Gretchen P. Oelsner , PhD
Gretchen Oelsner (she/her) is a Hydrologist with the Water Resources Mission Area Earth Systems Processes Division.
Gretchen’s work has focused on understanding water quality by analyzing surface-water quality, biogeochemistry, surface-water hydrology, groundwater-surface water interactions, and biogeochemistry, usually at a large scale (regional to national) as part of integrated and multidisciplinary studies. Her investigative projects have focused on understanding the hydrologic, climatic, biologic, land use/land cover, and anthropogenic controls on water-quality using statistical, machine-learning, or process-based models. Gretchen currently leads the IWAAs National Trends and Drivers in Water Availability Project.
Professional Experience
2023 – present | Hydrologist, USGS Water Mission Area, Earth System Processes Division - Albuquerque, NM
2011-2023 | Hydrologist, USGS, New Mexico Water Science Center - Albuquerque, NM
2007-2010 | Physical Scientist Postdoctoral Fellow, U.S. Environmental Protection Agency, Western Ecology Division, Freshwater Ecology Branch - Corvallis, OR
Education and Certifications
Ph.D. – 2007, Hydrology and Water Resources, University of Arizona, Tucson, AZ
M.S. – 2001, Geology and Geophysics, University of Wyoming, Laramie, WY
A.B. – 1995, Government and Geology, Smith College, Northampton, MA
Science and Products
Hydraulic Fracturing and Water Resources: An Assessment of the Potential Effects of Shale Gas Development on Water Resources in the United States
Shale gas is a key source of onshore domestic energy for the United States and production of this resource is increasing rapidly. Development and extraction of shale gas requires hydraulic fracturing, which entails horizontal drilling, perforation of steel casing and cement grout using explosive charges, and expansion of fractures using fluids under high pressure. Concern over potential environmen
Estimated seasonal nitrogen and phosphorus loads in selected streams of the conterminous United States, 1999 - 2020
Estimated seasonal total nitrogen and total phosphorus loads during 1999 through 2020 in selected streams of the conterminous United States and water-quality and stream flow data used to generate those estimates are presented in this dataset. Loads were generated as part of the Integrated Water-Availability Assessment (IWAA) Program of the U.S. Geological Survey (www.usgs.gov/mission-areas/water-r
Long-term water-quality trends for rivers and streams within the contiguous United States using Weighted Regressions on Time, Discharge, and Season (WRTDS)
The U.S. Geological Survey (USGS) Water Mission Area (WMA) is working to address a need to understand where the Nation is experiencing water shortages or surpluses relative to the demand for water need by delivering routine assessments of water supply and demand. It is also improving understanding of the natural and human factors affecting the balance between supply and demand. A key part of these
Water-quality and streamflow datasets used in Weighted Regressions on Time, Discharge, and Season (WRTDS) models to determine trends in the Nation’s rivers and streams, 1972-2017
In 1991, the U.S. Geological Survey (USGS) began a study of more than 50 major river basins across the Nation as part of the National Water-Quality Assessment (NAWQA) project. One of the major goals of the NAWQA project was to determine how river water quality has changed over time. To support that goal, long-term consistent and comparable monitoring has been conducted by the USGS on streams and r
Estimates of Road Salt Application across the Conterminous United States, 1992-2019 (ver. 2.0, August 2023)
Annual estimates of road salt application were developed for the conterminous United States for the calendar years 1992 through 2015. The final estimates (in pounds) were derived from several data sources, which include road density and proportion of developed land use, depth and spatial extent of long-term snowfall, and the production and distribution of salt sources by state. The extent is the c
Water-quality and streamflow datasets used in the Weighted Regressions on Time, Discharge, and Season (WRTDS) models to determine trends in the Nations rivers and streams, 1972-2012
In 1991, the U.S. Geological Survey (USGS) began a study of more than 50 major river basins across the Nation as part of the National Water-Quality Assessment (NAWQA) project of the National Water-Quality Program. One of the major goals of the NAWQA project is to determine how water-quality conditions change over time. To support that goal, long-term consistent and comparable monitoring has been c
Water-quality and streamflow datasets used in Seasonal Kendall trend tests for the Nations rivers and streams, 1972-2012
In 1991, the U.S. Geological Survey (USGS) began a study of more than 50 major river basins across the Nation as part of the National Water-Quality Assessment (NAWQA) project of the National Water-Quality Program. One of the major goals of the NAWQA project is to determine how water-quality conditions change over time. To support that goal, long-term consistent and comparable monitoring has been c
Simulated and measured water levels and estimated water-level changes in the Albuquerque area, central New Mexico, 1950-2012
The City of Albuquerque, the major population center in New Mexico, underwent a more than fivefold population increase between 1950 and 2010. Before 2009, groundwater was the primary source of the City of Albuquerque’s municipal water supply, but since that time, the city has diverted water through the San Juan-Chama Drinking Water Project to augment municipal water supplies. Consequently, there i
Integrated water resources trend assessments: State of the science, challenges, and opportunities for advancement
Water is vital to human life and healthy ecosystems. Here we outline the current state of national-scale water resources trend assessments, identify key gaps, and suggest advancements to better address critical issues related to changes in water resources that may threaten human development or the environment. Questions like, “Do we have less suitable drinking water now than we had 20 years ago?”
