Gregory Daniel Clark
Greg is a project chief in the groundwater and water quality section at the Wyoming-Montana Water Science Center.
Greg’s training is in hydrologic response to landscape disturbance and his work typically focuses on the linkages between water chemistry and watershed characteristics. He works with local, state, and federal partners to develop a scientific understanding of watershed response to significant landscape disturbances that can be used in future decision making. This work primarily centers on, but is not limited to, water quality response to wildfire, mining, and logging. Greg has a particular interest in using continuous water quality sensing to characterize event-based response in these landscapes.
Professional Experience
2019 - present Hydrologist [Project Chief], U.S. Geological Survey Wyoming-Montana Water Science Center.
2018 - 2019 Terrestrial Field Ecologist, NSF-Batelle, National Ecological Observatory Network, Front Royal, Virginia.
Education and Certifications
M.S. Environmental Science (Soils), Washington State University, 2018.
B.S. Environmental Resource Management (Water Science), Pennsylvania State University, 2016.
Science and Products
Filter Total Items: 24
The quality of our nation's waters: Nutrients in the nation's streams and groundwater, 1992-2004 The quality of our nation's waters: Nutrients in the nation's streams and groundwater, 1992-2004
National Findings and Their Implications Although the use of artificial fertilizer has supported increasing food production to meet the needs of a growing population, increases in nutrient loadings from agricultural and, to a lesser extent, urban sources have resulted in nutrient concentrations in many streams and parts of aquifers that exceed standards for protection of human health and...
Authors
Neil M. Dubrovsky, Karen R. Burow, Gregory M. Clark, JoAnn M. Gronberg, Pixie A. Hamilton, Kerie J. Hitt, David K. Mueller, Mark D. Munn, Bernard T. Nolan, Larry J. Puckett, Michael G. Rupert, Terry M. Short, Norman E. Spahr, Lori A. Sprague, William G. Wilber
Nutrient and Suspended-Sediment Transport and Trends in the Columbia River and Puget Sound Basins, 1993-2003 Nutrient and Suspended-Sediment Transport and Trends in the Columbia River and Puget Sound Basins, 1993-2003
This study focused on three areas that might be of interest to water-quality managers in the Pacific Northwest: (1) annual loads of total nitrogen (TN), total phosphorus (TP) and suspended sediment (SS) transported through the Columbia River and Puget Sound Basins, (2) annual yields of TN, TP, and SS relative to differences in landscape and climatic conditions between subbasin catchments...
Authors
Daniel R. Wise, Frank A. Rinella, Joseph F. Rinella, Greg J. Fuhrer, Sandra S. Embrey, Gregory M. Clark, Gregory E. Schwarz, Steven Sobieszczyk
Occurrence and transport of cadmium, lead, and zinc in the Spokane River basin, Idaho and Washington, water years 1999-2001 Occurrence and transport of cadmium, lead, and zinc in the Spokane River basin, Idaho and Washington, water years 1999-2001
A water-quality investigation of the Clark Fork-Pend Oreille and Spokane River Basins began in 1997 as part of the U.S. Geological Survey National Water-Quality Assessment Program. As part of the investigation, selected streams in the Spokane River Basin were sampled for trace metals during water years 1999–2001. These data, combined with data collected as part of a U.S. Environmental...
Authors
Gregory M. Clark
Water quality in the Northern Rockies Intermontane basins, Idaho, Montana, and Washington, 1999-2001 Water quality in the Northern Rockies Intermontane basins, Idaho, Montana, and Washington, 1999-2001
This report contains the major findings of a 1999–2001 assessment of water quality in the Northern Rockies Intermontane Basins. It is one of a series of reports by the National Water-Quality Assessment (NAWQA) Program that present major findings in 51 major river basins and aquifer systems across the Nation. In these reports, water quality is discussed in terms of local, State, and...
