Streamflow, Drought, and Water Supply Conditions

Water supply conditions

From The montana water supply outlook report 

June 1, 2019

Jefferson Basin: “May yielded variable precipitation to the Jefferson Drainage as the Ruby received just a third of its average while the Big Hole, Beaverhead, and Boulder were only slightly below normal. The good news is water year to date numbers are spot on at 101% of average and snowpack in the Ruby is 128% of normal while the basin-wide average is near normal. Reservoir storage is up to 119% of average as water managers are trying to hold back as much as they can with an average snowpack above them in the mountains. Water supplies are looking sufficient for now, but keep in mind that we still need to receive normal amounts of precipitation from June to August to avoid water shortages towards the end of the irrigation season.”

Big Hole Sub-basin Snowpack: 101% of normal (1981-2010 median)

About the Montana Water Supply Outlook Report: The Montana NRCS Snow Survey Program provides mountain snowpack and precipitation information via the SNOwpack TELemetry (SNOTEL) network in order to issue streamflow forecasts for Montana and Wyoming. Common applications of snow survey products include water supply management, flood control, climate modeling, recreation, and conservation planning. The Snow Survey Program issues the Montana Water Supply Outlook Report on the 5th business day of each month. (January 1 – June 1).  

Period of Record Monthly Climate Summary – Period of Record : 01/01/1923 to 06/09/2016

See details below from Western Regional Climate Center:


Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
Average Max. Temperature (F) 26.4 31.1 38.5 49.2 60.3 68.6 79.4 77.8 67.6 55.0 38.0 28.0 51.7
Average Min. Temperature (F) 1.2 3.3 10.8 21.2 28.7 36.1 38.2 34.7 27.8 21.3 12.3 3.6 19.9
Average Total Precipitation (in.) 0.70 0.52 0.74 0.95 1.64 1.96 1.09 1.03 0.99 0.83 0.76 0.77 11.97
Average Total SnowFall (in.) 11.8 8.3 8.6 4.5 2.5 0.5 0.0 0.0 0.5 1.9 7.8 10.8 57.0
Average Snow Depth (in.) 9 10 8 1 0 0 0 0 0 0 2 5 3

Percent of possible observations for period of record.
Max. Temp.: 98.7% Min. Temp.: 98.6% Precipitation: 98.6% Snowfall: 76.4% Snow Depth: 50.3%


National Water Supply Reports

Nation-wide information for water supply and climate prediction & forecasts. 

National Weather Service Climate Prediction Center – Three Month Outlook Report


Montana Water Supply Reports & resources

Statewide information for water supply and drought conditions. Report breaks out conditions by major basins:

Montana Water Supply Outlook Reports

Guide to Using the New Montana Water Supply Report

Water supply and drought condition information specific to the Upper Missouri Basin:

Upper Missouri River Basin

Water Monitoring Resources from the Montana Watershed Coordination Council

Montana Watershed Coordination Council Water Monitoring webpage


Past Streamflow & Snowpack Reports

May 2019 Streamflow/Snowpack Report (PDF)

April 2019 Streamflow/Snowpack Report (PDF)

March 2019 Streamflow/Snowpack Report (PDF)

November 2018 Streamflow/Snowpack Report (PDF)

October 2018 Streamflow/Snowpack Report (PDF)

September 2018 Streamflow/Snowpack Report (PDF)

June 2018 Streamflow/Snowpack Report (PDF)

May 2018 Streamflow/Snowpack Report (PDF)

April 2018 Streamflow/Snowpack Report (PDF)

March 2018 Streamflow/Snowpack Report (PDF)

February 2018 Streamflow/Snowpack Report (PDF)

November 2017 Streamflow/Snowpack Report (PDF)

October 2017 Streamflow/Snowpack Report (PDF)

August 2017 Streamflow/Snowpack Report (PDF)

June 2017 Streamflow/Snowpack Report (PDF)

April 2017 Streamflow/Snowpack Report (PDF)

March 2017 Snowpack Report (PDF)

February 2017 Snowpack Report (PDF)

November 2016 Streamflow/Snowpack Report (PDF)

September 2016 Streamflow/Snowpack Report (PDF)

May 2016 Streamflow/Snowpack Report (PDF)

April 2016 Streamflow/Snowpack Report (PDF)

March 2016 Streamflow/Snowpack/CCAA Report (PDF)

February 2016 Streamflow/Snowpack Report (PDF)