While recent rains have seen water restrictions lowered in many parts of the Cowichan Valley, there hasn’t been enough to raise water levels in Cowichan Lake.
Brian Houle, the environment manager at Catalyst Crofton, which operates the weir on Cowichan Lake, said on Oct. 10 that with the lake level continuing downward, the rainfall that is forecast to begin in earnest in the region this weekend and continue for several days would be very welcome.
“A weather system beginning this coming Saturday and lasting four to five days shows 100 mm of rainfall at [the] east side of the lake and 120 mm on [the] west side of the lake,” Houle said.
“If this weather system brings the rainfall that it is predicted to bring, the lake level should begin to refill in the coming seven days.”
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Due to the severe drought that struck the region last summer that lowered water levels in the Cowichan River dramatically, Catalyst began using 20 pumps on Sept. 15 to pump water over the weir in Lake Cowichan to sustain water levels in the river with a base flow of 4.5 cubic metres per second, and the pumps are still in place.
The Cowichan Basin has experienced 14 droughts since 1998.
A winter with below average snowpack followed by a drought beginning in mid May are the root cause of this year’s conditions.
Houle said concerns were raised last week about fish pooling on the river side of the weir.
He said that with the pumps being used to sustain base flow in the river, the four control gates are fully closed and in this condition, and with lake levels very low, there is a flow of water moving in the reverse direction through the fish ladder at the south end of the weir/gate system.
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“An inspection on (Oct. 6) during morning hours, including representatives from Fisheries and Oceans Canada, did not identify any fish pooling close to the weir or gate structure,” Houle said.
“It’s likely that the fish are not stressed and that they are OK in this section of the river, waiting for rainfall to open up their passage into the lake. Extra monitoring was guided by DFO representatives to observe the condition of fish pooling on the river side of [the] weir.”
Houle said with all 20 pumps currently operating at the weir, there is no opportunity to open up the gates at the weir to allow the pooling fish passage into the lake.
He said that with the DFO fish count indicating that there are just about 10,000 large Chinook now registered in the Cowichan River, sustaining the base flow of water is critical to these salmon.
