Maps are updated approximately the first week of the month as follows: Surface Water Supply Index (Jan. - Oct.), Snow Water Equivalent (Dec. - June), Precipitation (year round), Streamflow Forecast (March – June), Reservoir Levels (year round).
View statewide maps of Surface Water Supply Index, Snow Water Equivalent, Precipitation, Streamflow Forecast, and Reservoir Levels
View individual basin maps of Streamflow Forecasts, Snow Water Equivalent, Precipitation, and Reservoir Levels
View pre-2016 Snow and Water Supply Maps
These maps are produced in partnership with the NRCS. Data are compiled by the Montana
Snow Survey Program of the USDA Natural Resources Conservation Service. Please see
the NRCS web site for explanations of their data collection programs.
For additional information, contact:
Lucas Zukiewicz, Hydrologist
Natural Resources Conservation Service
The Montana State Library utilizes the ePass system for application login. You will be temporarily redirected to the secure Montana.gov website for authentication.
If you previously used a login to access State Library services, you will have an opportunity to connect that information with our updated system.
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The Montana State Library makes every effort to ensure that everyone may access the resources of our library including online resources through our website. If you cannot access a resource or service please contact our library staff at 406-444-3115.