Rebuilding the Weir
A Cowichan River Resiliency Project
Hulitun tst tu qa’ (Water is Life).
Planning for a new weir at Cowichan Lake is underway to help keep the Cowichan River flowing well throughout the dry seasons. By storing water in the spring and releasing it through the summer, it helps maintain river levels during the driest months. A higher weir is needed for everyone and everything the river sustains.
May 2026 – Why are low flows still a problem?
The closure of the Domtar (Crofton) mill has led some to hope that river conditions will improve on their own. However, mill water withdrawals happen near Duncan in the lower river—meaning that roughly 80% of the river is unaffected by those withdrawals (which also supply water to Crofton residents). Recent fish kills, including the one in 2023, took place in the upper river, where mill operations have no effect.
The real drivers of low water conditions are:
- Climate change, which is disrupting how water is stored. Snowpack once acted as a natural reservoir; as it declines, that storage is disappearing.
- Hotter, drier summers that increase evaporation and demand.
- Physical changes in the river itself, including fewer deep pools, more gravel buildup, and less large woody debris.
- Reduced industrial water use will help the lower river, but it cannot solve the watershed‑wide effects of climate change.
Why we still need the weir – Project Updates:
Without the existing weir, the river would be in far worse shape. The weir captures spring water that would otherwise flow downstream too early. If it weren’t there, summer flows would drop much lower—and in some dry years, modelling shows they could approach zero.
The current weir cannot store enough water to meet ecological flow targets as summers become increasingly dry. Raising the weir is widely seen as the single most effective way to protect the river for the future.
Adding 70 cm to the weir will:
- Increase the amount of water stored in Cowichan Lake
- Help maintain steadier summer flows
- Lower stress on fish populations
Work now focuses on:
- Determining long‑term ownership and operation of the weir
- Securing the remaining funding for construction, plus ongoing maintenance and operations
- Completing environmental and technical planning
- Improving coordination among partners during drought conditions
There is also a growing need to ensure the weir can operate reliably no matter what changes occur in industrial activity.
