Lake Roosevelt is being held at a level about 47 feet below the full mark while maintnenace is completed on the drum gates that hold the water back when the lake is full.
The Bureau of Reclamation, which operates Grand Coulee Dam, reports the lake will likely remain below 1,255 feet above sea level until May 10.
The water forecast for the Columbia River drainage above Grand Coulee Dam, from April to August this year, is estimated to 82.5 percent of normal, so the maximum level allowed for flood control right now would actually be 1,283.3 feet, less than 7 feet below spilling over.
But such flood control elevations are the maximum elevations allowed to ensure enough room in the lake for the spring runoff. Actual elevations may be lower “based on power demand, unforeseen power emergencies, changes in weather events, maintenance on the dam, etc,” the bureau explains on its website.