M. Alisa Mast
Alisa is an hydrologist for the Colorado Water Science Center
Science and Products
Filter Total Items: 72
Estimation of salt loads for the Dolores River in the Paradox Valley, Colorado, 1980–2015
Regression models that relate total dissolved solids (TDS) concentrations to specific conductance were used to estimate salt loads for two sites on the Dolores River in the Paradox Valley in western Colorado. The salt-load estimates will be used by the Bureau of Reclamation to evaluate salt loading to the river coming from the Paradox Valley and the effect of the Paradox Valley Unit (PVU), a proje
Authors
M. Alisa Mast
Climate-change signals in national atmospheric deposition program precipitation data
National Atmospheric Deposition Program (NADP)/National Trends Network precipitation type, snow-season duration, and annual timing of selected chemical wet-deposition maxima vary with latitude and longitude within a 35-year (1979–2013) data record for the contiguous United States and Alaska. From the NADP data collected within the region bounded by 35.6645°–48.782° north latitude and 124°–68° west
Authors
Gregory A. Wetherbee, M. Alisa Mast
Controls on selenium distribution and mobilization in an irrigated shallow groundwater system underlain by Mancos Shale, Uncompahgre River Basin, Colorado, USA
Elevated selenium (Se) concentrations in surface water and groundwater have become a concern in areas of the Western United States due to the deleterious effects of Se on aquatic ecosystems. Elevated Se concentrations are most prevalent in irrigated alluvial valleys underlain by Se-bearing marine shales where Se can be leached from geologic materials into the shallow groundwater and surface water
Authors
Taylor J. Mills, M. Alisa Mast, Judith C. Thomas, Gabrielle L. Keith
Spatiotemporal patterns of mercury accumulation in lake sediments of western North America
For the Western North America Mercury Synthesis, we compiled mercury records from 165 dated sediment cores from 138 natural lakes across western North America. Lake sediments are accepted as faithful recorders of historical mercury accumulation rates, and regional and sub-regional temporal and spatial trends were analyzed with descriptive and inferential statistics. Mercury accumulation rates in s
Authors
Paul Drevnick, Colin A. Cooke, Daniella Barraza, Jules M. Blais, Kenneth Coale, Brian F. Cumming, Chris Curtis, Biplob Das, William F. Donahue, Collin A. Eagles-Smith, Daniel R. Engstrom, William F. Fitzgerald, Chad V. Furl, John R. Gray, Roland I. Hall, Togwell A. Jackson, Kathleen R. Laird, W. Lyle Lockhart, Robie W. Macdonald, M. Alisa Mast, Callie Mathieu, Derek C.G. Muir, Peter Outridge, Scott Reinemann, Sarah E. Rothenberg, Ana Carolina Ruiz-Fernandex, V.L. St. Louis, Rhea Sanders, Hamed Sanei, Elliott Skierszkan, Peter C. Van Metre, Timothy Veverica, Johan A. Wiklund, Brent B. Wolfe
Water-quality response to a high-elevation wildfire in the Colorado Front Range
Water quality of the Big Thompson River in the Front Range of Colorado was studied for 2 years following a high‐elevation wildfire that started in October 2012 and burned 15% of the watershed. A combination of fixed‐interval sampling and continuous water‐quality monitors was used to examine the timing and magnitude of water‐quality changes caused by the wildfire. Prefire water quality was well cha
Authors
M. Alisa Mast, Sheila F. Murphy, David W. Clow, Colin A. Penn, Graham A. Sexstone
Isotopes in North American Rocky Mountain snowpack 1993–2014
We present ∼1300 new isotopic measurements (δ18O and δ2H) from a network of snowpack sites in the Rocky Mountains that have been sampled since 1993. The network includes 177 locations where depth-integrated snow samples are collected each spring near peak accumulation. At 57 of these locations snowpack samples were obtained for 10–21 years and their isotopic measurements provide unprecedented spat
Authors
Lesleigh Anderson, Max Berkelhammer, M. Alisa Mast
2013 Monitoring and tracking wet nitrogen deposition at Rocky Mountain National Park
In 2004, multiple agencies including the Colorado Department of Public Health and Environment (CDPHE), the National Park Service (NPS), and the U.S. Environmental Protection Agency (U.S. EPA) met to address the effects and trends of nitrogen deposition and related air quality issues at Rocky Mountain National Park (RMNP). These agencies signed a Memorandum of Understanding (MOU) to facilitate inte
Authors
Kristi Morris, M. Alisa Mast, David W. Clow, Gregory A. Wetherbee, Jill Baron, Curt Taipale, Tamara Blett, David A. Gay, Daniel Bowker
Links between N deposition and nitrate export from a high-elevation watershed in the Colorado Front Range
