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The Upper Colorado River Basin (UCRB) provides drinking water for 40 million people in the United States and Mexico. USGS research in the UCRB examines the key potential factors affecting water supply in the upper portion of the basin—snow processes and water storage, wildfire and basin hydrology, and salinity concentrations and water quality.
The Colorado River and its tributaries supply drinking water for 40 million people in the U.S. and Mexico, irrigation water for 5.5 million acres of land, and are essential sources of water for at least 29 federally recognized tribes, 7 National Wildlife Refuges, 4 National Recreation Areas, and 11 National Parks. The Colorado River Compact of 1922 divided the Colorado River into upper and lower basins at Lees Ferry, Arizona. The Compact divides water in the Colorado River equally between the upper and lower basin states, with each basin receiving 7.5 million acre-feet (maf) per year. An additional 1.5 maf per year of Colorado River water is guaranteed to Mexico, per a 1944 treaty.
The water in the Colorado River was apportioned based on hydrologic data that are now known to have been collected during an unusually wet period in the upper basin. Present day normal flow conditions may not produce sufficient water for all apportioned uses. Extended drought and patterns of aridification in the basin may have a profound effect on resulting streamflow and resulting reservoir storage in the UCRB. These issues are likely to create challenges for water managers to deliver on compact and treaty agreements. The IWS work will provide basin stakeholders and managers with an improved understanding of past, current, and future water supply that is needed to determine if there will be enough water of suitable quality to meet a multitude of human and ecosystem demands.
The primary sources of water in the UCRB are the annual winter snowpack in the mountains and the resulting spring snowmelt that flows down through tributaries of the Colorado River. High-altitude areas are cold enough to receive most of their precipitation as winter snow that accumulates as a seasonal snowpack. These areas produce a large portion of the runoff to streams in the basin: about 15 percent of the basin area contributes about 85 percent of the mean-annual runoff. Changes in weather patterns are affecting the amount of snow accumulation, the timing of snow melt, and the relative contribution of precipitation that falls as rain versus snow.
The effect of salinity, or dissolved solids, on water availability for human and ecosystem use is also a major concern in the Colorado River Basin in both the United States and Mexico, with quantified damages estimated to be about \$447 million per year at 2023 salinity concentrations. These economic damages are mostly from corrosion and reduced agricultural yields. The Colorado River is naturally saline because of the underlying geology and arid climate, although both natural and human sources contribute to the river's salinity levels. Recent work suggests that groundwater is a critical resource for sustaining streamflow as well as a source of salinity.
Because groundwater and surface water are a single, interconnected resource, future management practices that collectively manage groundwater and surface water may be required to maximize available water in the basin. Changes in water supply and demand in the basin, including a 20-plus year ongoing drought, are expected to continue in the future, and projecting the effects of these changes on water availability will help inform future water planning efforts to meet human and ecosystem needs.
With so many people relying on water from the Colorado River, studying the UCRB is important for a variety of reasons--and no issue affects UCRB communities more than better defining snowmelt runoff. Snow accumulation is the primary source of water availability in the Colorado River basin, driving streamflow, salinity transport and storage, and stream temperature.
USGS scientists aim to improve our understanding of how snow accumulation and melt processes contribute to surface and groundwater availability (quantity and dissolved solids) for human and ecological use as environmental conditions change.
Regional Water Availability Assessments are scientific assessments of water availability in different hydrologic regions across the Nation. In the UCRB, the USGS is conducting a focused study of how snowpack and snowmelt influence hydrology and water quality as part of an integrated and comprehensive evaluation of multiple water quantity, quality, and use factors.
Regional Water Availability Assessments evaluate water quantity and quality in both surface and groundwater, determine whether there is enough water for human and ecosystem needs, and investigate how human and natural influences affect the amount of available water. Specifically, the Regional Water Availability Assessment research scientists in the UCRB are addressing questions such as:
The NGWOS provides high-fidelity, real-time data on water quantity, quality, and use to support modern prediction and decision support systems that are necessary for informing water operations on a daily basis and decision-making during water emergencies.To better address how snowmelt affects the UCRB flow regime, NGWOS has expanded monitoring of snow, water temperature, streamflow, groundwater, and water quality in the Colorado River Headwaters & Gunnison River subbasins. These subbasins provide an opportunity to implement NGWOS in a snowmelt-dominated system in the mountain west.
