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Natalie K Day

Natalie is a Biologist with the Colorado Water Science Center (COWSC), Western Colorado Office, in Grand Junction, CO.

Natalie is a cross-disciplinary biologist working on the Colorado Plateau. She seeks to provide relevant information to land managers, policy makers, and the public. Some of her research interests include assessing the effects of land disturbance in drylands on regional hydrology, understanding controls on riverine algal blooms, and assessing long-term changes in streamflow and water quality. Natalie works to improve the sharing of information among different fields and conducts research that is collaborative and useful.

Professional Experience

  • Biologist, USGS-Colorado Water Science Center, Grand Junction, CO, Fall 2019-present

  • Biologist, USGS-Canyonland Research Station, Moab, UT, 2016-2019

  • Biological Field Technician, USGS-Canyonland Research Station, Moab, UT, 2010-2011

  • Research Assistant, Utah Water Research Lab/Utah State University Biogeochemistry Lab, Logan, UT, 2008-2010

Education and Certifications

  • Master of Science in Biogeochemistry, the University of Wyoming, Laramie, WY, 2015
    Focus: Nitrogen cycling in headwater streams in Rocky Mountain National Park, CO
    Advised by Robert O. Hall, Jr.

  • Bachelor of Arts in Biology, Lewis & Clark College, Portland, OR, 2008
    Focus: Aquatic biogeochemistry

Science and Products

Image: Endangered Humpback Chub

Assessment of Mercury and Selenium Accumulation in Upper Colorado River Basin Fish

More than 50 years of existing mercury and selenium concentrations in native and nonnative fish species residing in streams within the Upper Colorado River Basin were compiled and analyzed to provide an understanding of concentrations among different species, sampling years, and locations to determine potential health risks. Concentrations of mercury and selenium were above health benchmarks in 13...
By
Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology
Assessment of Mercury and Selenium Accumulation in Upper Colorado River Basin Fish

Assessment of Mercury and Selenium Accumulation in Upper Colorado River Basin Fish

More than 50 years of existing mercury and selenium concentrations in native and nonnative fish species residing in streams within the Upper Colorado River Basin were compiled and analyzed to provide an understanding of concentrations among different species, sampling years, and locations to determine potential health risks. Concentrations of mercury and selenium were above health benchmarks in 13...
Learn More
Image: Endangered Humpback Chub

Assessment of Mercury and Selenium Accumulation in Upper Colorado River Basin Fish

More than 50 years of existing mercury and selenium concentrations in native and nonnative fish species residing in streams within the Upper Colorado River Basin were compiled and analyzed to provide an understanding of concentrations among different species, sampling years, and locations to determine potential health risks. Concentrations of mercury and selenium were above health benchmarks in 13...
By
Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology
Assessment of Mercury and Selenium Accumulation in Upper Colorado River Basin Fish

Assessment of Mercury and Selenium Accumulation in Upper Colorado River Basin Fish

More than 50 years of existing mercury and selenium concentrations in native and nonnative fish species residing in streams within the Upper Colorado River Basin were compiled and analyzed to provide an understanding of concentrations among different species, sampling years, and locations to determine potential health risks. Concentrations of mercury and selenium were above health benchmarks in 13...
Learn More
Image: Endangered Humpback Chub

Assessment of Mercury and Selenium Accumulation in Upper Colorado River Basin Fish

More than 50 years of existing mercury and selenium concentrations in native and nonnative fish species residing in streams within the Upper Colorado River Basin were compiled and analyzed to provide an understanding of concentrations among different species, sampling years, and locations to determine potential health risks. Concentrations of mercury and selenium were above health benchmarks in 13...
By
Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology
Assessment of Mercury and Selenium Accumulation in Upper Colorado River Basin Fish

Assessment of Mercury and Selenium Accumulation in Upper Colorado River Basin Fish

More than 50 years of existing mercury and selenium concentrations in native and nonnative fish species residing in streams within the Upper Colorado River Basin were compiled and analyzed to provide an understanding of concentrations among different species, sampling years, and locations to determine potential health risks. Concentrations of mercury and selenium were above health benchmarks in 13...
Learn More
Image: Yampa River Basin, Colorado

Characterization of Streamflow, Suspended Sediment, and Nutrients in the Upper Yampa River Basin

