Streamflow dropped at Merwin Dam to save water for fall

ARIEL, Wash. — State and federal officials have agreed to allow PacifiCorp to reduce streamflows in the North Fork of the Lewis River at Merwin Dam this spring in order to preserve water for the important fall chinook spawning period.

The federal license calls for a minimum flow of 2,700 cubic feet per second at Merwin Dam through June 30.

However, the Lewis River Flow Coordination Committee and Washington Department of Ecology agreed last week to reduce the flow at Merwin to 2,300 cubic feet per second.

The committee includes NOAA Fisheries, the U.S. Fish and Wildlife Service and Washington Department of Fish and Wildlife among others.

According to Briana Weatherly, environmental compliance manager for PacifiCorp, the lower Columbia River basin is at 19 percent of average snow-water-equivalent currently, with a dry, hot summer forecast.

PacifiCorp has about 18 feet of vacant storage in Merwin, Yale and Swift reservoirs.

“Reducing flows will allow us to refill the reservoirs in an effort to preserve water for increased flows in the fall during the more biologically sensitive spawning period,” Weatherly said, in an email.

The North Fork of the Lewis River is home of the largest population of wild-spawning fall chinook salmon in the lower Columbia basin.