Fred D Tillman, Jr., Ph.D.
Fred Tillman joined the USGS Arizona Water Science Center in Tucson, AZ in 2006 after two-plus years as a National Research Council (NRC) fellow with the USEPA Office of Research and Development (ORD) in Athens, Georgia.
Prior to joining the USGS, Fred was a post-doctoral researcher with the Ecosystems Research Division of USEPA’s ORD from 2004 through mid-2006, working with Dr. James W. Weaver on issues related to soil vapor intrusion, particularly from leaking underground storage tanks. Fred joined EPA after completion of his doctoral degree in Environmental Engineering at the University of Virginia in 2003, where he worked with Dr. James A. Smith on the response of volatile organic compound (VOC) vapors in the unsaturated zone to natural barometric pressure fluctuations (barometric pumping).
Education and Certifications
Ph.D. 2003, Environmental Engineering, University of Virginia, Charlottesville, VA
M.S. 1998, Environmental Engineering, University of Virginia, Charlottesville, VA
B.S. 1990, Electrical Engineering, Florida State University, Tallahassee, FL
Science and Products
Filter Total Items: 46
Trends in recent historical and projected climate data for the Colorado River Basin and potential effects on groundwater availability Trends in recent historical and projected climate data for the Colorado River Basin and potential effects on groundwater availability
Understanding recent historical and projected trends in precipitation and temperature in the Colorado River Basin, and estimating what the projected changes in these climate parameters may mean for groundwater resources in the region, is important for water managers and policymakers to sustainably manage water resources in the basin. Historical (1896–2019) precipitation and temperature...
Authors
Fred D. Tillman, Subhrendu Gangopadhyay, Tom Pruitt
Assessing uranium and select trace elements associated with breccia pipe uranium deposits in the Colorado River and main tributaries in Grand Canyon, USA Assessing uranium and select trace elements associated with breccia pipe uranium deposits in the Colorado River and main tributaries in Grand Canyon, USA
Assessing chemical loading from streams in remote, difficult-to-access watersheds is challenging. The Grand Canyon area in northern Arizona, an international tourist destination and sacred place for many Native Americans, is characterized by broad plateaus divided by canyons as much as two-thousand meters deep and hosts some of the highest-grade uranium deposits in the U.S. From 2015...
Authors
Fred D. Tillman, Jessica R. Anderson, Joel A. Unema, Thomas Chapin
Geochemical characterization of groundwater evolution south of Grand Canyon, Arizona (USA) Geochemical characterization of groundwater evolution south of Grand Canyon, Arizona (USA)
Better characterization of the geochemical evolution of groundwater south of Grand Canyon, Arizona (USA), is needed to understand natural conditions and assess potential effects from breccia-pipe uranium mining in the region. Geochemical signatures of groundwater at 28 sampling locations were evaluated; baseline concentrations for select trace elements (As, B, Ba, Cr, Li, Mo, Rb, Se, Sr...
Authors
Kimberly R. Beisner, John E. Solder, Fred D. Tillman, Jessica R. Anderson, Ronald C. Antweiler
Investigation of recent decadal-scale cyclical fluctuations in salinity in the lower Colorado river Investigation of recent decadal-scale cyclical fluctuations in salinity in the lower Colorado river
Beginning in the late 1970s, 10- to 15-year cyclical oscillations in salinity were observed at lower Colorado River monitoring sites, moving upstream from the international border with Mexico, above Imperial Dam, below Hoover Dam, and at Lees Ferry. The cause of these cyclical trends in salinity was unknown. These salinity cycles complicate the U.S. Bureau of Reclamation's (Reclamation)
Authors
Fred D. Tillman, Alissa L. Coes, David W. Anning, Jon P. Mason, Tyler B. Coplen
Effect of spatial and temporal scale on simulated groundwater recharge investigations Effect of spatial and temporal scale on simulated groundwater recharge investigations
Hydrologic model input datasets such as climate, land use, elevation, soil, and geology information are available in a range of scales for use in water resources investigations. Smaller spatial and temporal scale input data allow groundwater recharge models to simulate more physically realistic processes and presumably result in more accurate estimates of groundwater recharge. Projected...
