Data, Tools, and Reports Available to the Public
Snow and Water Interactive Map
Report Generator is a web application developed by the Natural Resources Conservation Service (NRCS) National Water and Climate Center (NWCC).
The application uses long-term snowpack, precipitation, reservoir, streamflow, and soils data from a variety of quality-controlled sources to create reports.
Users can choose from predefined templates or build custom reports.
Data from tabular reports may be exported to different formats, including comma-separated value (CSV) files. Charts can be saved to graphics formats, such as JPG and PNG.
AWDB Web Service Tool
- Monthly Reservoir Update Report
- Basin Data Reports - Select "Reservoir" as report type
- California Current Reservoir Storage Summary - California Dept. of Water Resources
Western U.S. Reservoir Storage Bar Graph and Data Reports (Preliminary posted on 5th working day, final on 10th working day each month)
30-Year Medians and Averages
- Reservoir 30-Year Medians and Averages (1991-2020) Effective Oct. 1, 2021
Learn How We Collect Data from Far and Wide
Telemetry and Data Transmission
Most of the SNOTEL network uses meteor burst communication technology to send and receive data in near real-time. Each SNOTEL site transmits a radio signal into the sky, and this signal bounces off a band of ionized meteorites existing about 50 to 80 miles above the earth. This technique allows communication to take place between remote sites and a master station up to 1200 miles away.
At the master station, the remote site data are checked for completeness. If complete, an acknowledgment message, returning over the same path, tells the remote site not to transmit again during this polling period. The entire process takes less than a tenth of a second.
Meteor burst communication system
In a cellular network, signals carrying voice, text, and digital data are transmitted via radio waves through a global network of transmitters and receivers. Signals are distributed over land through cells, where each cell includes a fixed location transceiver known as a base station.
The Soil/Climate Analysis Network (SCAN) uses cellular data transmission for many sites, especially in the eastern U.S. Cellular modems installed in the electronics enclosure transmit data back to the Water and Climate Information System database.
The Geostationary Operational Environmental Satellite (GOES) system is operated by the U.S. National Environmental Satellite, Data, and Information Service. The system supports weather forecasting, severe storm tracking, and meteorology research. The system is currently composed of two geostationary satellites, GOES-East and GOES-West. SNOTEL, Snolite, and SCAN sites with GOES transmitters send data to the GOES-West satellite, where they are then transmitted back to a receiver station. Once received, the data are converted to meteor burst format and incorporated into the Water and Climate Information System.
Similar to the GOES system, the Iridium Satellite System consists of a network of 66 cross-linked satellites, which operate in near-circular low-Earth orbits (LEOs) about 480 miles (772 kilometers) above the Earth’s surface. Each satellite can project 48 spot beams on the Earth’s surface, and the satellites are cross-linked so that each satellite can “talk” with other nearby satellites.
Much like a cellular network where data are transmitted via multiple cellular towers, the Iridium Satellite System data are relayed from satellite to satellite until they are downlinked at an Iridium gateway and then transmitted to the Water and Climate Information System database.
Iridium Satellite System
Manual Snow Monitoring
Snow courses are locations where manual snow measurements are taken during the winter season to determine the depth and water content of the snowpack. Snow courses are permanent locations and represent the snowpack conditions at a given elevation in a given area.
Generally, snow courses are about 1,000 feet (300 meters) long and are situated in small meadows protected from the wind. They consist of a variable number of individual sample points, typically 5 to 10, which are evenly-spaced between points.
Snow surveyors travel to snow courses using skis, over-snow machines, or helicopters. Once onsite, the surveyors use snow samplers at each sample point to measure the depth of the snowpack and then weigh the snow to determine the snow water equivalent. The data collected are then entered into the Water and Climate Information System database.
A surveyor uses a snow tube at a sample point on a snow course to measure the snowpack depth and water equivalent. The remote location of this snow course requires the use of a helicopter.
Historically, snow course measurements were the first form of snowpack data collection, starting in 1906 when Dr. James Church from the University of Nevada measured a course he laid out on Mt. Rose near Reno. Prior to the 1970s and the inception of the automated Snow Telemetry (SNOTEL) network, snow courses were the primary means of collecting snowpack data. As a result, snow course data records often start earlier than SNOTEL records.
Aerial markers are used to measure the depth of snow. Surveyors then use an estimated density to calculate snow water equivalent. The markers are located in remote locations that are difficult to reach by over-snow travel. They consist of one measuring point marked by a pipe with cross members that can be easily observed by aircraft flyover.
Harts Pass aerial marker, Washington
Automated Snow Monitoring
Snow Telemetry (SNOTEL) Network
The SNOTEL network is composed of over 900 automated data collection sites located in remote, high-elevation mountain watersheds in the western U.S. They are used to monitor snowpack, precipitation, temperature, and other climatic conditions. The data collected at SNOTEL sites are transmitted to a central database, called the Water and Climate Information System, where they are used to make water supply forecasts.
SNOTEL sites are designed to operate unattended and without maintenance for a year or more. A typical SNOTEL remote site consists of measuring devices and sensors, an equipment shelter for the radio telemetry equipment, and an antenna that also supports the solar panels used to keep batteries charged.
A standard sensor configuration includes a snow pillow, a storage precipitation gage, and a temperature sensor. The snow pillow measures how much water is in the snowpack by weighing the snow with a pressure transducer. Automatic measuring devices in the shelter house convert the weight of the snow into an electrical reading of the snow's water equivalent -- that is, the actual amount of water in a given volume of snow.
SNOTEL stations also collect data on snow depth, all-season precipitation accumulation, and air temperature with daily maximums, minimums, and averages. Many enhanced SNOTEL sites are equipped to take soil moisture and soil temperature measurements at various depths, as well as solar radiation, wind speed, and relative humidity. The configuration at each site is tailored to the physical conditions, the climate, and the specific requirements of the data users.
The data collected at SNOTEL sites are generally reported multiple times per day, with some sensors reporting hourly. More on SNOTEL sensors
SNOTEL automated data collection site
Since the early days of the snow survey program, aerial markers have been used to measure snowpack in very remote areas where accessibility is limited.
In the last few years, some aerial markers have been outfitted with basic sensors, such as temperature and snow depth, and telemetered using the Iridium Satellite System. Aerial markers with these sensors are called Snolite sites.
Snolite automated aerial marker
State Snow Programs
States in the West collect mountain snowpack and precipitation data in their areas, and offer regular reports on those areas utilizing the national database. Individuals, organizations, and state and federal agencies use the information provided for decisions relating to agricultural production, fish and wildlife management, municipal and industrial water supply, urban development, flood control, recreation, power generation, and water quality management.