Northwest Water Supply Remains Suppressed
April and early May showers not enough to overcome one of the ‘lowest statewide snow seasons on record’
By Micah Drew
Water supply specialists report snowpack totals in the northern Flathead River basin at about 68% of the 30-year normal, a decline from last year’s drought conditions when northwest basins registered a May 1 snowpack around 88%.
That’s according to experts with the U.S. Department of Agriculture’s Natural Resources Conservation Service (NRCS), which releases snowpack and water supply reports at the beginning of each month to help forecast spring runoff, flooding, irrigation and potential wildland fire behavior.
“April is typically a wet month in Montana, and total precipitation last month did not meet that standard,” NRCS Water supply specialist Eric Larson said in a press release this week, even though “a couple mid-month storms did provide significant snowfall.”
Well above normal precipitation was needed last month to erase water supply deficits that have been adding up since October, the start of the water year. Across most of the state, April precipitation was between 65% and 80% of normal. The Bighorn and Absoroka mountains were an exception, receiving between 110% and 150% of normal precipitation, while the Upper Missouri, Sun-Teton-Marias and Saint Mary River basins received just 60-70% of normal. Many SNOTEL sites along the Rocky Mountain Front, including the southern end of the Mission Mountains, are reporting their lowest water year precipitation in 30-40 years.
The Flathead basin received 80% of normal precipitation, bringing the total water year up to 81%.
Snowpack in Montana tends to peak in late April or early May depending on the elevation, but the NRCS report indicates that many basins experienced significant snowmelt throughout April. According to the report, 2024 will go down as “one of the lowest statewide snow seasons on record,” similar to 2015, 2005 and 2001, all significant low-water years in Montana that led to severe drought conditions. The U.S. Drought Monitor reported Thursday that 43% of Montana is experiencing moderate to extreme drought, with 25% of Flathead County under extreme drought.
Prior to this week’s widespread storms that dumped snow across the south-central region of the state, not a single river basin had a snowpack exceeding 86% of normal, with just four exceeding 75% of normal.
Current snow water equivalent peaks compared to normal vary significantly across the northwest. High elevations in the northern Flathead and Kootenai River basins peaked between six and eight inches below normal. An exception in the region is the Noisy Basin SNOTEL site in the Swan Mountains, which on Friday registered 45.7 inches of SWE, 106% of the median.
During a meeting of the Governor’s Drought and Water Supply Advisory Committee on Thursday, Larson said that early May storms, including winter storms across the southern stretches of Montana, helped the river basins recover, but warmer temperatures forecast over the next week are likely to accelerate the melt out of additional snowfall.
“While this storm is helpful, this one storm alone will not likely make up for the water year precipitation deficit across most of western Montana,” Larson said.
The Flathead River basin benefited from rain and high-elevation snow over the first week of May, but streamflow forecasts for the summer are still lower than expected.
According to Larson, runoff volume in the Flathead is expected to range between 60% and 85% of the 30-year median.
Speaking during the committee meeting, data management section chief for USGS Aaron Fiaschetti said that water supply reports and forecasts should always be taken within context — as a singular snapshot from when the data is collected.
“It’s still too early to really tell where streamflows will be, but with a low snowpack we’re starting in that glass half empty scenario,” he said. “Even if [a river’s volume] tracks with the average now, that doesn’t mean it will be average later. It’s dynamic, it can change.”
Anticipating another low-water year, Energy Keepers Inc., operators of Séliš Ksanka Ql̓ispe̓ Dam at the southern end of Flathead Lake, have coordinated with the U.S. Army Corps of Engineers for two water level variations this spring. The first variation, granted in April, raised the lake’s low-water level by 2 feet, increasing the chance of refilling to full-pool levels in the event of limited runoff. The second deviation, granted on May 2, allows Energy Keepers to raise Flathead Lake up to 2,892 feet by Memorial Day, 2 feet higher than the maximum level normally permitted by the dam’s federal license for the end of May.
“We’re responding to the conditions as provided by current weather trends,” Energy Keepers CEO Brian Lipscomb said in a press release. “Managing circumstances with a more robust snowpack would be preferred, but our team is responsible for managing whatever situation is generated by Mother Nature.”
A full report of conditions on May 1 can be found in the monthly Water Supply Outlook Report, and real-time snow survey data can be viewed on the Montana Snow Survey website.