Every week during the ‘control’ season when the weir spill gates and boat locks and is in use (closed or partly closed), Catalyst Paper Mill’s Environment Manager provides an update by email to anyone interested. Excerpt below re-posted with permission. The full update can be viewed at https://www.catalystpaper.com/page/cowichan-water-management-information
From: Houle, Brian (Crofton)
Sent: Thursday, April 29, 2020 11:44 AM
Subject: Weekly update of Cowichan
This morning the lake has arrived at 99% full and I expect with predicted rainfall that the weir could be overfull by end of the week.
Catalyst is authorized to operate the control or flood gates to control river flow only if the lake is at most 10 cm above full lake level. If lake level rises to above full supply and continues to rise toward 10 cm above full supply, the gates would be opened to keep lake level from rising further.
On Friday, May 1, the plan is to begin to ramp the river flow down from 25 cms to the seasonal 15 cms. The spring flow guidance of 15 cms begins on May 1 and continues through to June 15 and is needed for fish/fish habitat values. For example, by end of day Friday the flow from Cowichan Lake is targeted to be 2 cms less than it was in the morning – expect a flow of 23 cms by end of day.
The ramping will continue daily and expect the river flow will stabilize at 15 cms on Tuesday May 5 depending on rainfall.
Flows will remain higher if rainfall arrives given there is no where to store any more water in Cowichan Lake. Snow pack continues to melt and with more snow pack than last year, higher flows will be sustainable this year.
Brian Houle, Manager, Environment, Catalyst Crofton