developed springs) used for domestic water supply and 310 groundwater sites used for public water supply in the northern Sierra Nevada foothills. Water quality from domestic groundwater sites was assessed as part of the California State Water...
Dissolved Noble Gas Concentrations and Modeled Recharge Temperatures for Groundwater from Northern Sierra Nevada Foothills Shallow Aquifer Assessment Study Units, 2015-2017: Results from the California GAMA Priority Basin Project
This data release documents 155 sets of dissolved noble gas analyses (neon, argon, krypton, xenon) and 153 modeled recharge temperatures for groundwater sampled from domestic water supply wells and springs throughout the northern Sierra Nevada foothills as part of the California State Water Resources Control Board's Groundwater Ambient Monitoring and Assessment (GAMA) Program in 2015...
Filter Total Items: 17
Status and understanding of groundwater quality in the Mojave Basin Domestic-Supply Aquifer study unit, 2018—California GAMA Priority Basin Project
Groundwater quality in the western part of the Mojave Desert in San Bernardino County, California, was investigated in 2018 as part of the California State Water Resources Control Board Groundwater Ambient Monitoring and Assessment Program Priority Basin Project. The Mojave Basin Domestic-Supply Aquifer study unit (MOBS) region was divided into two study areas—floodplain and regional—to...
Authors
Krishangi D. Groover, Miranda Fram, Zeno Levy
Basin-scale responses of groundwater-resource quality to drought and recovery, San Joaquin Valley, California
Groundwater-resource quality is assumed to be less responsive to drought compared to that of surface water due to relatively long transit times of recharge to drinking-supply wells. Here, we evidence dynamic perturbations in aquifer pressure dynamics during drought and subsequent recovery periods cause dramatic shifts in groundwater quality on a basin scale. We used a novel application...
Authors
Zeno F. Levy, Bryant Jurgens, Kirsten Faulkner, Jennifer S. Harkness, Miranda Fram
Salinity trends in a groundwater system supplemented by 50 years of imported Colorado River water
The Indio subbasin of the Coachella Valley is a desert area of southern California where a growing population depends primarily on groundwater for drinking and agricultural uses. The aquifer system has been supplemented with Colorado River water through managed recharge and widespread irrigation since the mid-20th century. We use a combination of geochemical modeling and trend analysis...
Authors
Jennifer S. Harkness, Patrick Michael McCarthy, Bryant Jurgens, Zeno F. Levy
Comparing domestic and public-supply groundwater quality in the northern San Joaquin Valley, 2019—California GAMA Priority Basin Project
Groundwater quality in the Northern San Joaquin Valley region of California was studied as part of California State Water Resources Control Board (SWRCB) Groundwater Ambient Monitoring and Assessment Program-Priority Basin Project (GAMA-PBP). The GAMA-PBP made a spatially unbiased assessment of the aquifer system used for domestic drinking-water supply in the study region and compared...
Authors
George L. Bennett, Emily A. Haugen, Zeno F. Levy
Quality of groundwater used for domestic drinking-water supply in the Coachella Valley, 2020
Groundwater is the primary source of drinking water in the Coachella Valley in the desert region of southern California. Although most people in Coachella Valley are served by public drinking-water systems, about 20,000 people rely on private domestic or small-system wells (referred to herein as domestic wells). Recently, the U.S. Geological Survey (USGS) found that 39 percent of the...
Authors
Andrew L. Soldavini, Jennifer S. Harkness, Zeno F. Levy, Miranda S. Fram
Quality of groundwater used for domestic supply in the Modesto, Turlock, and Merced Subbasins of the San Joaquin Valley, California
Summary More than 2 million Californians rely on groundwater from privately owned domestic wells for drinking-water supply. This report summarizes a water-quality survey of domestic and small-system drinking-water supply wells in the Modesto, Turlock, and Merced subbasins of the San Joaquin Valley where more than 78,000 residents are estimated to use privately owned domestic wells...
Authors
Zeno F. Levy, Mariia Balkan, Jennifer L. Shelton
Modeling the dynamic penetration depth of post-1950s water in unconfined aquifers using environmental tracers: Central Valley, California
The penetration depth of post-1950s recharge (D-1950) in aquifers is a marker that is frequently used to identify groundwater that is susceptible to anthropogenic contamination. Here, we compute D-1950 values at wells, interpolate them in space, and project them across time to map the moving front of modern recharge in four dimensions in the Central Valley aquifer system, California, USA...