Authors
Sarah M. Stackpoole, Gretchen P. Oelsner, Edward G. Stets, Jory Seth Hecht, Zachary Johnson, Anthony J. Tesoriero, Michelle A. Walvoord, Jeffrey G. Chanat, Krista A. Dunne, Phillip J. Goodling, Bruce D. Lindsey, Michael Meador, Sarah Spaulding
Comparison of surrogate models to estimate pesticide concentrations at six U.S. Geological Survey National Water Quality Network sites during water years 2013–18
During water years 2013–18, the U.S. Geological Survey National Water-Quality Assessment Project sampled the National Water Quality Network for Rivers and Streams year-round and reported on 221 pesticides at 72 sites across the United States. Pesticides are difficult to measure, their concentrations often represent discrete snapshots in time, and capturing peak concentrations is expensive. Three t
Authors
S. Alex Covert, Aubrey R. Bunch, Charles G. Crawford, Gretchen P. Oelsner
Landscape drivers of dynamic change in water quality of US rivers
Water security is a top concern for social well-being and dramatic changes in the availability of freshwater have occurred as a result of human uses and landscape management. Elevated nutrient loading and perturbations to major ion composition have resulted from human activities and have degraded freshwater resources. This study addresses the emerging nature of stream water quality in the 21st ce
Authors
Edward G. Stets, Lori A. Sprague, Gretchen P. Oelsner, Henry M. Johnson, Jennifer C. Murphy, Karen R. Ryberg, Aldo V. Vecchia, Robert E. Zuellig, James A. Falcone, Melissa L. Riskin
Recent trends in nutrient and sediment loading to coastal areas of the conterminous U.S.: Insights and global context
Coastal areas in the U.S. and worldwide have experienced massive population and land use changes contributing to significant degradation of coastal ecosystems. Excess nutrient pollution causes coastal ecosystem degradation, and both regulatory and management efforts have targeted reducing nutrient and sediment loading to coastal rivers. Decadal trends in flow-normalized nutrient and sediment loads
Authors
Gretchen P. Oelsner, Edward G. Stets
Water-quality trends in the nation’s rivers and streams, 1972–2012—Data preparation, statistical methods, and trend results
Since passage of the Clean Water Act in 1972, Federal, State, and local governments have invested billions of dollars to reduce pollution entering rivers and streams. To understand the return on these investments and to effectively manage and protect the Nation’s water resources in the future, we need to know how and why water quality has been changing over time. As part of the National Water-Qual
Authors
Gretchen P. Oelsner, Lori A. Sprague, Jennifer C. Murphy, Robert E. Zuellig, Henry M. Johnson, Karen R. Ryberg, James A. Falcone, Edward G. Stets, Aldo V. Vecchia, Melissa L. Riskin, Laura A. De Cicco, Taylor J. Mills, William H. Farmer
Challenges with secondary use of multi-source water-quality data in the United States
Combining water-quality data from multiple sources can help counterbalance diminishing resources for stream monitoring in the United States and lead to important regional and national insights that would not otherwise be possible. Individual monitoring organizations understand their own data very well, but issues can arise when their data are combined with data from other organizations that have u
Authors
Lori A. Sprague, Gretchen P. Oelsner, Denise M. Argue
Groundwater hydrology and estimation of horizontal groundwater flux from the Rio Grande at selected locations in Albuquerque, New Mexico, 2009–10
The Albuquerque area of New Mexico has two principal sources of water: (1) groundwater from the Santa Fe Group aquifer system, and (2) surface water from the Rio Grande. From 1960 to 2002, pumping from the Santa Fe Group aquifer system caused groundwater levels to decline more than 120 feet while water-level declines along the Rio Grande in Albuquerque were generally less than 40 feet. These diffe
Authors
Dale R. Rankin, Gretchen P. Oelsner, Kurt J. McCoy, Goeff J.M. Moret, Jeffery A. Worthington, Kimberly M. Bandy-Baldwin
Summary of urban stormwater quality in Albuquerque, New Mexico, 2003-12
Urban stormwater in the Albuquerque metropolitan area was sampled by the U.S. Geological Survey in cooperation with the City of Albuquerque, the Albuquerque Metropolitan Arroyo Flood Control Authority, the New Mexico Department of Transportation, and the University of New Mexico. Stormwater was sampled from a network of monitoring stations from 2003 to 2012 by following regulatory requirements for
Authors
Erik F. Storms, Gretchen P. Oelsner, Evan A. Locke, Michael R. Stevens, Orlando C. Romero
Assessment of surface water chloride and conductivity trends in areas of unconventional oil and gas development — Why existing national data sets cannot tell us what we would like to know
