Operations for the year at the Cowichan Lake weir are set to begin on April 2, and the hope is that pumps won’t have to be used during the expected upcoming dry season in 2024.
Brian Houle, the environment manager at the Catalyst Crofton mill which owns and operates the weir, said spring maintenance services on the weir equipment will also begin on April 2, and the weir’s boat-lock gates will be put down at end of that day.
He said after two days with the boat-lock gates in use, closing the weir’s control flood gates will begin, and for 2024, a new ramp-down rate of as much as five cms/day will be used to quickly lower the river flow down to the ideal seasonal flow of 25 cms.
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“Wet weather is predicted for the coming three to four days (up to April 1) and then the next seven days shows steady wet weather again, and that should help us keep the lake close to 100 per cent full.
“The snow pack (in the mountains) made significant growth in recent weeks, but is still well below the average snow pack for the region…and this will negatively impact summer conditions.”
Houle said that with the water flow over the weir controlled at 25 cms, discussions among stakeholders about lower flows is planned for early to mid-April.
He said weir operations this year may be revised to respond to the fish kill in the Cowichan River last summer, which was due to low water flows and high temperatures, and it is possible the ideal flows of 25 cms in April and 15 cms in May to June 15 will be revised to lower flow targets in order to secure enough water for seven cms through July and August.
“It is hoped that for 2024, the river flow will be sustained at seven cms through the hottest summer days of July and August to sustain a base water flow in the river, which would avoid the use of pumps,” Houle said.
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Houle said he was pleased with the recent announcement that the province will be investing $14 million into the construction of a new and higher weir that will allow the lake to hold more water in storage, and the visit by Premier David Eby to Lake Cowichan on March 23 to celebrate the funding.
“Thanks go out to all the people involved over the previous decades, when work has been ongoing to get to this very place; a commitment for a new higher weir,” he said.
“(Last summer) included five weeks of pumping from lake to river, and 2023 would not have needed one day of pumping and river flow would have been seven cms all summer if the new dam were in place last spring. The new higher weir can and will be very helpful in sustaining higher river flows through future dry seasons, and this benefit was illustrated just last year. And a huge appreciation to the federal government who, a few years ago, also stepped up by committing funding for the new higher weir.”