There were a few drier-than-average areas in February, but precipitation fell where it counts most to assure, or nearly so, that the Columbia/Snake river basin will be provided a normal water supply during the coming spring and summer.
The Northwest River Forecast Center's March 7 monthly "final" water supply forecast says that the mostly likely result will be runoff at 101 percent of normal (99.1 million acre feet) during the April-September period as measured at The Dalles Dam on the lower Columbia. The NWRFC's July forecast last year showed runoff at 86 percent of normal, 85.2 maf.
The new forecast is up from the Feb. 7 final, which pegged the anticipated water volume at 97.3 maf, which would be 99 percent of the 30-year average. All of the runoff from the Snake River and upper Columbia channel past The Dalles.
The Columbia basin water supply has only been above average once, in 2006, over the past eight years.
"Being in the business of dividing up scarcity is not a happy time," Idaho Gov. Butch Otter said of a state that has been wracked with drought over the past 10 years. Otter on Tuesday addressed the Northwest Power and Conservation Council during its meeting in Boise.
"We have other things that we have to think about with our water besides producing power -- protecting the fish runs, also protecting the other species which obviously enjoy the use water. This is a good year for us," Otter said. "It looks like right now, statewide we're at about 127 percent of normal, which means we should be able to fill all of our reservoirs. We were hoping for 106 percent to fill all of our reservoirs, which has been decimated and drained, they pulled the plug, the bath tub's empty."
Those Idaho reservoirs feed municipalities and thousands of acres of cropland. The federal reservoirs are also tapped, if enough water is available in summer, to augment flows for salmon and steelhead far downriver in the lower Snake and Columbia rivers. That water is purchased from willing water rights holders.
Snowfall in the Columbia basin's upper reaches in British Columbia and northwestern Montana, "areas that generate a lot of the flow" was near or above average during February, according to Stephen King of the NWRFC. The mountain snowpack in those regions normally produce about 60 percent of the basin's runoff.
The Canadian snowpack increased from 103 percent of average snow-water equivalent on Feb. 1 to 110 percent on March 1, according to Jim Ruff, NPCC manager, mainstem passage and river operations. The Columbia basin snowpack in drainages above Grand Coulee Dam is now 107 percent of average, compared to 105 percent last year and 103 percent on Feb 1. The Snake Basin snowpack above Ice Harbor Dam is at 110 percent of average, compared to 82 percent last year and 112 percent last month.
"Most areas in the basin have snowpack in the 105 to 115 percent range, which is good news," Ruff told the Council Wednesday.
The highest March 1 snow-water equivalent values are in Cascade Mountain snowpacks, ranging from 150 percent of average in northwest Washington to 180 percent in Oregon. The lowest are just east of Cascades in Similkameen drainage in British Columbia (84percent), the Kettle basin (86 percent), the Hoback drainage the Snake's headwaters in Wyoming, the upper Clark Fork (90 percent), and the Okanogan basin in eastern Washington (93 percent), Ruff said.
And "runoff in general was low" in February aside from the lowest elevations, King said. Lower yet was the runoff, and air temperature, in January. The colder than normal start of the New Year followed a heavy snow accumulation in December.
"What has fallen in the mountains hasn't hit the streams yet," King said. It will be called on to answer the many spring-summer demands – power generation, irrigation, municipal water supplies, flow augmentation for salmon, steelhead and other species.
With much of the winter past, the odds of the actual outcome straying too far from the forecast are reduced. A very dry finale could drop the runoff to 82.3 MAF, which would be the ninth lowest total in a 48-year record. An extremely wet end to winter and spring could boost the total as high as 117.5 maf, which would be the 13th highest, according to NWRFS records.
The forecast judged as the most probable outcome would rank as the 28th wettest. It is based on an assumption of average precipitation.
NOAA's Climate Prediction Center forecasts a 40 percent chance of above average precipitation in the Northwest in March, and equal chances of above average, average and below average for the March-May period.
The NWRFC March final predicts runoff past central Washington's Grand Coulee Dam will total 65 maf, 102 percent of normal, during April-September. All the water from the upper Columbia flows past Grand Coulee.
The runoff forecast for the lower Snake River's Lower Granite Dam is 25.6 maf, 106 percent of average for the period.
A Snake feeder that is important to salmon recovery efforts will be fed by a deep snowpack. The runoff forecast for the North Fork of the Clearwater, which feeds into Dworshak Reservoir, is 3.14 maf, 112 percent of average, for the April-September timeframe. The reservoir's cool waters are called on in mid-summer to bring down temperatures below in the Snake River for migrating juvenile salmon and into the early fall for returning adult fish.
The March forecast by the U.S. Army Corps of Engineers, which operates Dworshak Dam, predicts the North Fork's runoff at 105 percent of normal for the April-August timeframe, which would be much improved over last year's 67 percent.
Through March 13 snowpacks in Idaho's Clearwater and Salmon river drainages were at 111 percent of average in terms of snow-water equivalent, according to the Natural Resources Conservation Service SNOTEL update report. The automated system monitors snowpacks across the basin.
In northwest Montana, the Kootenai River inflow to Libby Dam's reservoir is expected to be 6.24 maf, 100 percent of average, and the South Fork of the Flathead River's inflow to Hungry Horse reservoir is forecast at 96 percent of normal, 2.04 maf, for April-September, according to the NWRFC March final. The Corps' forecast for Libby is 102 percent of average for April-August.