Authors
Fred D. Tillman, Tom Pruitt, Subhrendu Gangopadhyay
Managing salinity in Upper Colorado River Basin streams: Selecting catchments for sediment control efforts using watershed characteristics and random forests models Managing salinity in Upper Colorado River Basin streams: Selecting catchments for sediment control efforts using watershed characteristics and random forests models
Elevated concentrations of dissolved-solids (salinity) including calcium, sodium, sulfate, and chloride, among others, in the Colorado River cause substantial problems for its water users. Previous efforts to reduce dissolved solids in upper Colorado River basin (UCRB) streams often focused on reducing suspended-sediment transport to streams, but few studies have investigated the...
Authors
Fred D. Tillman, David W. Anning, Julian A. Heilman, Susan G. Buto, Matthew P. Miller
Changes in projected spatial and seasonal groundwater recharge in the upper Colorado River Basin Changes in projected spatial and seasonal groundwater recharge in the upper Colorado River Basin
The Colorado River is an important source of water in the western United States, supplying the needs of more than 38 million people in the United States and Mexico. Groundwater discharge to streams has been shown to be a critical component of streamflow in the Upper Colorado River Basin (UCRB), particularly during low-flow periods. Understanding impacts on groundwater in the basin from...
Authors
Fred D. Tillman, Subhrendu Gangopadhyay, Tom Pruitt
Geochemical characterization of groundwater discharging from springs north of the Grand Canyon, Arizona, 2009–2016 Geochemical characterization of groundwater discharging from springs north of the Grand Canyon, Arizona, 2009–2016
A geochemical study was conducted on 37 springs discharging from the Toroweap Formation, Coconino Sandstone, Hermit Formation, Supai Group, and Redwall Limestone north of the Grand Canyon near areas of breccia-pipe uranium mining. Baseline concentrations were established for the elements As, B, Li, Se, SiO2, Sr, Tl, U, and V. Three springs exceeded U.S. Environmental Protection Agency...
Authors
Kimberly R. Beisner, Fred D. Tillman, Jessica R. Anderson, Ronald C. Antweiler, Donald J. Bills
Geochemistry and hydrology of perched groundwater springs: assessing elevated uranium concentrations at Pigeon Spring relative to nearby Pigeon Mine, Arizona (USA) Geochemistry and hydrology of perched groundwater springs: assessing elevated uranium concentrations at Pigeon Spring relative to nearby Pigeon Mine, Arizona (USA)
The processes that affect water chemistry as the water flows from recharge areas through breccia-pipe uranium deposits in the Grand Canyon region of the southwestern United States are not well understood. Pigeon Spring had elevated uranium in 1982 (44 μg/L), compared to other perched springs (2.7–18 μg/L), prior to mining operations at the nearby Pigeon Mine. Perched groundwater springs...
Authors
Kimberly R. Beisner, Nicholas V. Paretti, Fred D. Tillman, David L. Naftz, Donald J. Bills, Katherine Walton-Day, Tanya J. Gallegos
Understanding the past to interpret the future: Comparison of simulated groundwater recharge in the upper Colorado River basin (USA) using observed and general-circulation-model historical climate data Understanding the past to interpret the future: Comparison of simulated groundwater recharge in the upper Colorado River basin (USA) using observed and general-circulation-model historical climate data
In evaluating potential impacts of climate change on water resources, water managers seek to understand how future conditions may differ from the recent past. Studies of climate impacts on groundwater recharge often compare simulated recharge from future and historical time periods on an average monthly or overall average annual basis, or compare average recharge from future decades to...
Authors
Fred D. Tillman, Subhrendu Gangopadhyay, Tom Pruitt
A case study on evaluating impacts of potential climate change on groundwater resources: Groundwater recharge in the Upper Colorado River Basin A case study on evaluating impacts of potential climate change on groundwater resources: Groundwater recharge in the Upper Colorado River Basin
An investigation of the change in groundwater recharge in response to potential climate change was performed for the UCRB using the SWB groundwater recharge model and downscaled climate data from the CMIP5 multi-model dataset. Climate projections from 97 downscaled CMIP5 datasets were assumed to be equally likely and recharge simulation results were combined. Results for the UCRB suggest...
