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Letter: Regarding weir replacement at Cowichan Lake


In response to your article on raising the weir at the above location the whole issue of water supplies is more complex than just dealing with the weir.

Water supply in the CVRD feeds water to many areas through the public water supply/water mains. In those areas served by water supply infrastructure homeowners get the benefit of lower insurance rates to a perceived lowering of the fire risk where properties are protected.

New developments in certain areas not served by the existing water infrastructure have to either provide private water supplies or can offset fire risk by providing automatic sprinklers in each building. Depending on the available fire service response it may or may not justify the provision of fire hydrants.

While all distribution piping is fed from Lake Cowichan, some areas have to compensate by providing their own infrastructure. Due to shortage of water and/or infrastructure in some areas- particularly where development is occurring on the boundaries of the municipality such as in Union Bay- more reliance is being placed on tank storage. For instance, we are using 5000- gallon tanks in lieu of mains-fed hydrants where infrastructure does not exist or where there are significant challenges connecting to the existing water supply system. This is an alternative approach to qualify homeowners for insurance rate reductions.

Pressures on the system are increasing due to climate change, long and dryer summers as well as other factors. However, there is a surfeit of water in the winter. While increasing the capacity of water in Lake Cowichan will mitigate the potential problem of continuity of the supply in summer, this is a short-term solution. The extended dry periods in the summer suggest that secondary storage may be required in the long term. This would mean pumping excess water in the winter into an adjoining valley. Mosaic are well -equipped to assess this option.

This supply would then be brought on stream to maintain the water levels constant rather reliance on a higher weir to improve storage capacity. The pumping capacity and valve controls required to bring a second supply on stream would be relatively conventional and all fully automatic. This would also reduce dependence of the Crofton Mill on the Lake Cowichan Lake level.

John Ivison