Heightened concern regarding the potential effects of unconventional oil and gas development on regional water quality has emerged, but the few studies on this topic are limited in geographic scope. Here we evaluate the potential utility of national and publicly available water-quality data sets for addressing questions regarding unconventional oil and gas development. We used existing U.S. Geolog
Authors
Zachary H. Bowen, Gretchen P. Oelsner, Brian S. Cade, Tanya J. Gallegos, Aïda M. Farag, David N. Mott, Christopher J. Potter, Peter J. Cinotto, Melanie L. Clark, William M. Kappel, Timothy M. Kresse, Cynthia P. Melcher, Suzanne S. Paschke, David D. Susong, Brian A. Varela
By
Ecosystems Mission Area, Water Resources Mission Area, Energy Resources Program, Central Energy Resources Science Center, Colorado Water Science Center, Columbia Environmental Research Center, Fort Collins Science Center, Geology, Energy & Minerals Science Center, John Wesley Powell Center for Analysis and Synthesis, Lower Mississippi-Gulf Water Science Center, New Mexico Water Science Center, New York Water Science Center, Ohio-Kentucky-Indiana Water Science Center, Oklahoma-Texas Water Science Center, Utah Water Science Center, Wyoming-Montana Water Science Center
Water quality studied in areas of unconventional oil and gas development, including areas where hydraulic fracturing techniques are used, in the United States
Domestic oil and gas production and clean water are critical for economic growth, public health, and national security of the United States. As domestic oil and gas production increases in new areas and old fields are enhanced, there is increasing public concern about the effects of energy production on surface-water and groundwater quality. To a great extent, this concern arises from the improved
Authors
David D. Susong, Tanya J. Gallegos, Gretchen P. Oelsner
Contrasting water quality from paired domestic/public supply wells, central High Plains
Closely located domestic and public supply wells were sampled using identical sampling procedures to allow comparison of water quality associated with well type. Water samples from 15 pairs of wells with similar screened intervals completed in the central High Plains regional aquifer in parts of Kansas, Oklahoma, and Texas were analyzed for more than 200 water quality constituents. No statisticall
Authors
B. W. Bruce, G.P. Oelsner
Science and Products
Hydraulic Fracturing and Water Resources: An Assessment of the Potential Effects of Shale Gas Development on Water Resources in the United States
Shale gas is a key source of onshore domestic energy for the United States and production of this resource is increasing rapidly. Development and extraction of shale gas requires hydraulic fracturing, which entails horizontal drilling, perforation of steel casing and cement grout using explosive charges, and expansion of fractures using fluids under high pressure. Concern over potential environmen
Estimated seasonal nitrogen and phosphorus loads in selected streams of the conterminous United States, 1999 - 2020
Estimated seasonal total nitrogen and total phosphorus loads during 1999 through 2020 in selected streams of the conterminous United States and water-quality and stream flow data used to generate those estimates are presented in this dataset. Loads were generated as part of the Integrated Water-Availability Assessment (IWAA) Program of the U.S. Geological Survey (www.usgs.gov/mission-areas/water-r
Long-term water-quality trends for rivers and streams within the contiguous United States using Weighted Regressions on Time, Discharge, and Season (WRTDS)
The U.S. Geological Survey (USGS) Water Mission Area (WMA) is working to address a need to understand where the Nation is experiencing water shortages or surpluses relative to the demand for water need by delivering routine assessments of water supply and demand. It is also improving understanding of the natural and human factors affecting the balance between supply and demand. A key part of these
Water-quality and streamflow datasets used in Weighted Regressions on Time, Discharge, and Season (WRTDS) models to determine trends in the Nation’s rivers and streams, 1972-2017
In 1991, the U.S. Geological Survey (USGS) began a study of more than 50 major river basins across the Nation as part of the National Water-Quality Assessment (NAWQA) project. One of the major goals of the NAWQA project was to determine how river water quality has changed over time. To support that goal, long-term consistent and comparable monitoring has been conducted by the USGS on streams and r
Estimates of Road Salt Application across the Conterminous United States, 1992-2019 (ver. 2.0, August 2023)