Authors
Kirsten Faulkner, Bryant Jurgens, Stefan Voss, Danielle Dupuy, Zeno Levy
Lessons learned from wetlands research at the Cottonwood Lake Study Area, Stutsman County, North Dakota, 1967–2021
Depressional wetlands in the Prairie Pothole Region of North America have a long history of investigation owing to their importance in maintaining migratory-bird populations, especially waterfowl. One area of particularly intensive study is the Cottonwood Lake study area in Stutsman County, North Dakota. Studies at the Cottonwood Lake study area began in 1967 and continue through the...
Authors
David M. Mushet, Ned H. Euliss, Donald O. Rosenberry, James W. LaBaugh, Sheel Bansal, Zeno F. Levy, Owen P. McKenna, Kyle McLean, Christopher T. Mills, Brian P. Neff, Richard D. Nelson, Matthew J. Solensky, Brian Tangen
Critical aquifer overdraft accelerates degradation of groundwater quality in California’s Central Valley during drought
Drought-induced pumpage has precipitated dramatic groundwater-level declines in California’s Central Valley over the past 30 years, but the impacts of aquifer overdraft on water quality are poorly understood. This study coupled over 160,000 measurements of nitrate from ∼6,000 public-supply wells with a 30-year reconstruction of groundwater levels throughout the Central Valley to evaluate...
Authors
Zeno Levy, Bryant Jurgens, Karen R. Burow, Stefan Voss, Kirsten Faulkner, Jose Alfredo Arroyo-Lopez, Miranda S. Fram
Quality of groundwater used for domestic supply in the northern San Joaquin Valley, California
Groundwater provides more than 40 percent of California’s drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project (PBP) of the GAMA Program provides a comprehensive assessment of the State’s groundwater quality and provides increased public access to groundwater-quality...
Authors
Zeno F. Levy, Mariia Balkan, Jennifer L. Shelton
Status and understanding of groundwater quality in the northern Sierra Nevada foothills domestic-supply aquifer study units, 2015–17—California GAMA Priority Basin Project
Groundwater quality in the northern Sierra Nevada foothills region of California was investigated as part of California State Water Resources Control Board (SWRCB) Groundwater Ambient Monitoring Assessment Priority Basin Project (GAMA-PBP). The region was divided into two study units: the Yuba-Bear watersheds (YBW) study unit and the American-Cosumnes-Mokelumne watersheds (ACMW) study...
Authors
Zeno F. Levy, Miranda S. Fram
Geologic influences on the quality of groundwater used for domestic supply in the northern Sierra Nevada Foothills
Approximately 2 million California residents depend on groundwater from domestic wells for their drinking-water supply. The State of California, in collaboration with the U.S. Geological Survey, created the Groundwater Ambient Monitoring and Assessment Program Priority Basin Project (GAMA-PBP) to assess the quality of groundwater used for domestic supply throughout the state and...
Authors
Zeno F. Levy, Miranda S. Fram
Non-USGS Publications**
Levy ZF, Rosenberry DO, Moucha R, Mushet DM, Goldhaber MB, LaBaugh JW, Fiorentino AJ, Siegel DI. 2018. Drought-induced recharge promotes long-term storage of porewater salinity beneath a prairie wetland. Journal of Hydrology 557: 391-406, https://doi.org/10.1016/j.jhydrol.2017.12.005.
Levy ZF, Mills CT, Lu Z, Goldhaber MB, Rosenberry DO, Mushet DM, Lautz LK, Zhou X, Siegel DI. 2018. Using halogens (Cl, Br, I) to understand the hydrogeochemical evolution of drought-derived saline porewater beneath a prairie wetland. Chemical Geology 476: 191-207, https://doi.org/10.1016/j.chemgeo.2017.11.017.
Levy ZF, Siegel DI, Glaser PH, Samson SD, Dasgupta SS. 2016. Peat porewaters have contrasting geochemical fingerprints for groundwater recharge and discharge due to matrix diffusion in a large, northern bog-fen complex. Journal of Hydrology 541: 941-951, https://dx.doi.org/10.1016/j.jhydrol.2016.08.001.
