Your PUD News Release

Lake Chelan runoff forecast stays at 82 percent of average

Chelan County PUD
News Release
3/3/2011

The March 1 forecast for 82 percent of average runoff would result in an estimated 430,582 second-feet-day (sfd) or 853,844 acre-feet (af) of water. Last year’s actual runoff from April 1 through July 31 was 531,049 SFD, which was 101 percent of average.

Snow water equivalent at the above listed sites ranged from 73 percent to 93 percent of average. Snowpack densities at the above listed sites range from 32 percent to 33 percent, while average density at this time of year is 36 percent.

The Northwest River Forecast Center’s Feb. 24 early bird runoff forecast for January through July is 104 percent of average at Grand Coulee Dam and 101 percent of average at The Dalles, while the early bird forecast for April through September is 84 percent of average for the Wenatchee River and 89 percent of average for the Okanogan River.

The March 1 NW Fish Letter reported that “The equatorial Pacific is once again beginning to warm up after La Nina conditions peaked in January. Most climate models are forecasting a return to normal conditions by next winter—but it (La Nina) could come back again”. Colder temperatures and above-average precipitation are expected to prevail this spring, bringing more snow across the interior Northwest, and mostly rain west of the Cascades.

The elevation of Lake Chelan on March 1, 2011, was 1086.4 feet, which is 0.7 feet higher than the expected average under the current operating license and 3.9 feet lower than last year. This year the elevation of Lake Chelan is slightly higher than the expected average because of significant inflow into Lake Chelan during mid-January 2011.

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 on March 1, 2011. Note that snowpack in North Central Washington basins range mostly from 50 percent to 99 percent of average.