Long-term patterns of stream nitrate export and atmospheric N deposition were evaluated over three decades in Loch Vale, a high-elevation watershed in the Colorado Front Range. Stream nitrate concentrations increased in the early 1990s, peaked in the mid-2000s, and have since declined by over 40%, coincident with trends in nitrogen oxide emissions over the past decade. Similarities in the timing a
Authors
M. Alisa Mast, David W. Clow, Jill Baron, Gregory A. Wetherbee
Mobilization of selenium from the Mancos Shale and associated soils in the lower Uncompahgre River Basin, Colorado
This study investigates processes controlling mobilization of selenium in the lower part of the Uncompahgre River Basin in western Colorado. Selenium occurs naturally in the underlying Mancos Shale and is leached to groundwater and surface water by limited natural runoff, agricultural and domestic irrigation, and leakage from irrigation canals. Soil and sediment samples from the study area were te
Authors
M. Alisa Mast, Taylor J. Mills, Suzanne S. Paschke, Gabrielle Keith, Joshua I. Linard
Long-term soil monitoring at U.S. Geological Survey reference watersheds
Monitoring the environment by making repeated measurements through time is essential to evaluate and track the health of ecosystems (fig. 1). Long-term datasets produced by such monitoring are indispensable for evaluating the effectiveness of environmental legislation and for designing mitigation strategies to address environmental changes in an era when human activities are altering the environme
Authors
Michael R. McHale, Jason Siemion, Gregory B. Lawrence, M. Alisa Mast
Evaluation of stream chemistry trends in US Geological Survey reference watersheds, 1970-2010
The Hydrologic Benchmark Network (HBN) is a long-term monitoring program established by the US Geological Survey in the 1960s to track changes in the streamflow and stream chemistry in undeveloped watersheds across the USA. Trends in stream chemistry were tested at 15 HBN stations over two periods (1970–2010 and 1990–2010) using the parametric Load Estimator (LOADEST) model and the nonparametric s
Authors
M. Alisa Mast
Effect of power plant emission reductions on a nearby wilderness area: a case study in northwestern Colorado
This study evaluates the effect of emission reductions at two coal-fired power plants in northwestern Colorado on a nearby wilderness area. Control equipment was installed at both plants during 1999–2004 to reduce SO2 and NOx emissions. One challenge was separating the effects of local from regional emissions, which also declined during the study period. The long-term datasets examined confirm tha
Authors
M. Alisa Mast, Daniel Ely
Science and Products
Filter Total Items: 72
Estimation of salt loads for the Dolores River in the Paradox Valley, Colorado, 1980–2015
Regression models that relate total dissolved solids (TDS) concentrations to specific conductance were used to estimate salt loads for two sites on the Dolores River in the Paradox Valley in western Colorado. The salt-load estimates will be used by the Bureau of Reclamation to evaluate salt loading to the river coming from the Paradox Valley and the effect of the Paradox Valley Unit (PVU), a proje
Authors
M. Alisa Mast
Climate-change signals in national atmospheric deposition program precipitation data
National Atmospheric Deposition Program (NADP)/National Trends Network precipitation type, snow-season duration, and annual timing of selected chemical wet-deposition maxima vary with latitude and longitude within a 35-year (1979–2013) data record for the contiguous United States and Alaska. From the NADP data collected within the region bounded by 35.6645°–48.782° north latitude and 124°–68° west
Authors
Gregory A. Wetherbee, M. Alisa Mast
Controls on selenium distribution and mobilization in an irrigated shallow groundwater system underlain by Mancos Shale, Uncompahgre River Basin, Colorado, USA
Elevated selenium (Se) concentrations in surface water and groundwater have become a concern in areas of the Western United States due to the deleterious effects of Se on aquatic ecosystems. Elevated Se concentrations are most prevalent in irrigated alluvial valleys underlain by Se-bearing marine shales where Se can be leached from geologic materials into the shallow groundwater and surface water
Authors
Taylor J. Mills, M. Alisa Mast, Judith C. Thomas, Gabrielle L. Keith
Spatiotemporal patterns of mercury accumulation in lake sediments of western North America
For the Western North America Mercury Synthesis, we compiled mercury records from 165 dated sediment cores from 138 natural lakes across western North America. Lake sediments are accepted as faithful recorders of historical mercury accumulation rates, and regional and sub-regional temporal and spatial trends were analyzed with descriptive and inferential statistics. Mercury accumulation rates in s
Authors