Levy ZF, Smardon RC, Bays JS, Meyer D. 2014. A Point Source of a Different Color: Identifying a Gap in United States Regulatory Policy for “Green” CSO Treatment Using Constructed Wetlands. Sustainability 6(5): 2392-2412, https://dx.doi.org/10.3390/su6052392.
Levy ZF, Siegel DI, Dasgupta SS, Glaser PH, Welker JM. 2014. Stable isotopes of water show deep seasonal recharge in northern bogs and fens. Hydrological Processes 228: 4938-4952, https://dx.doi.org/10.1002/hyp.9983.
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Science and Products
Groundwater Ambient Monitoring & Assessment (GAMA)
The Groundwater Ambient Monitoring and Assessment Program’s Priority Basin Project (GAMA-PBP) was established by the California State Water Resources Control Board (SWRCB) in response to the Ground-Water Quality Monitoring Act of 2001 (Sections 10780-10782.3 of the California Water Code). The USGS is the technical lead for the GAMA-PBP and between 2004-2012 focused on characterizing the quality of...
Environmental chemistry from selected sites in Lakeport, Lake County, California (version 1.1, August 2023)
This data release documents chemical analyses of environmental samples collected by the U.S. Geological Survey (USGS) in Lakeport (Lake County, California) during July 11-12, 2022. Environmental samples were collected at selected sites to assess the effects of lead-based paint on soil chemistry. This sampling was made as part of a broader study to attribute sources of lead in soils in...
Compilation of Public-Supply Well Construction Depths in California
This data release is a compilation of construction depth information for 12,383 active and inactive public-supply wells (PSWs) in California from various data sources. Construction data from multiple sources were indexed by the California State Water Resources Control Board Division of Drinking Water (DDW) primary station code (PS Code). Five different data sources were compared with the...
Groundwater-quality data in the Modesto-Turlock-Merced Domestic-Supply Aquifer Study Unit, 2020-2021: Results from the California GAMA Priority Basin Project
The U.S. Geological Survey collected groundwater samples from 71 wells used for domestic and small system drinking water supplies in Stanislaus and Merced counties of California during 2020-2021. The wells were sampled for the Modesto-Turlock-Merced Domestic-Supply Aquifer Study Unit of the State Water Resources Control Board Groundwater Ambient Monitoring and Assessment (GAMA) Program...
Groundwater-quality data in the Northern San Joaquin Valley Domestic-Supply Aquifer Study Unit, 2019: Results from the California GAMA Priority Basin Project
The U.S. Geological Survey collected groundwater samples from 46 wells used for domestic and small system drinking water supplies in San Joaquin, Calaveras, and Stanislaus counties, California in 2019. The wells were sampled for the Northern San Joaquin Valley Domestic-Supply Aquifer Study Unit of the California State Water Resources Control Board Groundwater Ambient Monitoring and...
Grid Cells and Modeled Groundwater Levels to Characterize Hydrologic Conditions for Public-supply Aquifers in California's Central Valley, 1990-2020
This data release documents grid cells and modeled groundwater levels for hydrologic characterization of aquifer areas used for public drinking-water supply in California’s Central Valley from 1990 to 2020. Observations of spring groundwater level (median depth to groundwater measured from January through April) were calculated for selected wells from the California Department of Water...
Potential Explanatory Factors for Groundwater Quality in the Northern Sierra Nevada Foothills Domestic-Aquifer Assessment Study Units, 2015-2017: California GAMA Priority Basin Project
This data release codifies and attributes explanatory factors that could potentially impact groundwater quality at 142 groundwater sites (wells or developed springs) used for domestic water supply and 310 groundwater sites used for public water supply in the northern Sierra Nevada foothills. Water quality from domestic groundwater sites was assessed as part of the California State Water...
Dissolved Noble Gas Concentrations and Modeled Recharge Temperatures for Groundwater from Northern Sierra Nevada Foothills Shallow Aquifer Assessment Study Units, 2015-2017: Results from the California GAMA Priority Basin Project
This data release documents 155 sets of dissolved noble gas analyses (neon, argon, krypton, xenon) and 153 modeled recharge temperatures for groundwater sampled from domestic water supply wells and springs throughout the northern Sierra Nevada foothills as part of the California State Water Resources Control Board's Groundwater Ambient Monitoring and Assessment (GAMA) Program in 2015...