The Upper Yampa River Basin (UYRB) drains approximately 1,800 square miles west of the Continental Divide in northwestern Colorado. In 2019, the USGS, in cooperation with local stakeholders in the UYRB water community, initiated a study to characterize streamflow, suspended sediment, and nutrients using historic and recently acquired water-quality data from a long-term monitoring program initiated...
By
Colorado Water Science Center
Characterization of Streamflow, Suspended Sediment, and Nutrients in the Upper Yampa River Basin

Characterization of Streamflow, Suspended Sediment, and Nutrients in the Upper Yampa River Basin

The Upper Yampa River Basin (UYRB) drains approximately 1,800 square miles west of the Continental Divide in northwestern Colorado. In 2019, the USGS, in cooperation with local stakeholders in the UYRB water community, initiated a study to characterize streamflow, suspended sediment, and nutrients using historic and recently acquired water-quality data from a long-term monitoring program initiated...
Learn More
Filter Total Items: 13

Turbidity model input and output data and associated imagery from May 2022 to November 2023 at Colorado River near Cameo, Colorado Turbidity model input and output data and associated imagery from May 2022 to November 2023 at Colorado River near Cameo, Colorado

Regression models were developed with reflectance values from remote-sensing imagery and concurrent turbidity measurements during a 2 year period at Colorado River near Cameo, Colorado streamgage (U.S. Geological Survey station number 09095500). Three types of remote sensing systems were tested including satellite- and ground-based sensors. Models relate the explanatory variables...
By
Colorado Water Science Center

Phytoplankton, algal toxin, and water-quality data for Blue Mesa Reservoir, Colorado, 1970–2023 Phytoplankton, algal toxin, and water-quality data for Blue Mesa Reservoir, Colorado, 1970–2023

Blue Mesa Reservoir (Blue Mesa) is the largest storage reservoir in Colorado and is used for water supply and recreation. The reservoir consists of three distinct basins which are, moving from east to west, Iola, Cebolla, and Sapinero. This data release includes a wide variety of data collected to understand conditions that contribute to algal blooms in Blue Mesa. Data include...
By
Colorado Water Science Center

Input and output data used to assess the effects of climate on the temporal variability in streamflow and total dissolved solids loads in the Upper Colorado River Basin, water years 1986-2021 Input and output data used to assess the effects of climate on the temporal variability in streamflow and total dissolved solids loads in the Upper Colorado River Basin, water years 1986-2021

This data release contains the input and output used to assess the potential effect of climate on streamflow and salinity (measured as total dissolved solids [TDS]) yields across the Upper Colorado River Basin from water years 1986 to 2021. This analysis included estimation of the spatiotemporal variability in mean annual climatic variables (air temperature, snow water equivalent...
By
Colorado Water Science Center

Analyte concentrations and stable isotopes in fish tissue collected across the upper Colorado River Basin in 2016 and 2017 Analyte concentrations and stable isotopes in fish tissue collected across the upper Colorado River Basin in 2016 and 2017

These data were compiled to examine analyte concentrations, including mercury and selenium, and stable isotopes in native and non-native fish across rivers in the Upper Colorado River Basin. Data were collected in 2016 and 2017. Tissue samples were collected as whole-body or muscle plugs (biopsies). Tissue samples were analyzed for stable isotopes in 772 samples, for selenium and 54...
By
Colorado Water Science Center

Long-term trends in annual, seasonal, and monthly streamflow metrics at streamgages in the Upper Colorado River Basin, 1981-2022 Long-term trends in annual, seasonal, and monthly streamflow metrics at streamgages in the Upper Colorado River Basin, 1981-2022

Identifying long-term trends in water availability, including surface water quantity, is a key part of the U.S. Geological Survey (USGS) Integrated Water Availability Assessments (IWAAs) mission. This data release includes input and output data used in Mann-Kendall trend analyses to characterize streamflow conditions at 124 USGS streamgages in the Upper Colorado River Basin for water...
By
Colorado Water Science Center

Benthic algae community composition data from the Colorado River Basin, Colorado, from 2022-23 Benthic algae community composition data from the Colorado River Basin, Colorado, from 2022-23

This dataset includes benthic algae community composition data in the Colorado River near Cameo, Colorado, U.S. Geological Survey (USGS) site number 09095500, from 2022 to 2023, and from three sites in the upper White River Basin, Colorado, in 2022. Taxonomic classification of algae species is not known well in theses rivers, and this study was conducted to record different algae species...
By
Colorado Water Science Center
Filter Total Items: 17

