Contractors will painstakingly search for fish in the lower Cascade River, stun them with an electric shock, scoop them into nets and carefully carry them in aerated buckets to the nearby Bow River.
This electrofishing effort is part of a plan to save fish before TransAlta halts the river flow during a major overhaul of one its generating units at the Cascade hydro plant.
As water flows subside in the lower reaches of the Banff National Park river, any stranded fish will also be rescued from shallow water, dry ground or isolated holding areas.
Parks Canada officials say they are working closely with the power giant to make sure fish aren’t killed and critical habitat is eventually restored as a result of the work.
“Every time they have to shut down the water, the concern is obviously for fish and for fish populations living in the Cascade,” said Charlie Pacas, aquatics specialist for Banff National Park.
“To address or mitigate that, there’s a fish salvage that will occur, where teams of electro-fishers will catch fish and put them into the Bow River.”
With approximately $3 billion in annual revenue and more than $9 billion in assets, TransAlta has power plants in Canada, the United States and Australia.
The Cascade hydropower plant, which is part of the Bow River electric system, is located on the Cascade River northeast of the Banff townsite. It is the only power development in a Canadian national park.
The work at the Cascade plant is a part of scheduled maintenance, and will result in significantly reduced water releases during the three-month project, which gets underway this summer.
For safety reasons, the project also involves completely shutting off the flows for two to three days at both the start and end of the project when the headgate is closed.
TransAlta officials say lower flows have the potential to affect holding areas used by juveniles and adult fish, or result in stranding fish in shallow, dry areas.
To minimize this, they said, the company will slowly ramp down flows at the facility to allow fish to move from shallow areas into deeper water in the lower Cascade.
“We continue to demonstrate we take situations like this very seriously,” said Bob Klager, a spokesman for TransAlta.
“We’ve hired an external consultant to salvage the fish and we’re working in conjunction with Parks and DFO (now Fisheries and Oceans Canada) on habitat mitigation projects following the maintenance work.”
During the main portion of the project, flows in the lower Cascade will range from 0.17 to 21.3 cubic metres per second, compared to the unusual 0.34 to 42.5 cubic metres per second.
When the headgate is closed, the flow will halt, although a tiny trickle will still go to a nearby stream wetland via a portable pump and piping.
Teams of electrofishers will scour the 4.2-kilometre stretch of the lower Cascade River between the station and confluence with the Bow River at the start of each low flow period.
Electrofishing equipment passes an electric current through the water, stunning fish and causing them to rise to the surface of the water where they are netted.
When performed correctly, electrofishing reportedly results in no permanent harm to fish, which return to their natural state in as little as two minutes after being stunned.
All fish will be transported in aerated buckets or coolers to the Bow River at the Cascade River confluence, which is about 8 km downstream of Bow Falls, and followup surveys will be done.
In 2009, TransAlta did complete a habitat restoration project in the Cascade below the power station, using floating tree cover, to offset fish habitat loss that may have occurred from maintenance on the dam.
Pacas said Parks Canada wanted to make sure there was functional habitat for fish in the lower stretches of the river. Fish include brown trout, brook trout and mountain whitefish.
“We evaluated that (project) about a month ago to get a sense of how well it worked, and it didn’t work as well as we had hoped and so that is being reevaluated as part of this new work,” he said.
“We hope to enhance perhaps half a dozen or so areas below the Trans-Canada Highway to create better holding areas and better habitat for fish.”
TransAlta bought the Cascade plant from the federal government in 1941. The following year, the company built a new dam and power plant to replace the original and added a second generating unit in 1957.
When the plant was built, Lake Minnewanka was created as a storage reservoir. Water now flows from Minnewanka into Two Jack Lake, then along a canal to the plant. From there, it flows another 4.2 km into the Bow.
While hydropower is considered one of the cheapest ways to generate electricity, it doesn’t come without its share of environmental damage.
The damming of rivers permanently alters river systems and wildlife habitat, and the effects on river life can be devastating. Fish, for one, are no longer able to swim upstream.
Habitats become separated, fish cannot reach spawning grounds, animals which feed on fish downstream find their food source reduced and so on.
Parks Canada officials say the Cascade River is no exception, given it has been regulated for decades.
“It’s a system that I would consider has a lot of struggles,” said Pacas. “There’s a lack of good habitat.”
The negative effects of using water for power generation on river systems have also been seen recently as a result of malfunctions at TransAlta’s Spray hydroelectric plant near Canmore.
A generator was down for scheduled maintenance when a second unit failed May 23, resulting in major concerns for fish survival and destruction of critical fish habitat in the Spray, Bow and Goat Creek.
To repair the generators, TransAlta was forced to shut off the flow of water and let it build up at Spray Lakes Reservoir, in part controlled by the Canyon Dam, upstream of the hydroelectric plant.
The company initially diverted water into Goat Creek, but, making matters worse, water breached the spillway at Canyon Dam into the Spray River around mid-July.
The diversions of huge water volumes into the two rivers, which meander through provincial and federal lands, combined with a big spring runoff, stirred up great amounts of silt and mud.
Parks Canada and TransAlta crews went into the Spray Friday (Aug. 19) to get a better idea of the flows and affects on habitat, particularly for struggling westslope cutthroat trout.
However, the water is still spilling over the top of the spillway next to Canyon Dam, located just outside Banff National Park, and any restoration work to create new fish habitat in the Spray is on hold until the flows subside.
Water levels peaked at the end of July, flows are continuing to decline and turbidity is vastly improving. At Canyon Dam, there is about 8.5 feet of water above the concrete sill, but the level is dropping.
Klager said TransAlta hopes one of the units at the Spray facility will be operational by early September, but they are working around the clock to get both generators back up and running.
He said the company also continues to work closely with all government regulators, as well as a third-party environmental consultant.
“As part of a pilot project, Parks Canada and TransAlta are collaborating to create new fish habitat along a 20-km stretch of the Spray in Banff National Park,” said Klager.
“TransAlta will fund the initial phase of remediation of the Spray River. I don’t know those exact figures because we’re still assessing costs.”
Meanwhile, TransAlta officials recently met with fishing guides in Canmore who are concerned for their businesses, as well as the future of the Bow River environment.
They guide on the Bow outside the national park, and at almost $500 a trip, they say they have lost significant business this season as a result of TransAlta’s problems.
The guides are not talking to the media at this point, but Klager said the meeting in Canmore was constructive and the issue of compensation was discussed.
“We committed to them to take away and evaluate internally what compensation might look like if we chose to go that way,” said Klager. “We continue to communicate with them as we evaluate internally.”
Bill Hunt, resource conservation manager for Banff National Park, said TransAlta has been good to work with on the Spray River issue, as well as their plans for maintenance at the Cascade plant.
“They are very open to our suggestions and very supportive of mitigations, which makes it a lot easier to be successful,” said Hunt.
“They’ve done everything they can to be very good partners, to be good corporate citizens.”
