Proceedings - Teaching and Learning Centre - Simon Fraser ...

Fraser River Action Plan 3rd Research Workshop
Water Quality Conditions in an Urban Watershed
K. Hall
Civil Engineering and Westwater Research Centre
University of British Columbia
The Brunette River watershed is one of the most highly urbanized watersheds in the Lower Fraser Valley. The
major transportation corridor in the valley passes through the watershed and with the exponential population
growth, land use changes have resulted in more impervious surface areas that prevent the adsorption of
contaminants by soil and vegetation. This results in the transport of contaminants to the waterways in stormwater
runoff.
Dry weather monitoring shows high levels of fecal coliforms in several creeks, especially Still Creek where
domestic wastewaters are entering the upper reaches. This severely restricts the recreational use of many of these
areas. Low dissolved oxygen levels in lower Still Creek and the Brunette River, just below the dam at the outlet
of Burnaby Lake, can cause fish mortality or restrict fish movement in these reaches in summer.
Stormwater runoff contains high levels of many contaminants such as trace metals, nutrients and suspended
solids. Contaminant transport is closely coupled to the intensity of the rainfall event and the transport of
suspended solids since many of the contaminants are readily adsorbed to this particulate material. The quality of
the runoff from streets is related to the level of vehicular traffic in the area. Monitoring of contaminants over the
period of a year along with flow measurements will allow the calculation of contaminant loading from
stormwater runoff. A source control program integrated with best management practices will be necessary to
regulate this source of non-point pollution and prevent further degradation of this urban watershed.
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