Your PUD News Release

March 1 runoff forecast is 100 percent of average

Chelan County PUD
News Release
3/7/2012

The forecast for 100 percent of average runoff would result in an estimated 525,100 second-feet-day (sfd), or 1,041,273 acre-feet (af), 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 densities at the sites listed below range from 31-36 percent, while average at this time of year is 36 percent. Accumulated precipitation in Stehekin from October through February was 28.5 inches, which is 104 percent of average and 85 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 (ESP) Forecast issued March 3, 2012, for January through July is 95 percent of average at Grand Coulee Dam and 94 percent of average below Rock Island Dam, while the January through September forecast is 96 percent of average for the Wenatchee River and 95 percent of average for the Okanogan River.

One notable weather forecasting agency is predicting cold and wet conditions through early spring, cool and wet conditions through mid-spring, then cool and drier conditions during late spring.

The elevation of Lake Chelan on March 1, 2012, was 1084.9 feet above sea level, which is 0.8 feet lower than the expected average under the current operating license and 1.5 feet 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 average snowpack for the majority of North Central Washington basins and extremely dry conditions in California and Nevada.