Your PUD News Release

Share

River Basin Snow Water Content

Click image for larger verson.


Home

Final Lake Chelan runoff forecast is 120 percent of average

Chelan County PUD
News Release
4/9/2012

The April 1, 2012, runoff forecast for the Lake Chelan drainage basin is 120 percent of average for April 1 through July 31.

The forecast for 120 percent of average runoff would result in an estimated 630,120 second-feet-day (SFD), or 1,249,528 acre-feet, of water to run off between April 1 and July 31. Last year’s actual runoff from April 1 through July 31 was 659,313 SFD, which was 126 percent of average.

Snowpack accumulation is 121 percent of average at the sites listed below and 105 percent of last year at this time. Snowpack densities are all 35 percent, while average at this time of year is 38 percent. Accumulated precipitation in Stehekin from November through March was 31.2 inches, which is 122 percent of average and 94 percent of last year’s accumulation at this time. Moisture content in the soil is near average.     

The Northwest River Forecast Center’s Ensemble Streamflow Prediction Forecast issued April 4 for January through July is 108 percent of average at Grand Coulee Dam and 108 percent of average below Rock Island Dam, while the April through September forecast is 118 percent of average for the Wenatchee River and 110 percent of average for the Okanogan River.

For the Northwest, one notable weather forecasting agency is predicting cool and dry conditions mid-spring, warm and dry conditions late spring and average conditions in the summer.

The elevation of Lake Chelan on April 1, 2012, was 1083.5 feet above sea level, which is 1.9 feet lower than the expected average under the current operating license and 1 foot lower than last year.

Generation will be managed this winter and spring with the intent of meeting operating objectives in the Lake Chelan Hydro Operating License as well as minimum lake elevation targets.

At right is a color-coded diagram of the Western United States and the Columbia River Basin in Canada, which shows mountain snowpack in percent of average snow water equivalent. Note near or above average snowpack for the majority of Washington basins and extremely dry conditions in the southwestern United States.

Snotel Site

Elev

Snow Depth

Water
Content

Adjusted
to Apr. 1

% of last yr
Apr. 1

% of Avg

Lyman Lake

5,900'

188"

65.2"

65.9"

101%

114%

Park Creek Ridge

4,600'

147"

51.8"

52.5"

117%

124%

Rainy Pass

4,780'

136"

48.1"

48.3"

97%

117%

         

Total Average

 121%