Authors
Fred D. Tillman, Subhrendu Gangopadhyay, Tom Pruitt
Changes in groundwater recharge under projected climate in the upper Colorado River basin Changes in groundwater recharge under projected climate in the upper Colorado River basin
Understanding groundwater-budget components, particularly groundwater recharge, is important to sustainably manage both groundwater and surface water supplies in the Colorado River basin now and in the future. This study quantifies projected changes in upper Colorado River basin (UCRB) groundwater recharge from recent historical (1950–2015) through future (2016–2099) time periods, using...
Authors
Fred D. Tillman, Subhrendu Gangopadhyay, Tom Pruitt
Non-USGS Publications**
Tillman, F.D and Weaver, J.W., 2007, Parameter sets for upper and lower bounds on soil-to-indoor-air contaminant attenuation predicted by the Johnson and Ettinger vapor intrusion model. Atmospheric Environment, 41, no. 27, p. 5797–5806.
Tillman, F.D and Weaver, J.W., 2007, Temporal moisture content variability beneath and external to a building and the potential effects on vapor intrusion risk assessment. Science of the Total Environment, 379, no. 1, p. 1-15.
Tillman, F.D and Weaver, J.W., 2006, Uncertainty from synergistic effects of multiple parameters in the Johnson and Ettinger (1991) vapor intrusion model. Atmospheric Environment, 40, no. 22, p. 4098–4112.
Tillman, F.D and Weaver, J.W., 2005, Review of recent research on vapor intrusion. U.S. Environmental Protection Agency Publication No. EPA/600/R-05/106, 40 p.
Weaver, J.W. and Tillman, F.D, 2005, Uncertainty and the Johnson-Ettinger model for vapor intrusion calculations. U.S. Environmental Protection Agency Publication No. EPA/600/R-05/110, 43 p.
Tillman, F.D and Smith, J.A., 2005, Vapor transport in the unsaturated zone, in Lehr, J.H., and Keely, J., eds., Water Encyclopedia: Ground Water. New Jersey, John Wiley & Sons, p. 543–548
Tillman, F.D and Smith, J.A., 2005, Site characteristics controlling airflow in the shallow unsaturated zone at Picatinny Arsenal, NJ. Environmental Engineering Science, 22, no. 1, p. 25–37.
Tillman, F.D, Bartelt-Hunt, S.L., Craver, V.A, Smith, J.A., and Alther, G.R., 2005, Relative metal ion sorption on natural and engineered sorbents: Batch and column studies. Environmental Engineering Science, 22. no. 3, p. 400–410.
Alther, G.R., Tillman, F.D, and Smith, J.A., 2005, Evaluation of Two Organoclays, Clinoptilolite, and Hydroxy-Apatite as Sorbents for Heavy Metal Removal from Water, in Calabrese E.J., Kostecki P.T., Dragun J. (eds) Contaminated Soils, Sediments and Water. Springer, Boston, MA, p. 457–468.
Tillman, F.D, Bartelt-Hunt, S.L., Smith, J.A., and Alther, G.R., 2004, Evaluation of an organoclay, an organoclay-anthracite blend, clinoptilolite, and hydroxy-apatite as sorbents for heavy metal removal from water. Bulletin of Environmental Contamination and Toxicology, 72, no. 6, p. 1134–1141.
Tillman, F.D and Smith, J.A., 2004, Design and laboratory testing of a chamber device to measure total flux of volatile organic compounds from the unsaturated zone under natural conditions. Journal of Contaminant Hydrology, 75, no. 1-2, p. 71–94.
Tillman, F.D, Choi, J.-W., and Smith, J.A., 2003, A comparison of direct measurement and model simulation of total flux of volatile organic compounds from the subsurface to the atmosphere under natural field conditions. Water Resources Research, 39, no. 10, p. 1284–1294.
Choi, J.-W., Tillman, F.D, and Smith, J.A, 2002, Relative Importance of Gas-Phase Diffusive and Advective Trichloroethene (TCE) Fluxes in the Unsaturated Zone under Natural Conditions. Environmental Science and Technology, 36, no. 14, p. 3157–3164.
Olson, M.S., Tillman, F.D, Choi, J.-W., and Smith, J.A., 2001, Comparison of three techniques to measure unsaturated-zone air permeability at Picatinny Arsenal, New Jersey. Journal of Contaminant Hydrology, 53, no. 1-2, p. 1–19.
