Samuel (Sam) F Lopez
Sam is a Hydrologist with the Utah Water Science Center. He specializes in contaminant hydrology and synthesis of large datasets to support regional modeling efforts related to water availability and use. He has been with the U.S. Geological Survey since 2021.
Sam has a PhD in geology from the University of Utah and a bachelor's in chemistry from Grinnell College. At the U.S. Geological Survey, he is involved with large regional modeling efforts in the Upper Colorado River and Great Salt Lake basins, compilation of analytical databases for critical minerals throughout the Intermountain West, and contaminant source and cycling studies throughout the Great Basin, particularly at Great Salt Lake.
Education and Certifications
PhD, Geology, University of Utah, 2024
B.A., Chemistry, Grinnell College, 2018 (concentration: Environmental Studies)
Honors and Awards
University of Utah Graduate Research Fellowship recipient (2022); Doyle W. Stephens Scholarship recipient (2022)
Science and Products
Model application data for co-developed surface watershed and groundwater hydrologic models for the Upper Colorado River Basin Model application data for co-developed surface watershed and groundwater hydrologic models for the Upper Colorado River Basin
Co-developed surface and subsurface hydrologic models for the Upper Colorado River Basin and the Colorado Plateaus principal aquifer system were used to investigate the drivers of change in hydrologic water budget components during contrasting recent wet (1982–1999) and drought (2000–2022) time periods in select headwater subregions of the Upper Colorado River Basin. The hydrologic...
Compilation of surface water diversion sites and daily withdrawals for the Upper Colorado River Basin, 1980-2022 Compilation of surface water diversion sites and daily withdrawals for the Upper Colorado River Basin, 1980-2022
This data release contains an inventory of 1,358 major surface water diversion structures with associated daily time series withdrawal records (1980-2022) for structures within the Upper Colorado River and Little Colorado River Basins. Diversion structures were included in this dataset if they were determined to have the capacity to divert water at rates greater than 10 cubic feet per...
Assessment of Mercury, Mercury Stable Isotopes, and Trace Metals in Waters, Sediments, and Biota from Great Salt Lake, Utah Assessment of Mercury, Mercury Stable Isotopes, and Trace Metals in Waters, Sediments, and Biota from Great Salt Lake, Utah
Great Salt Lake (GSL) is a designated Site of Hemispheric Importance for migratory birds by the Western Hemisphere Shorebird Reserve Network. Elevated mercury (Hg) and methylmercury (MeHg) levels related to current inputs and past industrial contamination pose a potential threat to GSL biota, in addition to waterfowl hunters that utilize GSL and surrounding wetland areas. Sediments...
Hydrologic response of groundwater and streamflow to natural and anthropogenic drivers of change in headwaters of the upper Colorado River basin during recent wet (1982–1999) and drought (2000–2022) conditions Hydrologic response of groundwater and streamflow to natural and anthropogenic drivers of change in headwaters of the upper Colorado River basin during recent wet (1982–1999) and drought (2000–2022) conditions
Study region: Headwaters of the upper Colorado River basin (UCOL), USA Study focus: Surface-water and groundwater numerical models incorporating water-use information were used to investigate changes in climate, water use, and simulated hydrologic responses of snow processes, evapotranspiration, groundwater, and streamflow during recent wet (1982–1999) and drought (2000–2022) periods in...
Authors
Fred Tillman, Melissa Masbruch, Jacob E. Knight, John Engott, Samuel Lopez, Casey Jones, Jesse Dickinson, Matthew P. Miller
Application of mercury stable isotopes to examine sources and hydrologic factors impacting mercury bioaccumulation and cycling in invertebrates of a model saline lake Application of mercury stable isotopes to examine sources and hydrologic factors impacting mercury bioaccumulation and cycling in invertebrates of a model saline lake
Invertebrates, such as brine shrimp and brine flies, are key prey items for millions of resident and migratory birds that utilize saline lakes such as Great Salt Lake (GSL). Elevated methylmercury (MeHg) in invertebrate and waterfowl species of GSL has been assumed to be linked to elevated MeHg in GSL’s anoxic Deep Brine Layer (DBL) where aqueous concentrations can exceed 30 ng/L. Here...
