Avista to open Post Falls dam gates

The waterfall below Post Falls Dam should be spectacular this afternoon, when Avista Corp. spills more water over the dam. Heavy rainfall in the mountains over the past 24 hours has caused Lake Coeur d’Alene to rise. Avista will open one of the dam’s large spillway gates this afternoon to let more water through. The Spokane River is already running at 15,500 cubic feet per second below the dam. “That’s very high for this time of year,” said Hugh Imhof, Avista spokesman. Flows below the dam will increase after the spillway gate is opened, but they won’t hit flood stage, Imhof said. Avista is waiting to open the biggest gate until this afternoon to allow Spokane River users to move their boats and equipment to a safe location in the river. Once the bigger spillway gate is opened, river levels above the dam will drop. Lake Coeur d’Alene is slightly above its normal summer level of 2,128 feet above sea level, which Avista is required to maintain until after Labor Day. Increasing the flows over Post Falls Dam will return the lake to summer levels, Imhof said. To the north of Spokane, the Pend Oreille River behind Box Canyon Dam was about a foot below the level where authorities take action and post no wake rules, an emergency services worker in Pend Oreille County said. The river was at 2,040 feet, she said.