'Water year' off to slow start
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January 4, 2014 |
The bad news is that the Pacific Northwest and
its Columbia River basin have only received
about 50 percent of average precipitation over
the first three months of the “water year” –
October 1 through December 30.
The good news is that there is a big chunk of
the winter of 2013-14 to come, during which
precipitation could soak the soil and fortify
mountain snowpacks.
According a report created December 31 by NOAA
National Weather Service’s Northwest River
Forecast Center, precipitation upstream of the
lower Columbia’s The Dalles Dam from October 1
through December 30 was 50 percent of the
1971-2000 average. The Dalles, located at
Columbia River mile 191.5 along the
Oregon-Washington border, passes water from the
Snake River basin and the upper Columbia.
Early season precipitation totals, as a percent
of average, were lowest in the Snake River
basin. The precipitation totals since October 1
were 43 percent of the 30-year average as
measured upstream of the lower Snake’s Ice
Harbor Dam. Ice Harbor, in southeast Washington,
channels flows from the upper Snake in Idaho,
Wyoming and Utah as well as lower river
tributaries such as the Malheur-Owyhee-Boise
river basins, the Clearwater and Salmon from
central Idaho and the Grande Ronde River basin,
which is nested in northeast Oregon.
Ice Harbor is the last of four lower Snake River
mainstem dams before the river joins the
Columbia in southeast Washington.
The upper Columbia River basin, in British
Columbia, northern Idaho and northwestern
Montana has been blessed with more plentiful
precipitation, though the totals are still well
below average.
The Columbia River basin upstream of southern
British Columbia’s Arrow Dam has received 71
percent of its average precipitation so far this
water year. Tributaries include the Clark Fork
(42 percent of average from Oct. 1-Dec. 30),
Flathead (64 percent), Pend Oreille in Canada
above Waneta Dam (53 percent), Kootenai (68
percent) and Spokane River basin (65 percent).
Precipitation so far in the water year in the
Columbia River basin upstream of central
Washington’s Grand Coulee Dam has been 62
percent of average. Grand Coulee passes water
from the above-mentioned upper Columbia region.
Precipitation has been scarce in western Oregon
and Washington with October-December totals
ranging from 21 percent of average
(Rogue-Illinois basins in Oregon) to 58 percent
in northwest Washington’s Snohomish River basin.
The Willamette River basin upstream of Portland
has received 42 percent of its average
precipitation.
Temperatures in the Columbia River basin over
the past few months have generally been below
normal, according to data posted online by the
NWRFC.
Snowpacks, though in the early building stages,
are at or above average for this time of year in
some of those northern Columbia areas. The
Kootenai River basin’s Montana geography has 96
percent of its average snowpack for December 31,
according to Natural Resource Conservation
Service’s Columbia River Basin SNOTEL
snow/precipitation update report. The Kootenai
originates in Canada and flows south into
Montana, westerly into the Idaho Panhandle and
then north before joining the Columbia in
British Columbia.
Montana’s Flathead River basin had 115 percent
of its average snowpack snow-water equivalent
through December 31 and the upper Clark Fork
basin had 109 percent.
West-central Idaho’s Clearwater River basin had
snowpack at 84 percent of average through
December 31. The Clearwater feeds into the lower
Snake River. |
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