Friday, February 23, 2024

Big spill ongoing

| June 14, 2006 12:00 AM

By ROGER MORRIS Western News Publisher

The potential for severe thunderstorms in the upper Kootenai drainage has the U.S. Army Corps of Engineers considering another increase in the amount of spill from Libby Dam.

As of Monday afternoon, the Corps was releasing 38,000 cubic-feet per second with 14,000 cfs coming over the spillway to the chagrin of property owners along the river and Kootenai River fishing guides.

With the reservoir within two feet of full pool Monday morning, the Corps was carefully watching flows into the reservoir from the Kootenai River out of Canada. There was a 14-hour period where the level of Koocanusa had not risen, said Libby Dam project manager Mick Shea.

Inflows had dropped to about 32,000 cfs, well below the 38,000 being released at the dam and well below the 54,900 cfs coming into the reservoir on Friday from a combination of rain upstream and warmer weather.

The Corps was planning on starting a small spill, 1,500 to 1,700 cfs, late last week to make room in the reservoir thus avoiding the need for a bigger spill which could negatively impact the river's fishery, cause local property damage to people living along the river and possibly flood areas near Bonners Ferry.

However, a large rainstorm on the west side of the Kootenai drainage in Canada forced the dam managers to begin releasing 8,000 cfs at 5 p.m. on Thursday. As inflows from Canada continued to increase Friday morning, the spill was increased to 14,000 cfs.

The latest weather forecast, for up to three inches of precipitation in Canada by the National Weather Service, is bumping the runoff forecast inflow to 59,000 to 60,000 cfs by Friday, Shea said. That could cause the Corps to begin spilling more than 16,000 cfs and raising overall releases from the dam to more than 40,000 cfs.

"We're thinking about it but we haven't made that decision," said Cindy Henriksen at the Corps' Reservoir Control Center in Portland.

Henriksen said she has been talking to weather forecasters through the drainage in Canada, including BC Hydro, and they're not sure the weather event will produce that much precipitation.

Bonners Ferry remains a big concern this week if a rain event pushed

the Yaak and Moyie rivers to higher flows thus boosting the Kootenai. The weather forecast and the river modeling show the river could be two feet above flood stage at the Idaho city by late Wednesday or early Friday.

"We're watching local streams for the remainder of the week," she said.

Henriksen noted that the runoff situation, forecast at 98 percent of normal in April, worsened in late May with unseasonably hot weather melting snow. It boosted the inflows to the reservoir from 30,000 to 77,000 cfs in four days. Libby Dam was already releasing at powerhouse capacity, in excess of 24,000 cfs through the turbines.

"That weather was three times outside the standard deviation for a peak," Henriksen said.

That hot weather has been followed by continuously wet weather.