Annual estimates of road salt application were developed for the conterminous United States for the calendar years 1992 through 2015. The final estimates (in pounds) were derived from several data sources, which include road density and proportion of developed land use, depth and spatial extent of long-term snowfall, and the production and distribution of salt sources by state. The extent is the c
Water-quality and streamflow datasets used in the Weighted Regressions on Time, Discharge, and Season (WRTDS) models to determine trends in the Nations rivers and streams, 1972-2012
In 1991, the U.S. Geological Survey (USGS) began a study of more than 50 major river basins across the Nation as part of the National Water-Quality Assessment (NAWQA) project of the National Water-Quality Program. One of the major goals of the NAWQA project is to determine how water-quality conditions change over time. To support that goal, long-term consistent and comparable monitoring has been c
Water-quality and streamflow datasets used in Seasonal Kendall trend tests for the Nations rivers and streams, 1972-2012
In 1991, the U.S. Geological Survey (USGS) began a study of more than 50 major river basins across the Nation as part of the National Water-Quality Assessment (NAWQA) project of the National Water-Quality Program. One of the major goals of the NAWQA project is to determine how water-quality conditions change over time. To support that goal, long-term consistent and comparable monitoring has been c
Simulated and measured water levels and estimated water-level changes in the Albuquerque area, central New Mexico, 1950-2012
The City of Albuquerque, the major population center in New Mexico, underwent a more than fivefold population increase between 1950 and 2010. Before 2009, groundwater was the primary source of the City of Albuquerque’s municipal water supply, but since that time, the city has diverted water through the San Juan-Chama Drinking Water Project to augment municipal water supplies. Consequently, there i
Integrated water resources trend assessments: State of the science, challenges, and opportunities for advancement
Water is vital to human life and healthy ecosystems. Here we outline the current state of national-scale water resources trend assessments, identify key gaps, and suggest advancements to better address critical issues related to changes in water resources that may threaten human development or the environment. Questions like, “Do we have less suitable drinking water now than we had 20 years ago?”
Authors
Sarah M. Stackpoole, Gretchen P. Oelsner, Edward G. Stets, Jory Seth Hecht, Zachary Johnson, Anthony J. Tesoriero, Michelle A. Walvoord, Jeffrey G. Chanat, Krista A. Dunne, Phillip J. Goodling, Bruce D. Lindsey, Michael Meador, Sarah Spaulding
Comparison of surrogate models to estimate pesticide concentrations at six U.S. Geological Survey National Water Quality Network sites during water years 2013–18
During water years 2013–18, the U.S. Geological Survey National Water-Quality Assessment Project sampled the National Water Quality Network for Rivers and Streams year-round and reported on 221 pesticides at 72 sites across the United States. Pesticides are difficult to measure, their concentrations often represent discrete snapshots in time, and capturing peak concentrations is expensive. Three t
Authors
S. Alex Covert, Aubrey R. Bunch, Charles G. Crawford, Gretchen P. Oelsner
Landscape drivers of dynamic change in water quality of US rivers
Water security is a top concern for social well-being and dramatic changes in the availability of freshwater have occurred as a result of human uses and landscape management. Elevated nutrient loading and perturbations to major ion composition have resulted from human activities and have degraded freshwater resources. This study addresses the emerging nature of stream water quality in the 21st ce
Authors
Edward G. Stets, Lori A. Sprague, Gretchen P. Oelsner, Henry M. Johnson, Jennifer C. Murphy, Karen R. Ryberg, Aldo V. Vecchia, Robert E. Zuellig, James A. Falcone, Melissa L. Riskin
Recent trends in nutrient and sediment loading to coastal areas of the conterminous U.S.: Insights and global context
Coastal areas in the U.S. and worldwide have experienced massive population and land use changes contributing to significant degradation of coastal ecosystems. Excess nutrient pollution causes coastal ecosystem degradation, and both regulatory and management efforts have targeted reducing nutrient and sediment loading to coastal rivers. Decadal trends in flow-normalized nutrient and sediment loads
Authors
Gretchen P. Oelsner, Edward G. Stets
Water-quality trends in the nation’s rivers and streams, 1972–2012—Data preparation, statistical methods, and trend results
