Rachel G Gidley
Rachel is a Hydrologist with the USGS Colorado Water Science Center, Western Colorado Office, in Grand Junction, CO.
Rachel works on projects related to water quality in western Colorado, including selenium, salinity, and E. coli.
Education and Certifications
M.S. Environmental Science, University of Colorado Denver
B.S. Environmental Science, Indiana University
Science and Products
Concentrations of microbial source tracking markers in cattle fecal samples, western Colorado, 2023
The U.S. Geological Survey is investigating sources of fecal bacteria in streams in the Grand Valley of western Colorado by using quantitative polymerase chain reaction microbial source tracking (MST) markers. The CowM2 MST marker was not detected in water-quality samples collected in 2022, which raised questions about the use of the marker for investigations in western Colorado. The presence or a
Basin Characteristics and Salinity and Selenium Loads and Yields for Selected Subbasins in the Lower Gunnison River Basin, Western Colorado, 1992─2013
Mitigating the effects of salinity (total dissolved solids) and selenium on water quality in the lower Gunnison River Basin (LGRB) of western Colorado is a major concern for land managers. In cooperation with the Bureau of Reclamation, the U.S. Geological Survey completed a study to develop multiple linear regression models to estimate salinity and selenium loads. The objective of the study was to
Channel Characteristics, benthic algae, and water quality model data for selected sites in the upper White River Basin, Colorado, 2018-21
This U.S. Geological Survey (USGS) data release provides benthic algae and stream channel characteristics data collected from 20 water-quality sites in the Upper White River Basin, Colorado., during 2018-2021. Also included are input and output data from streamflow and water-quality regression models used to characterize streamflow and water-quality conditions at 3 sites in the Upper White River B
Analysis of Escherichia coli, total recoverable iron, and dissolved selenium concentrations and loads for selected 303(d) listed segments in the Grand Valley, western Colorado, 1991-2018 (ver. 3.0, August 2021)
The U.S. Geological Survey (USGS), in cooperation with the Grand Valley Drainage District and the Colorado Water Conservation Board, conducted a loading analysis for selected constituents and tributaries to the Colorado River in the Grand Valley, western Colorado, using data from 1991 to 2018, to characterize concentrations, stream loading, and load reductions for Escherichia coli, total recoverab
Salinity and selenium yield maps derived from geostatistical modeling in the lower Gunnison River Basin, western Colorado, 1992–2013
Salinity is known to affect drinking-water supplies and damage irrigated agricultural lands. Selenium in high concentrations is harmful to fish and other wildlife. Land managers, water providers, and agricultural producers in the lower Gunnison River Basin in western Colorado expend resources mitigating the effects of these constituents. The U.S. Geological Survey revised existing salinity (total
Authors
Cory A. Williams, Rachel G. Gidley, Michael R. Stevens
Potential factors controlling benthic algae in the upper White River Basin, Colorado, 2018–21
Nuisance levels of benthic algae are becoming increasingly common in surface waters of the western United States and can compromise aesthetic quality, limit recreational activities, block water infrastructure, and negatively affect aquatic life. In cooperation with the White River and Douglas Creek Conservation Districts, the Colorado River Basin Salinity Control Forum, and the Colorado River Wate
Authors
Rachel G. Gidley, Natalie K. Day
Analysis of Escherichia coli, total recoverable iron, and dissolved selenium concentrations, loading, and identifying data gaps for selected 303(d) listed streams, Grand Valley, western Colorado, 1980–2018
Tributaries to the Colorado River in the Grand Valley in western Colorado (segment COLCLC13b) have been placed on the State of Colorado 303(d) list as impaired for Escherichia coli (E. coli), total recoverable iron, and dissolved selenium. The Colorado Department of Public Health and Environment Water Quality Control Division is required to develop total maximum daily loads for these constituents
Authors
Lisa D. Miller, Rachel G. Gidley, Natalie K. Day, Judith C. Thomas
Science and Products
Concentrations of microbial source tracking markers in cattle fecal samples, western Colorado, 2023
The U.S. Geological Survey is investigating sources of fecal bacteria in streams in the Grand Valley of western Colorado by using quantitative polymerase chain reaction microbial source tracking (MST) markers. The CowM2 MST marker was not detected in water-quality samples collected in 2022, which raised questions about the use of the marker for investigations in western Colorado. The presence or a
Basin Characteristics and Salinity and Selenium Loads and Yields for Selected Subbasins in the Lower Gunnison River Basin, Western Colorado, 1992─2013
Mitigating the effects of salinity (total dissolved solids) and selenium on water quality in the lower Gunnison River Basin (LGRB) of western Colorado is a major concern for land managers. In cooperation with the Bureau of Reclamation, the U.S. Geological Survey completed a study to develop multiple linear regression models to estimate salinity and selenium loads. The objective of the study was to
Channel Characteristics, benthic algae, and water quality model data for selected sites in the upper White River Basin, Colorado, 2018-21
This U.S. Geological Survey (USGS) data release provides benthic algae and stream channel characteristics data collected from 20 water-quality sites in the Upper White River Basin, Colorado., during 2018-2021. Also included are input and output data from streamflow and water-quality regression models used to characterize streamflow and water-quality conditions at 3 sites in the Upper White River B
Analysis of Escherichia coli, total recoverable iron, and dissolved selenium concentrations and loads for selected 303(d) listed segments in the Grand Valley, western Colorado, 1991-2018 (ver. 3.0, August 2021)
The U.S. Geological Survey (USGS), in cooperation with the Grand Valley Drainage District and the Colorado Water Conservation Board, conducted a loading analysis for selected constituents and tributaries to the Colorado River in the Grand Valley, western Colorado, using data from 1991 to 2018, to characterize concentrations, stream loading, and load reductions for Escherichia coli, total recoverab
Salinity and selenium yield maps derived from geostatistical modeling in the lower Gunnison River Basin, western Colorado, 1992–2013
Salinity is known to affect drinking-water supplies and damage irrigated agricultural lands. Selenium in high concentrations is harmful to fish and other wildlife. Land managers, water providers, and agricultural producers in the lower Gunnison River Basin in western Colorado expend resources mitigating the effects of these constituents. The U.S. Geological Survey revised existing salinity (total
Authors
Cory A. Williams, Rachel G. Gidley, Michael R. Stevens
Potential factors controlling benthic algae in the upper White River Basin, Colorado, 2018–21
Nuisance levels of benthic algae are becoming increasingly common in surface waters of the western United States and can compromise aesthetic quality, limit recreational activities, block water infrastructure, and negatively affect aquatic life. In cooperation with the White River and Douglas Creek Conservation Districts, the Colorado River Basin Salinity Control Forum, and the Colorado River Wate
Authors
Rachel G. Gidley, Natalie K. Day
Analysis of Escherichia coli, total recoverable iron, and dissolved selenium concentrations, loading, and identifying data gaps for selected 303(d) listed streams, Grand Valley, western Colorado, 1980–2018
Tributaries to the Colorado River in the Grand Valley in western Colorado (segment COLCLC13b) have been placed on the State of Colorado 303(d) list as impaired for Escherichia coli (E. coli), total recoverable iron, and dissolved selenium. The Colorado Department of Public Health and Environment Water Quality Control Division is required to develop total maximum daily loads for these constituents
Authors
Lisa D. Miller, Rachel G. Gidley, Natalie K. Day, Judith C. Thomas