Adequate treatment of wastewater is important not only for sanitary reasons but also for environmental considerations. Recent findings from Environment Canada indicate that one of the largest point source of phosphorus to marine and fresh waters in Canada is municipal sewage.14 Inadequate wastewater treatment, especially in rural and remote areas, is one of the factors contributing to high phosphate concentration which has been linked to the growth of blue-green algae. Overflows from combined sanitary and storm sewers in many cities may also contribute to phosphate loadings in lakes and rivers.
The average age of wastewater treatment facilities increased slightly from 17.4 years in 2001 to 17.8 in 2007. Most of the recent ageing in this asset has been led by Quebec, where the average age went from 16.9 in 2001 to 19.1 years in 2007, second oldest in the country after Prince Edward Island. British Columbia also contributed to the ageing process at the national level as the average age of its wastewater treatment facilities rose from 14.6 in 2001 to 17.2 years in 2007. The average dropped in all other provinces.
The average age of Canada's wastewater treatment facilities has been increasing steadily since the late 1970s. The average useful life for this asset is estimated at 28.2 years. In 2007, these facilities passed 63% of their useful life nationally, the highest ratio among the five public infrastructure assets. Provincial figures were all above the 60% mark with Prince Edward Island ranking at the top.
Unlike other infrastructure assets, the value of Canada's wastewater treatment stock has diminished in recent years, declining 1.1% a year on average from 2001 to 2007, when it was worth $24.0 billion. The decline spread across all provinces except Nova Scotia and Alberta.
The declines in wastewater treatment stocks were due to large investments made in the early 1980s which became older than their average useful life and were therefore subtracted from gross stocks. Recent investments were not large enough to compensate for these declines. It should be noted that a drop in the stock doesn't imply a decline in the volume of wastewater treatment. Recent investments might have been sufficient to maintain capacity or capacity utilisation might have increased.
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14. See "Canadian Environmental Sustainability Indicators", Environnement Canada, Health Canada and Statistics Canada, 2007, Statistics Canada Catalogue No. 16-251-XIE, http://www.statcan.ca/bsolc/english/bsolc?catno=16-251-XIE (accessed December 12, 2007).