Authors
Gregory M. Clark, Rodney R. Caldwell, Terry R. Maret, Craig L. Bowers, DeAnn M. Dutton, Michael A. Becksmith
Evaluating the influence of source basins on downstream water quality in the Mississippi River Evaluating the influence of source basins on downstream water quality in the Mississippi River
Chemical variability in the Mississippi River during water years 1989 to 1998 was evaluated using stream discharge and water‐quality data in conjunction with the DAFLOW/BLTM hydraulic model. Model simulations were used to identify subbasin contributions of water and chemical constituents to the Mississippi River upstream from its confluence with the Ohio and the Mississippi River and at...
Authors
Gregory M. Clark, Robert E. Broshears, Richard P. Hooper, Donald A. Goolsby
Occurrence and load of selected herbicides and metabolites in the lower Mississippi River Occurrence and load of selected herbicides and metabolites in the lower Mississippi River
Analyses of water samples collected from the Mississippi River at Baton Rouge, Louisiana, during 1991–1997 indicate that hundreds of metric tons of herbicides and herbicide metabolites are being discharged annually to the Gulf of Mexico. Atrazine, metolachlor, and the ethane-sulfonic acid metabolite of alachlor (alachlor ESA) were the most frequently detected herbicides and, in general...
Authors
Gregory M. Clark, Donald A. Goolsby
Discharge of herbicides from the Mississippi River Basin to the Gulf of Mexico, 1991-97 Discharge of herbicides from the Mississippi River Basin to the Gulf of Mexico, 1991-97
No abstract available.
Authors
Gregory M. Clark, Donald A. Goolsby
Water quality in the upper Snake River basin, Idaho and Wyoming, 1992-95 Water quality in the upper Snake River basin, Idaho and Wyoming, 1992-95
This report is intended to summarize major findings that emerged between 1992 and 1995 from the water-quality assessment of the Upper Snake River Basin Study Unit and to relate these findings to water-quality issues of regional and national concern. This information is primarily intended for those who are involved in water-resource management. Yet, the information contained here may also...
Authors
Gregory M. Clark, T.R. Maret, M.G. Rupert, M.A. Maupin, W. H. Low, D.S. Ott
Organochlorine compounds and trace elements in fish tissue and bed sediments in the lower Snake River basin, Idaho and Oregon Organochlorine compounds and trace elements in fish tissue and bed sediments in the lower Snake River basin, Idaho and Oregon
Fish-tissue and bed-sediment samples were collected to determine the occurrence and distribution of organochlorine compounds and trace elements in the lower Snake River Basin. Whole-body composite samples of suckers and carp from seven sites were analyzed for organochlorine compounds; liver samples were analyzed for trace elements. Fillets from selected sportfish were analyzed for...
Authors
Gregory M. Clark, Terry R. Maret
Assessment of nutrients, suspended sediment, and pesticides in surface water of the upper Snake River basin, Idaho and western Wyoming, water years 1991-95 Assessment of nutrients, suspended sediment, and pesticides in surface water of the upper Snake River basin, Idaho and western Wyoming, water years 1991-95
A water-quality investigation of the upper Snake River Basin began in 1991 as part of the U.S. Geological Survey's National Water- Quality Assessment Program. As part of the investigation, intensive monitoring was conducted during water years 1993 through 1995 to assess surface-water quality in the basin. Sampling and analysis focused on nutrients, suspended sediments, and pesticides
Authors
Gregory M. Clark
Assessment of selected constituents in surface water of the upper Snake River basin, Idaho and western Wyoming, water years 1975-89 Assessment of selected constituents in surface water of the upper Snake River basin, Idaho and western Wyoming, water years 1975-89
In 1991, a water-quality investigation of the upper Snake River Basin was initiated as part of the U.S. Geological Survey's National Water-Quality Assessment Program. The initial task of the assessment was to compile and analyze available nutrient, suspended sediment, and pesticide data collected in the basin. For analysis of nutrients and suspended sediment, data collected during water
Authors
Gregory M. Clark
Identification of dissolved-constituent sources in mine-site ground water using batch mixing Identification of dissolved-constituent sources in mine-site ground water using batch mixing
Batch-mixing experiments were used to help identify lithologic and mineralogic sources of increased concentrations of dissolved solids in water affected by surface coal mining in northwestern Colorado. Ten overburden core samples were analyzed for mineral composition and mixed with distilled water for 90 days until mineral-water equilibrium was reached. Between one day and 90 days after...
