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Avista Reduces Water Flow Through Post Falls Dam Due To Drought

Doug Nadvornick/SPR

The drought conditions in the Inland Northwest are changing the way Avista manages the Spokane River system this summer.

The utility has announced that, due to lower-than-normal water levels in Lake Coeur d’Alene, it plans to release less water through its Post Falls Dam.“We’ve been able to have Lake Spokane, behind Long Lake Dam, and Lake Coeur d’Alene at normal levels and they’re still at normal levels. But Coeur d’Alene Lake is coming down slowly," said Patrick Maher, Avista's principal hydro operations engineer.

That means there’s less water to send down the river channel toward Spokane.

“Right now we’re estimating we have 700-to-750 cubic feet per second that had entered the lake, but it just disappears into the air because it evaporates. The warmer the water is in the lake, the more you get evaporation, you get it. If it continues to be hot, hot, hot, then you lose more water to evaporation," he said.

Avista has been releasing 600 cubic feet per second. Maher says that will be lowered to 500, which is the minimum allowed in the dam’s license, so that there can be at least a bit of water going over Spokane Falls, even during the dry summer months. Maher says that means the lake level will drop a little faster than usual in August, but he doubts many people who use the lake for recreation will notice much difference.