A comparison of non-contact methods for measuring turbidity in the Colorado River A comparison of non-contact methods for measuring turbidity in the Colorado River

Monitoring suspended-sediment concentration (SSC) is essential to better understand how sediment transport could adversely affect water availability for human communities and ecosystems. Aquatic remote sensing methods are increasingly utilized to estimate SSC and turbidity in rivers; however, an evaluation of their quantitative performance is limited. This study evaluates the performance...
Authors
Natalie K. Day, Tyler V. King, Adam R. Mosbrucker
By
Volcano Hazards Program, Volcano Science Center, Colorado Water Science Center, Idaho Water Science Center, Cascades Volcano Observatory

Environmental characterization of Blue Mesa Reservoir and potential causes of and management strategies for harmful algal blooms, 1970 through 2023, Curecanti National Recreation Area, Colorado Environmental characterization of Blue Mesa Reservoir and potential causes of and management strategies for harmful algal blooms, 1970 through 2023, Curecanti National Recreation Area, Colorado

Blue Mesa Reservoir, in the Curecanti National Recreation Area, is the largest storage reservoir in Colorado and consists of three distinct basins: Iola (the shallowest), Cebolla, and Sapinero. After algal toxins were first documented in Iola basin in 2018, the U.S. Geological Survey began a study in cooperation with the National Park Service, Colorado River Water Conservation District...
Authors
Katherine Walton-Day, Natalie K. Day, M. Alisa Mast, Rachel G. Gidley, Evan J. Gohring, Tyler V. King, Warren C. Day, Nicole D. Gibney, Nancy J. Bauch
By
Colorado Water Science Center

Effects of climate on temporal variability in streamflow and salinity in the Upper Colorado River Basin Effects of climate on temporal variability in streamflow and salinity in the Upper Colorado River Basin

Study RegionThe Upper Colorado River Basin, a critical water source for more than 40 million people in the western United States.Study FocusPotential decreasing streamflow and elevated salinity concentrations threaten this resource. Climate variability has a large and well-studied effect on streamflow in the basin; however, the effect on salinity loading is less understood. This study...
Authors
Natalie K. Day, Patrick C. Longley, Daniel Wise, Morgan C. McDonnell
By
Colorado Water Science Center

Remote sensing of chlorophyll a and temperature to support algal bloom monitoring in Blue Mesa Reservoir, Colorado Remote sensing of chlorophyll a and temperature to support algal bloom monitoring in Blue Mesa Reservoir, Colorado

We present methods to reconstruct historical chlorophyll a and surface water temperatures from satellite-based remote sensing products for Blue Mesa Reservoir, Colorado, to support algal bloom monitoring. A machine learning model was trained to construct chlorophyll a concentrations from Sentinel-2 satellite imagery and in situ measurements of chlorophyll a concentrations (out of bag...
Authors
Tyler V. King, Robert Allen Bean, Katherine Walton-Day, M. Alisa Mast, Evan J. Gohring, Rachel G. Gidley, Natalie K. Day, Nicole D. Gibney
By
Colorado Water Science Center, Idaho Water Science Center

Applying U.S. Geological Survey science to understand effects to water supply in the Upper Colorado River Basin Applying U.S. Geological Survey science to understand effects to water supply in the Upper Colorado River Basin

Introduction The Colorado River Basin is a vital source of water to more than 40 million people in the Western United States and Mexico, including in major cities like Denver, Las Vegas, Phoenix, Tucson, Los Angeles, and San Diego, and supports irrigation for about 16,000 square kilometers of agricultural land. Since 2000, the southwestern United States has been unusually dry due to low
Authors
Natalie K. Day, Cory A. Williams
By
Colorado Water Science Center

Salinity or sum of constituents— Methods comparison for computing dissolved solids concentrations in streams of the Upper Colorado River Basin Salinity or sum of constituents— Methods comparison for computing dissolved solids concentrations in streams of the Upper Colorado River Basin

The Colorado River is an important water source in the southwestern United States and northern Mexico. High concentrations of dissolved solids in the river, sourced mainly from the Upper Colorado River Basin (UCOL), cause hundreds of millions of dollars in damages annually to crops and infrastructure. Determinations of total dissolved solids (TDS) in river and tributary samples often...
Authors
Fred D. Tillman, Matthew P. Miller, Daniel Wise, R. Blaine McCleskey, Natalie K. Day
By
Water Resources Mission Area, Arizona Water Science Center