Filter Total Items: 17
Status and understanding of groundwater quality in the Mojave Basin Domestic-Supply Aquifer study unit, 2018—California GAMA Priority Basin Project
Groundwater quality in the western part of the Mojave Desert in San Bernardino County, California, was investigated in 2018 as part of the California State Water Resources Control Board Groundwater Ambient Monitoring and Assessment Program Priority Basin Project. The Mojave Basin Domestic-Supply Aquifer study unit (MOBS) region was divided into two study areas—floodplain and regional—to...
Authors
Krishangi D. Groover, Miranda Fram, Zeno Levy
Basin-scale responses of groundwater-resource quality to drought and recovery, San Joaquin Valley, California
Groundwater-resource quality is assumed to be less responsive to drought compared to that of surface water due to relatively long transit times of recharge to drinking-supply wells. Here, we evidence dynamic perturbations in aquifer pressure dynamics during drought and subsequent recovery periods cause dramatic shifts in groundwater quality on a basin scale. We used a novel application...
Authors
Zeno F. Levy, Bryant Jurgens, Kirsten Faulkner, Jennifer S. Harkness, Miranda Fram
Salinity trends in a groundwater system supplemented by 50 years of imported Colorado River water
The Indio subbasin of the Coachella Valley is a desert area of southern California where a growing population depends primarily on groundwater for drinking and agricultural uses. The aquifer system has been supplemented with Colorado River water through managed recharge and widespread irrigation since the mid-20th century. We use a combination of geochemical modeling and trend analysis...
Authors
Jennifer S. Harkness, Patrick Michael McCarthy, Bryant Jurgens, Zeno F. Levy
Comparing domestic and public-supply groundwater quality in the northern San Joaquin Valley, 2019—California GAMA Priority Basin Project
Groundwater quality in the Northern San Joaquin Valley region of California was studied as part of California State Water Resources Control Board (SWRCB) Groundwater Ambient Monitoring and Assessment Program-Priority Basin Project (GAMA-PBP). The GAMA-PBP made a spatially unbiased assessment of the aquifer system used for domestic drinking-water supply in the study region and compared...
Authors
George L. Bennett, Emily A. Haugen, Zeno F. Levy
Quality of groundwater used for domestic drinking-water supply in the Coachella Valley, 2020
Groundwater is the primary source of drinking water in the Coachella Valley in the desert region of southern California. Although most people in Coachella Valley are served by public drinking-water systems, about 20,000 people rely on private domestic or small-system wells (referred to herein as domestic wells). Recently, the U.S. Geological Survey (USGS) found that 39 percent of the...
Authors
Andrew L. Soldavini, Jennifer S. Harkness, Zeno F. Levy, Miranda S. Fram
Quality of groundwater used for domestic supply in the Modesto, Turlock, and Merced Subbasins of the San Joaquin Valley, California
Summary More than 2 million Californians rely on groundwater from privately owned domestic wells for drinking-water supply. This report summarizes a water-quality survey of domestic and small-system drinking-water supply wells in the Modesto, Turlock, and Merced subbasins of the San Joaquin Valley where more than 78,000 residents are estimated to use privately owned domestic wells...
Authors
Zeno F. Levy, Mariia Balkan, Jennifer L. Shelton
Modeling the dynamic penetration depth of post-1950s water in unconfined aquifers using environmental tracers: Central Valley, California
The penetration depth of post-1950s recharge (D-1950) in aquifers is a marker that is frequently used to identify groundwater that is susceptible to anthropogenic contamination. Here, we compute D-1950 values at wells, interpolate them in space, and project them across time to map the moving front of modern recharge in four dimensions in the Central Valley aquifer system, California, USA...
Authors
Kirsten Faulkner, Bryant Jurgens, Stefan Voss, Danielle Dupuy, Zeno Levy
Lessons learned from wetlands research at the Cottonwood Lake Study Area, Stutsman County, North Dakota, 1967–2021
Depressional wetlands in the Prairie Pothole Region of North America have a long history of investigation owing to their importance in maintaining migratory-bird populations, especially waterfowl. One area of particularly intensive study is the Cottonwood Lake study area in Stutsman County, North Dakota. Studies at the Cottonwood Lake study area began in 1967 and continue through the...