Authors
Gregory M. Clark, Robert S. Williams
Non-USGS Publications**
GD Clark, KB Moffett (2018). Multiple wildfire disturbances amplify seasonal moisture stress in a moist, mixed-conifer montane ecosystem. Washington State University. Pullman, Washington.
**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: 24
The quality of our nation's waters: Nutrients in the nation's streams and groundwater, 1992-2004 The quality of our nation's waters: Nutrients in the nation's streams and groundwater, 1992-2004
National Findings and Their Implications Although the use of artificial fertilizer has supported increasing food production to meet the needs of a growing population, increases in nutrient loadings from agricultural and, to a lesser extent, urban sources have resulted in nutrient concentrations in many streams and parts of aquifers that exceed standards for protection of human health and...
Authors
Neil M. Dubrovsky, Karen R. Burow, Gregory M. Clark, JoAnn M. Gronberg, Pixie A. Hamilton, Kerie J. Hitt, David K. Mueller, Mark D. Munn, Bernard T. Nolan, Larry J. Puckett, Michael G. Rupert, Terry M. Short, Norman E. Spahr, Lori A. Sprague, William G. Wilber
Nutrient and Suspended-Sediment Transport and Trends in the Columbia River and Puget Sound Basins, 1993-2003 Nutrient and Suspended-Sediment Transport and Trends in the Columbia River and Puget Sound Basins, 1993-2003
This study focused on three areas that might be of interest to water-quality managers in the Pacific Northwest: (1) annual loads of total nitrogen (TN), total phosphorus (TP) and suspended sediment (SS) transported through the Columbia River and Puget Sound Basins, (2) annual yields of TN, TP, and SS relative to differences in landscape and climatic conditions between subbasin catchments...
Authors
Daniel R. Wise, Frank A. Rinella, Joseph F. Rinella, Greg J. Fuhrer, Sandra S. Embrey, Gregory M. Clark, Gregory E. Schwarz, Steven Sobieszczyk
Occurrence and transport of cadmium, lead, and zinc in the Spokane River basin, Idaho and Washington, water years 1999-2001 Occurrence and transport of cadmium, lead, and zinc in the Spokane River basin, Idaho and Washington, water years 1999-2001
A water-quality investigation of the Clark Fork-Pend Oreille and Spokane River Basins began in 1997 as part of the U.S. Geological Survey National Water-Quality Assessment Program. As part of the investigation, selected streams in the Spokane River Basin were sampled for trace metals during water years 1999–2001. These data, combined with data collected as part of a U.S. Environmental...
Authors
Gregory M. Clark
Water quality in the Northern Rockies Intermontane basins, Idaho, Montana, and Washington, 1999-2001 Water quality in the Northern Rockies Intermontane basins, Idaho, Montana, and Washington, 1999-2001
This report contains the major findings of a 1999–2001 assessment of water quality in the Northern Rockies Intermontane Basins. It is one of a series of reports by the National Water-Quality Assessment (NAWQA) Program that present major findings in 51 major river basins and aquifer systems across the Nation. In these reports, water quality is discussed in terms of local, State, and...
Authors
Gregory M. Clark, Rodney R. Caldwell, Terry R. Maret, Craig L. Bowers, DeAnn M. Dutton, Michael A. Becksmith
Evaluating the influence of source basins on downstream water quality in the Mississippi River Evaluating the influence of source basins on downstream water quality in the Mississippi River
Chemical variability in the Mississippi River during water years 1989 to 1998 was evaluated using stream discharge and water‐quality data in conjunction with the DAFLOW/BLTM hydraulic model. Model simulations were used to identify subbasin contributions of water and chemical constituents to the Mississippi River upstream from its confluence with the Ohio and the Mississippi River and at...
