Drought Strains Lake Coeur d' Alene Water Level

Aug 3, 2015

Slowly - too slowly for the naked eye to discern - Lake Coeur d'Alene is shrinking, dropping below the normal summertime lake-full level. And that puts Avista Utilities in a bind.

A trail through Coeur d'Alene
Credit https://www.flickr.com/photos/gregraisman/sets/72157601851711041

 The Spokane power company is finding it impossible to maintain the lake water level when the primary rivers feeding it are so parched and puny. At the same time, Avista is obligated under its federal dam renewal license to discharge a minimum amount of water from the Post Falls dam - 500 cubic feet a second.

To do that, we have to sacrifice the lake level, said Steve Esch, a senior operating engineer.

Esch said it became clear earlier in the year that a crunch was coming between water coming into the lake and water going out, so Avista took control of the flow in late spring. Some of the discharge was required to keep water flowing over fish spawning beds in the Spokane River.

He said a complicating factor is evaporation from the lake surface, caused by heat, wind and very low humidity.

As of Monday morning, the lake level was more than 5 inches below the lake full mark and expected to drop slowly over the next few days. The discharge rate from the Post Falls dam is the least it can be under Avista's license.

To Esch and his power company colleagues, "good weather" right now means rain - lots of it. But there's none in sight and there may not be until fall.