Data and tools
This section of the Colorado River Science Wiki automatically collates all of the information found under the Data and tools headings on every page in the Science and applications section, and lists those datasets and tools below in the same order as the the pages in the Science and applications section.
The “CAG” tool is a versatile tool that can be used to generate many types of charts, maps, and analyses from NOAA’s official nClimGrid monthly gridded climate dataset. Selecting "Regional" and "Time series" at top brings up several dozen region options, including the Upper Basin and Lower Basin. Selecting "Regional" and "Mapping" allows data to be mapped with river basin boundaries.
This tool, developed by researchers at the U. of California-Merced and partners, generates climographs of average (1981-2010) monthly temperature and precipitation for any point, county, HUC8 watershed, or user-selected area, from the gridMET gridded (4 km) climate dataset.
The “CAG” tool is a versatile tool that can be used to generate many types of charts, maps, and analyses from NOAA’s official nClimGrid monthly gridded (5 km) climate dataset. The link above opens the Regional and Time Series options, allowing users to plot temperature, precipitation, and other variables for the Upper Basin, Lower Basin, or many other U.S. basins and regions. All variables can be plotted from 1895 to present.
This tool, developed by researchers at the U. of California-Merced and partners, generates time series plots for any point, county, HUC8 watershed, or user-selected area from the gridMET gridded (4 km) climate dataset. Many more variables are available from gridMET than from NOAA's nClimGrid; however, gridMET only extends back to 1979. Some drought-related variables calculated from other climate datasets are available through this tool.
Weather station data
This site created by the University of Utah provides map-based access to 1000s of observations from the NWS and FAA (ASOS/AWOS) automated networks, RAWS, SNOTEL, APRSWXNET/CWOP (citizen weather stations), and many other networks. Very useful for real-time monitoring of temperature, winds, humidity, and recent precipitation; users can also access historical observations.
These maps, generated from weather station observations from the NWS COOP network and updated daily, are very helpful for monitoring conditions from weekly to annual timescales. Note that the "shaded" maps are created using a very simple interpolation, unlike that used for gridded climate products.
Gridded climate products
This versatile tool can be used to generate many types of charts, maps, and analyses from NOAA’s official nClimGrid gridded climate dataset, updated monthly.
This toolset, developed by researchers at the U. of California-Merced and partners, generates many different types of charts and analyses from the gridMET gridded (4 km) climate dataset, updated daily.
These maps display the PRISM gridded climate product, updated monthly, for climate (temperature, precipitation) variables as well as drought indices (PDSI, SPI, SPEI). The "Percentile" maps show how unusual recent conditions are relative to the historical record.
The National Weather Service (NWS) homepage has a national map that, on-click, opens up the homepage for that local Weather Forecast Office, which has a region map that on-click brings up the NWS official local weather forecasts (nowcast to 7-day) and any hazard watches/warnings.
This interactive map presents a seamless mosaic of all of the local forecasts (out to 7 days) issued by the Weather Forecast Offices across the U.S., for temperature, precipitation, and several dozen other variables.
QPFs are specific forecasts of the most likely precipitation amounts over the next 1-7 days, issued as national maps. QPFs are used as inputs to the CBRFC's streamflow forecasts made on both short-term (10-day) and seasonal timescales. The NWS WPC QPF is based on guidance from several different weather models.
This is the QPF as used by CBRFC to drive their streamflow forecast model system. Days 2-7 are taken from the NWS WPC QPF product shown above; Day 1 comes from the very similar NWS National Blend of Models (NBM) QPF.
This is another way of displaying a QPF (here, an 8-day ensemble forecast from the GFS weather model), for a single location. This URL shows the forecasted cumulative precipitation for KASE (Aspen, CO); zoom in on the map to select any other of ~20 locations within the Colorado River Basin. The plume shows the uncertainty in the forecast given our imperfect knowledge about the initial atmospheric conditions.
Because the skill of weather forecasts for beyond 7 days out is much lower, the official NWS "week 2" (8-14-day) forecasts are issued (daily) as probabilistic outlooks, indicating enhanced likelihoods that conditions over that period will fall into the 3 categories of above normal (upper 1/3), near-normal (middle 1/3), or below normal (lower 1/3 of all historical observations). Monthly and seasonal outlooks also use these "tercile" categories.