Non-USGS Publications**

Jech, S.D., Dohrenwend, K., Day, N., Barger, N.N., Antoninka, A., Bowker, M.A., Reed, S., and Tucker, C., 2025, Developing biocrust field cultivation techniques for soil restoration: An assessment of bacterial communities: Applied Soil Ecology, v. 206, article 10586, https://doi.org/10.1016/j.apsoil.2024.105861.
Antoninka, A., Rowe, H., Weser, J., Langenfeld, D., Brady, J., Sprague, T., Day, N., 2024. Comparing greenhouse and field biocrust cultivation methods in the Sonoran Desert. Ecological Solutions and Evidence.
Jech, S.D., Day, N., Barger, N.N., Antoninka, A., Bowker, M.A., Reed, S., Tucker, C., 2023. Cultivating Resilience in Dryland Soils: An Assisted Migration Approach to Biological Soil Crust Restoration. Microorganisms Special Issue New Horizons in Terrestrial Cyanobacteria: Advancing Fundamental Understanding of Physiology, Ecology and Genomics.
Tillman, Fred D, Natalie K. Day, Matthew P. Miller, Olivia L. Miller, Christine A. Rumsey, Daniel R. Wise, Patrick C. Longley, and Morgan C. McDonnell. 2022. "A Review of Current Capabilities and Science Gaps in Water Supply Data, Modeling, and Trends for Water Availability Assessments in the Upper Colorado River Basin" Water 14, no. 23: 3813. https://doi.org/10.3390/w14233813
Sutfin, N.A., Wohl, E., Fegel, T., Day, N., Lynch, L., 2021. Logjams and Channel Morphology Influence Sediment Storage, Transformation of Organic Matter, and Carbon Storage Within Mountain Stream Corridors. Water resources research. v. 57(5), https://doi.org/10.1029/2020WR028046
Fick, S.E., Day, N., Duniway, M.C., Hoy‐Skubik, S. and Barger, N.N., 2019. Microsite enhancements for soil stabilization and rapid biocrust colonization in degraded drylands. Restoration Ecology.
Tucker, C., Antoninka, A., Day, N., Poff, B. and Reed, S., 2020. Biological soil crust salvage for dryland restoration: an opportunity for natural resource restoration. Restoration Ecology.
Amendments fail to hasten biocrust recovery or soil stability at a disturbed dryland sandy site
Day, N.K., Hall Jr, R.O. 2017. Ammonium uptake kinetics and nitrification in mountain streams. Freshwater Science v. 36.1, p. 41-54.
Day, N.K., Likens, G.E., Judd, K.E., 2006. Nitrogen cycling in streams: A comparison of the roles of debris dams and mosses. Institute of Ecosystem Studies.

**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

Image: Endangered Humpback Chub

Assessment of Mercury and Selenium Accumulation in Upper Colorado River Basin Fish

More than 50 years of existing mercury and selenium concentrations in native and nonnative fish species residing in streams within the Upper Colorado River Basin were compiled and analyzed to provide an understanding of concentrations among different species, sampling years, and locations to determine potential health risks. Concentrations of mercury and selenium were above health benchmarks in 13...
By
Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology
Assessment of Mercury and Selenium Accumulation in Upper Colorado River Basin Fish

Assessment of Mercury and Selenium Accumulation in Upper Colorado River Basin Fish

More than 50 years of existing mercury and selenium concentrations in native and nonnative fish species residing in streams within the Upper Colorado River Basin were compiled and analyzed to provide an understanding of concentrations among different species, sampling years, and locations to determine potential health risks. Concentrations of mercury and selenium were above health benchmarks in 13...
Learn More
Image: Endangered Humpback Chub

Assessment of Mercury and Selenium Accumulation in Upper Colorado River Basin Fish

More than 50 years of existing mercury and selenium concentrations in native and nonnative fish species residing in streams within the Upper Colorado River Basin were compiled and analyzed to provide an understanding of concentrations among different species, sampling years, and locations to determine potential health risks. Concentrations of mercury and selenium were above health benchmarks in 13...
By
Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology
Assessment of Mercury and Selenium Accumulation in Upper Colorado River Basin Fish

Assessment of Mercury and Selenium Accumulation in Upper Colorado River Basin Fish