Below are other projects associated with the Upper Colorado River IWS Basin
This recorded webinar details the significance and finding of the National Water Availability Assessment Release. This new assessment is the first of its kind, offering new insights on where there is a potential imbalance between water supply and demand in the United States. The assessment uses state-of-the-art models to fill in gaps between monitoring sites and sampling events and integrates...
Map of the Upper Colorado River Basin —referred to as an Integrated Water Science (IWS) basins—are intensively monitored study basins representing a wide range of environmental, hydrologic, and landscape settings and human stressors of water resources to improve our understanding of water availability across the Nation.
Map of the Upper Colorado River Basin —referred to as an Integrated Water Science (IWS) basins—are intensively monitored study basins representing a wide range of environmental, hydrologic, and landscape settings and human stressors of water resources to improve our understanding of water availability across the Nation.
Map of the NGWOS Upper Colorado River Basin study area and the focus study watersheds for studies of groundwater/surface-water connections.
Map of the NGWOS Upper Colorado River Basin study area and the focus study watersheds for studies of groundwater/surface-water connections.
Webcam at USGS Streamgage 393259107194801 Colorado River above Roaring Fork River at Glenwood Springs, CO.
Webcam at USGS Streamgage 393259107194801 Colorado River above Roaring Fork River at Glenwood Springs, CO.
Selected reference basins (darker shaded basins)—referred to as Integrated Water Science (IWS) basins—are intensively monitored study basins representing a wide range of environmental, hydrologic, and landscape settings and human stressors of water resources to improve our understanding of water availability across the Nation.
Selected reference basins (darker shaded basins)—referred to as Integrated Water Science (IWS) basins—are intensively monitored study basins representing a wide range of environmental, hydrologic, and landscape settings and human stressors of water resources to improve our understanding of water availability across the Nation.
Map showing the major tritium-monitoring sites in the NGWOS study area of the Upper Colorado River Basin where Water Isotope Network samples of precipitation and streamflow are collected, as well as sites where snowpack samples are collected for comparison to total precipitation.
Map showing the major tritium-monitoring sites in the NGWOS study area of the Upper Colorado River Basin where Water Isotope Network samples of precipitation and streamflow are collected, as well as sites where snowpack samples are collected for comparison to total precipitation.
Illustration of Colorado River Basin, showing upper and lower basins with a red text box around the Colorado River in Grand Canyon. Reduced-size map of the Colorado River Basin from the USGS ASIST Initiative, Sept. 3, 2024.
Illustration of Colorado River Basin, showing upper and lower basins with a red text box around the Colorado River in Grand Canyon. Reduced-size map of the Colorado River Basin from the USGS ASIST Initiative, Sept. 3, 2024.
March-August daily average streamflow for the last 30 years (1991-2022) (dark gray lines) compared to 2023, showing the periods where 2023 streamflow was above (blue) and below (orange) the historical average. Individual years of the relevant historical streamflow period are shown in light gray.
March-August daily average streamflow for the last 30 years (1991-2022) (dark gray lines) compared to 2023, showing the periods where 2023 streamflow was above (blue) and below (orange) the historical average. Individual years of the relevant historical streamflow period are shown in light gray.
Conceptual illustration showing how USGS's Next Generation Water Observing System will enhance the spatial and temporal monitoring of water within reference basins and larger hydrologic regions in all U.S. states and territories.
Conceptual illustration showing how USGS's Next Generation Water Observing System will enhance the spatial and temporal monitoring of water within reference basins and larger hydrologic regions in all U.S. states and territories.
A time series of streamflow drought events occurring across 122 stream gages in the Upper Colorado River basin from 1980 to present. Periods of streamflow drought are indicated for each of 122 gages in a beeswarm-like chart, with time on the x-axis. During time periods where many gages experienced drought, the swarm bulges due to many co-occurring events.
A time series of streamflow drought events occurring across 122 stream gages in the Upper Colorado River basin from 1980 to present. Periods of streamflow drought are indicated for each of 122 gages in a beeswarm-like chart, with time on the x-axis. During time periods where many gages experienced drought, the swarm bulges due to many co-occurring events.