Since passage of the Clean Water Act in 1972, Federal, State, and local governments have invested billions of dollars to reduce pollution entering rivers and streams. To understand the return on these investments and to effectively manage and protect the Nation’s water resources in the future, we need to know how and why water quality has been changing over time. As part of the National Water-Qual
Authors
Gretchen P. Oelsner, Lori A. Sprague, Jennifer C. Murphy, Robert E. Zuellig, Henry M. Johnson, Karen R. Ryberg, James A. Falcone, Edward G. Stets, Aldo V. Vecchia, Melissa L. Riskin, Laura A. De Cicco, Taylor J. Mills, William H. Farmer
Challenges with secondary use of multi-source water-quality data in the United States
Combining water-quality data from multiple sources can help counterbalance diminishing resources for stream monitoring in the United States and lead to important regional and national insights that would not otherwise be possible. Individual monitoring organizations understand their own data very well, but issues can arise when their data are combined with data from other organizations that have u
Authors
Lori A. Sprague, Gretchen P. Oelsner, Denise M. Argue
Groundwater hydrology and estimation of horizontal groundwater flux from the Rio Grande at selected locations in Albuquerque, New Mexico, 2009–10
The Albuquerque area of New Mexico has two principal sources of water: (1) groundwater from the Santa Fe Group aquifer system, and (2) surface water from the Rio Grande. From 1960 to 2002, pumping from the Santa Fe Group aquifer system caused groundwater levels to decline more than 120 feet while water-level declines along the Rio Grande in Albuquerque were generally less than 40 feet. These diffe
Authors
Dale R. Rankin, Gretchen P. Oelsner, Kurt J. McCoy, Goeff J.M. Moret, Jeffery A. Worthington, Kimberly M. Bandy-Baldwin
Summary of urban stormwater quality in Albuquerque, New Mexico, 2003-12
Urban stormwater in the Albuquerque metropolitan area was sampled by the U.S. Geological Survey in cooperation with the City of Albuquerque, the Albuquerque Metropolitan Arroyo Flood Control Authority, the New Mexico Department of Transportation, and the University of New Mexico. Stormwater was sampled from a network of monitoring stations from 2003 to 2012 by following regulatory requirements for
Authors
Erik F. Storms, Gretchen P. Oelsner, Evan A. Locke, Michael R. Stevens, Orlando C. Romero
Assessment of surface water chloride and conductivity trends in areas of unconventional oil and gas development — Why existing national data sets cannot tell us what we would like to know
Heightened concern regarding the potential effects of unconventional oil and gas development on regional water quality has emerged, but the few studies on this topic are limited in geographic scope. Here we evaluate the potential utility of national and publicly available water-quality data sets for addressing questions regarding unconventional oil and gas development. We used existing U.S. Geolog
Authors
Zachary H. Bowen, Gretchen P. Oelsner, Brian S. Cade, Tanya J. Gallegos, Aïda M. Farag, David N. Mott, Christopher J. Potter, Peter J. Cinotto, Melanie L. Clark, William M. Kappel, Timothy M. Kresse, Cynthia P. Melcher, Suzanne S. Paschke, David D. Susong, Brian A. Varela
By
Ecosystems Mission Area, Water Resources Mission Area, Energy Resources Program, Central Energy Resources Science Center, Colorado Water Science Center, Columbia Environmental Research Center, Fort Collins Science Center, Geology, Energy & Minerals Science Center, John Wesley Powell Center for Analysis and Synthesis, Lower Mississippi-Gulf Water Science Center, New Mexico Water Science Center, New York Water Science Center, Ohio-Kentucky-Indiana Water Science Center, Oklahoma-Texas Water Science Center, Utah Water Science Center, Wyoming-Montana Water Science Center
Water quality studied in areas of unconventional oil and gas development, including areas where hydraulic fracturing techniques are used, in the United States
Domestic oil and gas production and clean water are critical for economic growth, public health, and national security of the United States. As domestic oil and gas production increases in new areas and old fields are enhanced, there is increasing public concern about the effects of energy production on surface-water and groundwater quality. To a great extent, this concern arises from the improved
Authors
David D. Susong, Tanya J. Gallegos, Gretchen P. Oelsner
Contrasting water quality from paired domestic/public supply wells, central High Plains
Closely located domestic and public supply wells were sampled using identical sampling procedures to allow comparison of water quality associated with well type. Water samples from 15 pairs of wells with similar screened intervals completed in the central High Plains regional aquifer in parts of Kansas, Oklahoma, and Texas were analyzed for more than 200 water quality constituents. No statisticall
Authors
B. W. Bruce, G.P. Oelsner