Sub-seasonal Climate Forecasts
These "Week 3-4" outlooks (i.e., for the period 15-30 days after the forecast date) are issued weekly and show enhanced likelihoods that conditions for the forecast period will be in one of 2 categories: above or below the historical median. The Temperature outlook is an official forecast product, but the Precipitation outlook is still considered "experimental" due to low skill/reliability.
These monthly outlooks are issued for each full month (January, February, etc.) at two lead times: 0.5 months lead (i.e, issued in middle of prior month) and zero lead (end of prior month). Not surprisingly, the zero-lead monthly outlooks are more skillful since they incorporate short-term weather (0-14 days) forecast guidance, in addition to longer term guidance (equivalent to the Week 3-4 outlooks).
This interactive web tool, developed by NCAR and Reclamation, presents specific ("deterministic") forecasts of temperature and precipitation anomalies (departures from normal) from several weather/climate models, which can be viewed individually or as an 7-model ensemble ("NMME") average. These models are used as guidance for the NWS sub-seasonal outlooks listed above. The sub-seasonal forecasts available are for weeks 2-3 and 3-4 (CFSv2 only); and 1-month (all NMME models), at three lead times: zero, 1 month, and 2 months; the seasonal forecasts available are for 3-month seasons at three lead times: zero, 1 month, and 2 months.
Seasonal Climate Forecasts
These seasonal outlooks are issued monthly for overlapping 3-month periods (Jan-Mar, Feb-April, etc.) at lead times ranging from 0.5 months to 12.5 months. The shorter-lead outlooks are generally more skillful, but skill is relatively low for precipitation at all lead times. As with the CPC 8-14 day outlooks, the seasonal outlooks are probabilistic and based on 3 categories (above normal, near-normal, and below normal).
The Climate Explorer interactive tool (developed by NOAA and its partners) allows users to generate zoomable climate change maps for temperature and precipitation for the U.S. and northern Mexico, and time-series plots of projected future temperature and precipitation for U.S. counties. Other areas for analysis, such as river basin, cannot be selected. All projected climate data are from the LOCA-downscaled CMIP5 dataset (32 models).
The Climate Toolbox is a diverse set of interactive tools developed by researchers at U. Cal-Merced and partners. All projected climate data are from the MACA-downscaled CMIP5 dataset (20 models).
The Climate Mapper tool allows users to generate zoomable climate change maps for temperature as well as precipitation and a broad set of drought, agricultural, and fire-risk indicators. To access the projections, "Future: Projections" must be selected under Choose Data - Time Scale in the upper left. Projected climate data are from the MACA-downscaled CMIP5 dataset (20 models).
The Future Time Series tool allows users to generate time series for temperature as well as precipitation and a broad set of drought, agricultural, and fire-risk indicators. To access the projections, "Future: Projections" must be selected under Choose Data - Time Scale in the upper left. Projected climate data are from the MACA-downscaled CMIP5 dataset (20 models).
The National Climate Change Viewer (NCCV) is a versatile interactive viewer developed by USGS. It allows users to generate zoomable change maps, time series, monthly climographs, and scatterplots for multiple climate variables. This viewer's analysis areas are river basins/watersheds (HUC2, HUC4, and HUC8); a separate viewer allows analyses by state or county. All projected climate data are from the MACA-downscaled CMIP5 dataset (20 models), same as for the Climate Toolbox.
SNOTEL and other in-situ snow data
This very versatile tool provides a clear spatial overview of snowpack (SNOTEL) and other hydroclimate conditions across the western U.S., while allowing users to easily drill down into site-level data. Displays both near-real-time data (previous day) and historical data.
NRCS State Snow Survey Snow Products
The NRCS state snow survey sites provide many additional options--varying by state-- for viewing current and historical SNOTEL and snow course data, including monthly summary reports (Basin Outlook Reports).
Provides current year's time-series plots of SNOTEL SWE averaged across multiple SNOTEL sites (“snow groups”) selected to represent a particular catchment or area; ~300 options for catchments within the Colorado River Basin and eastern Great Basin.
Provides daily new snow depth and SWE, and snow depth and SWE on the ground, from the hundreds of volunteer CoCoRaHS observers in the basin. Select Map Options > What to map these snow variables.