A map showing the locations of the Upper and Lower Colorado river basins in the contiguous U.S. and all 1,865 NWIS sites used to calculate total flow.
A map showing the locations of the Upper and Lower Colorado river basins in the contiguous U.S. and all 1,865 NWIS sites used to calculate total flow.
An ecological site group map for the Upper Colorado River Basin that displays a quantitative soil-geomorphic framework in the Four Corners region, USA.
An ecological site group map for the Upper Colorado River Basin that displays a quantitative soil-geomorphic framework in the Four Corners region, USA.
Webcam at USGS Streamgage 09095500 Colorado River near Cameo, CO.
Visit Water Data For the Nation to get current data for this site.
Webcam at USGS Streamgage 09095500 Colorado River near Cameo, CO.
Visit Water Data For the Nation to get current data for this site.
Webcam at USGS Streamgage 09071750 Colorado River above Glenwood Springs, CO.
Visit Water Data For the Nation to get current data for this site.
Webcam at USGS Streamgage 09071750 Colorado River above Glenwood Springs, CO.
Visit Water Data For the Nation to get current data for this site.
The USGS National Integrated Water Availability Assessments (IWAAs) concept map shows daily estimates of natural water storage (water present on the landscape such as standing water, snowpack, soil water, and shallow groundwater) for approximately 110,00
The USGS National Integrated Water Availability Assessments (IWAAs) concept map shows daily estimates of natural water storage (water present on the landscape such as standing water, snowpack, soil water, and shallow groundwater) for approximately 110,00
This is a PDF of an in-house Power Point presentation to other Utah Water Science Center employees to invite discussion and input.
This is a PDF of an in-house Power Point presentation to other Utah Water Science Center employees to invite discussion and input.
Next Generation Water Observing System Upper Colorado & Gunnison River Basin briefing sheet.
Next Generation Water Observing System Upper Colorado & Gunnison River Basin briefing sheet.
Below are news releases and announcements associated with the Upper Colorado River Integrated Water Science Basin.
The Upper Colorado River Basin (UCRB) provides drinking water for 40 million people in the United States and Mexico. USGS research in the UCRB examines the key potential factors affecting water supply in the upper portion of the basin—snow processes and water storage, wildfire and basin hydrology, and salinity concentrations and water quality.
The Colorado River and its tributaries supply drinking water for 40 million people in the U.S. and Mexico, irrigation water for 5.5 million acres of land, and are essential sources of water for at least 29 federally recognized tribes, 7 National Wildlife Refuges, 4 National Recreation Areas, and 11 National Parks. The Colorado River Compact of 1922 divided the Colorado River into upper and lower basins at Lees Ferry, Arizona. The Compact divides water in the Colorado River equally between the upper and lower basin states, with each basin receiving 7.5 million acre-feet (maf) per year. An additional 1.5 maf per year of Colorado River water is guaranteed to Mexico, per a 1944 treaty.
The water in the Colorado River was apportioned based on hydrologic data that are now known to have been collected during an unusually wet period in the upper basin. Present day normal flow conditions may not produce sufficient water for all apportioned uses. Extended drought and patterns of aridification in the basin may have a profound effect on resulting streamflow and resulting reservoir storage in the UCRB. These issues are likely to create challenges for water managers to deliver on compact and treaty agreements. The IWS work will provide basin stakeholders and managers with an improved understanding of past, current, and future water supply that is needed to determine if there will be enough water of suitable quality to meet a multitude of human and ecosystem demands.
The primary sources of water in the UCRB are the annual winter snowpack in the mountains and the resulting spring snowmelt that flows down through tributaries of the Colorado River. High-altitude areas are cold enough to receive most of their precipitation as winter snow that accumulates as a seasonal snowpack. These areas produce a large portion of the runoff to streams in the basin: about 15 percent of the basin area contributes about 85 percent of the mean-annual runoff. Changes in weather patterns are affecting the amount of snow accumulation, the timing of snow melt, and the relative contribution of precipitation that falls as rain versus snow.
