What’s a Weir?
In the 1950’s, a 97 cm high weir was built at Cowichan Lake to store enough water so that Cowichan River flows could be sustained throughout the dry season. It is a cement structure, spanning the lake at the head of the river, and includes a boat lock and several ‘spill gates’. The weir is owned and operated by Catalyst Paper under license from the BC Government.
This weir has served an important function economically and ecologically. Unlike a dam, the Cowichan Lake weir controls seasonal water level fluctuations but does not exceed natural “high water” levels, so that the natural shorelines and riparian habitats are intact. Learn more here.
What’s the Problem?
This weir is no longer adequate to meet the demands of our longer drier summers due to climate change . In five of the last six summers, the river has fallen below ecologically acceptable flows and this trend is predicted to worsen. Scientists recently concluded that:
”The Cowichan River is one of the most productive rivers on the eastern side of Vancouver Island and without action it will look radically different by the 2050s. Salmon stocks that utilize the river to spawn and rear during the summer and early fall period will be decimated. Chinook, Coho and Steelhead are particularly vulnerable.” Source: Cowichan Water Use Plan (2018) www.cowichanwup.ca.
Cowichan Valley Regional District published Climate Projections for the Cowichan Valley Regional District in 2017. The report provides detailed projections of wetter winters, hotter, drier summers, and an increase in extreme weather events for the 2050s and 2080s. See the Cowichan Lake water level chart (at right) for water levels at the weir over the past decade.
How does this Impact our Community?
These low river flows affect our collective well-being. They threaten the five species of salmon, four species of trout and vibrant ecosystems that comprise the Cowichan watershed; they impact Indigenous cultures that are interconnected with healthy watersheds; they threaten 600 union jobs at the Crofton mill; they could cause water quality issues tied to sewage dilution or impact drinking water supplies for some. River-based recreation and tourism are major contributors to the local economy and the quality of life of citizens. Many wildlife species are also negatively affected by drought and low river flows. Read more.
Unlike many coastal watersheds, there is an option for our community to be resilient in the face of climate change, and keep our river flowing for generations. An extensive community planning process in 2017-2018 resulted in a broad-based consensus to replace the weir with a higher structure to address the water supply challenges.
The Cowichan Water Use Plan process was initiated by a partnership of the Cowichan Valley Regional District, Cowichan Tribes, the Cowichan Watershed Board and Catalyst Paper. It involved a 19 member Public Advisory Group (PAG) including representatives from local, provincial and federal governments, First Nations, industry, local community and interest groups and area residents.
The group discussed and evaluated potential water supply and storage options for the Cowichan Lake and River system. After careful consideration of the tradeoffs between ensuring adequate flows for fish and other aquatic species, avoiding any increase to flood risk for lakeshore residents, and minimizing impacts on water user on the lake and river, the group agreed that replacing the current weir with a higher structure was needed. Read the full recommendations of the PAG here.
There is a high level of support for this solution. See Community Response and Community Partners to learn about the many stewardship organizations, political leaders, and government departments working towards this goal.
Are there Other Options?
All proposed options were explored during the Water Use Plan. Many were deemed too expensive or likely to cause worse impacts. In particular, the option of doing nothing was thoroughly explored and rejected.
This summer we expect the lake’s water storage will hit ‘zero’ for the second time since the weir was built, and Catalyst will begin pumping water out of the lake to maintain flows in the river. While this is a preferred situation to seeing the Cowichan River run completely dry, it is not a long term solution. There are limits to how low the lake can be drawn down safely due to potential impacts to nearshore habitats, riparian vegetation, water intakes, beaches, docks, & more. Due to these limits, the river would still run dry some years.
This summer, the partners that initiated the Water Use Plan (see above) hope to begin the next phase of the solution. This would include:
- engineering work to locate and design the new structure
- development of operational protocols and
- the survey work necessary to accurately quantify the upstream impacts of increased storage as recommended by the Cowichan Water Use Plan and required to accompany a conservation water license application.
Thanks for taking the time to learn about this situation. The science is clear that the status quo is not sustainable. We hope you will join the growing number of people saying, “Weir Ready” to keep our river flowing for future generations. Read more: We Can Fix This