Authors
David M. Mushet, Ned H. Euliss, Donald O. Rosenberry, James W. LaBaugh, Sheel Bansal, Zeno F. Levy, Owen P. McKenna, Kyle McLean, Christopher T. Mills, Brian P. Neff, Richard D. Nelson, Matthew J. Solensky, Brian Tangen
Critical aquifer overdraft accelerates degradation of groundwater quality in California’s Central Valley during drought
Drought-induced pumpage has precipitated dramatic groundwater-level declines in California’s Central Valley over the past 30 years, but the impacts of aquifer overdraft on water quality are poorly understood. This study coupled over 160,000 measurements of nitrate from ∼6,000 public-supply wells with a 30-year reconstruction of groundwater levels throughout the Central Valley to evaluate...
Authors
Zeno Levy, Bryant Jurgens, Karen R. Burow, Stefan Voss, Kirsten Faulkner, Jose Alfredo Arroyo-Lopez, Miranda S. Fram
Quality of groundwater used for domestic supply in the northern San Joaquin Valley, California
Groundwater provides more than 40 percent of California’s drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project (PBP) of the GAMA Program provides a comprehensive assessment of the State’s groundwater quality and provides increased public access to groundwater-quality...
Authors
Zeno F. Levy, Mariia Balkan, Jennifer L. Shelton
Status and understanding of groundwater quality in the northern Sierra Nevada foothills domestic-supply aquifer study units, 2015–17—California GAMA Priority Basin Project
Groundwater quality in the northern Sierra Nevada foothills region of California was investigated as part of California State Water Resources Control Board (SWRCB) Groundwater Ambient Monitoring Assessment Priority Basin Project (GAMA-PBP). The region was divided into two study units: the Yuba-Bear watersheds (YBW) study unit and the American-Cosumnes-Mokelumne watersheds (ACMW) study...
Authors
Zeno F. Levy, Miranda S. Fram
Geologic influences on the quality of groundwater used for domestic supply in the northern Sierra Nevada Foothills
Approximately 2 million California residents depend on groundwater from domestic wells for their drinking-water supply. The State of California, in collaboration with the U.S. Geological Survey, created the Groundwater Ambient Monitoring and Assessment Program Priority Basin Project (GAMA-PBP) to assess the quality of groundwater used for domestic supply throughout the state and...
Authors
Zeno F. Levy, Miranda S. Fram
Non-USGS Publications**
Levy ZF, Rosenberry DO, Moucha R, Mushet DM, Goldhaber MB, LaBaugh JW, Fiorentino AJ, Siegel DI. 2018. Drought-induced recharge promotes long-term storage of porewater salinity beneath a prairie wetland. Journal of Hydrology 557: 391-406, https://doi.org/10.1016/j.jhydrol.2017.12.005.
Levy ZF, Mills CT, Lu Z, Goldhaber MB, Rosenberry DO, Mushet DM, Lautz LK, Zhou X, Siegel DI. 2018. Using halogens (Cl, Br, I) to understand the hydrogeochemical evolution of drought-derived saline porewater beneath a prairie wetland. Chemical Geology 476: 191-207, https://doi.org/10.1016/j.chemgeo.2017.11.017.
Levy ZF, Siegel DI, Glaser PH, Samson SD, Dasgupta SS. 2016. Peat porewaters have contrasting geochemical fingerprints for groundwater recharge and discharge due to matrix diffusion in a large, northern bog-fen complex. Journal of Hydrology 541: 941-951, https://dx.doi.org/10.1016/j.jhydrol.2016.08.001.
Levy ZF, Smardon RC, Bays JS, Meyer D. 2014. A Point Source of a Different Color: Identifying a Gap in United States Regulatory Policy for “Green” CSO Treatment Using Constructed Wetlands. Sustainability 6(5): 2392-2412, https://dx.doi.org/10.3390/su6052392.
Levy ZF, Siegel DI, Dasgupta SS, Glaser PH, Welker JM. 2014. Stable isotopes of water show deep seasonal recharge in northern bogs and fens. Hydrological Processes 228: 4938-4952, https://dx.doi.org/10.1002/hyp.9983.
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.