Burrard Inlet Environmental Indicators Report - the BIEAP and ...

Burrard Inlet Environmental Indicators Report February 2008
6. Water and Sediment Quality
Why look at water and sediment quality?
Water and sediment quality reflect the state of the aquatic
environment and the effects of activities on land, water and
air. Good quality water is linked to the health of all living
organisms, including humans.
Contaminants such as metals, nutrients, pesticides,
hydrocarbons and chlorinated organic compounds enter
Burrard Inlet from many sources, including combined
sewer overflows, wastewater treatment plant discharges
and non-point sources such as stormwater runoff and
Intertidal area, north shore of Burrard Inlet
atmospheric deposition.
These contaminants can be dissolved, attach to particles that float on the water surface and/or
settle in sediment on the ocean floor. Contaminants that settle on the sediment can either become
covered over time by further sedimentation, resuspended in the water column, or move into the
food chain as they are consumed by bottom feeders.
Current status: Levels of copper and polychlorinated biphenyls (PCBs) in sediment have declined
since 1985, although levels remain above provincial sediment quality objectives to protect marine
life (100 mg/kg copper, 0.03 mg/kg PCBs) in areas such as the Inner Harbour and False Creek.
Copper levels in water are above guidelines (0.003 mg/L) in 20% of samples collected over the
past 20 years, but there are no clear trends over time or space.
Copper in the environment
Copper occurs naturally in water,
and is also introduced through
many human activities. The most
common sources of copper for
Burrard Inlet are wastewater
treatment plant effluents, combined
sewer overflows, stormwater runoff
and industrial discharges.
Copper is an essential element for
many plants and animals, but in
high concentrations it is toxic for
humans and aquatic organisms,
including crustaceans, cyprinids,
salmonids, worms and algae.
Young fish are particularly sensitive,
as elevated copper levels can
interfere with ion transport (affecting
gill activity) and can reduce the
ability of coho salmon smolts to
adapt to seawater.
Water and sediment quality as an indicator
There has been considerable monitoring of metals and
organic compounds in water and sediment of Burrard Inlet
over the past 35 years by Metro Vancouver, Environment
Canada and the BC Ministry of Environment (Goyette and
Boyd 1989; Boyd et al. 1998; Paine 2004; McPherson et
al. 2005, 2005a, 2006; Ministry of Environment 2007).
Results are compared to provincial guidelines for
protection of marine life. BIEAP selected copper and
PCBs as indicators of water and sediment quality
because they have been identified as persistent concerns
over the years. Levels of some other contaminants also
exceed guidelines occasionally. Other assessment
approaches, such as the Canadian Water Quality Index,
may be considered in the future.
Historic monitoring programs have differed in terms of
sampling locations, frequency and parameters measured,
making it a challenge to develop an accurate monitoring
baseline. However, Metro Vancouver has developed an
ambient monitoring program to consistently monitor
sediment and water quality at seven locations across the
Inlet (Nautilus 2006). Data for this BIEAP indicator have been summarized to be consistent with the
Metro Vancouver sampling design, to help address these historic differences. Provincial objectives
for Burrard Inlet (Nijman and Swain 1990) were used. The sediment objective for PCB is being
reviewed and may be lowered to provide greater protection for organisms at higher trophic levels.
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