Paul Drevnick, Colin A. Cooke, Daniella Barraza, Jules M. Blais, Kenneth Coale, Brian F. Cumming, Chris Curtis, Biplob Das, William F. Donahue, Collin A. Eagles-Smith, Daniel R. Engstrom, William F. Fitzgerald, Chad V. Furl, John R. Gray, Roland I. Hall, Togwell A. Jackson, Kathleen R. Laird, W. Lyle Lockhart, Robie W. Macdonald, M. Alisa Mast, Callie Mathieu, Derek C.G. Muir, Peter Outridge, Scott Reinemann, Sarah E. Rothenberg, Ana Carolina Ruiz-Fernandex, V.L. St. Louis, Rhea Sanders, Hamed Sanei, Elliott Skierszkan, Peter C. Van Metre, Timothy Veverica, Johan A. Wiklund, Brent B. Wolfe
Water-quality response to a high-elevation wildfire in the Colorado Front Range
Water quality of the Big Thompson River in the Front Range of Colorado was studied for 2 years following a high‐elevation wildfire that started in October 2012 and burned 15% of the watershed. A combination of fixed‐interval sampling and continuous water‐quality monitors was used to examine the timing and magnitude of water‐quality changes caused by the wildfire. Prefire water quality was well cha
Authors
M. Alisa Mast, Sheila F. Murphy, David W. Clow, Colin A. Penn, Graham A. Sexstone
Isotopes in North American Rocky Mountain snowpack 1993–2014
We present ∼1300 new isotopic measurements (δ18O and δ2H) from a network of snowpack sites in the Rocky Mountains that have been sampled since 1993. The network includes 177 locations where depth-integrated snow samples are collected each spring near peak accumulation. At 57 of these locations snowpack samples were obtained for 10–21 years and their isotopic measurements provide unprecedented spat
Authors
Lesleigh Anderson, Max Berkelhammer, M. Alisa Mast
2013 Monitoring and tracking wet nitrogen deposition at Rocky Mountain National Park
In 2004, multiple agencies including the Colorado Department of Public Health and Environment (CDPHE), the National Park Service (NPS), and the U.S. Environmental Protection Agency (U.S. EPA) met to address the effects and trends of nitrogen deposition and related air quality issues at Rocky Mountain National Park (RMNP). These agencies signed a Memorandum of Understanding (MOU) to facilitate inte
Authors
Kristi Morris, M. Alisa Mast, David W. Clow, Gregory A. Wetherbee, Jill Baron, Curt Taipale, Tamara Blett, David A. Gay, Daniel Bowker
Links between N deposition and nitrate export from a high-elevation watershed in the Colorado Front Range
Long-term patterns of stream nitrate export and atmospheric N deposition were evaluated over three decades in Loch Vale, a high-elevation watershed in the Colorado Front Range. Stream nitrate concentrations increased in the early 1990s, peaked in the mid-2000s, and have since declined by over 40%, coincident with trends in nitrogen oxide emissions over the past decade. Similarities in the timing a
Authors
M. Alisa Mast, David W. Clow, Jill Baron, Gregory A. Wetherbee
Mobilization of selenium from the Mancos Shale and associated soils in the lower Uncompahgre River Basin, Colorado
This study investigates processes controlling mobilization of selenium in the lower part of the Uncompahgre River Basin in western Colorado. Selenium occurs naturally in the underlying Mancos Shale and is leached to groundwater and surface water by limited natural runoff, agricultural and domestic irrigation, and leakage from irrigation canals. Soil and sediment samples from the study area were te
Authors
M. Alisa Mast, Taylor J. Mills, Suzanne S. Paschke, Gabrielle Keith, Joshua I. Linard
Long-term soil monitoring at U.S. Geological Survey reference watersheds
Monitoring the environment by making repeated measurements through time is essential to evaluate and track the health of ecosystems (fig. 1). Long-term datasets produced by such monitoring are indispensable for evaluating the effectiveness of environmental legislation and for designing mitigation strategies to address environmental changes in an era when human activities are altering the environme
Authors
Michael R. McHale, Jason Siemion, Gregory B. Lawrence, M. Alisa Mast
Evaluation of stream chemistry trends in US Geological Survey reference watersheds, 1970-2010
The Hydrologic Benchmark Network (HBN) is a long-term monitoring program established by the US Geological Survey in the 1960s to track changes in the streamflow and stream chemistry in undeveloped watersheds across the USA. Trends in stream chemistry were tested at 15 HBN stations over two periods (1970–2010 and 1990–2010) using the parametric Load Estimator (LOADEST) model and the nonparametric s
Authors
M. Alisa Mast
Effect of power plant emission reductions on a nearby wilderness area: a case study in northwestern Colorado
This study evaluates the effect of emission reductions at two coal-fired power plants in northwestern Colorado on a nearby wilderness area. Control equipment was installed at both plants during 1999–2004 to reduce SO2 and NOx emissions. One challenge was separating the effects of local from regional emissions, which also declined during the study period. The long-term datasets examined confirm tha
Authors
M. Alisa Mast, Daniel Ely