Tillman, F.D, Choi, J.-W., Katchmark, W., Smith, J. A., and Wood, H.G.III, 2001, Unsaturated-zone airflow: Implications for natural remediation of ground water by contaminant transport through the subsurface, in Smith, J.A., and Burns, S.E., eds., Physicochemical Groundwater Remediation. New York, Kluwer Academic/Plenum Publishing, ISBN 978-0-306-46928-2, p. 307–340.
**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
Filter Total Items: 46
Trends in recent historical and projected climate data for the Colorado River Basin and potential effects on groundwater availability Trends in recent historical and projected climate data for the Colorado River Basin and potential effects on groundwater availability
Understanding recent historical and projected trends in precipitation and temperature in the Colorado River Basin, and estimating what the projected changes in these climate parameters may mean for groundwater resources in the region, is important for water managers and policymakers to sustainably manage water resources in the basin. Historical (1896–2019) precipitation and temperature...
Authors
Fred D. Tillman, Subhrendu Gangopadhyay, Tom Pruitt
Assessing uranium and select trace elements associated with breccia pipe uranium deposits in the Colorado River and main tributaries in Grand Canyon, USA Assessing uranium and select trace elements associated with breccia pipe uranium deposits in the Colorado River and main tributaries in Grand Canyon, USA
Assessing chemical loading from streams in remote, difficult-to-access watersheds is challenging. The Grand Canyon area in northern Arizona, an international tourist destination and sacred place for many Native Americans, is characterized by broad plateaus divided by canyons as much as two-thousand meters deep and hosts some of the highest-grade uranium deposits in the U.S. From 2015...
Authors
Fred D. Tillman, Jessica R. Anderson, Joel A. Unema, Thomas Chapin
Geochemical characterization of groundwater evolution south of Grand Canyon, Arizona (USA) Geochemical characterization of groundwater evolution south of Grand Canyon, Arizona (USA)
Better characterization of the geochemical evolution of groundwater south of Grand Canyon, Arizona (USA), is needed to understand natural conditions and assess potential effects from breccia-pipe uranium mining in the region. Geochemical signatures of groundwater at 28 sampling locations were evaluated; baseline concentrations for select trace elements (As, B, Ba, Cr, Li, Mo, Rb, Se, Sr...
Authors
Kimberly R. Beisner, John E. Solder, Fred D. Tillman, Jessica R. Anderson, Ronald C. Antweiler
Investigation of recent decadal-scale cyclical fluctuations in salinity in the lower Colorado river Investigation of recent decadal-scale cyclical fluctuations in salinity in the lower Colorado river
Beginning in the late 1970s, 10- to 15-year cyclical oscillations in salinity were observed at lower Colorado River monitoring sites, moving upstream from the international border with Mexico, above Imperial Dam, below Hoover Dam, and at Lees Ferry. The cause of these cyclical trends in salinity was unknown. These salinity cycles complicate the U.S. Bureau of Reclamation's (Reclamation)
Authors
Fred D. Tillman, Alissa L. Coes, David W. Anning, Jon P. Mason, Tyler B. Coplen
Effect of spatial and temporal scale on simulated groundwater recharge investigations Effect of spatial and temporal scale on simulated groundwater recharge investigations
Hydrologic model input datasets such as climate, land use, elevation, soil, and geology information are available in a range of scales for use in water resources investigations. Smaller spatial and temporal scale input data allow groundwater recharge models to simulate more physically realistic processes and presumably result in more accurate estimates of groundwater recharge. Projected...
Authors
Fred D. Tillman, Tom Pruitt, Subhrendu Gangopadhyay
Managing salinity in Upper Colorado River Basin streams: Selecting catchments for sediment control efforts using watershed characteristics and random forests models Managing salinity in Upper Colorado River Basin streams: Selecting catchments for sediment control efforts using watershed characteristics and random forests models
Elevated concentrations of dissolved-solids (salinity) including calcium, sodium, sulfate, and chloride, among others, in the Colorado River cause substantial problems for its water users. Previous efforts to reduce dissolved solids in upper Colorado River basin (UCRB) streams often focused on reducing suspended-sediment transport to streams, but few studies have investigated the...
