Sea life 'degraded' at sewage outfall
Jan 25 2012
The shrimp, mollusk and sea worm population near the Macaulay Point sewage outfall station has been "highly degraded," although the precise cause isn't known, according to a report to be given to the region's environment committee today.
Macaulay Point is one of the sites where screened liquid waste is dispersed into the ocean. A similar situation was not found at the other key site, Clover Point.
The findings are part of an annual report by the Capital Regional District to monitor and assess the impact of sewage discharge on the ocean and on public health.
The region has long discharged its sewage into the ocean via the outfalls, where sewage that is left after going through six-millimetre screens is carried via a pipe. At Macaulay Point, the sewage is put into the ocean 1.7 kilometres from shore through 28 diffusers at the end of the pipe. That allows the liquid waste to be discharged through all of the "ports" so it is spread more efficiently through the water, the report says. At Clover Point, the pipe extends 1.1 kilometres into the ocean and the sewage is dispersed through 37 ports.
Supporters of the system say the region has a unique marine environment that allows sewage to diffuse without causing problems.
But others say it is a black eye for the region and has drawn worldwide attention for damaging the environment.
The province has mandated the CRD to have a secondary sewage treatment system in place by 2016. The date is likely to be pushed into the future because the region is still waiting for the provincial and federal governments to confirm their parts of three-way funding for the $782-million project.
Although tidal currents take away most of the wastewater, about one per cent settles on the ocean floor. It is this material that could be causing a problem for sea life near Macaulay Point.
The benthic invertebrate communities - animals that live in the sediment - have significantly declined in health since 2008, the report says. The most significant outfall effects are within about 200 metres east of the end of the Macaulay Point pipe. However, the report noted that "more detailed assessments indicate that truly negative effects have become more pronounced since 2008."
The degradation has expanded to areas 400 metres east and southeast of the outfall, near spots that previously showed neutral effects. They are now experiencing slightly negative effects, the report says.
"At this point in time, it is not possible to confirm the cause of the observed declined in the benthic community health," the report says. "Macaulay Point wastewater and sediment quality have both been improving or have remained relatively constant over the same time period and one would, therefore, expect improvements in benthic community health over the same time period."
CRD staff are consulting experts to determine whether the decline is a result of an unmeasured outfall impact, or whether it indicates a broader environmental shift, such as climate change in the Strait of Georgia and Juan de Fuca Strait.
The environment committee is due to discuss the report today.