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Low-water conditions raise fish concerns on Chemainus River

The Chemainus River is the latest Cowichan Valley stream to generate concerns about drought-related impacts on fish stocks.

Chief James Thomas of the Halalt First Nations told that early drought conditions on the river raise fears for juvenile salmon, trout and steelhead.

He added that low water flows also pose a “major concern" for returning adult chinook salmon.

Conditions are “putting climate change at the forefront” in terms of water scarcity, snow packs, and water storage in watersheds, said Thomas, calling for development of a sustainable watershed plan for the Chemainus.

Others say that clearcut logging in the Chemainus watershed has exacerbated the drought problem, as well as flood risks in winter.


“The moisture-holding capacity that we used to have in these forests isn’t there anymore,” said Erik Piikkila, a consulting forest and watershed ecologist based in Ladysmith. “That natural water sponge has disappeared.”

Piikkila, who also sits on the steering committee of the Coastal Douglas-fir Conservation Partnership, said that logging over the decades has altered landscapes, including fish streams, throughout the Cowichan Valley.

“Clearcutting doesn’t help any of this,” he said.

Domenico Iannidinardo, chief forester for Mosaic Forest Management, said “watershed science is very complex,” with numerous factors impacting hydrology.

He pointed to a Hatfield Consultants report on the Koksilah River (Xwulqw'selu Sto’lo) watershed for Cowichan Tribes in 2021 that determined climate change and “increased use of both groundwater and surface water” in the lower river were important factors in low summer flows.

The influence of forestry varied depending on the level of clearcutting and stage of regrowth.

"In the future, as trees in the watershed are in active growth, it is possible that moderate age trees (40-50 years old) become dominant in the watershed,” the report read. "Moderate aged trees use more water than mature trees (100 years old or more) and more water than very young trees (10-20 years old). If moderate trees become dominant, this could reduce water availability in the watershed and decrease the flows in the river.”

The report confirmed that forestry "has also been linked to other concerns such as greater winter runoff, channel aggradation (which is excess sediment deposition in the stream and can result in what was surface water instead flowing through gravels leading to less surface water depth), sediment erosion and turbidity in the river.”

Read the full report:

Meanwhile, the Crofton pulp and paper mill, which controls the dam on Cowichan Lake, announced in a news release Wednesday that rains earlier this week had little impact on the lake level and that pumping from the lake to the river may be necessary if dry conditions persist.

“Catalyst Paper has begun to make preparations for the pumps as preparations can take a long time…” said environment manager Brian Houle.

River flows are being held at 4.5 cubic metres per second “until fall rains return and support higher flows,” he said.

The forecast is for continued dry weather in our area.

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— Larry Pynn, July 27, 2023

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