SEDIMENT STUDIES PROVIDE KEY INFORMATION ON THE NEED TO TREAT SEWAGE DISCHARGED TO SEA BY A MAJOR CANADIAN CITY

Relatively untreated (screened) municipal wastes from the City of Vict oria, B.C and environs am discharged to the sea as effluent from two l ong outfall pipes, only one of which (Macaulay Point) discharges to a depositional zone. Sediments along transects away from the Macaulay Po int outfall were collected and the following parameters determined: co ntamination (selected chemicals of concern), toxicity (polychaete surv ival and growth, amphipod survival, and bivalve larvae abnormalities), and benthic infaunal community structure. Significant sediment contam ination was restricted to within 100-400 m of the outfall with the exc eption of high PAH contamination due to the shipwreck of a collier in 1891. Sediment toxicity was restricted to effects on growth and develo pment, also within 100-400 m of the outfall; survival was near control levels even at the outfall terminus. Benthic infaunal community struc ture indicated ''moderate pollution'' within 100 m of the outfall and showed a classic organic enrichment pattern or increasing species rich ness and lower abundance with distance from the outfall. Overall, the impact of the outfall on the sediments is minimal, highly restricted a n extent, an not of major environmental concern. A public referendum, conducted after the release of this and of other scientific studies, r esulted in the deferral of primary effluent treatment.