Streamflow, Drought, and Water Supply Conditions

Water supply conditions as of 3/1/2019

From The montana water supply outlook report

Jefferson Basin: The snowpack is getting deep in the headwaters of the Jefferson! While out collecting snow course data this month it was difficult to make it across flat fields, much less up into the mountains to sample select snow courses dating back to the early 1960’s. What’s there at low elevation is pretty much bottomless due to the cold temperatures “rotting” the snow during the prolonged cold snaps this winter. Bloody Dick SNOTEL recorded the lowest density mid-winter snowpack it ever has just last week at 19%, while much of the state is around the 27% mark. Even if the cold temps have created a weak snowpack, it all melts the same come spring time, and there’s plenty of it. Snowfall was well above normal (>150%) to record setting across the basin during the month of February. SNOTEL sites in the Red Rock and Ruby River basins experienced their 1st or 2nd “snowiest” February on record, bringing some areas from well below normal on February 1st to near or above normal on March 1st. Not to be left out, the SNOTEL sites in the Tobacco Roots also experienced their 1st or 2nd snowiest February on record. While measurement locations in the Big Hole didn’t set records for the month, the above normal snowfall was enough to improve snowpack to near or above normal at most locations. It was quite the turnaround in southwest MT, where the ideal snow producing weather pattern occurred throughout the month. Streamflow forecasts issued on March 1st for the April 1st – July 31st period across the basin range from near average to above average depending on the sub-basin. With reservoir levels at 127% for this date, and favorable early season streamflow forecasts, the story for spring and summer is looking much rosier than on February 1st. March through May typically make up about 25% of the typical seasons snowfall, so the story isn’t over yet, but it’s not a horror novel anymore.

Big Hole Sub-basin Snowpack: 108% of normal (1981-2010 median)

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

February 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)