The effect of salinity, or dissolved solids, on water availability for human and ecosystem use is also a major concern in the Colorado River Basin in both the United States and Mexico, with quantified damages estimated to be about \$447 million per year at 2023 salinity concentrations. These economic damages are mostly from corrosion and reduced agricultural yields. The Colorado River is naturally saline because of the underlying geology and arid climate, although both natural and human sources contribute to the river's salinity levels. Recent work suggests that groundwater is a critical resource for sustaining streamflow as well as a source of salinity.
Because groundwater and surface water are a single, interconnected resource, future management practices that collectively manage groundwater and surface water may be required to maximize available water in the basin. Changes in water supply and demand in the basin, including a 20-plus year ongoing drought, are expected to continue in the future, and projecting the effects of these changes on water availability will help inform future water planning efforts to meet human and ecosystem needs.
With so many people relying on water from the Colorado River, studying the UCRB is important for a variety of reasons--and no issue affects UCRB communities more than better defining snowmelt runoff. Snow accumulation is the primary source of water availability in the Colorado River basin, driving streamflow, salinity transport and storage, and stream temperature.
USGS scientists aim to improve our understanding of how snow accumulation and melt processes contribute to surface and groundwater availability (quantity and dissolved solids) for human and ecological use as environmental conditions change.
Regional Water Availability Assessments are scientific assessments of water availability in different hydrologic regions across the Nation. In the UCRB, the USGS is conducting a focused study of how snowpack and snowmelt influence hydrology and water quality as part of an integrated and comprehensive evaluation of multiple water quantity, quality, and use factors.
Regional Water Availability Assessments evaluate water quantity and quality in both surface and groundwater, determine whether there is enough water for human and ecosystem needs, and investigate how human and natural influences affect the amount of available water. Specifically, the Regional Water Availability Assessment research scientists in the UCRB are addressing questions such as:
The NGWOS provides high-fidelity, real-time data on water quantity, quality, and use to support modern prediction and decision support systems that are necessary for informing water operations on a daily basis and decision-making during water emergencies.To better address how snowmelt affects the UCRB flow regime, NGWOS has expanded monitoring of snow, water temperature, streamflow, groundwater, and water quality in the Colorado River Headwaters & Gunnison River subbasins. These subbasins provide an opportunity to implement NGWOS in a snowmelt-dominated system in the mountain west.
Below are other projects associated with the Upper Colorado River IWS Basin
This recorded webinar details the significance and finding of the National Water Availability Assessment Release. This new assessment is the first of its kind, offering new insights on where there is a potential imbalance between water supply and demand in the United States. The assessment uses state-of-the-art models to fill in gaps between monitoring sites and sampling events and integrates...
Map of the Upper Colorado River Basin —referred to as an Integrated Water Science (IWS) basins—are intensively monitored study basins representing a wide range of environmental, hydrologic, and landscape settings and human stressors of water resources to improve our understanding of water availability across the Nation.
Map of the Upper Colorado River Basin —referred to as an Integrated Water Science (IWS) basins—are intensively monitored study basins representing a wide range of environmental, hydrologic, and landscape settings and human stressors of water resources to improve our understanding of water availability across the Nation.
Map of the NGWOS Upper Colorado River Basin study area and the focus study watersheds for studies of groundwater/surface-water connections.
Map of the NGWOS Upper Colorado River Basin study area and the focus study watersheds for studies of groundwater/surface-water connections.
Webcam at USGS Streamgage 393259107194801 Colorado River above Roaring Fork River at Glenwood Springs, CO.
Webcam at USGS Streamgage 393259107194801 Colorado River above Roaring Fork River at Glenwood Springs, CO.
Selected reference basins (darker shaded basins)—referred to as Integrated Water Science (IWS) basins—are intensively monitored study basins representing a wide range of environmental, hydrologic, and landscape settings and human stressors of water resources to improve our understanding of water availability across the Nation.
Selected reference basins (darker shaded basins)—referred to as Integrated Water Science (IWS) basins—are intensively monitored study basins representing a wide range of environmental, hydrologic, and landscape settings and human stressors of water resources to improve our understanding of water availability across the Nation.
Map showing the major tritium-monitoring sites in the NGWOS study area of the Upper Colorado River Basin where Water Isotope Network samples of precipitation and streamflow are collected, as well as sites where snowpack samples are collected for comparison to total precipitation.