Authors
Gregory M. Clark, Robert E. Broshears, Richard P. Hooper, Donald A. Goolsby
Occurrence and load of selected herbicides and metabolites in the lower Mississippi River Occurrence and load of selected herbicides and metabolites in the lower Mississippi River
Analyses of water samples collected from the Mississippi River at Baton Rouge, Louisiana, during 1991–1997 indicate that hundreds of metric tons of herbicides and herbicide metabolites are being discharged annually to the Gulf of Mexico. Atrazine, metolachlor, and the ethane-sulfonic acid metabolite of alachlor (alachlor ESA) were the most frequently detected herbicides and, in general...
Authors
Gregory M. Clark, Donald A. Goolsby
Discharge of herbicides from the Mississippi River Basin to the Gulf of Mexico, 1991-97 Discharge of herbicides from the Mississippi River Basin to the Gulf of Mexico, 1991-97
No abstract available.
Authors
Gregory M. Clark, Donald A. Goolsby
Water quality in the upper Snake River basin, Idaho and Wyoming, 1992-95 Water quality in the upper Snake River basin, Idaho and Wyoming, 1992-95
This report is intended to summarize major findings that emerged between 1992 and 1995 from the water-quality assessment of the Upper Snake River Basin Study Unit and to relate these findings to water-quality issues of regional and national concern. This information is primarily intended for those who are involved in water-resource management. Yet, the information contained here may also...
Authors
Gregory M. Clark, T.R. Maret, M.G. Rupert, M.A. Maupin, W. H. Low, D.S. Ott
Organochlorine compounds and trace elements in fish tissue and bed sediments in the lower Snake River basin, Idaho and Oregon Organochlorine compounds and trace elements in fish tissue and bed sediments in the lower Snake River basin, Idaho and Oregon
Fish-tissue and bed-sediment samples were collected to determine the occurrence and distribution of organochlorine compounds and trace elements in the lower Snake River Basin. Whole-body composite samples of suckers and carp from seven sites were analyzed for organochlorine compounds; liver samples were analyzed for trace elements. Fillets from selected sportfish were analyzed for...
Authors
Gregory M. Clark, Terry R. Maret
Assessment of nutrients, suspended sediment, and pesticides in surface water of the upper Snake River basin, Idaho and western Wyoming, water years 1991-95 Assessment of nutrients, suspended sediment, and pesticides in surface water of the upper Snake River basin, Idaho and western Wyoming, water years 1991-95
A water-quality investigation of the upper Snake River Basin began in 1991 as part of the U.S. Geological Survey's National Water- Quality Assessment Program. As part of the investigation, intensive monitoring was conducted during water years 1993 through 1995 to assess surface-water quality in the basin. Sampling and analysis focused on nutrients, suspended sediments, and pesticides
Authors
Gregory M. Clark
Assessment of selected constituents in surface water of the upper Snake River basin, Idaho and western Wyoming, water years 1975-89 Assessment of selected constituents in surface water of the upper Snake River basin, Idaho and western Wyoming, water years 1975-89
In 1991, a water-quality investigation of the upper Snake River Basin was initiated as part of the U.S. Geological Survey's National Water-Quality Assessment Program. The initial task of the assessment was to compile and analyze available nutrient, suspended sediment, and pesticide data collected in the basin. For analysis of nutrients and suspended sediment, data collected during water
Authors
Gregory M. Clark
Identification of dissolved-constituent sources in mine-site ground water using batch mixing Identification of dissolved-constituent sources in mine-site ground water using batch mixing
Batch-mixing experiments were used to help identify lithologic and mineralogic sources of increased concentrations of dissolved solids in water affected by surface coal mining in northwestern Colorado. Ten overburden core samples were analyzed for mineral composition and mixed with distilled water for 90 days until mineral-water equilibrium was reached. Between one day and 90 days after...
Authors
Gregory M. Clark, Robert S. Williams
Non-USGS Publications**
GD Clark, KB Moffett (2018). Multiple wildfire disturbances amplify seasonal moisture stress in a moist, mixed-conifer montane ecosystem. Washington State University. Pullman, Washington.
**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.