Koocanusa reservoir should be within five to seven feet of full this summer, according to the U.S. Army Corps of Engineers.
The Corps operates Libby Dam, the energy generating facility that controls the flow from the reservoir into the Kootenay River downstream of Koocanusa.
This week the Corps joined BC Hydro for a series of public meetings, one in Baynes Lake and three in the U.S., to discuss predictions for summer operations of the dam.
Both BC Hydro and the Corps were a little reluctant to offer predictions for the season this year, since the past two years have been anything but predictable in the region.
In 2012, above average snow pack and a June full of rainstorms saw widespread flooding in the Columbia Basin.
BC Hydro and the Corps reached a rare agreement that allowed Koocanusa to go a foot above its full level to prevent further flooding downstream in Idaho and Kootenay Lake. Koocanusa saw record amounts of water flow into it in the month of June 2012.
Then, last year, after the Corps had predicted a sedate rise of Koocanusa through spring, the region was hit by a massive rain storm at the end of June.
The storm, which flooded parts of the East Kootenay and southwest Alberta, again saw record amounts of inflow to Koocanusa.
“June 2012 was the record precipitation month for the whole month. And then in three days (in June 2013) we got 70 per cent of that precipitation volume,” said Joel Fenolio, Upper Columbia Senior Water Manager, U.S. Army Corps of Engineers.
In one day, Libby Dam saw the highest inflow peak it has experienced since it was built in 1972.
Before the storm hit, the dam was seeing 30,000 cubic feet a second come in. Over the course of three days, that tripled to 90,000 cubic feet a second.
In a normal spring, the peak inflows are between 50,000 and 60,000 cubic feet a second.
“That was completely unexpected,” said Fenolio. “Luckily there wasn’t a lot of snowpack and that storm last year hit above the dam. Bonners Ferry was five feet from flood stage.”
Downstream, Kootenay Lake didn’t experience flood concerns, either.
This year, both BC Hydro and the Army Corps are hoping for a more predictable season.
“We are hoping for 2011 again, where we had above average snowpack conditions, not unprecedented precipitation, it just kind of dribbles off. That would be the best scenario at this point,” said Fenolio.
Snowpack in the region that feeds into Koocanusa is at about 120 per cent of average.
“For the fourth year now, we are seeing above average snowpack conditions. So we are watching that carefully,” he said.
The Corps has just finished a week where the maximum amount of water was let go through Libby Dam, an attempt to encourage endangered Kootenay white sturgeon to move upstream from Bonners Ferry to spawn.
The largest freshwater fish in North America, white sturgeon can grow to 12 feet in length and weigh up to 1,000 pounds in their 100-year life span.
The fish, which don’t begin reproducing until about age 30, have been in decline since the 1950s.
Biologists are trying to entice the fish to spawn upstream of Bonners Ferry, where the river bed is covered with gravel, instead of downstream of Bonners Ferry where the sandy, silty river bed suffocates the eggs.
So far, experiments have failed to see the sturgeon spawn further upstream. But last year the U.S. Fish and Wildlife Service saw some results, thanks to the maximum outflow tests that are being repeated this year.
“We did see a higher proportion of tagged spawning sturgeon migrate upstream of Bonners Ferry, but it doesn’t look like they stayed there very long or that they spawned up there, which is what we want them to do,” said Jason Flory, a fish and wildlife biologist. “But it was enough of a difference to justify doing it again, to see if we could do something maybe a little bit different to give them that final push upstream.
“We just finished the first peak to coincide with the local low-elevation snow melt. Then once the higher elevation snow melt starts to come off, we will start the second peak. We will hold the peak powerhouse flows for about seven days and then it will start to taper off, depending on flood control operations.”
Fenolio said that, given the above average snowpack, once the second peak outflow period ends in June, the Corps may continue to let the maximum amount out of Libby Dam.
“We are probably going to make a decision on whether we are going to continue releasing powerhouse just to control how fast Libby refills.”
The Corps is predicting that, bar another June like the last two, Koocanusa will be within five to seven feet of full pool around the middle of July.
Koocanusa is considered full at 2,459 feet. The Corps would like to see the reservoir no higher than 2,454 this summer.
“We have heard from marina owners that when we fill it right to the top, they lose all their beach space so they prefer us to be in the top 10 feet,” said Fenolio.
Predicted operations are to keep the reservoir at that level until the end of August, when the Corps will begin letting water out of Libby Dam, aiming to be down to 2,449 by the end of September.
Meanwhile, BC Hydro will again spend more than usual on debris removal in Koocanusa this year.
“Typically we spend in the range of $75-90,000. This year we are going to be spending $140,000. That is going to facilitate some additional work that results from all of the debris from the last two years when we had those high water levels. It just takes time to clean it up,” said Diane Tammen, East Kootenay community relations manager.
“We got some really good feedback last year. I got lots of calls from people saying how pleased they were with the debris removal.”
Contractor Purcell Services, which has been performing debris removal on Koocanusa for the past 22 years, has already begun that work this spring.