Map showing the major tritium-monitoring sites in the NGWOS study area of the Upper Colorado River Basin where Water Isotope Network samples of precipitation and streamflow are collected, as well as sites where snowpack samples are collected for comparison to total precipitation.
Illustration of Colorado River Basin, showing upper and lower basins with a red text box around the Colorado River in Grand Canyon. Reduced-size map of the Colorado River Basin from the USGS ASIST Initiative, Sept. 3, 2024.
Illustration of Colorado River Basin, showing upper and lower basins with a red text box around the Colorado River in Grand Canyon. Reduced-size map of the Colorado River Basin from the USGS ASIST Initiative, Sept. 3, 2024.
March-August daily average streamflow for the last 30 years (1991-2022) (dark gray lines) compared to 2023, showing the periods where 2023 streamflow was above (blue) and below (orange) the historical average. Individual years of the relevant historical streamflow period are shown in light gray.
March-August daily average streamflow for the last 30 years (1991-2022) (dark gray lines) compared to 2023, showing the periods where 2023 streamflow was above (blue) and below (orange) the historical average. Individual years of the relevant historical streamflow period are shown in light gray.
Conceptual illustration showing how USGS's Next Generation Water Observing System will enhance the spatial and temporal monitoring of water within reference basins and larger hydrologic regions in all U.S. states and territories.
Conceptual illustration showing how USGS's Next Generation Water Observing System will enhance the spatial and temporal monitoring of water within reference basins and larger hydrologic regions in all U.S. states and territories.
A time series of streamflow drought events occurring across 122 stream gages in the Upper Colorado River basin from 1980 to present. Periods of streamflow drought are indicated for each of 122 gages in a beeswarm-like chart, with time on the x-axis. During time periods where many gages experienced drought, the swarm bulges due to many co-occurring events.
A time series of streamflow drought events occurring across 122 stream gages in the Upper Colorado River basin from 1980 to present. Periods of streamflow drought are indicated for each of 122 gages in a beeswarm-like chart, with time on the x-axis. During time periods where many gages experienced drought, the swarm bulges due to many co-occurring events.
A map showing the locations of the Upper and Lower Colorado river basins in the contiguous U.S. and all 1,865 NWIS sites used to calculate total flow.
A map showing the locations of the Upper and Lower Colorado river basins in the contiguous U.S. and all 1,865 NWIS sites used to calculate total flow.
An ecological site group map for the Upper Colorado River Basin that displays a quantitative soil-geomorphic framework in the Four Corners region, USA.
An ecological site group map for the Upper Colorado River Basin that displays a quantitative soil-geomorphic framework in the Four Corners region, USA.
Webcam at USGS Streamgage 09095500 Colorado River near Cameo, CO.
Visit Water Data For the Nation to get current data for this site.
Webcam at USGS Streamgage 09095500 Colorado River near Cameo, CO.
Visit Water Data For the Nation to get current data for this site.
Webcam at USGS Streamgage 09071750 Colorado River above Glenwood Springs, CO.
Visit Water Data For the Nation to get current data for this site.
Webcam at USGS Streamgage 09071750 Colorado River above Glenwood Springs, CO.
Visit Water Data For the Nation to get current data for this site.
The USGS National Integrated Water Availability Assessments (IWAAs) concept map shows daily estimates of natural water storage (water present on the landscape such as standing water, snowpack, soil water, and shallow groundwater) for approximately 110,00
The USGS National Integrated Water Availability Assessments (IWAAs) concept map shows daily estimates of natural water storage (water present on the landscape such as standing water, snowpack, soil water, and shallow groundwater) for approximately 110,00
This is a PDF of an in-house Power Point presentation to other Utah Water Science Center employees to invite discussion and input.
This is a PDF of an in-house Power Point presentation to other Utah Water Science Center employees to invite discussion and input.
Next Generation Water Observing System Upper Colorado & Gunnison River Basin briefing sheet.
Next Generation Water Observing System Upper Colorado & Gunnison River Basin briefing sheet.
Below are news releases and announcements associated with the Upper Colorado River Integrated Water Science Basin.
