Dam spills from Libby causing problems

Vast amounts of water are being released over the spillways at Libby Dam, to the detriment of property owners and fish downstream as far as Boundary County, Idaho.

The spill operation started Thursday because of the rapidly rising level of Lake Koocanusa above the dam. With inflows exceeding the dam's powerhouse capacity, the lake has risen to 1.5 feet of full pool.

Weather over the next few days will determine if spill volumes will increase.

"It's very much an evolving situation," said Mick Shea, Libby Dam project superintendent for the U.S. Army Corps of Engineers. Forecasters with the Corps, Bonneville Power Administration and the National Weather Service were assessing the potential for thunderstorms in the Kootenai River Basin above Lake Koocanusa, a reservoir that stretches 67 miles from the dam north into British Columbia.

The Yaak River, which is downstream from Libby, is projected to reach flood stage by late Thursday or early Friday. In the Kootenai basin above Libby Dam, storm activity could force an increase in spills from the dam.

As of Monday afternoon, flows into Lake Koocanusa had dropped from a weekend high of 55,000 to about 45,000 cubic feet per second. The dam was releasing a maximum 24,000 cfs through its turbines and an additional 14,000 cfs over the spillways.

If the lake reaches full pool, the Corps would have to spill all inflows over 28,000 cfs.

Flood potential at Bonners Ferry, Idaho, is compounded by flows from the Yaak River and other tributaries below the dam.

In Idaho, there already are reports of crop damage due to water seeping through riverbank levees. The high water prompted Idaho Gov. Jim Risch to declare a state of emergency, with as much as $2.5 million in crop damage over the last two weeks, The Associated Press reported.

So far, there is considerably less potential for flood damage in the Libby and Troy areas.

Lincoln County Commissioner Rita Windom said current flows on the Kootenai are troublesome to a half dozen residents. One, for example, is pumping water from her back yard to avoid damage in her daylight basement, Windom said.

"My concern is that the weather patterns that we're seeing, we could still have another large rain event in Canada, and if that happens, they will have to pass that water through the dam and we will have very high flows on the Kootenai," she said.

If Kootenai River flows increased to the range of 45,000 to 50,000 cfs, the threat to property in the flood plain also would increase substantially, she said.

"We are prepared," Windom said. "We have a lot of sandbags and the Corps has a lot of sandbags and we are all primed to go."

Fisheries below the dam already are being damaged, Windom said.

Releasing water over the dam's spillways for prolonged periods can produce dissolved gases that cause trauma to fish, including bubbles in the eyes or lateral lines. Fish can survive, but it's unknown if "gas bubble trauma" causes lasting effects to vision or reproductive systems.

Brian Marotz, fisheries projects leader for Montana Fish, Wildlife and Parks, said state officials will monitor for adverse effects on the river this week, using instruments that measure dissolved gases and patrolling the river for evidence of fish mortality.

The duration of the spill will play a big part in any harm to fish, Marotz said.

The situation has yet to match an emergency spill that occurred over 20 days in May and June 2002. That spill resulted in obvious gas bubble trauma, along with fish physically damaged by spillway turbulence.

"I'm fairly confident of what's going to happen - fish are going to be impacted," state fisheries biologist Jim Dunnigan said.

What's harmful for bull and cutthroat trout, however, may help Kootenai River white sturgeon.

A recently released U.S. Fish and Wildlife Service biological opinion calls for intentionally spilling from Libby Dam to improve flows and spawning conditions for sturgeon just upstream from Bonners Ferry.

The Corps, however, deferred action on a planned spill largely because the state of Montana has threatened to sue because spilling water at Libby Dam violates state water-quality standards.

Reporter Jim Mann may be reached at 758-4407 or by e-mail at jmann@dailyinterlake.com