The 2015 water year has ended, and the next has begun, but neither look good for Montana’s water supply.
On Thursday, the Governor’s Drought and Water Supply Advisory Council heard the details of the toll that this hot summer took on water in most of the state. The implications for next year are bad, because the forecast is for a hot, dry winter.
Representatives of the Natural Resources Conservation Service, the U.S. Geological Service and the Bureau of Reclamation all reported that Montana’s water didn’t start off bad in January. But the lack of winter snowpack and spring moisture meant that by July, water was hard to come by in many areas of the state.
The 2015 water year ended on Sept. 30, and NRCS representative Eric Larson said the statewide average for precipitation ended up being 31.2 inches, putting the year at the fifth driest in the past 35 years. The wettest year in that period, 1997, had almost 45 inches of moisture.
The southwest and northwest were the driest parts of Montana in 2015 and are already starting out the 2016 water year with the least precipitation.
National Weather Service forecaster Gina Loss said some areas of the southeast and west of the Continental Divide had only 40 to 60 percent of average precipitation for the entire water year.
That’s why so many of Montana’s rivers ran so low this year especially west of the Divide, said USGS hydrologist Wayne Berkus. Montana Fish, Wildlife & Parks had to make the unusual decision to close several of the rivers early in the summer because of low flows.
Berkus showed the hydrographs for several rivers and most followed the same pattern: the streamflow peaked early in March or April, and then with no snowpack to sustain them, they plummeted to low levels and continued to decrease through the summer.
With climate change, it could become the new pattern for Montana’s rivers.
Streamflows on five rivers are the lowest they’ve ever been: the North Fork of the Sun River, the Two Medicine River, Fisher River, Prospect Creek, and the St. Regis River.
“The poster child of terrible: the St. Regis near St. Regis did very well early in the year, but it basically all came out early in the year. It’s been way below normal, setting new records almost every day,” Berkus said.
Many of Montana’s reservoirs had to be drawn down to augment the low flows in July and August, causing some to be a little low going into the winter.
For example, Molly Myeloma of the Bureau of Reclamation said levels in Hungry Horse Reservoir were hurt by the lack of a late runoff. The reservoir received only 64 percent of the runoff it usually receives, it had to release water for demands downstream, and then it couldn’t refill to the full level.
“Everything was so dry that nothing we tried worked out,” Myeloma said.
Things don’t look to improve in October with most of the state receiving just a third of an inch so far. Some areas of southwest Montana have less than 25 percent of normal precipitation. Only Cascade County is sitting pretty with its fourth wettest October on record, Los said.
September temperatures were mostly near average in the northwest half of the state, but in the southeast, temperatures were 2 to 8 degrees above average.
That hasn’t changed as we’ve moved into what is supposed to be the cooler month of October, as both high and low temperatures remain well above normal. In the south central and southeast regions, nighttime lows have been 4 to 6 degrees above average and in the west, high temperatures have been 6 to 10 degrees above average.
Larson said none of Montana’s SNOTEL sites have any snow as of Oct. 14. That’s not unheard of – the Hoodoo Basin site has had no snow in 32 out of the past 50 years. But most sites usually have snow, such as Beartooth Pass, which has had snow at this time of year in 29 of 36 years.
The lack of precipitation means soils are drying out and will need more water to recover.
The NRCS measures moisture levels at 8 and 20 inches below the surface and the 8-inch depth tends to dry out first.
At a site east of Lincoln, the soils have only 15 percent moisture.
While most of Montana’s SNOTEL sites are high enough in the mountains that they get some moisture, the Blacktail site is low on the west slope of Flathead Lake and provides an indication of what is happening to valley soils. The soils there have no moisture at 8 inches and only 3 percent moisture 20 inches down.
All of this has kept wildfires burning in Montana well past when they should have been extinguished by a big moisture event, said Harold Gemmel of the Montana Department of Natural Resources and Conservation. Plus, with the dry conditions, people are accidentally starting new fires, such as the 8,600-acre Cottonwood Gulch Fire northwest of Bozeman.
Meanwhile, large fires in the national forests, such as the Sheep Fire on the Rocky Mountain Front, continue to burn.
“We’ve had a benign season compared to our federal counterparts,” Gemmel said. “But fuel moistures are below normal so we might expect next year to be like this year.”
Loss said that might be so because the El Nino weather pattern is looking to be strong compared to the years since 1982. That means across the state, temperatures will be higher than normal and precipitation will be lower than normal.
“I want to demonstrate how strong this is getting to be, compare to our previous events. If you compare now to 1997’s event and 1992’s event, we’re getting very close to that. For those two events, we came in with well-below precipitation on the west side of the divide and in central Montana, and below normal in the southwest, south central and north central divisions,” Loss said.
Loss said the drought will persist in western Montana at least through January, and drought will develop over central into eastern Montana during the early winter months.