Authors
Fred D. Tillman, David W. Anning, Julian A. Heilman, Susan G. Buto, Matthew P. Miller
Changes in projected spatial and seasonal groundwater recharge in the upper Colorado River Basin Changes in projected spatial and seasonal groundwater recharge in the upper Colorado River Basin
The Colorado River is an important source of water in the western United States, supplying the needs of more than 38 million people in the United States and Mexico. Groundwater discharge to streams has been shown to be a critical component of streamflow in the Upper Colorado River Basin (UCRB), particularly during low-flow periods. Understanding impacts on groundwater in the basin from...
Authors
Fred D. Tillman, Subhrendu Gangopadhyay, Tom Pruitt
Geochemical characterization of groundwater discharging from springs north of the Grand Canyon, Arizona, 2009–2016 Geochemical characterization of groundwater discharging from springs north of the Grand Canyon, Arizona, 2009–2016
A geochemical study was conducted on 37 springs discharging from the Toroweap Formation, Coconino Sandstone, Hermit Formation, Supai Group, and Redwall Limestone north of the Grand Canyon near areas of breccia-pipe uranium mining. Baseline concentrations were established for the elements As, B, Li, Se, SiO2, Sr, Tl, U, and V. Three springs exceeded U.S. Environmental Protection Agency...
Authors
Kimberly R. Beisner, Fred D. Tillman, Jessica R. Anderson, Ronald C. Antweiler, Donald J. Bills
Geochemistry and hydrology of perched groundwater springs: assessing elevated uranium concentrations at Pigeon Spring relative to nearby Pigeon Mine, Arizona (USA) Geochemistry and hydrology of perched groundwater springs: assessing elevated uranium concentrations at Pigeon Spring relative to nearby Pigeon Mine, Arizona (USA)
The processes that affect water chemistry as the water flows from recharge areas through breccia-pipe uranium deposits in the Grand Canyon region of the southwestern United States are not well understood. Pigeon Spring had elevated uranium in 1982 (44 μg/L), compared to other perched springs (2.7–18 μg/L), prior to mining operations at the nearby Pigeon Mine. Perched groundwater springs...
Authors
Kimberly R. Beisner, Nicholas V. Paretti, Fred D. Tillman, David L. Naftz, Donald J. Bills, Katherine Walton-Day, Tanya J. Gallegos
Understanding the past to interpret the future: Comparison of simulated groundwater recharge in the upper Colorado River basin (USA) using observed and general-circulation-model historical climate data Understanding the past to interpret the future: Comparison of simulated groundwater recharge in the upper Colorado River basin (USA) using observed and general-circulation-model historical climate data
In evaluating potential impacts of climate change on water resources, water managers seek to understand how future conditions may differ from the recent past. Studies of climate impacts on groundwater recharge often compare simulated recharge from future and historical time periods on an average monthly or overall average annual basis, or compare average recharge from future decades to...
Authors
Fred D. Tillman, Subhrendu Gangopadhyay, Tom Pruitt
A case study on evaluating impacts of potential climate change on groundwater resources: Groundwater recharge in the Upper Colorado River Basin A case study on evaluating impacts of potential climate change on groundwater resources: Groundwater recharge in the Upper Colorado River Basin
An investigation of the change in groundwater recharge in response to potential climate change was performed for the UCRB using the SWB groundwater recharge model and downscaled climate data from the CMIP5 multi-model dataset. Climate projections from 97 downscaled CMIP5 datasets were assumed to be equally likely and recharge simulation results were combined. Results for the UCRB suggest...
Authors
Fred D. Tillman, Subhrendu Gangopadhyay, Tom Pruitt
Changes in groundwater recharge under projected climate in the upper Colorado River basin Changes in groundwater recharge under projected climate in the upper Colorado River basin
Understanding groundwater-budget components, particularly groundwater recharge, is important to sustainably manage both groundwater and surface water supplies in the Colorado River basin now and in the future. This study quantifies projected changes in upper Colorado River basin (UCRB) groundwater recharge from recent historical (1950–2015) through future (2016–2099) time periods, using...