More than 50 years of existing mercury and selenium concentrations in native and nonnative fish species residing in streams within the Upper Colorado River Basin were compiled and analyzed to provide an understanding of concentrations among different species, sampling years, and locations to determine potential health risks. Concentrations of mercury and selenium were above health benchmarks in 13...
Learn More
Image: Endangered Humpback Chub

Assessment of Mercury and Selenium Accumulation in Upper Colorado River Basin Fish

More than 50 years of existing mercury and selenium concentrations in native and nonnative fish species residing in streams within the Upper Colorado River Basin were compiled and analyzed to provide an understanding of concentrations among different species, sampling years, and locations to determine potential health risks. Concentrations of mercury and selenium were above health benchmarks in 13...
By
Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology
Assessment of Mercury and Selenium Accumulation in Upper Colorado River Basin Fish

Assessment of Mercury and Selenium Accumulation in Upper Colorado River Basin Fish

More than 50 years of existing mercury and selenium concentrations in native and nonnative fish species residing in streams within the Upper Colorado River Basin were compiled and analyzed to provide an understanding of concentrations among different species, sampling years, and locations to determine potential health risks. Concentrations of mercury and selenium were above health benchmarks in 13...
Learn More
Image: Yampa River Basin, Colorado

Characterization of Streamflow, Suspended Sediment, and Nutrients in the Upper Yampa River Basin

The Upper Yampa River Basin (UYRB) drains approximately 1,800 square miles west of the Continental Divide in northwestern Colorado. In 2019, the USGS, in cooperation with local stakeholders in the UYRB water community, initiated a study to characterize streamflow, suspended sediment, and nutrients using historic and recently acquired water-quality data from a long-term monitoring program initiated...
By
Colorado Water Science Center
Characterization of Streamflow, Suspended Sediment, and Nutrients in the Upper Yampa River Basin

Characterization of Streamflow, Suspended Sediment, and Nutrients in the Upper Yampa River Basin

The Upper Yampa River Basin (UYRB) drains approximately 1,800 square miles west of the Continental Divide in northwestern Colorado. In 2019, the USGS, in cooperation with local stakeholders in the UYRB water community, initiated a study to characterize streamflow, suspended sediment, and nutrients using historic and recently acquired water-quality data from a long-term monitoring program initiated...
Learn More
Filter Total Items: 13

Turbidity model input and output data and associated imagery from May 2022 to November 2023 at Colorado River near Cameo, Colorado Turbidity model input and output data and associated imagery from May 2022 to November 2023 at Colorado River near Cameo, Colorado

Regression models were developed with reflectance values from remote-sensing imagery and concurrent turbidity measurements during a 2 year period at Colorado River near Cameo, Colorado streamgage (U.S. Geological Survey station number 09095500). Three types of remote sensing systems were tested including satellite- and ground-based sensors. Models relate the explanatory variables...
By
Colorado Water Science Center

Phytoplankton, algal toxin, and water-quality data for Blue Mesa Reservoir, Colorado, 1970–2023 Phytoplankton, algal toxin, and water-quality data for Blue Mesa Reservoir, Colorado, 1970–2023

Blue Mesa Reservoir (Blue Mesa) is the largest storage reservoir in Colorado and is used for water supply and recreation. The reservoir consists of three distinct basins which are, moving from east to west, Iola, Cebolla, and Sapinero. This data release includes a wide variety of data collected to understand conditions that contribute to algal blooms in Blue Mesa. Data include...
By
Colorado Water Science Center

Input and output data used to assess the effects of climate on the temporal variability in streamflow and total dissolved solids loads in the Upper Colorado River Basin, water years 1986-2021 Input and output data used to assess the effects of climate on the temporal variability in streamflow and total dissolved solids loads in the Upper Colorado River Basin, water years 1986-2021

This data release contains the input and output used to assess the potential effect of climate on streamflow and salinity (measured as total dissolved solids [TDS]) yields across the Upper Colorado River Basin from water years 1986 to 2021. This analysis included estimation of the spatiotemporal variability in mean annual climatic variables (air temperature, snow water equivalent...
By
Colorado Water Science Center

Analyte concentrations and stable isotopes in fish tissue collected across the upper Colorado River Basin in 2016 and 2017 Analyte concentrations and stable isotopes in fish tissue collected across the upper Colorado River Basin in 2016 and 2017

