Libby Dam operations update
by Joel Fenolio, P.E., Upper Columbia Senior Water Manager
June 21, 2013
A rare, extreme rainfall pattern developed over the Kootenai and upper Columbia basins during the last two days. Twenty four hour rainfall totals were impressive; from one to six inches. Greater amounts (~10") were seen near the Continental Divide. The circulation of air and uncommon track of an upper level low with moisture mainly from the east, combined with moisture from the Pacific, to produce this heavy rainfall event. The rainfall is winding down today (Friday, June 21, 2013), with drier weather forecast Saturday.
The precipitation totals in the Basin above Libby Dam were 4 to 6 inches on June 20th. For relational value; in June of 2012 the basin above Libby Dam had 6 inches for the entire month, which was extremely high for a monthly total in June. Today we expect to see a peak inflow of 90 kcfs or higher; base flow conditions earlier this week were 30 kcfs of inflow to Koocanusa Reservoir. Yesterday we increased releases from 16 kcfs to powerhouse capacity of 25 kcfs, once we saw the precipitation in Idaho and Montana drop off, to control the refill rate of Koocanusa Reservoir. We will start to spill 3 kcfs this evening and plan to do so through the weekend to save space for any potential rainstorms through the first part of July.
The Northwest River Forecast Center creates daily forecasts for short term projections throughout the Kootenai and Columbia River Basins. These forecasts can be updated multiple times in a day and can be updated at anytime as conditions change. Links to those projections can be found below:
Short term forecasts for Libby Dam elevations and inflows: http://www.nwrfc.noaa.gov/river/station/flowplot/flowplot.cgi?lid=LYDM8
Short term forecasts for Libby Dam releases: http://www.nwrfc.noaa.gov/river/station/flowplot/flowplot.cgi?lid=KBDM8
Short term forecasts for Bonners Ferry: http://www.nwrfc.noaa.gov/river/station/flowplot/flowplot.cgi?lid=BFEI1
Please note the National Weather Service's disclaimer on forecasts beyond 3 days.
All forecasts and model projections are based on the best information at the current time, as the weather changes so will the short- and long-term predictions.
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