Gridded and modeled snow products
Provides access to SNODAS daily gridded SWE and other snow variables; the SNODAS model builds and maintains a snowpack based on weather data and also assimilates SNOTEL data.
This tool, developed at the U. of Arizona, shows a daily gridded snow dataset (SWANN) that uses snow models, assimilated SNOTEL data, and machine-learning methods. Users can compare SWANN with SNODAS for a catchment of interest.
Interactive map that provides daily-updated modeled SWE for ~500 catchment-elevation zones in the Colorado River Basin and eastern Great Basin. These modeled SWE data are used as key inputs for CBRFC's seasonal streamflow forecasts.
Other snowpack information
The CODOS program at the Center for Snow and Avalanche Studies (CSAS) tracks the deposition and emergence of dust layers in the snowpack, and snowpack temperature and other metrics, at 11 mountain pass locations throughout Colorado.
A subset of the NRCS SNOTEL and SCAN stations are equipped with soil moisture sensors. The NRCS Interactive Map allows users to view current conditions at each station by selecting the desired measurement (e.g., soil moisture value at 20 in. depths). Navigate to individual stations to access data on previous soil moisture conditions.
The Colorado River Basin Forecast Center provides modeled soil moisture data (as opposed to single point observations) in map formats. Users can navigate to see either current conditions as compared to a percent normal value or may look at static, gridded maps of modeled soil moisture data from previous months (as in Figure 2).
The NASA GRACE-FO website provides maps of gridded soil moisture conditions for the contiguous United States based on wetness percentile. Maps are updated weekly.
Several weather-station networks in the basin states, mainly serving the agricultural sector, have instrumentation for all of the variables (temperature, solar radiation, humidity, winds) needed for real-time calculations of Reference ET. Typically, Reference ET is calculated hourly and daily, to the nearest 0.01 in. or 1 mm.
Colorado; 90 active stations in agricultural areas.
Arizona; 27 active stations in agricultural and urban areas.
Utah and adjacent areas in ID, WY, CO, NM; 130 active stations in agricultural and urban areas.
California; 150 active stations in agricultural and urban areas.
EDDI is based on Reference ET (calculated from gridded NLDAS-2 meteorological data, using the same method as for the in-situ data above) and standardized relative to historical Reference ET for each gridpoint over the time window (2 weeks to 1 year) of interest. EDDI can offer early warning of agricultural and hydrologic drought by providing near-real-time information on the emergence or persistence of anomalous evaporative demand.
OpenET is an open-source platform and data viewing tool that brings together several satellite-based ET estimation methods to provide daily, monthly, and annual ET estimates at the field scale. The methods currently in the OpenET ensemble include ALEXI/DisAlexi, eeMETRIC, geeSEBAL, PT-JPL, SIMS, and SSEBop. Free registration required to view data.
Gaged streamflow - Real-time and Historical
This interactive map shows over 530 active gages across the Colorado River Basin, and hundreds more in adjacent basins (Figure 2). Zoom in to see all gages, mouse-over a gage to see a yellow popup with its name and current streamflow statistics, and click on that gage's name within that popup to open the real-time data page for that gage. On the real-time data page, click "Change time span" to plot and retrieve historical gaged flow data.
This interactive map is similar to the USGS Water Watch map but shows both the ~530 active gages (dark gray) and the ~380 inactive gages (light gray) across the basin for which daily streamflow over some period has been archived in the USGS National Water Information System. Click on a gage to get see the name; click "Access data" to go to the (old-USGS-style) data page for that gage.
Reclamation's BCOO provides near-real-time access to flow data from about 15 gages on the lower Colorado River, below Davis Dam, that are not part of the USGS network.
This interactive map shows over 360 active gages, and over 600 inactive ('historical') gages, within the 4 water divisions that comprise Colorado's portion of the Colorado River Basin. These gages include all those shown on the USGS map, along with others operated by DWR and local agencies. Zoom in to locate a gage of interest, mouse-over to see its name, and click to open a popup showing the length of the record. Click "View more details" to open the data page for that gage.