These data were compiled to examine analyte concentrations, including mercury and selenium, and stable isotopes in native and non-native fish across rivers in the Upper Colorado River Basin. Data were collected in 2016 and 2017. Tissue samples were collected as whole-body or muscle plugs (biopsies). Tissue samples were analyzed for stable isotopes in 772 samples, for selenium and 54...
By
Colorado Water Science Center

Long-term trends in annual, seasonal, and monthly streamflow metrics at streamgages in the Upper Colorado River Basin, 1981-2022 Long-term trends in annual, seasonal, and monthly streamflow metrics at streamgages in the Upper Colorado River Basin, 1981-2022

Identifying long-term trends in water availability, including surface water quantity, is a key part of the U.S. Geological Survey (USGS) Integrated Water Availability Assessments (IWAAs) mission. This data release includes input and output data used in Mann-Kendall trend analyses to characterize streamflow conditions at 124 USGS streamgages in the Upper Colorado River Basin for water...
By
Colorado Water Science Center

Benthic algae community composition data from the Colorado River Basin, Colorado, from 2022-23 Benthic algae community composition data from the Colorado River Basin, Colorado, from 2022-23

This dataset includes benthic algae community composition data in the Colorado River near Cameo, Colorado, U.S. Geological Survey (USGS) site number 09095500, from 2022 to 2023, and from three sites in the upper White River Basin, Colorado, in 2022. Taxonomic classification of algae species is not known well in theses rivers, and this study was conducted to record different algae species...
By
Colorado Water Science Center
Filter Total Items: 17

A comparison of non-contact methods for measuring turbidity in the Colorado River A comparison of non-contact methods for measuring turbidity in the Colorado River

Monitoring suspended-sediment concentration (SSC) is essential to better understand how sediment transport could adversely affect water availability for human communities and ecosystems. Aquatic remote sensing methods are increasingly utilized to estimate SSC and turbidity in rivers; however, an evaluation of their quantitative performance is limited. This study evaluates the performance...
Authors
Natalie K. Day, Tyler V. King, Adam R. Mosbrucker
By
Volcano Hazards Program, Volcano Science Center, Colorado Water Science Center, Idaho Water Science Center, Cascades Volcano Observatory

Environmental characterization of Blue Mesa Reservoir and potential causes of and management strategies for harmful algal blooms, 1970 through 2023, Curecanti National Recreation Area, Colorado Environmental characterization of Blue Mesa Reservoir and potential causes of and management strategies for harmful algal blooms, 1970 through 2023, Curecanti National Recreation Area, Colorado

Blue Mesa Reservoir, in the Curecanti National Recreation Area, is the largest storage reservoir in Colorado and consists of three distinct basins: Iola (the shallowest), Cebolla, and Sapinero. After algal toxins were first documented in Iola basin in 2018, the U.S. Geological Survey began a study in cooperation with the National Park Service, Colorado River Water Conservation District...
Authors
Katherine Walton-Day, Natalie K. Day, M. Alisa Mast, Rachel G. Gidley, Evan J. Gohring, Tyler V. King, Warren C. Day, Nicole D. Gibney, Nancy J. Bauch
By
Colorado Water Science Center

Effects of climate on temporal variability in streamflow and salinity in the Upper Colorado River Basin Effects of climate on temporal variability in streamflow and salinity in the Upper Colorado River Basin

Study RegionThe Upper Colorado River Basin, a critical water source for more than 40 million people in the western United States.Study FocusPotential decreasing streamflow and elevated salinity concentrations threaten this resource. Climate variability has a large and well-studied effect on streamflow in the basin; however, the effect on salinity loading is less understood. This study...
Authors
Natalie K. Day, Patrick C. Longley, Daniel Wise, Morgan C. McDonnell
By
Colorado Water Science Center

Remote sensing of chlorophyll a and temperature to support algal bloom monitoring in Blue Mesa Reservoir, Colorado Remote sensing of chlorophyll a and temperature to support algal bloom monitoring in Blue Mesa Reservoir, Colorado

We present methods to reconstruct historical chlorophyll a and surface water temperatures from satellite-based remote sensing products for Blue Mesa Reservoir, Colorado, to support algal bloom monitoring. A machine learning model was trained to construct chlorophyll a concentrations from Sentinel-2 satellite imagery and in situ measurements of chlorophyll a concentrations (out of bag...
Authors
Tyler V. King, Robert Allen Bean, Katherine Walton-Day, M. Alisa Mast, Evan J. Gohring, Rachel G. Gidley, Natalie K. Day, Nicole D. Gibney
By
Colorado Water Science Center, Idaho Water Science Center

