Latest CBB News | Archives | About Us | Free Newsletter




Latest CBB News
2017 Runoff: Central Idaho’s Deadwood Summit gets 147 Inches Snow; Sees Five Times Above Normal
Posted on Friday, April 07, 2017 (PST)

Big pieces are in place for a robust water year in the Columbia Basin states, with above-to-well above average snowpacks that are beginning to ripen for runoff in the coming months.


Most notable have been snow accumulations in the central Idaho mountains that feed the Salmon and Upper Snake River basins.


“This year’s mountain snowpack just keeps getting better,” the Natural Resources Conservation Service states in an early March report for Idaho. February storms brought abundant precipitation in the state resulting in record or near-record snow water contents in central Idaho, and significantly, much of the most recent snow has accumulated at mid and high-revelation automated snow measuring (SNOTEL) sites.


“As of the beginning of March, 24 SNOTEL sites in Idaho and western Wyoming have snow depths over 100 inches,” the NRCS reports. “Deadwood Summit, elevation 6,890 feet in central Idaho is the highest with 147 inches of snow depth.”


At several sites, including Deadwood Summit, precipitation was nearly five times normal February amounts, the NRCS reported, adding that many low-elevation sites have lost their snowpack already, causing flooding problems. But the bulk of the snowpack remains.


“As a result, gates are open on many reservoirs to make room for when the mid-and high-elevation snow melts,” the NRCS report states.


The current water supply conditions have been taking shape for months. “Abundant October precipitation likely saturated soils across most of the state,” the Idaho NRCS stated. “Some soils are still frozen due to colder-than-normal temperatures, which may reduce soil moisture infiltration rates.


“It is interesting to note that after last month’s melt of valley snow, a fast response in streams followed a rain event,” the report continues. “This likely means soils are still saturated or frozen.”


And this may translate to an increased, prolonged runoff. Idaho’s water supply conditions at several mid-to high elevations appear to be as high or higher than they have been for early March in 2011, 1998, 1997, 1984 and 1983.


The Northwest River Forecast Center held its monthly briefing on Thursday, April 6, again highlighting the heavy snow conditions in Idaho and pointing out that the water supply forecast for all other parts of the Columbia Basin appears to be above normal, with similar cold and wet weather being the norm in recent months.


Forecaster Kevin Berghoff noted that the upper elevation snowpack appears to be much heavier than it was last year. Last year, however, an unseasonably warm April rapidly diminished what was considered to be a healthy snowpack.


Berghoff said snow at lower elevations has been melting across the basin, and it has caused a “substantial flooding issue through much of Idaho.”


The Idaho Statesman has been reporting on flooding at locations along the Boise River, mostly "parks, fields, roads and other riverside open areas.” Emergency response personnel have been taking actions to counter current high water and they are preparing for worse flooding later this spring when Idaho’s mountain snowpack melts out.


The Statesman reports that managers don’t believe there is enough space in reservoirs upstream from Boise to manage the runoff; the river’s reservoir system was already 67 percent full this week.


Water supply conditions are looking good, despite the first snow melting at lower elevations at sites on the Cascade Mountains, and at lower elevation sites in northern Washington, Idaho and Montana.


“Some of these snowpacks are getting increasingly ripe,” Berghoff said, signaling the annual runoff is getting underway.


The outlook is for a robust streamflow from April through September, mainly due to cold and wet weather that has persisted throughout March.


For that five-month period, the water supply forecast is 107 percent of average at Mica Dam on the Columbia River in British Columbia; 117 percent at Libby Dam on the Kootenai River; 117 percent on the South Fork Flathead River, Hungry Horse Dam; 114 percent on the Spokane River; 114 percent on the Columbia River, Grand Coulee Dam; 141 percent on the Snake River at Jackson Lake; 168 percent on the Snake River, Palisades Dam; 202 percent on the Snake River, American Falls Dam; 140 percent on the Snake River, Lower Granite Dam.


The April through September water supply at seven Washington sites on the Cascades are at 102 percent to 116 percent of average; and at 12 Oregon sites on the Cascades, the five-month streamflow forecast ranges from 94 to 134 percent of average.

Bookmark and Share


The Columbia Basin Bulletin, Bend, Oregon. For information or comments call 541-312-8860.
Bend Oregon Website Design by Bend Oregon Website Design by Smart SolutionsProduced by Intermountain Communications  |  Site Map