Unregulated inflow - Reclamation
Reclamation's 24-Month Study Reports, in addition to projecting system inflows and conditions ~24 months into the future, includes the observed (unregulated) inflows to each system reservoir for 12 months prior to the report date. These observed flows are shaded in gray and labeled "Historical".
Unregulated streamflow and inflow - NOAA CBRFC
From the basin map shown, click the gage of interest so that the popup appears, then the link within the popup to open the webpage for that gage. For the current year and recent years, select the Water Year of interest at lower left (back to 2011); the forecast evolution plot will show that year's daily cumulative observed (unregulated) flows, in orange. For the full record (30-100 years), click Historical Volumes under "Data" in the lower right. A list of all historical April-July unregulated flows, in order of increasing flow, will be shown.
Adjusted streamflow - NRCS
This link shows the NRCS Interactive Map customized to show the adjusted streamflow for the current water-year-to-date, as a % of the period-of-record average. Click on a gage of interest to bring up a popup, click on the popup to expand it, and then click on Data Reports and either Water Year Table or Water Year Chart for the current year's monthly flows. For historical flows at that gage, open the Water Year Table, click on the Create/Modify Report tab in the upper left. When the tab opens, click the first checkbox for 'stream volume, adjusted' then below that, change Time Period to "Period of Record", then click on the View Report tab at upper left.
The Excel file linked on this page contains estimated monthly natural flows for the 20 locations in the Upper Basin, and 9 in the Lower Basin, that are the inflow points for the Colorado River Simulation System (CRSS). Most prominent among these is the Colorado River at Lees Ferry. These flow data are updated every year or so by Reclamation to extend the record forward, but they are always 1-2 years behind the most recently completed water year. Provisional data for the Lees Ferry gage only for the most recent water years are found on this page.
The TreeFlow resource provides access to data, metadata, and plots of nearly all existing tree-ring reconstructions of streamflow for the Colorado River Basin, as well as other river basins throughout the U.S. Currently there are 31 gages in the Upper Basin and 4 gages in the Lower Basin for which reconstructions are available.
- Meko et al. 2007 reconstruction of Lees Ferry gage (762-2005)
The Paleoflow tool provides additional analysis and plotting options for the Colorado River Basin reconstructions that are available on TreeFlow, including dynamic time-series plots, analysis of extreme events, and comparisons of distributions (probability density functions) between two periods. Make sure Time Resolution = Annual to see the full list of reconstructions.
CBRFC has multiple ways to access and view their seasonal water supply forecasts and related data:
The Conditions Map can display several different types of hydroclimate information, depending on the tab selected. The Water Supply Forecasts tab, when opened, defaults to the most probable (50% exceedance) values for the official 1st of month forecasts, but can also display the latest daily ESP forecasts ("Latest Model Guidance"). Clicking on the triangles (forecast points) brings up a thumbnail forecast evolution plot for that point; clicking within the plot opens a page specific to that forecast point, with an interactive forecast evolution plot and links to plots for previous years, calibration and validation data, and historical streamflow volumes for that point.
This page shows the most recent official forecasts for Lake Powell inflows (~all Upper Basin runoff) for April-July and the water year; maps of observed/modeled soil moisture, snowpack, and precipitation used to inform the forecasts; and graphs showing how the sub-basins' contributions and overall forecasted volume compares with average conditions.
This page features an interactive table with the official 1st of month forecasts for all forecast points. Like the forecast map, it links to the pages for each point.
This document (PDF) discusses provides a general overview of the official (1st and 15th of month) CBRFC forecasts, describing the weather/watershed conditions that have led to the forecasts, as well as forecasts and outlooks for upcoming weather.
From January through May, CRBFC presents one-hour webinars around the 7th of the month to explain the latest streamflow forecasts, the weather and snow conditions leading up to the forecasts, and the weather conditions forecasted for the next two weeks. Scroll down to "Presentations 20xx" for a link to the webinar archive for the current year; and then find the Water Supply Webinar" of interest. Both the slides and a recorded video with slides are available.
NRCS likewise has several ways to access and view their seasonal water supply forecasts and related data.