Applying U.S. Geological Survey science to understand effects to water supply in the Upper Colorado River Basin Applying U.S. Geological Survey science to understand effects to water supply in the Upper Colorado River Basin

Introduction The Colorado River Basin is a vital source of water to more than 40 million people in the Western United States and Mexico, including in major cities like Denver, Las Vegas, Phoenix, Tucson, Los Angeles, and San Diego, and supports irrigation for about 16,000 square kilometers of agricultural land. Since 2000, the southwestern United States has been unusually dry due to low
Authors
Natalie K. Day, Cory A. Williams
By
Colorado Water Science Center

Salinity or sum of constituents— Methods comparison for computing dissolved solids concentrations in streams of the Upper Colorado River Basin Salinity or sum of constituents— Methods comparison for computing dissolved solids concentrations in streams of the Upper Colorado River Basin

The Colorado River is an important water source in the southwestern United States and northern Mexico. High concentrations of dissolved solids in the river, sourced mainly from the Upper Colorado River Basin (UCOL), cause hundreds of millions of dollars in damages annually to crops and infrastructure. Determinations of total dissolved solids (TDS) in river and tributary samples often...
Authors
Fred D. Tillman, Matthew P. Miller, Daniel Wise, R. Blaine McCleskey, Natalie K. Day
By
Water Resources Mission Area, Arizona Water Science Center

Non-USGS Publications**

Jech, S.D., Dohrenwend, K., Day, N., Barger, N.N., Antoninka, A., Bowker, M.A., Reed, S., and Tucker, C., 2025, Developing biocrust field cultivation techniques for soil restoration: An assessment of bacterial communities: Applied Soil Ecology, v. 206, article 10586, https://doi.org/10.1016/j.apsoil.2024.105861.
Antoninka, A., Rowe, H., Weser, J., Langenfeld, D., Brady, J., Sprague, T., Day, N., 2024. Comparing greenhouse and field biocrust cultivation methods in the Sonoran Desert. Ecological Solutions and Evidence.
Jech, S.D., Day, N., Barger, N.N., Antoninka, A., Bowker, M.A., Reed, S., Tucker, C., 2023. Cultivating Resilience in Dryland Soils: An Assisted Migration Approach to Biological Soil Crust Restoration. Microorganisms Special Issue New Horizons in Terrestrial Cyanobacteria: Advancing Fundamental Understanding of Physiology, Ecology and Genomics.
Tillman, Fred D, Natalie K. Day, Matthew P. Miller, Olivia L. Miller, Christine A. Rumsey, Daniel R. Wise, Patrick C. Longley, and Morgan C. McDonnell. 2022. "A Review of Current Capabilities and Science Gaps in Water Supply Data, Modeling, and Trends for Water Availability Assessments in the Upper Colorado River Basin" Water 14, no. 23: 3813. https://doi.org/10.3390/w14233813
Sutfin, N.A., Wohl, E., Fegel, T., Day, N., Lynch, L., 2021. Logjams and Channel Morphology Influence Sediment Storage, Transformation of Organic Matter, and Carbon Storage Within Mountain Stream Corridors. Water resources research. v. 57(5), https://doi.org/10.1029/2020WR028046
Fick, S.E., Day, N., Duniway, M.C., Hoy‐Skubik, S. and Barger, N.N., 2019. Microsite enhancements for soil stabilization and rapid biocrust colonization in degraded drylands. Restoration Ecology.
Tucker, C., Antoninka, A., Day, N., Poff, B. and Reed, S., 2020. Biological soil crust salvage for dryland restoration: an opportunity for natural resource restoration. Restoration Ecology.
Amendments fail to hasten biocrust recovery or soil stability at a disturbed dryland sandy site
Day, N.K., Hall Jr, R.O. 2017. Ammonium uptake kinetics and nitrification in mountain streams. Freshwater Science v. 36.1, p. 41-54.
Day, N.K., Likens, G.E., Judd, K.E., 2006. Nitrogen cycling in streams: A comparison of the roles of debris dams and mosses. Institute of Ecosystem Studies.

**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.

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