JULY 8, 2010

Dworshak Reservoir drawdown starts

   Water levels began to be lowered Tuesday at Dworshak Reservoir on the North Fork of the Clearwater River. Each summer the cooler water of Dworshak is released downstream in what’s known as a drawdown, to cool the Snake River – protecting juvenile chinook and steelhead which are listed as threatened on the Endangered Species Act.

   The federal government – Army Corps of Engineers (ACE) operates a biological opinion plan which adjusts for warmer temperatures (caused by the dams on the Snake and Columbia Rivers) which are harmful to these fish.

   ACE began releasing water Tuesday through Wednesday at the rate of 7,000 to 7,500 cfs. Inflows were expected to drop to as low as 3,000 cfs on Tuesday.

   The elevation change in the water pool thus far, should not result in more than a few feet of elevation during the first week of the water drawdown.

   Typically, reservations for camping spots along the reservoir, drop off significantly once the pool drops about 20 feet below “full pool,” as it becomes difficult for campers to access mini-campsites from their boat tie-ups. The reservoir is often lowered as much as 80 feet between July 5 and mid-September.

   According to Dworshak Reservoir Association, “The affect on the reservoir level will depend on the rain. How fast [the reservoir drops] depends on the weather and river water temperatures.” The website goes on to say, “Outflow decisions are made based on the current water temps at three key locations, Clearwater River temp in Lewiston, Snake River at Anatone, and the Snake at the face of Granite dam.”