Authors
Samuel Lopez, Sarah E. Janssen, Michael T. Tate, Frank J. Black, Hannah Mcilwain, Laura Flucke, Jacob Ogorek, William Johnson
Using mercury and lead stable isotopes to assess mercury, lead, and trace metal source contributions to Great Salt Lake, Utah, USA Using mercury and lead stable isotopes to assess mercury, lead, and trace metal source contributions to Great Salt Lake, Utah, USA
Great Salt Lake is a critical habitat for migratory birds that is threatened by elevated metal concentrations, including mercury (Hg) and lead (Pb), and is subject to severe hydrologic changes, such as declining lake level. When assessing metal profiles recorded in Great Salt Lake sediment, a large data gap exists regarding the sources of metals within the system, which is complicated by...
Authors
Samuel Lopez, Sarah E. Janssen, Michael T. Tate, Diego Fernandez, Christopher Anderson, Grace Armstrong, Thomas Wang, William Johnson
Database of surface water diversion sites and daily withdrawals for the upper Colorado River Basin, 1980–2022 Database of surface water diversion sites and daily withdrawals for the upper Colorado River Basin, 1980–2022
The Colorado River drains about 8% of the conterminous United States, provides water for 40 million people, and is one of the most overallocated rivers in the world. As the upper Colorado River Basin (UCOL) contributes an estimated 92% of the total basin natural streamflow, knowledge of the location and amount of surface water withdrawals in the UCOL is important for managing the...
Authors
Samuel Lopez, Jacob E. Knight, Fred Tillman, Melissa Masbruch, Daniel Wise, Casey Jones, Matthew P. Miller
Non-USGS Publications**
Gustin, M.S., Allen, N., Dunham Cheatham, S.M., Choma, N., Lyman, S.N., Johnson, W., Lopez, S., Russell, A., Mei, E., Magand, O., Dommergue, A., Elgiar, T. 2023 Observations of the chemistry and concentrations of reactive Hg at locations with different ambient air chemistry, Science of the Total Environment, 904, 166184. https://doi.org/10.1016/j.scitotenv.2023.166184
Graham, A.M. Van Helten, S., Wadle, A. Mamrak, E., Morsch, J., Lopez, S., Smith, K. (2023). Mercury transport and methylmercury production in the lower Cedar River (Iowa) floodplain. Frontiers in Environmental Chemistry 4: https://doi.org/10.3389/fenvc.2023.1242813
**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
Model application data for co-developed surface watershed and groundwater hydrologic models for the Upper Colorado River Basin Model application data for co-developed surface watershed and groundwater hydrologic models for the Upper Colorado River Basin
Co-developed surface and subsurface hydrologic models for the Upper Colorado River Basin and the Colorado Plateaus principal aquifer system were used to investigate the drivers of change in hydrologic water budget components during contrasting recent wet (1982–1999) and drought (2000–2022) time periods in select headwater subregions of the Upper Colorado River Basin. The hydrologic...
Compilation of surface water diversion sites and daily withdrawals for the Upper Colorado River Basin, 1980-2022 Compilation of surface water diversion sites and daily withdrawals for the Upper Colorado River Basin, 1980-2022
This data release contains an inventory of 1,358 major surface water diversion structures with associated daily time series withdrawal records (1980-2022) for structures within the Upper Colorado River and Little Colorado River Basins. Diversion structures were included in this dataset if they were determined to have the capacity to divert water at rates greater than 10 cubic feet per...
Assessment of Mercury, Mercury Stable Isotopes, and Trace Metals in Waters, Sediments, and Biota from Great Salt Lake, Utah Assessment of Mercury, Mercury Stable Isotopes, and Trace Metals in Waters, Sediments, and Biota from Great Salt Lake, Utah
Great Salt Lake (GSL) is a designated Site of Hemispheric Importance for migratory birds by the Western Hemisphere Shorebird Reserve Network. Elevated mercury (Hg) and methylmercury (MeHg) levels related to current inputs and past industrial contamination pose a potential threat to GSL biota, in addition to waterfowl hunters that utilize GSL and surrounding wetland areas. Sediments...