The NRCS Interactive Map is a versatile tool to access and view all NRCS hydroclimate data, including the seasonal water supply forecasts. The link above has been specifically set up to show the most probable (50% exceedance) values for the current seasonal water supply forecasts, for individual points, but users can select other ways to visualize the forecast data, e.g., by basin, as percentiles, or for different forecast periods. Similar to the CBRFC Conditions Map, clicking on an individual forecast point will bring up a small window with the name of the point and forecasted streamflow volume; clicking on that window will bring up other options for viewing additional data for that point, including other statistics for the forecasted streamflow, and the observed streamflows for the water year.
The Water Supply Forecast Chart shows the potential range for the forecasted streamflows (90%-70%-50%-30%-10% exceedances), similar to the shaded bands on the CBRFC forecast evolution plots. Note that the sub-basins within the CRB are shown by state; forecasts for Colorado R at Glen Canyon Dam (i.e., Lake Powell inflows) are accessed under Utah >Southwestern Utah.
NRCS State Basin Outlook Reports
The Basin Outlook Reports (also known as Water Supply Outlook Reports in some states) are issued monthly or semi-monthly from January through June by the state-level NRCS Snow Survey Offices, and supplement the NRCS seasonal water supply forecasts with narratives of statewide precipitation, snowpack, and water supply conditions, and additional graphics showing the water supply forecasts by sub-basin, alongside snowpack, precipitation, and reservoir conditions.
The Climate Toolbox is a diverse set of interactive tools developed by researchers at U. Cal-Merced and partners. All projected climate data are from the MACA-downscaled CMIP5 dataset. The projections of hydrologic variables in Climate Toolbox are based on a reduced ensemble (10 vs. 20) of CMIP5-MACA climate projections (temperature and precipitation) that have been run through the VIC hydrologic model. Note that with 10 members, this ensemble of hydrologic projections may not reflect the full range of potential climate (and hydrology) futures shown across all CMIP5 projections.
The Future Streamflows tool allows users to generate monthly hydrographs of modeled historical and future streamflows (in cubic feet/second) for over 140 gages in basins across the western U.S. and Canada, including 15 gages within the Colorado River Basin. This is especially useful for visualizing the changes in streamflow timing associated with future climate change.
The Future Boxplots allows users to generate boxplots of modeled historical and future area-averaged projected runoff (in inches) for user-selected points, rectangular areas, counties, and HUC8 watersheds.
The National Climate Change Viewer (NCCV) allows users to generate zoomable change maps, time series, monthly climographs, and scatterplots for multiple climate and hydrology variables, including area-averaged runoff (in inches or cm). The viewer's analysis areas are river basins/watersheds (HUC2, HUC4, and HUC8). All projected climate data are from the MACA-downscaled CMIP5 dataset (all 20 models); the hydrology variables such as runoff are derived from a simple water-balance model driven with the projected temperature and precipitation.
This portal allows downloading of the CMIP5-LOCA-VIC projected hydrology dataset, from which Figures 1 and 2 are derived, in netCDF or ASCII (text) format. (There are no visualization tools on the site.) The tab "Projections: Complete Archive" allows users to download the entire dataset for all of CONUS; most users will want to select the "Projections: Subset Request" tab and step through the tabs to select the time period, area of interest, dataset and models, and data format.
24-Month Study Reports
The output of the primary monthly run of CRMMS in 24-Month Study mode (using most probable inflows) is released around the 15th of each month. These results are formatted by Reclamation as a standardized set of data tables totaling 17 pages. The Upper Colorado and Lower Colorado regional offices package this set of data tables differently; Upper Colorado adds a 9-page narrative summary for the Upper Colorado reservoirs, while Lower Colorado adds a single cover page with very a brief summary. Note that both report "flavors" contain the results for both Upper Basin and Lower Basin reservoirs.
24-Month Study Reports - as distributed by Upper Colorado Region
24-Month Study Reports - as distributed by Lower Colorado Region
Supplemental 24-Month Study runs
As noted above, two supplemental runs of CRMMS in 24-Month Study mode are performed either 4 times per year, or monthly (as is true as of March 2022), depending on the projected reservoir conditions. These runs, based on minimum probable and maximum probable inflows, bracket most of the uncertainty in future conditions.
This visualization tool shows the results of the latest month's runs of CRMMS in both 24-Month Study mode and Ensemble mode, for all 12 reservoirs represented in CRMMS. From the homepage, select the latest month, then the reservoir of interest, then "Dashboard" to see modeled monthly inflow, outflow, elevation, and storage, going out 24 months from the latest month.