Authors
Fred D. Tillman, Subhrendu Gangopadhyay, Tom Pruitt
Non-USGS Publications**
Tillman, F.D and Weaver, J.W., 2007, Parameter sets for upper and lower bounds on soil-to-indoor-air contaminant attenuation predicted by the Johnson and Ettinger vapor intrusion model. Atmospheric Environment, 41, no. 27, p. 5797–5806.
Tillman, F.D and Weaver, J.W., 2007, Temporal moisture content variability beneath and external to a building and the potential effects on vapor intrusion risk assessment. Science of the Total Environment, 379, no. 1, p. 1-15.
Tillman, F.D and Weaver, J.W., 2006, Uncertainty from synergistic effects of multiple parameters in the Johnson and Ettinger (1991) vapor intrusion model. Atmospheric Environment, 40, no. 22, p. 4098–4112.
Tillman, F.D and Weaver, J.W., 2005, Review of recent research on vapor intrusion. U.S. Environmental Protection Agency Publication No. EPA/600/R-05/106, 40 p.
Weaver, J.W. and Tillman, F.D, 2005, Uncertainty and the Johnson-Ettinger model for vapor intrusion calculations. U.S. Environmental Protection Agency Publication No. EPA/600/R-05/110, 43 p.
Tillman, F.D and Smith, J.A., 2005, Vapor transport in the unsaturated zone, in Lehr, J.H., and Keely, J., eds., Water Encyclopedia: Ground Water. New Jersey, John Wiley & Sons, p. 543–548
Tillman, F.D and Smith, J.A., 2005, Site characteristics controlling airflow in the shallow unsaturated zone at Picatinny Arsenal, NJ. Environmental Engineering Science, 22, no. 1, p. 25–37.
Tillman, F.D, Bartelt-Hunt, S.L., Craver, V.A, Smith, J.A., and Alther, G.R., 2005, Relative metal ion sorption on natural and engineered sorbents: Batch and column studies. Environmental Engineering Science, 22. no. 3, p. 400–410.
Alther, G.R., Tillman, F.D, and Smith, J.A., 2005, Evaluation of Two Organoclays, Clinoptilolite, and Hydroxy-Apatite as Sorbents for Heavy Metal Removal from Water, in Calabrese E.J., Kostecki P.T., Dragun J. (eds) Contaminated Soils, Sediments and Water. Springer, Boston, MA, p. 457–468.
Tillman, F.D, Bartelt-Hunt, S.L., Smith, J.A., and Alther, G.R., 2004, Evaluation of an organoclay, an organoclay-anthracite blend, clinoptilolite, and hydroxy-apatite as sorbents for heavy metal removal from water. Bulletin of Environmental Contamination and Toxicology, 72, no. 6, p. 1134–1141.
Tillman, F.D and Smith, J.A., 2004, Design and laboratory testing of a chamber device to measure total flux of volatile organic compounds from the unsaturated zone under natural conditions. Journal of Contaminant Hydrology, 75, no. 1-2, p. 71–94.
Tillman, F.D, Choi, J.-W., and Smith, J.A., 2003, A comparison of direct measurement and model simulation of total flux of volatile organic compounds from the subsurface to the atmosphere under natural field conditions. Water Resources Research, 39, no. 10, p. 1284–1294.
Choi, J.-W., Tillman, F.D, and Smith, J.A, 2002, Relative Importance of Gas-Phase Diffusive and Advective Trichloroethene (TCE) Fluxes in the Unsaturated Zone under Natural Conditions. Environmental Science and Technology, 36, no. 14, p. 3157–3164.
Olson, M.S., Tillman, F.D, Choi, J.-W., and Smith, J.A., 2001, Comparison of three techniques to measure unsaturated-zone air permeability at Picatinny Arsenal, New Jersey. Journal of Contaminant Hydrology, 53, no. 1-2, p. 1–19.
Tillman, F.D, Choi, J.-W., Katchmark, W., Smith, J. A., and Wood, H.G.III, 2001, Unsaturated-zone airflow: Implications for natural remediation of ground water by contaminant transport through the subsurface, in Smith, J.A., and Burns, S.E., eds., Physicochemical Groundwater Remediation. New York, Kluwer Academic/Plenum Publishing, ISBN 978-0-306-46928-2, p. 307–340.
**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.