Hydrologic response of groundwater and streamflow to natural and anthropogenic drivers of change in headwaters of the upper Colorado River basin during recent wet (1982–1999) and drought (2000–2022) conditions Hydrologic response of groundwater and streamflow to natural and anthropogenic drivers of change in headwaters of the upper Colorado River basin during recent wet (1982–1999) and drought (2000–2022) conditions
Study region: Headwaters of the upper Colorado River basin (UCOL), USA Study focus: Surface-water and groundwater numerical models incorporating water-use information were used to investigate changes in climate, water use, and simulated hydrologic responses of snow processes, evapotranspiration, groundwater, and streamflow during recent wet (1982–1999) and drought (2000–2022) periods in...
Authors
Fred Tillman, Melissa Masbruch, Jacob E. Knight, John Engott, Samuel Lopez, Casey Jones, Jesse Dickinson, Matthew P. Miller
Application of mercury stable isotopes to examine sources and hydrologic factors impacting mercury bioaccumulation and cycling in invertebrates of a model saline lake Application of mercury stable isotopes to examine sources and hydrologic factors impacting mercury bioaccumulation and cycling in invertebrates of a model saline lake
Invertebrates, such as brine shrimp and brine flies, are key prey items for millions of resident and migratory birds that utilize saline lakes such as Great Salt Lake (GSL). Elevated methylmercury (MeHg) in invertebrate and waterfowl species of GSL has been assumed to be linked to elevated MeHg in GSL’s anoxic Deep Brine Layer (DBL) where aqueous concentrations can exceed 30 ng/L. Here...
Authors
Samuel Lopez, Sarah E. Janssen, Michael T. Tate, Frank J. Black, Hannah Mcilwain, Laura Flucke, Jacob Ogorek, William Johnson
Using mercury and lead stable isotopes to assess mercury, lead, and trace metal source contributions to Great Salt Lake, Utah, USA Using mercury and lead stable isotopes to assess mercury, lead, and trace metal source contributions to Great Salt Lake, Utah, USA
Great Salt Lake is a critical habitat for migratory birds that is threatened by elevated metal concentrations, including mercury (Hg) and lead (Pb), and is subject to severe hydrologic changes, such as declining lake level. When assessing metal profiles recorded in Great Salt Lake sediment, a large data gap exists regarding the sources of metals within the system, which is complicated by...
Authors
Samuel Lopez, Sarah E. Janssen, Michael T. Tate, Diego Fernandez, Christopher Anderson, Grace Armstrong, Thomas Wang, William Johnson
Database of surface water diversion sites and daily withdrawals for the upper Colorado River Basin, 1980–2022 Database of surface water diversion sites and daily withdrawals for the upper Colorado River Basin, 1980–2022
The Colorado River drains about 8% of the conterminous United States, provides water for 40 million people, and is one of the most overallocated rivers in the world. As the upper Colorado River Basin (UCOL) contributes an estimated 92% of the total basin natural streamflow, knowledge of the location and amount of surface water withdrawals in the UCOL is important for managing the...
Authors
Samuel Lopez, Jacob E. Knight, Fred Tillman, Melissa Masbruch, Daniel Wise, Casey Jones, Matthew P. Miller
Non-USGS Publications**
Gustin, M.S., Allen, N., Dunham Cheatham, S.M., Choma, N., Lyman, S.N., Johnson, W., Lopez, S., Russell, A., Mei, E., Magand, O., Dommergue, A., Elgiar, T. 2023 Observations of the chemistry and concentrations of reactive Hg at locations with different ambient air chemistry, Science of the Total Environment, 904, 166184. https://doi.org/10.1016/j.scitotenv.2023.166184
Graham, A.M. Van Helten, S., Wadle, A. Mamrak, E., Morsch, J., Lopez, S., Smith, K. (2023). Mercury transport and methylmercury production in the lower Cedar River (Iowa) floodplain. Frontiers in Environmental Chemistry 4: https://doi.org/10.3389/fenvc.2023.1242813
**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.