By Gordon Hoekstra, Vancouver Sun, July 20, 2012
Heavy rains, higher-than-normal snowpack has increased stress on dams across the province
Melting snow and record rains have forced BC Hydro dam managers into an unprecedented balancing act this summer: spill water to keep dams at safe levels, but not so much that communities are flooded.
Kelvin Ketchum has been managing dam water levels for BC Hydro for more than two decades, but he's never seen anything like what's happened this year at reservoirs around the province.
A higher-than-normal snowpack and torrential rains in June and July have pushed BC Hydro's reservoirs in the Interior and northern B.C. to historic levels.
This is the first time since BC Hydro's largest interior dams were built in the 1960s that water has had to be spilled in the same season at all of its major dams: the W.A.C. Bennett and Peace Canyon dams in northern B.C., and the Mica, Revelstoke and Duncan dams in the southern Interior.
Spilling at the John Hart Dam on Vancouver Island has reached levels not seen in 25 years.
Ketchum said while water managers are always vigilant, the high reservoir levels this year have increased pressure more than ever.
"This is a time of lots of stress around here," said Ketchum, manager of systems optimization.
So far, the effects of the historic water levels have been kept to a minimum, but more rain is forecast in the southern Interior for today and for the weekend.
On Thursday afternoon, BC Hydro issued an advisory it has had to increase flows by 10 per cent from the Hugh Keenleyside Dam on the Arrow Lake Reservoir.
That is expected to bring the Columbia River by Sun-day to its highest level since the dams were built.
The Castlegar-Trail area, where parks are already under water and some homes are threatened, remains under the greatest risk of impact from spilled dam water. Only a small additional amount of water can be stored behind the Mica, Revelstoke and Arrow reservoirs, said Ketchum.
"We're running out of room," he said. "It's not a dam safety issue. At some point, we'll have to pass all the water. But we'd prefer to do that when that results in less impacts downstream."
BC Hydro uses computer modelling to help man-age its reservoir levels on a yearly and monthly basis, but also relies on instant data that is fed to a round-the-clock monitoring centre in Vancouver to make adjustments.
The real-time information led Hydro to ease back on spilling water from the Arrow Reservoir last Tues-day after torrential rains hit Castlegar, with 50 millimetres falling in one hour.
Castlegar Mayor Lawrence Chernoff said Thurs-day his community is bracing for the Columbia River to rise another 15 to 30 centimetres.
He said BC Hydro has been doing a great job of managing water levels, even though Millennium Park, adjacent to the Columbia River, is already under water.
"[BC Hydro] has been easing up as much as they can, but at some point they have to spill," said Chernoff.
In the tiny community of Genelle south of Castle-gar, where about 20 mobile homes are threatened by rising Columbia River levels, resident Gordon Soukoreff said he also believes Hydro is managing the reservoirs well. Worse flooding took place before the dams were built, he said.
According to the Crown corporation, the historic water levels do cost Hydro money in overtime and clearing higher-than-nor-mal amounts of debris from reservoirs, but that could be offset by full reservoirs in the fall heading into a high electricity-demand season.
Despite the need to spill water, the dam system has helped prevent worse flooding this summer. Without the Duncan Dam in the southern Interior and the Libby Dam in the United States, Kootenay Lake levels would have been two metres higher, said Hydro.
Still, Kootenay Lake has hit a nearly 40-year high, causing some flooding of marinas and properties as a remarkable amount of rain has fallen in the region.
In Castlegar, more than three times as much rain fell in June - 227.7 millimetres - as is normal, nearly doubling the previous 2005 record.
To date in July, more than twice as much rain - 108.6 mm - has fallen than is nor-mal in the entire month.
Similar rainfall has been experienced in Nelson. And another "potent" storm is moving in, which could bring 30 mm of rain today, according to Environment Canada.
Despite the heightened stress, BC Hydro's Ketchum, who has worked at the power authority for 33 years, said he is happy he didn't retire last year.
Managing historic water levels comes along only once in a career, he said. "It would have been quite disappointing to not be able to help."
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