The CRMMS 5-year probabilistic projections of future conditions of the Colorado River system are typically updated by Reclamation in January, April, and August. The linked page shows the results of the most recent projections in tabular form, along with a description of the modeling approach and assumptions.
Studies featuring long-term CRSS projections
Reclamation does not produce regular operational CRSS projections at long-term (>5-year) timescales. Instead, CRSS is run at longer timescales as needed for specific studies and policy analyses. Below are links to the studies (and report volumes therein) that drew on, and in some cases, presented CRSS results, in reverse chronological order:
- Drought Contingency Plans (2019)
- Colorado River Basin - Ten Tribes Partnership Tribal Water Study (2018) - The Ten Tribes Study included study-specific enhancements of CRSS to improve its simulation of tribal water use, prior to its use for future projections.
- International Boundary and Water Commission Minute 323 (2017)
- International Boundary and Water Commission Minute 319 (2012)
- Colorado River Interim Guidelines for Lower Basin Shortages and Coordinated Operations for Lake Powell and Lake Mead – Final Environmental Impact Statement (2007)
Reclamation reporting of consumptive uses and losses (CUL) data
Consumptive uses and losses (CUL) reports are prepared by Reclamation pursuant to the Colorado River Basin Project Act of 1968 (Public Law 90 537) and provide 5-year reports covering major uses within each basin (Upper and Lower) of the Colorado River. The reports for the Upper and Lower basins are not prepared in parallel and contain different metrics for consumptive uses and losses.
Prior to 2006, 5-year CUL reports that covered both the Upper Basin and Lower Basin (including deliveries to Mexico) were made available. Since 2006, the 5-year CUL reports only cover the Upper Basin. Lower Basin consumptive uses and Mexico deliveries are summarized in the annual Water Accounting Reports (issued since 1964), but these reports do not contain estimates of Lower Basin reservoir evaporation or other losses.
Reclamation reporting of consumptive uses and losses
The Reclamation Consumptive Uses and Losses Reports (since 2006, covering only the Upper Basin) contain estimates of aggregate agricultural use within the Upper Basin, based on mapped irrigated acreage and the calculated consumption by crop and location. These estimates may change significantly in the future due to the new method adopted in 2022 by the UCRC and Reclamation. The Reclamation Water Accounting Reports (covering only the Lower Basin) breaks down consumptive use by point of diversion, which identifies the individual water usage of a number of agricultural users and irrigation districts, but not all agricultural users.
- See Consumptive uses and losses for more details and links to these reports.
Richter (2023) study and data on Colorado River municipal water use
- Journal article: Decoupling Urban Water Use from Population Growth in The Colorado River (Note that the article is paywalled)
- Data: Spreadsheet summarizing water use for selected cities in 2000 and 2022 (Available via the Wiki courtesy of the author)
Reclamation reporting of Consumptive uses and losses (CUL) data
The Reclamation CUL Reports (since 2006, covering only the Upper Basin) contain estimates of aggregate municipal and industrial use within the Basin, based on population and assumed per-capita use. Municipal use that occurs outside of the basin (e.g., Colorado’s Front Range) is classified as “exports.” The Reclamation Water Accounting Reports (covering only the Lower Basin) breaks down consumptive use by point of diversion, which can identify the use by some of the municipalities and metropolitan areas in the Lower Basin states, but not others.
- See the Consumptive uses and losses page for more details and links to these reports.
Salinity Control Monitoring Reports
Measured salinity at the established monitoring locations (below Hoover Dam, below Parker Dam, and at Imperial Dam) are reported in the appendices of the Salinity Control Monitoring Reports by the Colorado River Basin Salinity Control Forum.
Both historical and future salinity and salt loads have been estimated using a variety of models. NRCS USGS, and Reclamation have used the SLOAD, and SPARROW models to estimate salinity in the Colorado River.
SPARROW (SPAtially Referenced Regression On Watershed attributes) - USGS  SPARROW uses nonlinear regression equations to estimate the transport of analytes (such as salts) through river networks, including estimates of upper Colorado River Basin salinity