Recent rainfall prompts Post Falls spill of water   

Tags: Avista Utilities, Electricity, Hydro power, Idaho, Lake Coeur d'Alene, Spokane River, Washington

Use caution as water levels continue to change

Post Falls Dam, North Channel
The North Channel of the Post Falls Dam.
Because of the recent heavy rainfall in the North Idaho mountains, Avista has been actively opening spill gates at our Post Falls Dam. Over the past several days, river flows and lake levels have risen steadily. The St. Joe and Coeur d’Alene rivers, which feed Coeur d’Alene Lake, have been rising for almost a week and continue to do so. Coeur d’Alene Lake reached summer elevation of 2,128 Wednesday, June 6 and continues to rise as flows into the lake exceed the amount that can flow out of the lake into the Spokane River.

Once Avista begins controlling the level of Lake Coeur d'Alene each spring, we are required to open the spill gates at Post Falls to prevent the lake from going above its summer elevation.

There is still above-average snowpack in the high mountains for this time of year, and the National Weather Service is predicting higher than normal precipitation and cooler temperatures for the month of June.

How does it all work?
You may wonder why river levels drop above Post Falls Dam when Avista opens the spill gates. In the summer, when all the spill gates are closed, the river is filled with water and acts more like a lake. Levels  are held at a level very close to that of Coeur d’Alene Lake. But when we open the spill gates (some of which open all the way down to the river bed), the river flows naturally and the elevation of the water drops to river level. This is naturally much lower than it is when the gates are closed and the water is stacked up behind the dam - in fact, when all the gates are open, the elevation of the river above the dam is eight vertical feet lower than the summer level when the gates are closed.

We want to remind you to always exercise caution on the water, as river and lake levels can change at any time depending on weather and other factors. The water is still cold, which puts those who are recreating in a lake or river at risk for hypothermia.

Call Avista’s 24-hour telephone information line for information regarding anticipated elevation changes on Coeur d’ Alene Lake, Lake Spokane, and the Spokane River.

In Idaho, call (208) 769-1357; in Washington, call (509) 495-8043.
 
Posted by  System Account  on  6/6/2012
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