Marine Monitoring of the Victoria Sewerage System

The Capital Regional District of British Columbia, Canada, is implementing for the Greater Victoria area, a major sewerage plan based mainly on marine discharge by submerged outfalls. To assess effects on the receiving ecosystem, a thirty month monitoring program has been carried out at the site of a newly constructed 6000 foot marine outfall. Of the standard water quality parameters, several were established during the pre-discharge period as "gross sewage field indicators" at beach outfalls: nitrite, phosphate, total and fecal coliform bacteria, Secchi depths, Forel colour and salinity. The remaining parameters were not sensitive to the presence of effluent: temperature, dissolved oxygen, nitrate, silicate and chlorophyll. In the water surrounding the diffuser of the extended outfall, only total coliform values showed the presence of effluent once discharge was diverted from the beach outfall. Profiling techniques were employed for measuring chlorophyll, turbidity and Rhodamine dye. A method was developed for mapping coliform bacteria in the sediment surrounding the diffuser, as an index of the ability of the receiving water to assimilate effluent loads being discharged into it. It is stressed that monitoring programs should be included in plans for any major coastal operation.